Poncet CM, Dupre GP, Freiche VG, et al. Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. J Small Anim Pract 2005;46:273-279.
OBJECTIVES: To determine the prevalence of gastrointestinal tract lesions in brachycephalic dogs with upper respiratory tract disease. METHODS: The gastrointestinal tract and respiratory disorders of 73 brachycephalic dogs presented with upper respiratory signs were evaluated. Clinical signs and endoscopic and histological anomalies of the upper digestive tract were analysed. RESULTS: A very high prevalence of gastrointestinal tract problems in brachycephalic dogs presented with upper respiratory problems was observed clinically, endoscopically and histologically. Endoscopic anomalies of the upper digestive tract were present even in dogs without digestive clinical signs. Furthermore, histological evaluation of the digestive tract sometimes showed inflammatory lesions not macroscopically visible at endoscopy. Statistical analysis showed a relationship between the severity of the respiratory and digestive signs. This was significant in French bulldogs, males and heavy brachycephalic dogs. CLINICAL SIGNIFICANCE: These observations show a correlation between upper respiratory and gastrointestinal tract problems in brachycephalic breeds with upper respiratory disease. Surgical treatment of respiratory disease could improve the digestive clinical signs, and/or gastro-oesophageal medical treatment could improve the outcome for surgically treated brachycephalic dogs.
Torrez CV, Hunt GB. Results of surgical correction of abnormalities associated with brachycephalic airway obstruction syndrome in dogs in Australia. J Small Anim Pract 2006;47:150-154.
OBJECTIVES: To describe clinical features of brachycephalic airway obstructive disease in dogs, the incidence of laryngeal collapse in dogs presenting for surgery and the outcome after surgery in dogs with laryngeal collapse. METHODS: Basic clinical details were reviewed retrospectively in 73 dogs. Presence of laryngeal collapse and short-term outcomes after surgery were determined for 64 dogs with complete medical records. Long-term outcomes were reviewed for 46 dogs by telephone survey between 19 and 77 months following surgery. RESULTS: Stenotic nares were present in 31 dogs (42.5 per cent), elongated soft palate in 63 (86.3 per cent) and everted laryngeal saccules in 43 (58.9 per cent). The most common breeds were the pug (19 dogs, 26 per cent), Cavalier King Charles spaniel (15 dogs, 20.5 per cent), British bulldog (14 dogs, 19.2 per cent) and Staffordshire bull terrier (4 dogs, 5.5 per cent). Laryngeal collapse was present in 34 of 64 (53 per cent) dogs. No dogs died perioperatively and only one dog was euthanased as a result of its respiratory disease three years after surgery. Telephone interviews indicated that 26 dogs (56.5 per cent) were much improved after surgery, 15 (32.6 per cent) had some improvement and 5 (10.9 per cent) showed no improvement. Signs that persisted after surgery were snoring during sleep (34 dogs, 73.9 per cent), stertor/stridor while conscious (23 dogs, 50 per cent), excessive panting (13 dogs, 28.3 per cent) and dyspnoea (10 dogs, 21.7 per cent). Long-term outcome was considered good, even in dogs with laryngeal collapse. CLINICAL SIGNIFICANCE: Laryngeal collapse is relatively common in dogs presented for surgical correction of brachycephalic airway obstructive disease. Dogs with severe laryngeal collapse often respond well to surgery. Clinical signs rarely resolve completely following surgery.
コメント：BOASを外科的に治療した転帰に関する論文。この研究において最も有病率の高い疾患は軟口蓋過長であり、喉頭虚脱の合併も多く認められた。周術期死亡はなく、約50%の症例において術後の長期予後も良好であったが、睡眠時のいびきやストライダーは残存する傾向にあった(ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）。
Riecks TW, Birchard SJ, Stephens JA. Surgical correction of brachycephalic syndrome in dogs: 62 cases (1991-2004). J Am Vet Med Assoc 2007;230:1324-1328.
OBJECTIVE: To assess results of surgical correction of brachycephalic syndrome (including stenotic nares, elongated soft palate, and everted laryngeal saccules) in dogs and determine whether dogs with hypoplastic trachea have a less favorable long-term outcome. DESIGN: Retrospective case series. ANIMALS: 62 dogs with brachycephalic syndrome. PROCEDURES: Medical records from 1991 to 2004 were reviewed for information regarding signalment, clinical signs, diagnosis, surgery, and long-term outcome. Surgical outcome was rated by owners as excellent, good, fair, or poor. Common abnormalities, treatments, and long-term outcomes among the 62 dogs were assessed. RESULTS: Predominantly affected breeds included English Bulldog, Pug, and Boston Terrier. Elongated soft palate was the most common abnormality (54/62 [87.1%] dogs); the most common combination of abnormalities was elongated soft palate, stenotic nares, and everted saccules (16/62 [25.8%] dogs). The English Bulldog was the most common breed for all abnormalities, including elongated soft palate (27/54 [50%] dogs), stenotic nares (14/36 [38.9%] dogs), everted saccules (20/36 [55.6%] dogs), hypoplastic trachea (7/13 [53.9%] dogs), and laryngeal collapse (2/5 [40%]). No dogs had everted saccules alone. Outcome did not differ between dogs under-going staphylectomy by use of laser or scissor resection. Follow-up information was obtained for 34 dogs; 16 (47.1%) had an excellent outcome, and 16 (47.1%) had a good outcome. Overall treatment success rate was 94.2%, and overall mortality rate was 3.2%. CONCLUSIONS AND CLINICAL RELEVANCE: Surgical treatment of brachycephalic syndrome in dogs appeared to be associated with a favorable long-term outcome, regardless of age, breed, specific diagnoses, or number and combinations of diagnoses.
コメント：BOASを外科的に治療した転帰に関する論文。この研究において最も有病率の高い疾患は軟口蓋過長であり、イングリッシュブルドッグは多くの種類のBOAS関連疾患を有する傾向にあった。また、軟口蓋過長に対する手術後の症状の改善率は約95%であった（ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）。
Ginn JA, Kumar MS, McKiernan BC, et al. Nasopharyngeal turbinates in brachycephalic dogs and cats. J Am Anim Hosp Assoc 2008;44:243-249.
This retrospective study reports the presence and incidence of nasal turbinates in the nasopharynx (nasopharyngeal turbinates) in a population of brachycephalic dogs and cats exhibiting signs of upper respiratory disease. Medical records were reviewed for 53 brachycephalic dogs and 10 brachycephalic cats undergoing upper airway endoscopy. Nasopharyngeal turbinates were identified in 21% of brachycephalic animals, including 21% of dogs and 20% of cats. Pugs accounted for 32% of all dogs in the study population and 82% of dogs with nasopharyngeal turbinates. The presence of nasopharyngeal turbinates may play a role in upper airway obstruction in the brachycephalic airway syndrome.
De Lorenzi D, Bertoncello D, Drigo M. Bronchial abnormalities found in a consecutive series of 40 brachycephalic dogs. J Am Vet Med Assoc 2009;235:835-840.
OBJECTIVE: To detect abnormalities of the lower respiratory tract (trachea, principal bronchi, and lobar bronchi) in brachycephalic dogs by use of endoscopy, evaluate the correlation between laryngeal collapse and bronchial abnormalities, and determine whether dogs with bronchial abnormalities have a less favorable postsurgical long-term outcome following correction of brachycephalic syndrome. DESIGN: Prospective case series study. ANIMALS: 40 client-owned brachycephalic dogs with stertorous breathing and clinical signs of respiratory distress. PROCEDURES: Brachycephalic dogs anesthetized for pharyngoscopy and laryngoscopy between January 2007 and June 2008 underwent flexible bronchoscopy for systematic evaluation of the principal and lobar bronchi. For dogs that underwent surgical correction of any component of brachycephalic syndrome, owners rated surgical outcome during a follow-up telephone survey. Correlation between laryngeal collapse and bronchial abnormalities and association between bronchial abnormalities and long-term outcome were assessed. RESULTS: Pugs (n = 20), English Bulldogs (13), and French Bulldogs (7) were affected. A fixed bronchial collapse was recognized in 35 of 40 dogs with a total of 94 bronchial stenoses. Abnormalities were irregularly distributed between hemithoraces; 15 of 94 bronchial abnormalities were detected in the right bronchial system, and 79 of 94 were detected in the left. The left cranial bronchus was the most commonly affected structure, and Pugs were the most severely affected breed. Laryngeal collapse was significantly correlated with severe bronchial collapse; no significant correlation was found between severity of bronchial abnormalities and postsurgical outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Bronchial collapse was a common finding in brachycephalic dogs, and long-term postsurgical outcome was not affected by bronchial stenosis.
Fasanella FJ, Shivley JM, Wardlaw JL, et al. Brachycephalic airway obstructive syndrome in dogs: 90 cases (1991-2008). J Am Vet Med Assoc 2010;237:1048-1051.
OBJECTIVE: To determine the prevalence of individual anatomic components of brachycephalic airway obstructive syndrome (BAOS), including everted tonsils, and analyze the frequency with which each component occurs with 1 or more other components of BAOS in brachycephalic dogs. DESIGN: Retrospective case series. ANIMALS: 90 dogs with BAOS. PROCEDURES: Medical records were reviewed for signalment, clinical signs at time of admission, historical and physical examination findings, BAOS components found on laryngoscopic examination of the pharynx and larynx, surgical procedures performed, and perioperative complications. RESULTS: English Bulldogs (55/90 [61%]), Pugs (19/90 [21%]), and Boston Terriers (8/90 [9%]) were the most common breeds with BAOS. The most common components of BAOS were elongated soft palate (85/90 [94%]), stenotic nares (69/90 [77%]), everted laryngeal saccules (59/90 [66%]), and everted tonsils (50/90 [56%]). Dogs most commonly had 3 or 4 components of BAOS, with the most common combination being stenotic nares, elongated soft palate, everted laryngeal saccules, and everted tonsils. Dogs with stenotic nares were significantly more likely to have everted laryngeal saccules (50/69 [72%]), and dogs with everted laryngeal saccules were significantly more likely to have everted tonsils (39/59 [66%]). Postoperative surgical complications occurred in 12% (10/83) of dogs that received corrective surgery. No specific BAOS component made dogs more likely to have complications. CONCLUSIONS AND CLINICAL RELEVANCE: The prevalence of components of BAOS in brachycephalic dogs of this study differed from that reported previously, especially for everted tonsils. Thorough examination of the pharynx and larynx is necessary for detection of BAOS components.
Bernaerts F, Talavera J, Leemans J, et al. Description of original endoscopic findings and respiratory functional assessment using barometric whole-body plethysmography in dogs suffering from brachycephalic airway obstruction syndrome. Vet J 2010;183:95-102.
The clinical features of brachycephalic airway obstructive disease in 11 brachycephalic dogs are described in this study. The respiratory strategy was assessed before (n=11) and after (n=6) surgery using barometric whole-body plethysmography (BWBP), with the relationship between BWBP variables and the severity of the clinical signs assessed by the use of a respiratory score based on clinical, radiographic and endoscopic findings. Partial collapse of the left main bronchus was a common finding not previously described as part of the brachycephalic airway obstructive disease syndrome. Epiglottic cysts, laryngeal granulomas and nasopharyngeal turbinates in English Bulldogs were other previously unreported findings. No significant correlation between the respiratory score and any of the BWBP variables was detected. Compared to healthy dogs, brachycephalic dogs had a significantly lower Te/Ti ratio (expiratory time over inspiratory time), peak inspiratory flow (PIF) per kg bodyweight (BW), significantly higher peak expiratory flow (PEF) per kgBW, PEF/PIF, and enhanced pause. These variations are compatible with upper airway obstructions primarily in the extrathoracic airways. Following surgery, a significant decrease in PEF/PIF was detected. The study showed that BWBP could be used to characterise the respiratory strategy in brachycephalic dogs before and after surgery.
コメント：内視鏡やプレチスモグラフィを用いてブルドッグにおけるBOASの特徴づけを試みた論文。左主気管支の虚脱が多くで認められた。また、非短頭種と比べて、短頭種ではTe/Ti ratioと吸気のピークフローが有意に低く、呼気のピークフローが有意に高くなっていた(ダクタリ動物病院東京医療センター 田畑達彦-2019.3.10）。
Senn D, Sigrist N, Forterre F, et al. Retrospective evaluation of postoperative nasotracheal tubes for oxygen supplementation in dogs following surgery for brachycephalic syndrome: 36 cases (2003-2007). J Vet Emerg Crit Care (San Antonio) 2011;21:261-267.
OBJECTIVE: To assess the utility of nasotracheal tubes in postoperative oxygen supplementation in dogs following corrective surgery for brachycephalic syndrome. DESIGN: Retrospective study 2003-2007. SETTING: University teaching hospital. ANIMALS: Thirty-six client-owned dogs that underwent corrective surgery for brachycephalic syndrome. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Medical records were reviewed for animals that underwent surgical interventions for brachycephalic syndrome including palatoplasty, ventriculectomy, and rhinoplasty. Data collected included signalment, presenting complaints, analgesic and surgical interventions, type of supplemental oxygen therapy, complications and mortality occurring during hospitalization. A nasotracheal tube (NTT) was placed in 20 dogs at the end of surgery; 16 dogs received other forms of oxygen supplementation (8) or no oxygen supplementation (8) during recovery. The total number of postoperative complications was similar in both groups (8/20 dogs with NTTs and 7/16 in those without NTTs). However, respiratory distress was observed in 5 dogs without NTTs but was not observed in any dog while an NTT was in place. One dog in each group died postoperatively. CONCLUSION: Placement of an NTT was found to be easy and may offer benefit in dogs with brachycephalic syndrome as a noninvasive means of delivering oxygen. The use of NTT may minimize severe postoperative morbidity, in particular by reducing postoperative respiratory distress.
Hoareau GL, Jourdan G, Mellema M, et al. Evaluation of arterial blood gases and arterial blood pressures in brachycephalic dogs. J Vet Intern Med 2012;26:897-904.
BACKGROUND: Brachycephalic dogs (BD) are prone to congenital upper airway obstruction (brachycephalic syndrome, BS). In humans suffering from sleep apnea, upper airway obstruction is known to cause hypertension. There is no information regarding the influence of BS in dogs on cardiorespiratory physiology.
HYPOTHESIS: BD are prone to lower P(a) O(2), higher P(a) CO (2), and hypertension compared with meso- or dolicocephalic dogs (MDD). ANIMALS: Eleven BD and 11 MDD.
METHODS: After a questionnaire was completed by the owner, a physical examination was performed. Height and thoracic circumferences were measured. Arterial blood gases, electrolyte concentrations, and packed cell volume (PCV) were measured. Systolic (SAP), mean (MAP), and diastolic (DAP) arterial blood pressure recordings were performed.
RESULTS: A total of 7 French and 4 English bulldogs met the inclusion criteria. The control group consisted in 6 Beagles, 2 mixed breed dogs, 1 Staffordshire Bull Terrier, 1 Parson Russell Terrier, and 1 Australian Cattle Dog. Statistically, BD had lower P(a) O(2), higher P(a) CO2, and higher PCV when compared with controls (86.2 +/- 15.9 versus 100.2 +/- 12.6 mmHg, P = .017; 36.3 +/- 4.6 versus 32.7 +/- 2.6 mmHg, P = .019; 48.2 +/- 3.5 versus 44.2 +/- 5.4%, P = .026, respectively). Also, they had significantly higher SAP (177.6 +/- 25.0 versus 153.5 +/- 21.7 mmHg, P = .013), MAP (123.3 +/- 17.1 versus 108.3 +/- 12.2 mmHg, P = .014), and DAP (95.3 +/- 19.2 versus 83.0 +/- 11.5 mmHg, P = .042). BD with a P(a) CO (2) >35 mmHg were significantly older than those with a P(a) CO (2) </=35 mmHg (58 +/- 16 and 30 +/- 11 months, P = .004).
CONCLUSION: Results of this study suggest that some BD are prone to lower P(a) O(2), higher P(a) CO (2), and hypertension when compared with MDD. Age may be a contributing factor.
White RN. Surgical management of laryngeal collapse associated with brachycephalic airway obstruction syndrome in dogs. J Small Anim Pract 2012;53:44-50.
OBJECTIVE: To describe the use of cricoarytenoid lateralisation combined with thyroarytenoid caudo- lateralisation (arytenoid laryngoplasty) for the management of stage II and III laryngeal collapse in dogs. METHODS: A retrospective study of a consecutive series of 12 dogs suffering from life-threatening stage II or III laryngeal collapse associated with brachycephalic airway obstruction syndrome. RESULTS: Pre-operatively, either stage II collapse (2/12) or stage III collapse (10/12) was confirmed on visual examination. In all cases, a left-sided arytenoid laryngoplasty was performed. Two dogs were euthanased postoperatively as a result of persistent life-threatening respiratory compromise. The procedure resulted in subjective enlargement of the rima glottidis and an associated improvement in respiratory function in the remaining 10 dogs. Follow-up, long-term outcome (median, 3.5 years) in these dogs indicated that all owners considered that the surgery had resulted in marked improvements in their dog’s respiratory function, tolerance to exercise, and quality of life. CLINICAL SIGNIFICANCE: Combined cricoarytenoid and thyroarytenoid caudo-lateralisation may be a useful procedure for treatment of stage II and III laryngeal collapse in the dog.
Johnson LR, Mayhew PD, Steffey MA, et al. Upper airway obstruction in Norwich Terriers: 16 cases. J Vet Intern Med 2013;27:1409-1415.
BACKGROUND: Norwich Terriers have grown increasingly popular as show animals and pets, and awareness of respiratory problems within the breed is growing. OBJECTIVE: To describe components of obstructive upper airway syndrome in a nonbrachycephalic terrier breed. ANIMALS: Sixteen Norwich Terriers; 12 with and 4 without clinical signs of respiratory disease. METHODS: Prospective case series. Physical and laryngoscopic examinations were performed by 1 investigator in all dogs. Medical and surgical interventions were summarized and results of follow-up examination or owner reports were recorded. RESULTS: The study population was comprised of 9 females (6 intact) and 7 males (5 intact). Median age was 3.0 years (range, 0.5-11 years). Of 12 dogs presented for a respiratory complaint, physical examination was normal in 4 dogs. Laryngoscopic examination was abnormal in 11/12 dogs with redundant supra-arytenoid folds, laryngeal collapse, everted laryngeal saccules, and a narrowed laryngeal opening in most. Of 4 dogs lacking clinical signs, all had normal physical examination; however, 3/4 dogs had similar appearance of the larynx to dogs with clinical signs. Response to surgical intervention was minimal to moderate in all dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Norwich Terriers suffer from an upper airway obstructive syndrome that differs from that encountered in brachycephalic breeds. Affected dogs are difficult to identify without laryngoscopic examination because of the lack of clinical signs and abnormalities in physical examination findings, despite severe airway obstruction. Care is warranted when anesthetizing Norwich Terriers because of the small size of the laryngeal opening.
Caccamo R, Buracco P, La Rosa G, et al. Glottic and skull indices in canine brachycephalic airway obstructive syndrome. BMC Vet Res 2014;10:12.
BACKGROUND: Forty dogs presented for brachycephalic airway obstructive syndrome with laryngeal collapse not over 1st degree (saccule eversion) underwent glottis endoscopic and radiographic skull measurements before surgery. Fifteen Pugs, fifteen French and ten English Bulldogs were included. The goals were prospectively to compare three common brachycephalic breeds for anatomical differences regarding glottis and skull measurements, and to assess if any correlation between glottis and skull measurements was present. Linear measurements were used to obtain glottis and skull indices. Correlations between glottis and skull indices and glottic measurements were evaluated. Finally, glottis indices were compared among the three breeds. RESULTS: No correlation was found for glottis and skull indices. The glottic index differed among the three breeds (smaller in Pugs and higher in English Bulldogs), ultimately representing a morphologic indicator of the different larynx shape in the three breeds (more rounded in English Bulldogs, more elliptical in Pugs and in-between in French Bulldogs). CONCLUSIONS: The lack of correlation between skull/glottic indices does not support skull morphology as predictor of glottic morphology. As Pugs had the lowest glottic index, it may be speculated that Pugs’ original narrow glottic width may predispose to further progressive respiratory deterioration more easily than in the other two breeds.
Ingman J, Naslund V, Hansson K. Comparison between tracheal ratio methods used by three observers at three occasions in English Bulldogs. Acta Vet Scand 2014;56:79.
BACKGROUND: Tracheal hypoplasia is a congenital condition described in mainly brachycephalic breeds and is one component of the brachycephalic obstructive airway syndrome (BOAS). Two radiographic methods have been described to evaluate the dimensions of the tracheal diameter in dogs and to distinguish between hypoplastic and non-hypoplastic tracheas: the tracheal lumen diameter to thoracic inlet distance ratio (TD/TI) and the ratio between the thoracic tracheal luminal diameter and the width of the proximal third of the third rib (TT/3R). The purpose of this study was to compare these two published radiographic methods between observers, different measuring occasions and to investigate the effect on classification of dogs as having hypoplastic or non-hypoplastic tracheas using four previously published mean ratios as cut-offs (<0.11, <0.127 and <0.144 for the TD/TI and <2.0 for the TT/3R method). Three observers evaluated right and left lateral recumbent radiographs from 56 adult English Bulldogs independently on three different occasions. TD/TI and TT/3R ratios were calculated and correlated between measuring occasions. Kappa, observed, positive, and negative agreements were calculated between observers and measuring occasions. Number of hypoplastic and non-hypoplastic dogs for each method and occasion was determined using <0.11, <0.127 and <0.144 as cut-offs for TD/TI and <2.0 for TT/3R. RESULTS: Intraobserver agreement varied with kappa between 0.45-0.94 for the TD/TI and 0.20-0.86 for the TT/3R method. Interobserver kappa varied between 0.27-0.70 for the TD/TI method and between 0.05-0.57 for the TT/3R method. There was poor agreement in classifying English Bulldogs as tracheal hypoplastic or non-hypoplastic, depending on measuring method, cut-off value and observer. CONCLUSIONS: The diagnostic value of both the TD/TI and TT/3R methods with such poor agreement is questionable, and significantly impacts their reliability for both clinical evaluation of dogs and use in health screening programs.
Packer RM, Hendricks A, Tivers MS, Burn CC. Impact of Facial Conformation on Canine Health: Brachycephalic Obstructive Airway Syndrome. PLoS One. 2015 Oct 28;10(10):e0137496.(Free full text)
The domestic dog may be the most morphologically diverse terrestrial mammalian species known to man; pedigree dogs are artificially selected for extreme aesthetics dictated by formal Breed Standards, and breed-related disorders linked to conformation are ubiquitous and diverse. Brachycephaly–foreshortening of the facial skeleton–is a discrete mutation that has been selected for in many popular dog breeds e.g. the Bulldog, Pug, and French Bulldog. A chronic, debilitating respiratory syndrome, whereby soft tissue blocks the airways, predominantly affects dogs with this conformation, and thus is labelled Brachycephalic Obstructive Airway Syndrome (BOAS). Despite the name of the syndrome, scientific evidence quantitatively linking brachycephaly with BOAS is lacking, but it could aid efforts to select for healthier conformations. Here we show, in (1) an exploratory study of 700 dogs of diverse breeds and conformations, and (2) a confirmatory study of 154 brachycephalic dogs, that BOAS risk increases sharply in a non-linear manner as relative muzzle length shortens. BOAS only occurred in dogs whose muzzles comprised less than half their cranial lengths. Thicker neck girths also increased BOAS risk in both populations: a risk factor for human sleep apnoea and not previously realised in dogs; and obesity was found to further increase BOAS risk. This study provides evidence that breeding for brachycephaly leads to an increased risk of BOAS in dogs, with risk increasing as the morphology becomes more exaggerated. As such, dog breeders and buyers should be aware of this risk when selecting dogs, and breeding organisations should actively discourage exaggeration of this high-risk conformation in breed standards and the show ring.
コメント：解剖学的な構造によって特徴づけられるBASは定量的な診断指標がない。今回、回顧的な検討により、マズル長が短縮する程にBAS発症のリスクが増加すること、BASは頭蓋長の半分以下のマズル長の犬のみで発症すること、頚囲の増大や肥満がBASの発症リスクを増加させることを発見した（ダクタリ動物病院 東京医療センター 田畑達彦-2018.11.29）。
Haimel G, Dupre G. Brachycephalic airway syndrome: a comparative study between pugs and French bulldogs. J Small Anim Pract 2015;56:714-719.
OBJECTIVE: To compare clinical features of brachycephalic airway syndrome and long-term surgical outcomes between pugs and French bulldogs and evaluate the influence of laryngeal collapse.
METHODS: This retrospective study included 72 dogs that underwent wedge rhinoplasty and folded flap palatoplasty for brachycephalic airway syndrome. Epidemiological data, clinical signs, postoperative complications and owners’ responses to a questionnaire at least six months after surgery were compared between pugs and French bulldogs. Spearman’s rank correlation tests were used for associating laryngeal collapse with age and respiratory signs before and after surgery.
RESULTS: On the basis of the results of the owners’ questionnaires (available in 52/72 dogs), French bulldogs presented with lower activity levels and more severe digestive signs than pugs. Owners perceived clinical improvement in 88 . 5% of all dogs. The grades of respiratory and digestive signs were not different between the breeds in the long-term follow-up, and the grade of laryngeal collapse did not influence the grade of respiratory signs or surgical outcome.
CLINICAL SIGNIFICANCE: Surgical treatment resulted in improved clinical signs in pugs and French bulldogs with brachycephalic airway syndrome, with a high owner satisfaction rate. There were no correlations between the severity of laryngeal collapse and overall respiratory signs or prognosis.
Packer RM, Tivers MS. Strategies for the management and prevention of conformation-related respiratory disorders in brachycephalic dogs. Vet Med(Auckl). 2015 Jun 4;6:219-232. (Free full text)
Brachycephalic (short-muzzled) dogs are increasingly popular pets worldwide, with marked increases in registrations of breeds such as the Pug and French Bulldog over the past decade in the UK. Despite their popularity, many brachycephalic breeds are affected by an early-onset, lifelong respiratory disorder, brachycephalic obstructive airway syndrome (BOAS). This disorder arises due to a mismatch in the proportions of the skull and the soft tissues held within the nose and pharynx, resulting in obstruction of the airway during respiration. Increased airway resistance encourages secondary changes such as eversion of the laryngeal saccules and collapse of the larynx. Clinical signs of BOAS are often early onset and chronic, including dyspnea, exercise intolerance, heat intolerance, and abnormal and increased respiratory noise. Episodes of severe dyspnea can also occur, leading to cyanosis, syncope, and death. BOAS may have a severe impact upon the welfare of affected dogs, compromising their ability to exercise, play, eat, and sleep. Although a well-described condition, with surgical treatments for the palliation of this disorder published since the 1920s, many dogs still experience airway restrictions postsurgically and a compromised quality of life. In addition, the prevalence of this disorder does not appear to have substantially reduced in this time, and may have increased. Ultimately, strategies to improve the breeding of these dogs to prevent BOAS are required to improve brachycephalic health and welfare. Recent studies have revealed conformational risk factors associated with BOAS, such as short muzzles and thick necks, which should be discouraged to avoid perpetuating this serious disorder. Positive changes to brachycephalic health may be impeded by a perception of BOAS being “normal for the breed”. This perception must be avoided by owners, breeders, and vets alike to prevent undertreatment of individuals and the perpetuation of this serious disorder to future generations of dogs.
コメント：短頭種の飼養頭数は増加しており、これらの犬種で認められる頭蓋骨と軟部組織比率のミスマッチによって生じるBASは、気道抵抗を上昇させることで喉頭小嚢の反転や喉頭虚脱、ひいてはチアノーゼや失神、死を引き起こしうる。BASに対する外科的治療は1920年代頃より文献が認められるが、いまだに術後の気流制限や不完全なQOLを経験している短頭種は多い。さらに、その罹患率は減るどころか、おそらく増加している。’その犬種では普通の構造である’という感覚が短頭種のQOLや健康を制限している（ダクタリ動物病院 東京医療センター 田畑達彦-2018.11.29）。
Kaye BM, Boroffka SA, Haagsman AN, et al. Computed Tomographic, Radiographic, and Endoscopic Tracheal Dimensions in English Bulldogs with Grade 1 Clinical Signs of Brachycephalic Airway Syndrome. Vet Radiol Ultrasound 2015;56:609-616.
Tracheal hypoplasia is commonly seen in English Bulldogs affected with brachycephalic airway syndrome. Previously published diagnostic criteria for tracheal hypoplasia in this breed have been a radiographic tracheal diameter:tracheal inlet ratio (TD:TI) < 0.12 or a tracheal diameter:third rib diameter ratio (TD:3R) < 2.0. Computed tomography has become increasingly used for airway evaluation, however published information is lacking regarding CT tracheal dimensions in English Bulldogs. Objectives of this prospective cross-sectional study were to describe radiographic and CT tracheal dimensions in a sample of clinically normal English Bulldogs and compare these values with tracheoscopy scores. Computed tomography (n = 40), radiography (n = 38), and tracheoscopy (n = 40) studies were performed during a single general anesthesia session for each included dog. Tracheal measurements were recorded at three locations: cervical, thoracic inlet, and thorax. Tracheal diameters were narrowest at the thoracic inlet with all techniques. Computed tomographic measurements averaged 19% greater than radiographic measurements. All included dogs had radiographic tracheal measurements greater than the previously published criteria for tracheal hypoplasia. Mean CT TD:TI was 0.26 (+/- 0.03, 0.20-0.33), and mean CT TT:3R was 2.27 (+/- 0.24, 1.71-2.74). Radiographic TD:TI and CT TD:TI were significantly correlated (P = 0.00); however radiographic TT:3R and CT TT:3R were not significantly correlated (P = 0.25). Tracheoscopy identified hypoplastic changes in all dogs and tracheoscopy scores were not correlated with CT or radiography diameter measurements. In conclusion, findings indicated that some CT and radiographic tracheal diameter measurements were comparable in English Bulldogs however diameters for both imaging techniques were not comparable with tracheoscopy scores.
コメント：短頭種における気管低形成の診断においてレントゲンとCTは同等、CTと比較して気管支鏡がより有用である可能性を示唆する論文(ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）
Vilaplana Grosso F, Haar GT, Boroffka SA. Gender, Weight, and Age Effects on Prevalence of Caudal Aberrant Nasal Turbinates in Clinically Healthy English Bulldogs: A Computed Tomographic Study and Classification. Vet Radiol Ultrasound 2015;56:486-493.
English Bulldogs have been reported to demonstrate abnormal growth and development of the nasal turbinates, which contribute to an increase in airway resistance and hence clinical signs of brachycephalic airway syndrome. The purpose of this prospective, cross-sectional study was to assess the prevalence and severity of caudal aberrant turbinate protrusion via CT studies of English Bulldogs with, according to the owners, none or minimal clinical signs of brachycephalic airway syndrome. An additional objective was to propose a classification scheme for describing the degree of caudal aberrant turbinate protrusion in English Bulldogs and to apply this scheme in assessing the effect of gender, weight, and age on prevalence and severity of turbinate protrusion. The nasal cavities of 40 clinically healthy English Bulldogs were examined. The prevalence of caudal aberrant turbinates in this group was 100%. Using our proposed classification scheme, Grade 1 (minimal) was detected in 7 of 40 (17.5%), Grade 2 (mild) in 28 of 40 (70%), and Grade 3 (moderate) in 5 of 40 (12.5%) English Bulldogs. No significant effect of gender, weight, and age on degree of protrusion was found. In conclusion, this study identified minimal to moderate protrusion of caudal aberrant turbinates toward the nasopharynx in all the sampled English Bulldogs, despite the absence of clinical signs of brachycephalic airway syndrome.
コメント：イングリッシュブルドッグにおける尾側鼻甲介の異常所見の有病率と重症度分類を、CTを用いて検討した論文。異常所見に対する性別、体重、年齢の影響は認められなかった(ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）。
Planellas M, Cuenca R, Tabar MD, et al. Clinical assessment and C-reactive protein (CRP), haptoglobin (Hp), and cardiac troponin I (cTnI) values of brachycephalic dogs with upper airway obstruction before and after surgery. Can J Vet Res 2015;79:58-63.
Brachycephalic dogs have unique upper respiratory anatomy with abnormal breathing patterns that are similar to those in humans with obstructive sleep apnea syndrome (OSAS). The objectives of this multicenter prospective study were to assess the effects of surgical correction on clinical signs in dogs with brachycephalic airway obstructive syndrome (BAOS) and to evaluate the levels of several biomarkers [C-reactive protein (CRP); haptoglobin (Hp), and cardiac troponin I (cTnI)] used to determine systemic inflammation and myocardial damage. This study was conducted on 33 dogs with BAOS that were evaluated before and 1 to 2 mo after surgical correction. Palatoplasty was carried out by means of 2 different surgical techniques: carbon dioxide (CO2) laser (n = 12) and electrical scalpel (n = 21). Biomarker levels (CRP, Hp, and cTnI) were determined before and after surgery. There was a significant reduction in respiratory and gastrointestinal signs in dogs with BAOS after surgical treatment (P < 0.001). A greater reduction in respiratory signs (P < 0.002) was obtained using the CO2 laser. No statistical differences were found between CRP and cTnI levels, either before or after surgical correction. Haptoglobin concentration did increase significantly in the postsurgical period (P < 0.008). Surgical treatment in dogs with BAOS reduces clinical signs, regardless of the anatomical components present. Surgical treatment for BAOS is not useful to reduce CRP and Hp levels, probably because BAOS does not induce as obvious an inflammatory process in dogs as in human patients with OSAS. No reduction in cTnI levels was observed 1 mo after surgery in dogs with BAOS, which suggests that some degree of myocardial damage remains.
コメント；ヒトの閉塞性睡眠時無呼吸症候群では炎症反応と心血管疾患の関連が確立されているが、犬の短頭種閉塞性気道症候群では元々明らかな炎症は誘発されておらず、軟口蓋切除などの外科的な治療前後でも変化は認められない。一方、なんらかの心筋障害は引き起こされているかもしれないが、外科治療により臨床症状が緩和しても改善はみられない（いいのペットクリニック 飯野 亮太-2019.2.7）。
Haimel G, Dupre G. Brachycephalic airway syndrome: a comparative study between pugs and French bulldogs. J Small Anim Pract 2015;56:714-719
OBJECTIVE: To compare clinical features of brachycephalic airway syndrome and long-term surgical outcomes between pugs and French bulldogs and evaluate the influence of laryngeal collapse. METHODS: This retrospective study included 72 dogs that underwent wedge rhinoplasty and folded flap palatoplasty for brachycephalic airway syndrome. Epidemiological data, clinical signs, postoperative complications and owners’ responses to a questionnaire at least six months after surgery were compared between pugs and French bulldogs. Spearman’s rank correlation tests were used for associating laryngeal collapse with age and respiratory signs before and after surgery. RESULTS: On the basis of the results of the owners’ questionnaires (available in 52/72 dogs), French bulldogs presented with lower activity levels and more severe digestive signs than pugs. Owners perceived clinical improvement in 88 . 5% of all dogs. The grades of respiratory and digestive signs were not different between the breeds in the long-term follow-up, and the grade of laryngeal collapse did not influence the grade of respiratory signs or surgical outcome. CLINICAL SIGNIFICANCE: Surgical treatment resulted in improved clinical signs in pugs and French bulldogs with brachycephalic airway syndrome, with a high owner satisfaction rate. There were no correlations between the severity of laryngeal collapse and overall respiratory signs or prognosis.
Pohl S, Roedler FS, Oechtering GU. How does multilevel upper airway surgery influence the lives of dogs with severe brachycephaly? Results of a structured pre- and postoperative owner questionnaire. Vet J 2016;210:39-45.
Brachycephalic airway syndrome in dogs is typified by a variety of anatomical abnormalities causing a diverse spectrum of clinical signs of varying intensity. This variability makes the assessment of the surgical outcome after upper airway surgery difficult. Using a structured questionnaire, the present study investigated the dog owner-perceived severity and frequency of a broad spectrum of welfare-relevant impairments 2 weeks before and 6 months after brachycephalic dogs underwent a recently developed multi-level upper airway surgery. All dogs underwent surgical treatment of stenotic nares (ala-vestibuloplasty), the nasal cavity (laser-assisted turbinectomy, LATE), the pharynx (palatoplasty and tonsillotomy), and if indicated, laryngeal surgery (laser-assisted ablation of everted ventricles and partial cuneiformectomy). Owners of brachycephalic dogs (n = 102) referred for upper airway surgery were eligible to participate. Questionnaire data from owners of 37 Pugs and 25 French bulldogs were evaluated. In all dogs, the clinical signs associated with brachycephaly improved markedly after surgery. Most encouraging was the striking reduction in life-threatening events by 90% (choking fits decreased from 60% to 5% and collapse from 27% to 3%). The incidence of sleeping problems decreased from 55% to 3%, and the occurrence of breathing sounds declined by approximately 50%. There was a marked improvement in exercise tolerance and a modest improvement in heat tolerance. Dogs with severe brachycephaly benefitted substantially from multi-level surgery, and there were particular improvements in the incidences of severe impairment and life-threatening events. However, despite the marked improvement perceived by dog owners, these dogs remained clinically affected and continued to show welfare-relevant impairments caused by these hereditary disorders.
Oechtering GU, Pohl S, Schlueter C, et al. A Novel Approach to Brachycephalic Syndrome. 1. Evaluation of Anatomical Intranasal Airway Obstruction. Vet Surg 2016;45:165-172.
OBJECTIVE: To evaluate airway obstruction due to abnormal intranasal anatomy in 3 brachycephalic dog breeds using computed tomography and rhinoscopy. STUDY DESIGN: Prospective clinical study. ANIMALS: A total of 132 brachycephalic dogs (66 Pugs, 55 French Bulldogs, and 11 English Bulldogs) with severe respiratory distress due to brachycephalic syndrome. METHODS: Computed tomography and anterior and posterior rhinoscopy were performed to evaluate endonasal obstruction. RESULTS: All dogs had abnormal conchal growth that obstructed the intranasal airways. Rostral aberrant turbinates (RAT) were common in Pugs (90.9%) but less frequent in French (56.4%) and English (36.4%) Bulldogs. Caudal aberrant turbinates (CAT) obstructing the nasopharyngeal meatus were commonly found in all breeds (66.7%). Deviation of the nasal septum was an almost consistent finding in Pugs (98.5%) but was less common in bulldogs. Obstructing turbinates had multiple points of mucosal contact responsible for obstruction of the intranasal airway. Interconchal and intraconchal mucosal contacts were evident in 91.7% of dogs. CONCLUSION: Selective breeding for short head conformation reduces the size of the nasal cavities to such an extent that intranasal structures grow aberrantly and malformed, leading to obstructed air conducting spaces. Intranasal airway obstruction of brachycephalic dogs may contribute to their exercise and heat intolerance because of impaired pulmonary ventilation and compromised thermoregulatory functions of the canine nose. Failure to address intranasal obstruction might be an explanation for lack of therapeutic success after conventional surgery for brachycephalic syndrome. Future consideration should be given to the diagnosis, management, and treatment of this newly described aspect of airway obstruction.
Oechtering GU, Pohl S, Schlueter C, et al. A Novel Approach to Brachycephalic Syndrome. 2. Laser-Assisted Turbinectomy (LATE). Vet Surg 2016;45:173-181.
OBJECTIVE: To introduce a new surgical procedure based on interventional, laser-assisted removal of obstructing turbinate tissue to improve endonasal airway patency in brachycephalic dogs and to confirm the short and long term results using computed tomography (CT) and rhinoscopy. STUDY DESIGN: Prospective clinical study. ANIMALS: Brachycephalic dogs (n = 158; 70 Pugs, 77 French Bulldogs, 11 English Bulldogs) referred for treatment of severe respiratory distress because of brachycephalic syndrome. METHODS: Computed tomography and anterior and posterior rhinoscopy were performed to evaluate endonasal obstruction. Laser-assisted turbinectomy (LATE) using a diode laser was performed as part of a multilevel surgery. Nasal conchae that were causing airway obstruction were removed. RESULTS: The obstructing parts of the conchae were safely and efficiently removed by LATE, shaping a patent nasal airway in all dogs. The newly developed surgical procedure involved 3 steps: turbinectomy of the (1) concha nasalis ventralis; (2) rostral aberrantly growing turbinates (RAT); and (3) caudal aberrantly growing turbinates (CAT). Complications of the procedure included transient intraoperative hemorrhage in 51 of 158 dogs (32.3%); however, a temporary tamponade was necessary in only 2/158 dogs (1.3%). After 6 months, regrowth of turbinates required resection of possibly re-obstructing tissue in 25/158 dogs (15.8%; 1 Pug and 24 French Bulldogs). CONCLUSION: LATE is an effective method for creating a patent nasal airway in brachycephalic dogs with intranasal obstruction.
Liu NC, Adams VJ, Kalmar L, et al. Whole-Body Barometric Plethysmography Characterizes Upper Airway Obstruction in 3 Brachycephalic Breeds of Dogs. J Vet Intern Med 2016;30:853-865.
BACKGROUND: A novel test using whole-body barometric plethysmography (WBBP) was developed recently to diagnose brachycephalic obstructive airway syndrome (BOAS) in unsedated French bulldogs. HYPOTHESIS/OBJECTIVES: The hypotheses of this study were: (1) respiratory characteristics are different between healthy nonbrachycephalic dogs and brachycephalic dogs; and among pugs, French bulldogs, and bulldogs; and (2) obesity and stenotic nares are risk factors for BOAS. The main objective was to establish a diagnostic test for BOAS in these 3 breeds. ANIMALS: A total of 266 brachycephalic dogs (100 pugs, 100 French bulldogs, and 66 bulldogs) and 28 nonbrachycephalic dogs. METHODS: Prospective study. Exercise tolerance tests with respiratory functional grading, and WBBP were performed on all dogs. Data from WBBP were associated with functional grades to train quadratic discriminant analysis tools to assign dogs to BOAS+ and BOAS- groups. A BOAS index (0-100%) was calculated for each dog. Receiver operating characteristic (ROC) curves were used to evaluate classification ability. RESULTS: Minute volume was decreased significantly in asymptomatic pugs (P = .009), French bulldogs (P = .026), and bulldogs (P < .0001) when compared to nonbrachycephalic controls. Respiratory characteristics were different among breeds and affected dogs had a significant increase in trace variation. The BOAS index predicted BOAS status for each breed with 94-97% (95% confidence interval [CI], 88.9-100%) accuracy (area under the ROC curve). Both obesity (P = .04) and stenotic nares (P = .004) were significantly associated with BOAS. CONCLUSIONS AND CLINICAL IMPORTANCE: The WBBP can be used as a clinical tool to diagnose BOAS noninvasively and objectively.
Heidenreich D, Gradner G, Kneissl S, et al. Nasopharyngeal Dimensions From Computed Tomography of Pugs and French Bulldogs With Brachycephalic Airway Syndrome. Vet Surg 2016;45:83-90.
OBJECTIVE: To describe the nasopharyngeal airway dimensions of two brachycephalic breeds and to localize the area of smallest airway dimensions. STUDY DESIGN: Prospective, descriptive, computed tomographic imaging study. ANIMALS: Thirty pugs and 30 French bulldogs with brachycephalic upper airway syndrome. METHODS: The thickness and length of the soft palate, cross-sectional area of the airway passage dorsal to the soft and hard palates, and cross-sectional area of the frontal sinus were measured and normalized to each dog’s skull index and body weight before statistical comparison between breeds. Nasopharyngeal turbinates and surrounding airway space, and a possible relationship between the canine tooth angulation and the severity of airway obstruction were assessed. RESULTS: Pugs had significantly smaller cross-sectional areas of the airway dorsal to the soft and hard palates than French bulldogs. In both breeds, the smallest nasopharyngeal cross-sectional areas were located dorsal to the caudal end of the soft palate. The soft palate of pugs was significantly shorter than that of French bulldogs and also significantly thinner when normalized to each dog’s skull index. Pugs more commonly exhibited nasopharyngeal turbinates. Pugs had significantly smaller air-filled cavities at the location of the frontal sinus. No correlation between the nasopharyngeal dimensions and canine tooth angulation was observed. CONCLUSION: Computed tomographic assessment of the upper airway morphology showed the smallest nasopharyngeal cross-sectional areas were located dorsal to the caudal end of the soft palate in both breeds. Pugs had a smaller nasopharyngeal cross-sectional area despite smaller soft palate dimensions than French bulldogs.
Kaye BM, Rutherford L, Perridge DJ, et al. Relationship between brachycephalic airway syndrome and gastrointestinal signs in three breeds of dog. J Small Anim Pract 2018;59:670-673.
OBJECTIVES: To assess the breed-specific prevalence of, and effects of corrective airway surgery on, gastrointestinal signs in French bulldogs, English bulldogs and pugs presenting with brachycephalic airway syndrome to a referral teaching hospital. MATERIALS AND METHODS: In this retrospective study, ptyalism, regurgitation and vomiting were graded at presentation using a previously established scoring system. Staphylectomy and nares resection were performed on all dogs. Gastrointestinal signs were re-assessed via telephone follow-up at least 6 weeks after surgery. RESULTS: Ninety-eight dogs were included: French bulldogs (n=43), English bulldogs (n=12) and pugs (n=43). Overall population prevalence of all gastrointestinal signs was 56%. Breed-specific prevalence for French bulldogs was 93%, English bulldogs 58% and pugs 16%. There was post-surgical clinical improvement in gastrointestinal signs for the whole study population, especially in French bulldogs. CLINICAL SIGNIFICANCE: The prevalence of gastrointestinal signs in dogs presenting with brachycephalic airway syndrome and improvement in these clinical signs following corrective surgery may vary between breeds.
Liu NC, Troconis EL, Kalmar L, et al. Conformational risk factors of brachycephalic obstructive airway syndrome (BOAS) in pugs, French bulldogs, and bulldogs. PLoS One 2017;12:e0181928.
Extremely brachycephalic, or short-muzzled, dog breeds such as pugs, French bulldogs, and bulldogs are prone to the conformation-related respiratory disorder-brachycephalic obstructive airway syndrome (BOAS). Affected dogs present with a wide range of clinical signs from snoring and exercise intolerance, to life-threatening events such as syncope. In this study, conformational risk factors for BOAS that could potentially aid in breeding away from BOAS were sought. Six hundred and four pugs, French bulldogs, and bulldogs were included in the study. Soft tape measurements of the head and body were used and the inter-observer reproducibility was evaluated. Breed-specific models were developed to assess the associations between the conformational factors and BOAS status based on functional grading. The models were further validated by means of a BOAS index, which is an objective measurement of respiratory function using whole-body barometric plethysmography. The final models have good predictive power for discriminating BOAS (-) and BOAS (+) phenotypes indicated by the area under the curve values of >80% on the receiver operating curves. When other factors were controlled, stenotic nostrils were associated with BOAS in all three breeds; pugs and bulldogs with higher body condition scores (BCS) had a higher risk of developing BOAS. Among the standardized conformational measurements (i.e. craniofacial ratio (CFR), eye width ratio (EWR), skull index (SI), neck girth ratio (NGR), and neck length ratio (NLR)), for pugs EWR and SI, for French bulldogs NGR and NLR, and for bulldogs SI and NGR showed significant associations with BOAS status. However, the NGR in bulldogs was the only significant predictor that also had satisfactory inter-observer reproducibility. A NGR higher than 0.71 in male bulldogs was predictive of BOAS with approximately 70% sensitivity and specificity. In conclusion, stenotic nostrils, BCS, and NGR were found to be valid, easily applicable predictors for BOAS (+).
Rutherford L, Beever L, Bruce M, et al. Assessment of computed tomography derived cricoid cartilage and tracheal dimensions to evaluate degree of cricoid narrowing in brachycephalic dogs. Vet Radiol Ultrasound 2017;58:634-646. doi:10.1111/vru.12526
The aims of this observational, analytical, retrospective study were to (i) obtain computed tomographic (CT) cricoid dimensions (height, width, and transverse-sectional area), (ii) compare the cricoid dimensions between brachycephalic and mesaticephalic breeds, and (iii) compare cricoid cartilage dimensions between dogs without and affected with brachycephalic airway syndrome. The study is important to help to further evaluate and understand the anatomical components of brachycephalic airway syndrome. Measurements were performed in 147 brachycephalic and 59 mesaticephalic dogs. The cricoid cartilage was found to be significantly more oval in Pugs and French Bulldogs compared to mesaticephalic breeds. The cricoid cartilage transverse-sectional area was smallest for the Pug and, after adjusting for weight, significantly smaller for Pugs (P < 0.001), Boston Terriers (P = 0.001), and French Bulldogs (P < 0.001) compared to Jack Russell Terriers. The tracheal transverse-sectional area at C4 of English Bulldogs was significantly smaller than for Jack Russell Terriers (P = 0.005) and Labradors (P < 0.001). The cricoid cartilage transverse-sectional area:weight ratio was significantly lower in brachycephalic breeds compared to mesaticephalic breeds (P < 0.001). The cricoid cartilage:trachea at C4 transverse-sectional area for brachycephalic dogs was significantly larger than for mesaticephalic dogs (<0.001), demonstrating that the trachea was the narrowest part of the airway. No significant differences were found for cricoid dimensions between dogs affected with and without brachycephalic airway syndrome. However, large individual variation was found among the brachycephalic breeds and further studies investigating the relationship between cricoid cartilage size, laryngeal collapse, concurrent tracheal hypoplasia, and/or severity of brachycephalic airway syndrome are warranted.
コメント：CTを用いて体重で標準化した輪状軟骨の横断径などを犬種別で比較した論文。パグ、フレンチブルドッグが特に喉頭の狭い犬種として挙げられている（ダクタリ動物病院 東京医療センター 田畑達彦-2018.12.30）
Ellis J, Leece EA. Nebulized Adrenaline in the Postoperative Management of Brachycephalic Obstructive Airway Syndrome in a Pug. J Am Anim Hosp Assoc 2017;53:107-110. doi: 10.5326/JAAHA-MS-6466
Brachycephalic obstructive airway syndrome is a common problem in certain breeds, and may necessitate surgical procedures, such as rhinoplasty, palatoplasty, laryngeal sacculectomy, and/or arytenoid laryngoplasty, to improve the quality of life. However, laryngeal edema may necessitate the use of temporary tracheostomy tubes postoperatively to maintain a patent airway. This case demonstrates that administration of nebulized adrenaline in the immediate postoperative period where upper airway obstruction is life threatening can be used to reduce edema, therefore avoiding the need for tracheostomy.
コメント：パグにおいて短頭種気道症候群ope後の喉頭浮腫に対し、一時気管切開でなくアドレナリン噴霧の有用性を検討した論文（ダクタリ動物病院 東京医療センター 田畑達彦-2018.11.29）。
Shaver SL, Barbur LA, Jimenez DA, et al. Evaluation of Gastroesophageal Reflux in Anesthetized Dogs with Brachycephalic Syndrome. J Am Anim Hosp Assoc 2017;53:24-31.
Brachycephalic airway syndrome may predispose to gastroesophageal reflux (GER) because of the high negative intrathoracic pressures required to overcome conformational partial upper airway obstruction. To investigate this, 20 dogs presenting for elective correction of brachycephalic airway syndrome (cases) and 20 non-brachycephalic dogs (controls) undergoing other elective surgeries were prospectively enrolled. Dogs underwent a standardized anesthetic protocol, and esophageal pH was monitored. Signalment, body weight, historical gastrointestinal and respiratory disease, complete blood count, serum biochemical values, radiographic findings, and anesthetic and surgical time were compared between cases and controls, and dogs that did and did not have basic (pH > 7.5), acidic (pH < 4), or any GER. Controls had higher mean esophageal pH (6.3) compared to cases (5.6, P = .019), but there was no difference in % with GER (cases 60%, controls 40%, P = .34). When all dogs were evaluated, dogs with GER had increased creatinine (P = .01), % positive for esophageal fluid on radiographs (P = .05), and body weight (P = .04) compared to those without GER. GER was common in both cases and controls, and cases had lower esophageal pH; however, greater numbers are required to determine if a true difference exists in % GER.
Reeve EJ, Sutton D, Friend EJ, Warren-Smith CMR. Documenting the prevalence of hiatal hernia and oesophageal abnormalities in brachycephalic dogs using fluoroscopy. J Small Anim Pract. 2017 Dec;58(12):703-708.
OBJECTIVES: To report the prevalence of abnormal fluoroscopic findings in brachycephalic dogs that were presented to a referral hospital for obstructive airway syndrome.
METHODS: Hospital records between May 2013 and November 2015 identified 36 brachycephalic dogs investigated for obstructive airway disease: 21 French bulldogs, six bulldogs, four Boston terriers, two pugs, two boxers and one shih-tzu. The presence or absence of hiatal hernia, delayed oesophageal transit, gastro-oesophageal reflux and redundant oesophagus were recorded.
RESULTS: Of the 36 dogs, 16 had hiatal hernia, all of which were French bulldogs; 31 dogs had delayed oesophageal transit time, 27 had gastro-oesophageal reflux, and four had redundant oesophagus.
CLINICAL SIGNIFICANCE: Clinical Significance: The prevalence of hiatal hernia is higher than expected in the French bulldog, and there was a high prevalence of oesophageal disease in this group in general. These results suggest a need to investigate similar cases for evidence of gastrointestinal disease that may also require attention.
コメント：単一施設において閉塞性気道疾患と診断された36頭の短頭種を用いた回顧的検討であり、食道裂孔ヘルニア、食道通過時間の遅延、胃食道逆流および食道過長の合併率を調査した。全体的に食道疾患の合併率は高く、特にFBは全例において食道裂孔ヘルニアを合併していた（ダクタリ動物病院 東京医療センター 田畑達彦-2018.11.29）。
Lilja-Maula L, Lappalainen AK, Hyytiainen HK, et al. Comparison of submaximal exercise test results and severity of brachycephalic obstructive airway syndrome in English bulldogs. Vet J 2017;219:22-26.
Canine brachycephalic obstructive airway syndrome (BOAS) is a complex respiratory disease related to congenitally flattened facial and skull anatomy. BOAS causes respiratory distress, heat and exercise intolerance, and gastrointestinal signs. English bulldogs (EB) have a high prevalence of BOAS. Currently, the severity of BOAS signs in veterinary practice is assessed subjectively. To reduce BOAS in brachycephalic breeds, an objective and easy-to-use tool could help breeders select healthier animals. Exercise tests, such as the 6 min walk test (distance walked measured) or the 1000 m walk test (duration measured), could be used to assess the severity of BOAS, as exercise intolerance and impaired recovery are key features of BOAS. This study evaluated the severity of signs and anatomic components of BOAS in a group of prospectively recruited young adult EBs (n = 28) and investigated the correlations of the 6 min walk test or the 1000 m walk test with a veterinary assessment of BOAS severity, using an ordinal 4 level scale of respiratory signs. EBs with more severe BOAS walked a shorter distance, more slowly and their recovery from exercise took longer than those with only mild signs of BOAS. Control dogs of different breeds (n = 10) performed the exercise tests significantly better (i.e. longer distance, faster time and recovery) than EBs. Increases in body temperature during exercise were significantly higher in EBs than in controls. The results of this study support the use of exercise tests for objective evaluation of the severity of BOAS in EBs.
コメント：イングリッシュブルドッグのBOASの重症度判定に運動負荷試験を用いることに関して提案している論文。重症度に比例して運動不耐性が認められる((ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）
Crane C, Rozanski EA, Abelson AL, et al. Severe brachycephalic obstructive airway syndrome is associated with hypercoagulability in dogs. J Vet Diagn Invest 2017;29:570-573.
We evaluated whether dogs with severe brachycephalic obstructive airway syndrome (BOAS) developed a hypercoagulable state similar to people with obstructive sleep apnea. Five dogs with grade 3 BOAS were included as well as 5 healthy control Labrador Retrievers. Venous blood samples were collected from each dog for performance of thromboelastography and determination of hematocrit and platelet count. Groups were compared using a t-test, with p < 0.05 considered significant. Thromboelastography results identified that all BOAS dogs were hypercoagulable compared to the Labradors, having significantly shortened clotting time with increased angle, maximal amplitude, and clot rigidity. BOAS dogs also had evidence of delayed fibrinolysis. These results are consistent with, but more severe than, those previously documented in apparently healthy Bulldogs. Together, these findings support the presence of a hypercoagulable state in brachycephalic dogs, and suggest that this state is amplified by increasing severity of BOAS.
Liu NC, Oechtering GU, Adams VJ, et al. Outcomes and prognostic factors of surgical treatments for brachycephalic obstructive airway syndrome in 3 breeds. Vet Surg 2017;46:271-280.
OBJECTIVE: To determine prognostic indicators for the surgical treatment of brachycephalic obstructive airway syndrome (BOAS) and to compare the prognosis of 2 multilevel surgical procedures. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Client-owned pugs, French bulldogs, and bulldogs (n = 50). METHODS: Noninvasive whole-body barometric plethysmography (WBBP) was used to assess respiratory function before, 1 month and 6 months after upper airway corrective surgery. Postoperatively, BOAS indices (ie, ascending severity score generated from WBBP data, 0%-100%) that equaled to or exceeded the cut-off values of BOAS in the diagnostic models were considered to have a “poor prognosis.” A multivariate logistic regression was used to assess predictors for prognosis. RESULTS: The median BOAS indices decreased after surgery (from 76% to 63%, P < .0001), although dogs with indices in this range would still be considered clinically affected. Age (odds ratios [OR] = 0.96, 95% confidence interval [CI]: 0.93-0.99, P < .05), body condition (OR = 0.06, 95% CI: 0.01-0.39, P < .01), laryngeal collapse (OR = 6.1, 95% CI: 1-37.22, P < .05), and surgical techniques (OR = 7.94, 95% CI: 1.17-54.01, P < .05) were associated with postoperative prognosis. The multivariate model suggests modified multilevel surgery (MMS) may have a better outcome than traditional multilevel surgery (TMS) (P = .034). The positive predictive value of the logistic model was 84% (95% CI: 68-94%) and the area under the receiver operating characteristic (ROC) curve was 89% (95% CI: 78-99%, P <.0001). CONCLUSIONS: Younger age, normal body condition, presence of laryngeal collapse, and treatment with TMS were negative prognostic factors after surgical treatment of BOAS. MMS is recommended, particularly in dogs with a higher probability of poor prognosis.
Hostnik ET, Scansen BA, Zielinski R, et al. Quantification of nasal airflow resistance in English bulldogs using computed tomography and computational fluid dynamics. Vet Radiol Ultrasound 2017;58:542-551.
Stenotic nares, edematous intranasal turbinates, mucosal swelling, and an elongated, thickened soft palate are common sources of airflow resistance for dogs with brachycephalic airway syndrome. Surgery has focused on enlarging the nasal apertures and reducing tissue of the soft palate. However, objective measures of surgical efficacy are lacking. Twenty-one English bulldogs without previous surgery were recruited for this prospective, pilot study. Computed tomography was performed using conscious sedation and without endotracheal intubation using a 128 multidetector computed tomography scanner. Raw multidetector computed tomography data were rendered to create a three-dimensional surface mesh model by automatic segmentation of the air-filled nasal passage from the nares to the caudal soft palate. Three-dimensional surface models were used to construct computational fluid dynamics models of nasal airflow resistance from the nares to the caudal aspect of the soft palate. The computational fluid dynamics models were used to simulate airflow in each dog and airway resistance varied widely with a median 36.46 (Pa/mm)/(l/s) and an interquartile range of 19.84 to 90.74 (Pa/mm)/(/s). In 19/21 dogs, the rostral third of the nasal passage exhibited a larger airflow resistance than the caudal and middle regions of the nasal passage. In addition, computational fluid dynamics data indicated that overall measures of airflow resistance may significantly underestimate the maximum local resistance. We conclude that computational fluid dynamics models derived from nasal multidetector computed tomography can quantify airway resistance in brachycephalic dogs. This methodology represents a novel approach to noninvasively quantify airflow resistance and may have utility for objectively studying effects of surgical interventions in canine brachycephalic airway syndrome.
Downing F, Gibson S. Anaesthesia of brachycephalic dogs. J Small Anim Pract 2018;59:725-733.
Brachycephalic breeds of dog have grown in popularity in the UK and so form an increasing proportion of cases requiring anaesthesia. These breeds are predisposed to several conditions, notably brachycephalic obstructive airway syndrome and gastro-oesophageal reflux, that have important implications for anaesthetic management and carry high risk for complications. This review incorporates peer-reviewed veterinary literature with clinical experience in a discussion on perioperative management of brachycephalic dogs. We focus on preoperative identification of common concurrent conditions, practical strategies for reducing anaesthetic risk and improving postoperative management. Comparisons of brachycephalic obstructive airway syndrome with the human condition of obstructive sleep apnoea are included where appropriate.
Sarran D, Caron A, Testault I, et al. Position of maximal nasopharyngeal maximal occlusion in relation to hamuli pterygoidei: use of hamuli pterygoidei as landmarks for palatoplasty in brachycephalic airway obstruction syndrome surgical treatment. J Small Anim Pract 2018. (PDFあり）
OBJECTIVES: To assess the influence of complete nasopharyngeal occlusion on respiratory signs in brachycephalic dogs. To determine the cranio-caudal position of rostral nasopharyngeal occlusion in relation to the hamuli pterygoidei in brachycephalic dogs. To determine whether using the hamuli pterygoidei as anatomical landmarks for palatoplasty results in clinical respiratory improvement. MATERIALS AND METHODS: Prospective study of dogs diagnosed with brachycephalic obstructive airway syndrome. The dogs were scored according to the severity of their clinical respiratory signs and the nasopharynx was CT scanned. The site of most rostral nasopharyngeal occlusion was measured in relation to the hamuli pterygoidei. Measurements were compared between brachycephalic obstructive airway syndrome group, completely occluded and partially occluded groups. The hamuli pterygoidei were used as the most cranial landmarks for the palatoplasty incision, such that the incision was made at the point of maximal nasopharyngeal occlusion. Owners were interviewed through telephone for the medium-term follow-up. RESULTS: Thirty-five dogs were included. There was no significant association between the severity of respiratory clinical signs and extent of nasopharyngeal occlusion. Maximal nasopharyngeal occlusion was always located directly caudal to the hamuli pterygoidei (mean +/-sd value of 94 +/-65 mm). hamuli pterygoidei were easily palpable perioperatively in all cases. There was a significant improvement of clinical grades postoperatively. CLINICAL SIGNIFICANCE: The hamuli pterygoidei are a reliable landmark for soft palate incision for palatoplasty in these cases but the distance between them and the site of maximal nasopharyngeal occlusion varied greatly.
Norgate D, Ter Haar G, Kulendra N, et al. A comparison of the effect of propofol and alfaxalone on laryngeal motion in nonbrachycephalic and brachycephalic dogs. Vet Anaesth Analg 2018;45:729-736. （PDFあり）
OBJECTIVE: To compare the effect of propofol and alfaxalone on laryngeal motion under a light plane of anaesthesia in nonbrachycephalic and brachycephalic dogs anaesthetized for nonemergency procedures. STUDY DESIGN: Prospective, randomized clinical trial. ANIMALS: A total of 48 client-owned dogs (24 nonbrachycephalic and 24 brachycephalic). METHODS: A standardized premedication of methadone (0.2 mg kg(-1)) and acepromazine (0.01 mg kg(-1)) was administered intramuscularly. Dogs were randomly assigned to be induced with increments of propofol (1-4 mg kg(-1)) or alfaxalone (0.5-2 mg kg(-1)). Laryngeal assessment was performed under a light plane of anaesthesia by a surgeon (GTH) who was unaware of the induction protocol. Laryngeal movement was assessed as either being present when abduction of the laryngeal cartilages upon inspiration was identified, or absent when abduction was not recognized. Simultaneously, a 60-second video was recorded. The same surgeon (GTH) and an additional surgeon (NK) re-evaluated the videos 1 month later. Categorical comparisons were studied using Chi square and Fisher’s exact test where appropriate. Pairwise evaluation of agreement between scorers was undertaken with the kappa statistic (kappa). RESULTS: There were no significant differences (p > 0.05) identified between the presence or absence of laryngeal motion between dogs administered propofol or alfaxalone, as well as when analysing nonbrachycephalic and brachycephalic dogs separately. The majority of dogs (>75%) maintained some degree of laryngeal motion with both protocols. Agreement between assessors was excellent (kappa = 0.822). CONCLUSIONS: Alfaxalone maintained laryngeal motion similarly to propofol in nonbrachycephalic and brachycephalic dogs. CLINICAL RELEVANCE: Both agents would appear appropriate for allowing assessment of laryngeal motion in nonbrachycephalic and brachycephalic dogs. The assessment technique of subjective evaluation of laryngeal motion via peroral laryngoscopy under a light plane of anaesthesia produced consistent results amongst assessors, regardless of the induction agent used.
(上大岡キルシェ動物病院 山下 智之-2019.3.12)
Liu NC, Genain MA, Kalmar L, et al. Objective effectiveness of and indications for laser-assisted turbinectomy in brachycephalic obstructive airway syndrome. Vet Surg 2019;48:79-87.
OBJECTIVE: To evaluate the effectiveness of laser-assisted turbinectomy (LATE) in treating brachycephalic obstructive airway syndrome (BOAS) and to investigate the potential indications. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Client-owned pugs, French bulldogs, and English bulldogs (n = 57). METHODS: A BOAS index was obtained from whole-body barometric plethysmography before BOAS conventional multilevel surgery (CMS) and 2-6 months post-CMS. Dogs with BOAS index >50% and BOAS functional grades II-III after CMS were considered candidates for LATE. A BOAS index was repeated 2-6 months after LATE. Intranasal lesions and a measurement of soft tissue proportion at the rostral entrance of choanae (STC) were recorded on the basis of computed tomography images. Logistic regressions were used to assess the intranasal predictors for being LATE candidates. RESULTS: Twenty-nine of 57 dogs were candidates for LATE, all of which were pugs or French bulldogs. The median BOAS index of dogs that were operated on (20/29 candidates) decreased from 67% post-CMS to 42% after LATE (P < .001). Soft tissue proportion at the rostral entrance of choanae was the only predictor for candidacy for LATE. Pugs (P = .021; cutoff = 64%) and French bulldogs (P = .008; cutoff = 55%) with higher STC were more likely to be candidates for LATE. After LATE, 12 of 20 dogs had temporary episodes of reverse sneezing, and nasal noise was noted in 8 of 20 dogs when sniffing and excited. CONCLUSION: Laser-assisted turbinectomy was an effective treatment for dogs with intranasal abnormalities and a poor response to CMS. Soft tissue proportion at the rostral entrance of choanae was a predictor of candidacy for LATE in pugs and French bulldogs. CLINICAL SIGNIFICANCE: Computed tomography-based measurement of STC can be used to predict whether LATE is required in addition to CMS in pugs and French bulldogs with BOAS.
Riggs J, Liu NC, Sutton DR, et al. Validation of exercise testing and laryngeal auscultation for grading brachycephalic obstructive airway syndrome in pugs, French bulldogs, and English bulldogs by using whole-body barometric plethysmography. Vet Surg 2019.
OBJECTIVE: To determine whether the sensitivity of clinical examination for assessing upper airway disease severity in 3 breeds of brachycephalic dogs can be improved by incorporating an exercise test (ET) or by auscultation of a laryngeal stridor to predict laryngeal collapse. STUDY DESIGN: Prospective clinical study. ANIMALS: Client-owned brachycephalic dogs (n = 44 ET; n = 57 laryngeal stridor assessment). METHODS: In the first part of the study, clinical examinations were performed at rest and after 5-minute walk and 3-minute trot tests, and a grade reflective of brachycephalic obstructive airway syndrome (BOAS) severity was assigned. Whole-body barometric plethysmography was used as a comparative, objective measure of disease severity. In the second part of the study, the degree of laryngeal collapse present in dogs undergoing BOAS surgery was compared to pre-exercise and postexercise laryngeal stridor detected during functional testing. RESULTS: The sensitivity of clinical examination for BOAS diagnosis was 56.7% pre-ET, 70% after a 5-minute walk test, and 93.3% after a 3-minute trot test. The sensitivity of laryngeal stridor as a predictor of laryngeal collapse was improved after exercise (70%) compared with before exercise (60%). Specificity of laryngeal stridor for laryngeal collapse was 100% (pre-exercise and postexercise). CONCLUSION: The sensitivity of clinical examination for BOAS diagnosis was improved by inclusion of an ET, particularly the 3-minute trot test. Audible laryngeal stridor was highly specific but only moderately sensitive for laryngeal collapse. CLINICAL SIGNIFICANCE: Inclusion of a 3-minute trot test and careful auscultation for laryngeal stridor are recommended during BOAS assessment of brachycephalic dogs.
コメント：BOASリスク犬種において、運動負荷試験および喉頭の聴診によってPhysical examinationによる上部気道閉塞の重症度判定および喉頭虚脱の有無の検出力の感度および特異度の上昇がみられた（ダクタリ動物病院東京医療センター 田畑達彦-2019.3.10）。
Sabino CV, Holowaychuk M, Bateman S. Management of acute respiratory distress syndrome in a French Bulldog using airway pressure release ventilation.J Vet Emerg Crit Care(San Antonio). 2013 Jul-Aug;23(4):447-54.
OBJECTIVE: To describe the successful clinical management of a dog with acute respiratory distress syndrome (ARDS) using airway pressure release ventilation (APRV).
CASE SUMMARY: An 18-month-old female French Bulldog was presented for routine ovariohysterectomy and correction of brachycephalic airway obstruction syndrome. Following the surgical procedures, the dog developed aspiration pneumonia and ARDS. Her clinical condition failed to improve with conventional pressure-support mechanical ventilation and she was subsequently managed with APRV. She recovered fully and exhibited no clinical or radiographic abnormalities during follow-up examinations.
NEW OR UNIQUE INFORMATION PROVIDED: This is the first reported use of APRV to manage refractory hypoxemia associated with ARDS in a dog. This alternative mode of mechanical ventilation can be considered a feasible alternative in canine patients with ARDS.
コメント：18か月雌FBの不妊およびBAS整復手術後に生じた吸引性肺炎に続発するARDSの管理において気道圧開放換気(APRV)が奏功した症例報告（ダクタリ動物病院 東京医療センター 田畑達彦-2018.11.29）
Schabbing KJ, Seaman JA. Resection and Primary Closure of Edematous Glossoepiglottic Mucosa in a Dog Causing Laryngeal Obstruction. J Am Anim Hosp Assoc 2017;53:180-184.
An approximately 22 mo old male neutered English bulldog was evaluated for acute onset of dyspnea with suspected brachycephalic obstructive airway syndrome (BOAS). Laryngoscopic exam revealed diffuse, severe edema and static displacement of redundant glossoepiglottic (GE) mucosa causing complete obstruction of the larynx and epiglottic entrapment. Static displacement of the GE mucosa was observed and determined to be the overriding component of dyspnea in this patient with BOAS. Resection and primary closure with two separate, simple continuous sutures of the GE mucosa were performed. Resection and primary closure of the GE mucosa resolved the acute onset of dyspnea in this patient. Surgical correction of the stenotic nares, elongated soft palate, and everted laryngeal saccules were performed under the same anesthetic procedure. Static displacement of the GE mucosa may occur in patients with BOAS. Surgical resection and closure of the GE mucosa resolved this patient’s dyspnea and is recommended in airway obstruction. It remains to be determined if primary closure and subsequent tensioning or scar tissue of the GE mucosa results in further complications related to restricted epiglottic movement.
コメント：BOASのブルドッグにおいて認められた舌喉頭蓋粘膜の浮腫を外科的に切除した報告（ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）。
Shaw TE, Harkin KR, Nietfeld J, et al. Aortic body tumor in full-sibling English bulldogs. J Am Anim Hosp Assoc 2010;46:366-370.
A 10-year-old, neutered male English bulldog died acutely from respiratory distress after a short history of progressive dyspnea. Less than 2 months later, a spayed female full sibling of that dog died suddenly during a nail trim. An aortic body tumor was the cause of death in both dogs based on postmortem and histological examinations. A pheochromocytoma was also diagnosed in the neutered male. Neither dog had a history of brachycephalic airway syndrome, and the implication for a genetic predisposition toward the development of paraganglioma is discussed. This is the first case report of aortic body tumors in sibling dogs, although the condition may not be an uncommon phenomenon.
コメント：大動脈小体腫瘍により別々の時期に急死した2頭のイングリッシュブルドッグ（同腹仔）に関するケースレポート（ダクタリ動物病院 東京医療センター 田畑達彦-2019.2.3）。
Suratt PM, Dee P, Atkinson RL, et al. Fluoroscopic and computed tomographic features of the pharyngeal airway in obstructive sleep apnea. Am Rev Respir Dis 1983;127:487-492.
Because it has been suggested that patients with obstructive sleep apnea have a narrower pharyngeal airway than normal persons, we performed lateral fluoroscopy and computed tomographic (CT) scans of the pharynx in patients with this syndrome. Fluoroscopy in 6 sleeping patients showed that the obstruction always began during inspiration when the soft palate touched the tongue and posterior pharyngeal wall. The CT scans in 9 awake subjects demonstrated that the narrowest section of the airway in patients and in control subjects was the region posterior to the soft palate. The cross-sectional area of this region was significantly narrower in patients than it was in control subjects (p less than 0.001). Because a narrow airway would be more likely to collapse during inspiration than a normal one would (Bernoulli’s Principle), we conclude that the narrow airways we observed in awake patients may be an important contributing factor in the pathogenesis of obstructive sleep apnea.
コメント：6名のOSA患者の睡眠時側臥位咽頭気道所見から、吸気時に軟口蓋が舌と咽頭後壁に接触した。9名のOSA患者と非OSA者の対照群の覚醒下CT検査所見ではともに軟口蓋の後部でもっとも気道は狭窄しており、OSA 患者の方が対照群より優位にこの部位が狭窄していた。覚醒期に正常より気道が狭窄していることはOSAの病態において重要な因子であると結論された。咽頭気道の透視検査は動物の横臥に相当する体位で評価されていた（犬・猫の呼吸器科 城下幸仁-2019.2.27）。
Petrof BJ, Pack AI, Kelly AM, et al. Pharyngeal myopathy of loaded upper airway in dogs with sleep apnea. J Appl Physiol (1985) 1994;76:1746-1752.
Recent work indicates that upper airway dilator muscles of individuals with obstructive sleep apnea syndrome (OSAS) demonstrate an increased level of activity during wakefulness compared with normal subjects. In addition, massive bursts of pharyngeal dilator activity are associated with the termination of upper airway occlusive events during sleep. This complex pattern of altered pharyngeal dilator activation is also observed in the English bulldog, an animal model of OSAS. In the present study, it was hypothesized that such alterations in activity level might lead to changes in the structure of pharyngeal muscles in the bulldog. Full-thickness biopsies were obtained from two pharyngeal dilator muscles, the sternohyoid (SH) and geniohyoid, as well as a limb muscle, the anterior tibialis, in bulldogs (n = 5) and control dogs (n = 7). Immunohistochemical analysis of myosin heavy chain expression revealed an increased contribution of fast type II myosin heavy-chain fibers to SH in bulldogs. The bulldog SH also demonstrated increased connective tissue content compared with control dogs, consistent with the presence of fibrosis. Both pharyngeal dilators in the bulldog exhibited an elevated proportion of morphologically abnormal fibers indicative of ongoing or prior injury. No differences in any of the above parameters were seen between bulldogs and control dogs in the anterior tibialis limb muscle. We conclude that the chronic load and altered pattern of usage imposed on the upper airway dilators in OSAS lead to myopathic changes that may ultimately impair the ability of these muscles to maintain pharyngeal patency.
城下幸仁. 【子どものいびき・睡眠時無呼吸症候群を探求する】 犬の短頭種気道症候群の病態から学ぶもの. 小児歯科臨床 2016;21:25-32.
Rubin JA, Holt DE, Reetz JA, et al. Signalment, clinical presentation, concurrent diseases, and diagnostic findings in 28 dogs with dynamic pharyngeal collapse (2008-2013). J Vet Intern Med 2015;29:815-821.
BACKGROUND: Most information about pharyngeal collapse in dogs is anecdotal and extrapolated from human medicine. A single case report describing dynamic pharyngeal collapse in a cat has been published, but there is no literature describing this disease process in dogs. OBJECTIVE: To describe the signalment, clinical presentation, concurrent disease processes, and imaging findings of a population of client-owned dogs with pharyngeal collapse. ANIMALS: Twenty-eight client-owned dogs with pharyngeal collapse. METHODS: Radiology reports of dogs for which fluoroscopy of the respiratory system was performed were reviewed retrospectively. Patients with a fluoroscopic diagnosis of pharyngeal collapse were included in the study population. Data regarding clinical signs, diagnostic, and pathologic findings were evaluated. RESULTS: Twenty-eight dogs met the inclusion criteria. The median age of affected patients was 6.6 years, whereas median body condition score was 7/9. The most common clinical signs were coughing (n = 20) and stertor (n = 5). In 27 of 28 cases, a concurrent or previously diagnosed cardiopulmonary disorder was detected. The most common concurrent disease processes were mainstem bronchi collapse (n = 18), tracheal collapse (n = 17), and brachycephalic airway syndrome (n = 8). Fluoroscopy identified complete pharyngeal collapse in 20 of 28 dogs. CONCLUSIONS: Pharyngeal collapse is a complex disease process that likely is secondary to long-term negative pressure gradients and anatomic and functional abnormalities. Based on the findings of this study, pharyngeal fluoroscopy may be useful diagnostic test in patients with suspected tracheal and mainstem bronchial collapse to identify concurrent pharyngeal collapse.
Pollard RE, Johnson LR, Marks SL. The prevalence of dynamic pharyngeal collapse is high in brachycephalic dogs undergoing videofluoroscopy. Vet Radiol Ultrasound 2018;59:529-534. https://www.ncbi.nlm.nih.gov/pubmed/25673910
The aim of this retrospective study was to determine the frequency of pharyngeal collapse in a large group of brachycephalic dogs undergoing videofluoroscopic assessment of swallowing or airway diameter. We hypothesized that brachycephalic dogs would have pharyngeal collapse more frequently than dolichocephalic or mesocephalic dogs with or without airway collapse. The medical records database was searched for brachycephalic dogs undergoing videofluoroscopy of swallowing or airway diameter between January 1, 2006 and December 31, 2015. A cohort of dolichocephalic/mesocephalic dogs with videofluoroscopically confirmed airway collapse was age and time matched for comparison. A control group of dolichocephalic/mesocephalic dogs that did not have documented airway collapse was also evaluated. All fluoroscopic studies were assessed by a board certified veterinary radiologist for the presence and degree of pharyngeal collapse. Results demonstrate that pharyngeal collapse was significantly more common in brachycephalic dogs (58/82; 72%) than in nonbrachycephalic dogs with (7/25; 28%) and without (2/30; 7%) airway collapse. Pharyngeal collapse is more prevalent in brachycephalic dogs undergoing videofluoroscopy than in dolichocephalic/mesocephalic dogs with or without airway collapse.
Schwartz AR, Eisele DW, Smith PL. Pharyngeal airway obstruction in obstructive sleep apnea: pathophysiology and clinical implications. Otolaryngol Clin North Am 1998;31:911-918.
In obstructive sleep apnea, airflow obstruction is caused by pharyngeal collapse. Current evidence suggests that anatomic alterations predispose to pharyngeal collapse. This article examines the role of structures that elongate and dilate the pharynx in maintaining pharyngeal patency. Their influence on pharyngeal collapsibility is considered. Insights gained are then presented within a conceptual framework that can be used for treating patients.
コメント：閉塞性睡眠時無呼吸の気道閉塞は睡眠時に咽頭気道が虚脱することによって生じる。この虚脱は、構造的問題と神経筋機能障害の両者のバランスによって生じると考えられているが、詳細機序は解明されていない。睡眠時の咽頭虚脱は、咽頭周囲圧で予測される。したがって、睡眠時に気流が生じ始める外鼻孔部での気道内圧でその程度を計測できる。終夜ポリソノグラフィーで持続陽圧呼吸（CPAP）を行ながら、その圧を測定することをCPAPタイトレーションと呼び、そのときの気道内圧は咽頭開存最小圧？（Pharyngeal critical pressure, Pcrit)と呼ばれる。この論文では、このPcrit計測を基準に睡眠時咽頭閉塞の病態について動物実験や臨床知見からレビューしている。Pcritは、咽頭気道を伸展させると低下する。これは、猫の分離した上気道の実験で、気管を後方に牽引して確認された。頚を伸展させると同様の効果が得られる。また、同様の実験で舌を前方に牽引すると咽頭気道が拡大した。しかしこの場合、Pcritはあまり低下しなかった。人では、仰臥位に比べ立位や横向き寝でPcirtが4〜5cmH2O低下した。逆の理論で、小下顎症での睡眠時無呼吸はこれで説明できる。 Pcritの治療目標は初期値の-5cmH2Oとするとおおよそ効果が得られる。Pcritがあまり高くなければ、15-20％の体重減量でこの治療目標をおおよそ達成できる。イングリッシュブルドッグをモデルとした研究では、構造的咽頭閉塞を代償するために咽頭筋の機能亢進が認められ、経年的に筋変性が生じていたことが確認された。人でも、無呼吸患者ではオトガイ舌筋の活動過剰が覚醒期に認められた。したがって現在では、構造的問題が咽頭虚脱性の主要因であり、さらにそれを代償するため神経筋活動の亢進を引き起こしていると推測されている。閉塞性無呼吸では、咽頭気道を伸展させたり、咽頭気道を広げたりするような治療を考案すればよいということになるが、未だ効果的な決定打はない（犬・猫の呼吸器科 城下幸仁-2018.2.27）。
Suto Y, Inoue Y. Sleep apnea syndrome. Examination of pharyngeal obstruction with high-speed MR and polysomnography. Acta Radiol 1996;37:315-320.
PURPOSE: We attempted to determine the usefulness of high-speed MR imaging for evaluating the severity of sleep apnea syndrome (SAS) by comparing findings of pharyngeal obstruction obtained with high-speed MR with those of all-night polysomnography (PSG). SUBJECTS AND METHODS: A total of 33 patients with SAS underwent turbo-FLASH MR examination, while awake and after i.v. injection of hydroxyzine hydrochloride. Serial images were examined by cinemode. Pharyngeal findings on MR were divided into single-site obstruction (SO) at the velopharynx, multiple-site obstruction (MO), and no obstruction (NO). PSG findings were analyzed to determine the predominant type of apnea, severity as evaluated by an apnea index (AI), and the lowest SaO2 value during sleep. RESULTS: Seventy-five percent of the central apnea group had SO, and 70% of the mixed apneas had MO, while only 15% of the obstructed apneas had MO. The percentage of patients with severe SAS (AI of 20% or higher) was 48% for the SO, and 70% for the MO. The lowest SaO2 value tended to be low in the mixed apnea in the case of PSG, and tended to be low in the MO at MR examination. CONCLUSION: Analysis of pharyngeal dynamics using high-speed MR may provide some useful information for evaluating the severity of SAS.
Fig. 2. Patient 2, a 65-year-old man with MO. a) Sagittal image when awake. b) Sagittal image with the subject asleep. During wakefulness, no obstruction was observed in the pharynx, but during sleep, obstructions were observed at the velopharynx (white arrow) and the tongue (black arrow head).
American Academy of Sleep Medicine : The international classification of sleep disorders, 2nded : Diagnostic and coding manual. American Academy of Sleep Medicine, Westchester, 2005
榊原博樹. 睡眠時無呼吸症候群 診療ハンドブック. 東京：医学書院, 2010
- 低呼吸（hypopnea）：換気量が規定以上に減少した状態。人ではresearch definitionおよびclinical definitionと呼ばれる2つの診断基準がある。research definitionでは3%以上の酸素飽和度低下あるいは覚醒反応を伴う呼吸気流の減少を低呼吸とする（ほとんどの施設がこの基準を採用）。clinical definitionでは呼吸気流の30%以上の減少に、4%以上の酸素飽和度低下を伴うイベントを低呼吸とする。
- 無呼吸指数（apnea index AI）：全睡眠時間（total sleep time TST）1時間当たりの無呼吸の回数
- 無呼吸低呼吸指数（apnea hypopnea index AHI）：TST1時間当たりの無呼吸＋低呼吸の回数
- 睡眠呼吸障害（sleep disordered breathing SDB）：睡眠時の無呼吸および低呼吸、あるいは酸素飽和度の低下を伴う呼吸異常のことで、症状の有無は問わない。
- 睡眠時無呼吸（sleep apnea SA）
- 閉塞型睡眠時無呼吸（obstructive sleep apnea OSA）：上気道閉塞による睡眠時無呼吸。呼吸気流の停止は見られるが、胸腹部の呼吸運動は残存している。
- 中枢型睡眠時無呼吸（central sleep apnea CSA）：呼吸中枢からの呼吸刺激出力の停止による睡眠無呼吸。呼吸気流の停止とともに、胸腹部の呼吸運動も停止する。
- 混合型睡眠時無呼吸（mixed sleep apnea MSA）：CSAに続いてOSAが生じる無呼吸
- 閉塞型睡眠時無呼吸症候群（obstructive sleep apnea syndrome OSAS）：1時間に5〜10以上のOSA主体のSDBが見られるSAS
- 中枢型睡眠時無呼吸症候群（central sleep apnea syndrome CSA）：1時間に5〜10以上のCSA主体のSDBが見られるSAS
- 睡眠呼吸異常症（sleep breathing disorder SBD）：SASに加えて、上気道抵抗症候群、いびき、肥満低換気症候群など睡眠時の呼吸異常を広く組み入れた概念のこと
- AHI ≧ 5
- AHI ≧ 15
磯野史朗. 【睡眠時無呼吸 最近の進歩と展望】 睡眠時無呼吸の病態生理と呼吸調節 閉塞型睡眠時無呼吸 咽頭閉塞とその周期性のメカニズム. 最新医学 2009;64:14-21.
Rosenow F, McCarthy V, Caruso AC. Sleep apnoea in endocrine diseases. J Sleep Res 1998;7:3-11.
The pertinent literature on the prevalence, clinical manifestations and pathogenic mechanisms of sleep apnoea (SA) in endocrine diseases, namely acromegaly, Cushing syndrome, hypothyroidism and diabetes mellitus was reviewed. An increased prevalence is well documented in patients with active and treated acromegaly. While most authors report peripheral obstruction, due to hypertrophy of tongue and pharyngeal tissues, to be the cause of SA in acromegaly, some findings argue for a role of hormone-induced changes of central respiratory control. SA is also more common in hypothyroidism, especially when myxedema is present. The associated edema and myopathy appear to be of pathogenic importance. Thyroxin substitution is frequently effective for the treatment of SA but nCPAP can be necessary initially and in some patients even after remission of clinical signs of hypothyroidism. In Cushing disease and syndrome, parapharyngeal fat accumulation can cause SA, but no epidemiological information is available. In non insulin dependent diabetes (NIDDM), obesity is the common risk factor for both, nocturnal hypoxia and insulin resistance. In IDDM, the development of autonomic neuropathy may predispose to SA. Where treatment of the underlying endocrine disease is unable cure the associated SA, nCPAP is usually the treatment of first choice. More prospective studies are clearly needed to establish prevalences and resolve the controversies regarding pathogenesis.
Corso R, Russotto V, Gregoretti C, et al. Perioperative management of obstructive sleep apnea: a systematic review. Minerva Anestesiol 2018;84:81-93.
INTRODUCTION: Obstructive sleep apnea (OSA) is the leading sleep disordered breathing condition, with a prevalence rate of moderate to severe OSA of approximately 10-17% in the general population. EVIDENCE ACQUISITION: We performed an Ovid-Medline search of all articles published up to August 2016. We included all articles providing updated evidence on epidemiology, pathophysiologic mechanisms and perioperative interventions. EVIDENCE SYNTHESIS: OSA is associated with a number of comorbidities and increased perioperative risks. Although in-laboratory polysomnography represents the gold-standard for diagnosis of OSA, it is costly and time-consuming. Anesthesiologists may screen patients for OSA through one of the available questionnaires, of which the snoring, tiredness, observed apnea, high blood pressure (STOP)-Body Mass Index, age, neck circumference and gender (Bang), STOP-bang questionnaire is the most externally validated. Although its sensitivity for the identification of mild OSA patients is 83.6%, its specificity is only 56.4%. OSA patients are associated with a higher risk of both difficult ventilation and intubation. However, practice guidelines refer to available guidelines for difficult airway management. Perioperative continuous positive airway pressure use may be of benefit since it has been reported to be associated with a reduction of both respiratory and cardiovascular complications and symptom relief. When feasible, regional anesthesia techniques and a multimodal analgesia approach should be adopted to reduce intraoperative and postoperative exposure to opioids. CONCLUSIONS: Preoperative screening of OSA patients is of relevance given the increased perioperative morbidity of these patients. Further studies are needed to provide conclusive data on which perioperative interventions are most effective at reducing this risk.
Faruqi S, Fahim A, Morice AH. Chronic cough and obstructive sleep apnoea: reflux-associated cough hypersensitivity? Eur Respir J 2012;40:1049-1050. doi:10.1183/09031936.00025012
Obstructive sleep apnoea (OSA) is being increasingly recognised as a cause of chronic cough. The impact of continuous positive airway pressure (CPAP) therapy and the mechanism of this association are not well understood. We describe a patient with OSA and chronic cough who responded well to CPAP. Objective and subjective assessments of cough on treatment with CPAP, off CPAP and on follow-up as well as pharyngeal pH monitoring suggest a possible mechanism for this association.
Birring SS, Ing AJ, Chan K, et al. Obstructive sleep apnoea: a cause of chronic cough. Cough 2007;3:7.
Chronic cough is a common reason for presentation to both general practice and respiratory clinics. In up to 25% of cases, the cause remains unclear after extensive investigations. We report 4 patients presenting with an isolated chronic cough who were subsequently found to have obstructive sleep apnoea. The cough improved rapidly with nocturnal continuous positive airway pressure therapy. Further studies are required to investigate the prevalence of coexistence of these common conditions.
磯野史朗. ピットフォール 乳幼児突然死症候群(SIDS)の病態生理 最近の概念. 呼吸(0286-9314) 2012;31:259-263.
Hendricks JC, Kline LR, Kovalski RJ, et al. The English bulldog: a natural model of sleep-disordered breathing. J Appl Physiol 1987;63:1344-1350. （PDFあり）
To establish a natural model of sleep-disordered breathing, we investigated respiration during wakefulness and sleep in the English bulldog. This breed is characterized by an abnormal upper airway anatomy, with enlargement of the soft palate and narrowing of the oropharynx. During sleep, the animals had disordered respiration and episodes of O2 desaturation. These were worst in rapid-eye-movement (REM) sleep, with most bulldogs having O2 saturations of less than 90% for prolonged durations. In contrast, control dogs never desaturated. In REM sleep, the bulldogs had episodes of both central and obstructive apnea, the latter being associated with paradoxical movements of the rib cage and abdomen. During wakefulness, the bulldogs were hypersomnolent as evidenced by a shortened sleep latency (mean of 12 min compared with greater than 150 min for controls). This animal model should facilitate studies of the natural history of the sleep apnea syndrome and its complications.
城下幸仁. 【犬と猫の睡眠】 睡眠時無呼吸症. MVM 2018;27:26-37.
Hinchliffe TA, Liu NC, Ladlow J. Sleep-disordered breathing in the Cavalier King Charles spaniel: A case series. Vet Surg 2018. http://doi org/10.1111/vsu.13148 （PDF）
OBJECTIVE: To describe sleep-disordered breathing (SDB) in the Cavalier King Charles spaniel (CKCS).
STUDY DESIGN: Retrospective case series.
ANIMALS: Five client-owned dogs referred for SDB.
METHODS: Medical records were reviewed including recheck appointments and routine preoperative and postoperative questionnaires. Whole-body barometric plethysmography was used to categorize SDB.
RESULTS: All dogs presented with multiple episodes of stertorous breathing, choking, and apnea during sleep. Severe nasal septal deviation, aberrant nasal turbinates, and soft palate elongation and thickening were noted on computed tomography and rhinoscopy of each dog. Whole-body barometric plethysmography measurements during sleep (in 3 dogs) documented periods of choking, snoring, and apnea. Treatment combined laser turbinectomy, folding flap palatoplasty, tonsillectomy, laryngeal sacculectomy, and cuneiform process resection. All dogs improved in terms of incidence and severity of sleep apnea within 1 week, with 4 of 5 dogs achieving complete resolution.
CONCLUSION: The objective measurements used to characterize SDB in this population of CKCS provided some evidence to support an obstructive cause for this condition, which improved with surgical treatment.
CLINICAL SIGNIFICANCE: Sleep-disordered breathing in the CKCS is a different clinical presentation of brachycephalic obstructive airway syndrome. Our finding of intranasal abnormalities in these 5 dogs with SDB provides justification for future research into its clinical significance.
Meira C, Joerger FB, Kutter APN, et al. Comparison of three continuous positive airway pressure (CPAP) interfaces in healthy Beagle dogs during medetomidine-propofol constant rate infusions. Vet Anaesth Analg 2018;45:145-157. doi: 10.1016/j.vaa.2017.11.001
OBJECTIVE: To compare the efficacy of three continuous positive airway pressure (CPAP) interfaces in dogs on gas exchange, lung volumes, amount of leak during CPAP and rebreathing in case of equipment failure or disconnection. STUDY DESIGN: Randomized, prospective, crossover, experimental trial. ANIMALS: Ten purpose-bred Beagle dogs. METHODS: Dogs were in dorsal recumbency during medetomidine-propofol constant rate infusions, breathing room air. Three interfaces were tested in each dog in a consecutive random order: custom-made mask (M), conical face mask (FM) and helmet (H). End-expiratory lung impedance (EELI) measured by electrical impedance tomography was assessed with no interface (baseline), with the interface only (No-CPAP for 3 minutes) and at 15 minutes of 7 cmH2O CPAP (CPAP-delivery). PaO2 was assessed at No-CPAP and CPAP-delivery, partial pressure of inspired carbon dioxide (PICO2; rebreathing assessment) at No-CPAP and the interface leak (DeltaPleak) at CPAP-delivery. Mixed-effects linear regression models were used for statistical analysis (p<0.05). RESULTS: During CPAP-delivery, all interfaces increased EELI by 7% (p<0.001). Higher DeltaPleak was observed with M and H (9 cmH2O) in comparison with FM (1 cmH2O) (p<0.001). At No-CPAP, less rebreathing occurred with M (0.5 kPa, 4 mmHg) than with FM (1.8 kPa, 14 mmHg) and with H (1.4 kPa, 11 mmHg), but also lower PaO2 was measured with M (9.3 kPa, 70 mmHg) than with H (11.9 kPa, 90 mmHg) and FM (10.8 kPa, 81 mmHg). CONCLUSIONS AND CLINICAL RELEVANCE: All three interfaces can be used to provide adequate CPAP in dogs. The leak during CPAP-delivery and the risk of rebreathing and hypoxaemia, when CPAP is not maintained, can be significant. Therefore, animals should always be supervised during administration of CPAP with any of the three interfaces. The performance of the custom-made M was not superior to the other interfaces.
Briganti A, Melanie P, Portela D, et al. Continuous positive airway pressure administered via face mask in tranquilized dogs. J Vet Emerg Crit Care (San Antonio) 2010;20:503-508.
OBJECTIVE: To evaluate the tolerance of a continuous positive airway pressure (CPAP) mask in tranquilized dogs and compare PaO(2) in arterial blood in dogs receiving oxygen with a regular face mask or CPAP mask set to maintain a pressure of 2.5 or 5 cm H(2)O. DESIGN: Prospective, randomized clinical study. SETTING: University teaching hospital. ANIMALS: Sixteen client-owned dogs without evidence of cardiopulmonary disease were studied. INTERVENTIONS: Eight animals were randomly assigned to each of 2 treatment groups: group A received 2.5 cm H(2)O CPAP and group B received 5 cm H(2)O CPAP after first receiving oxygen (5 L/min) by a regular face mask. Animals were tranquilized with acepromazine 0.05 mg/kg, i.v. and morphine 0.2 mg/kg, i.m.. An arterial catheter was then placed to facilitate blood sampling for pHa, PaO(2), and PaCO(2) determinations before and after treatments. Direct mean arterial pressure, heart rate, respiratory rate, and temperature were also recorded after each treatment. MEASUREMENTS AND MAIN RESULTS: CPAP administration was well tolerated by all animals. The mean arterial pressure, heart rate, respiratory rate, temperature, PaCO(2), and pHa, did not differ at any time point between groups. Differences were seen in oxygenation; in group A, PaO(2) significantly increased from a mean of 288.3 +/- 47.5 mm Hg with a standard mask to a mean of 390.3 +/- 65.5 mm Hg with the CPAP mask and in group B, PaO(2) increased similarly from 325.0 +/- 70.5 to 425.2 +/- 63.4 mm Hg (P<0.05); no differences were detected between the 2 CPAP treatments. CONCLUSIONS: In healthy tranquilized dogs noninvasive CPAP is well tolerated and increases PaO(2) above values obtained when using a regular face mask.
Staffieri F, Crovace A, De Monte V, et al. Noninvasive continuous positive airway pressure delivered using a pediatric helmet in dogs recovering from general anesthesia. J Vet Emerg Crit Care (San Antonio) 2014;24:578-585.
OBJECTIVE: To evaluate the feasibility and efficacy of noninvasive continuous positive airway pressure (CPAP) administered with a pediatric helmet in healthy dogs recovering from general anesthesia. DESIGN: Randomized, cross-over, clinical study. SETTING: University teaching hospital. ANIMALS: Fifteen healthy female, client-owned dogs recovering from general anesthesia following elective ovariohysterectomy. INTERVENTIONS: All dogs received the same standardized anesthetic protocol (acepromazine, morphine, propofol, and isoflurane in oxygen). After extubation, a pediatric helmet was placed on all dogs and connected to a venturi valve supplied with medical air. In all patients, the gas flow was set to 50 L/minute and the FiO2 to 0.21. Dogs received the following sequence of treatments, each lasting 20 minutes: 0 CPAP (pre-CPAP), CPAP of 5 cm H2 O (CPAP), and again 0 CPAP (post-CPAP). MEASUREMENTS AND MAIN RESULTS: During the entire study, the following data were collected: pressure and FiO2 inside the helmet, mean arterial pressure, respiratory rate, heart rate, sedation score (0 = awake, 10 = deep sedation), and tolerance to the helmet (0 = excellent, 4 = poor). At the end of each phase, an arterial blood sample was sampled. As compared with the pre-CPAP and the post-CPAP periods, during the CPAP period, the PaCO2 , alveolar-arterial oxygen gradient (P[A-a]O2 ), and respiratory rate significantly decreased. The PaO2 was higher at CPAP (105.6 +/- 4.0 mm Hg) compared with pre-CPAP (80.6 +/- 6.9 mm Hg) and post-CPAP (86.7 +/- 5.8 mm Hg). Tolerance and sedation scores during the CPAP period were not different from those in the pre-CPAP and post-CPAP periods. CONCLUSIONS: Noninvasive CPAP applied through a helmet is a feasible and effective supportive technique in dogs recovering from general anesthesia.
城下幸仁. 時間軸で考える短頭種気道症候群. 中島尚志編集. 時間軸で考える獣医外科病態生理学. 東京: インターズー, 2018;24-37.
Gruenheid M, Aarnes TK, McLoughlin MA, et al. Risk of anesthesia-related complications in brachycephalic dogs. J Am Vet Med Assoc 2018;253:301-306. (PDF)
OBJECTIVE To determine whether brachycephalic dogs were at greater risk of anesthesia-related complications than nonbrachycephalic dogs and identify other risk factors for such complications. DESIGN Retrospective cohort study.
ANIMALS 223 client-owned brachycephalic dogs undergoing general anesthesia for routine surgery or diagnostic imaging during 2012 and 223 nonbrachycephalic client-owned dogs matched by surgical procedure and other characteristics.
PROCEDURES Data were obtained from the medical records regarding dog signalment, clinical signs, anesthetic variables, surgery characteristics, and complications noted during or following anesthesia (prior to discharge from the hospital). Risk of complications was compared between brachycephalic and nonbrachycephalic dogs, controlling for other factors.
RESULTS Perianesthetic (intra-anesthetic and postanesthetic) complications were recorded for 49.1% (n = 219) of all 446 dogs (49.8% [111/223] of brachycephalic and 48.4% [108/223] of nonbrachycephalic dogs), and postanesthetic complications were recorded for 8.7% (39/446; 13.9% [31/223] of brachycephalic and 3.6% [8/223] of nonbrachycephalic dogs). Factors associated with a higher perianesthetic complication rate included brachycephalic status and longer (vs shorter) duration of anesthesia; the risk of perianesthetic complications decreased with increasing body weight and with orthopedic or radiologic procedures (vs soft tissue procedures). Factors associated with a higher postanesthetic complication rate included brachycephalic status, increasing American Society of Anesthesiologists status, use of ketamine plus a benzodiazepine (vs propofol with or without lidocaine) for anesthetic induction, and invasive (vs noninvasive) procedures.
CONCLUSIONS AND CLINICAL RELEVANCE Controlling for other factors, brachycephalic dogs undergoing routine surgery or imaging were at higher risk of peri- and postanesthetic complications than nonbrachycephalic dogs. Careful monitoring is recommended for brachycephalic dogs in the perianesthetic period.
Ree JJ, Milovancev M, MacIntyre LA, et al. Factors associated with major complications in the short-term postoperative period in dogs undergoing surgery for brachycephalic airway syndrome. Can Vet J 2016;57:976-980. https://www.ncbi.nlm.nih.gov/pubmed/27587891
Surgical correction of brachycephalic airway syndrome (BAS) in dogs has been reported to result in low complication rates and good long-term outcomes. Previous reports have not identified risk factors for the development of complications following BAS surgery. This retrospective study evaluated a wide variety of patient- and procedure-related, pre-operative, intra-operative, and post-operative factors for an association with the development of major postoperative complications in the short-term period following BAS surgery. The overall major complication rate, including death or euthanasia, was 4/55 (7%) dogs. Temporary tracheostomy was the only major surgical complication identified (n = 3). Multiple logistic regression identified postoperative radiographic evidence of pneumonia as associated with the development of any major complication overall, requirement of a temporary tracheostomy postoperatively, and death or euthanasia, within the short-term postoperative period. Future prospective studies should evaluate specific risk factors for an association with major complications following BAS surgery in dogs to improve patient outcomes.
非短頭種の咽頭閉塞性疾患「咽頭気道閉塞症候群、Pharyngeal airway obstruction syndrome (PAOS)」
城下幸仁、稲葉健一：咽頭気道閉塞症候群89例. 第39回動物臨床医学会年次大会プロシーディングno.3 2018:18-22.
コメント：2009.1~2013.10の犬・猫の呼吸器科（旧：相模が丘動物病院 呼吸器科）初診全例を対象とした。データ集計後、5年が経過しているが、本研究結果の矛盾する所見は未だに得られておらず、犬の上気道閉塞の一疾患としてのentityとして妥当であると考えられる（犬・猫の呼吸器科 城下幸仁-2018.11.28）。
Lopata M, Onal E. Mass loading, sleep apnea, and the pathogenesis of obesity hypoventilation. Am Rev Respir Dis1982;126:640-645.
To define the roles of mechanical loading, respiratory neuromuscular control, and sleep apnea in the pathogenesis of obesity hypoventilation, respiratory muscle drive and output, assessed by diaphragmatic electromyogram (EMGdi) and mouth occlusion pressure (P 0.15), respectively, were determined during CO2 chemostimulation in nonobese volunteers who were subjected to abdominal mass loading, and in three groups of markedly obese patients: eucapnic obese without sleep apnea (O), eucapnic obese with sleep apnea (OSA), and hypercapnic obese with sleep apnea (OH). The P0.15 responses were decreased in OSA and OH, but the EMGdi responses were not significantly different from those in control subjects. In O patients EMGdi responses were significantly greater than those in control subjects as well as those in OSA and OH patients. EMGdi and P0.15 responses increased in all nonobese subjects when they were subjected to mass loading. We conclude that both OSA and OH patients were equally unable to develop the expected increase in respiratory muscle drive and output. The presence of sleep apnea, possibly by causing nocturnal hypoxemia and/or sleep fragmentation, may result in impaired mass load compensation and predispose obese patients to develop hypercapnia.
Horner RL, Mohiaddin RH, Lowell DG, et al. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. Eur Respir J1989;2:613-622.
It has been suggested that deposition of fat in the soft tissues surrounding the upper airway may be an important factor in the pathogenesis of obstructive sleep apnoea (OSA) in obese subjects. We have used magnetic resonance imaging to determine the site(s) and size(s) of fat deposits around the upper airway in six obese patients with OSA (116-153% of ideal body weight) and five weight-matched controls without OSA (107-152% of ideal body weight). In all subjects, large deposits of fat were present postero-lateral to the oropharyngeal airspace at the level of the soft palate. Significantly more fat was present in these regions in the patients with OSA (p = 0.03). Fat deposits in the soft palate were observed in 4 of the 6 patients with OSA but none of the controls. Fatty streaks were observed in the tongue in 2 of the 5 controls and 3 of the 6 patients with OSA. Fat deposits were observed anterior to the laryngopharyngeal airspace, in submental regions, in all obese subjects. This study shows that more fat is present in those areas surrounding the collapsible segment of the pharynx in patients with OSA, compared to equally obese control subjects without OSA.
Ryan CF, Love LL. Mechanical properties of the velopharynx in obese patients with obstructive sleep apnea. Am J Respir Crit Care Med1996;154:806-812.
Epidemiologic data indicate that the relationship between obesity and obstructive sleep apnea (OSA) is largely explained by variation in neck size. Fat deposits in the neck may predispose to upper airway (UA) occlusion during sleep by altering the mechanical properties of the UA, particularly at the level of the velopharynx (VP). To determine whether effective compliance (CEFF) of the VP is related to obesity in the neck, we have performed anthropometrics, polysomnography, and dynamic UA videoendoscopy in 18 patients with OSA and eight nonapneic control subjects. Following topical anesthesia (cocaine 4%) to one nasal passage, subjects were examined with a thin fiberscope (outer diameter [OD] 3.8 mm) while awake, supine, breathing exclusively through the nose, during a maximal vital capacity (VC) maneuver against an unoccluded airway. UA cross-sectional area (CSA), anteroposterior (AP) and lateral (L) diameters were measured from stored images. CEFF was expressed as the ratio of CSAVP in expiration (E) to inspiration (I) during the maximal VC maneuver (expiratory CSAMAX/inspiratory CSAMIN), and airway shape as AP/L diameter. The OSA patients were divided into two groups based on median neck circumference (NC). CEFF of the VP was greater in OSA patients compared with control subjects (CEFF 2.0 +/- 0.8 versus 1.1 +/- 0.5; p < 0.001). CEFF was greater in the large NC group compared with both the small NC group (p < 0.05) and control subjects (p < 0.01), but the difference between the small NC group and control subjects was not significant. CEFF was related to NC (r = 0.63; p = 0.001; n = 26), body mass index (r = 0.54; p < 0.01, n = 26), and apnea-hypopnea index (r = 0.43; p < 0.05; n = 23). The change in CSAVP during the maximal VC maneuver was mainly due to inspiratory narrowing. Obese patients with large necks have a more collapsible velopharynx during wakefulness, which may predispose to upper airway obstruction during sleep.
Peppard PE, Young T, Palta M, et al. Longitudinal study of moderate weight change and sleep-disordered breathing. JAMA2000;284:3015-3021.
CONTEXT: Excess body weight is positively associated with sleep-disordered breathing (SDB),a prevalent condition in the US general population. No large study has been conducted of the longitudinal association between SDB and change in weight. OBJECTIVE: To measure the independent longitudinal association between weight change and change in SDB severity. DESIGN: Population-based, prospective cohort study conducted from July 1989 to January 2000. SETTING AND PARTICIPANTS: Six hundred ninety randomly selected employed Wisconsin residents (mean age at baseline, 46 years; 56% male) who were evaluated twice at 4-year intervals for SDB. MAIN OUTCOME MEASURES: Percentage change in the apnea-hypopnea index (AHI; apnea events + hypopnea events per hour of sleep) and odds of developing moderate-to-severe SDB (defined by an AHI > or =15 events per hour of sleep), with respect to change in weight. RESULTS: Relative to stable weight, a 10% weight gain predicted an approximate 32% (95% confidence interval [CI], 20%-45%) increase in the AHI. A 10% weight loss predicted a 26% (95% CI, 18%-34%) decrease in the AHI. A 10% increase in weight predicted a 6-fold (95% CI, 2.2-17.0) increase in the odds of developing moderate-to-severe SDB. CONCLUSIONS: Our data indicate that clinical and public health programs that result in even modest weight control are likely to be effective in managing SDB and reducing new occurrence of SDB.
Namyslowski G, Scierski W, Mrowka-Kata K, et al. Sleep study in patients with overweight and obesity. J Physiol Pharmacol2005;56 Suppl 6:59-65.
Obstructive sleep apnea syndrome (OSAS) is a disorder characterized by repetitive collapse of the pharyngeal airway during sleep, which leads to oxygen desaturation, sleep fragmentation and daytime somnolence. Obesity is one of the most important risk factor for the development of OSAS. The exact mechanisms responsible for the relationship between obesity and OSAS are still unclear. The fat deposits in the pharynx region as well as the reduction in the lung volume have been considered as factors that might be responsible for the increase of the upper airway collapsibility. The aim of our study was to evaluate the correlation between the Body Mass Index (BMI) and sleep study parameters in overweight and obese patients suffering from breathing disturbances during sleep. In all cases, BMI and sleep studies (PolyMESAM) were examined. We evaluated relationship between the BMI and sleep study parameters such as Respiratory Disturbance Index (RDI), Apnea Index (AI), Desaturation Index (DI) and Average of Lowest Saturation (LSAT). The results showed the lack of significant statistical correlations between BMI and all the sleep parameters studied in the overweight patients and the statistical positive correlation between the BMI and RDI in the obese cases. We conclude that BMI determination may be considered as a simple, yet important predictor, of the OSAS in the group of obese patients.
榊原博樹. 睡眠呼吸障害. 日本呼吸器学会肺生理専門委員会編集. 臨床呼吸機能検査 第７版. 東京: メディカルレビュー社, 2008;224-245.
磯野史朗. 【睡眠時無呼吸 最近の進歩と展望】 睡眠時無呼吸の病態生理と呼吸調節 閉塞型睡眠時無呼吸 咽頭閉塞とその周期性のメカニズム. 最新医学2009;64:14-21.
Brennick MJ, Pack AI, Ko K, et al. Altered upper airway and soft tissue structures in the New Zealand Obese mouse. Am J Respir Crit Care Med2009;179:158-169.
RATIONALE: The effect of obesity on upper airway soft tissue structure and size was examined in the New Zealand Obese (NZO) mouse and in a control lean mouse, the New Zealand White (NZW). OBJECTIVES: We hypothesized that the NZO mouse has increased volume of neck fat and upper airway soft tissues and decreased pharyngeal airway caliber. METHODS: Pharyngeal airway size, volume of the upper airway soft tissue structures, and distribution of fat in the neck and body were measured using magnetic resonance imaging (MRI). Dynamic MRI was used to examine the differences in upper airway caliber between inspiration and expiration in NZO versus NZW mice. MEASUREMENTS AND MAIN RESULTS: The data support the hypothesis that, in obese NZO versus lean NZW mice,airway caliber was significantly smaller (P < 0.03), with greater parapharyngeal fat pad volumes (P < 0.0001) and a greater volume of other upper airway soft tissue structures (tongue, P = 0.003; lateral pharyngeal walls, P = 0.01; soft palate, P = 0.02).Dynamic MRI showed that the airway of the obese NZO mouse dilated during inspiration, whereas in the lean NZW mouse, the upper airway was reduced in size during inspiration. CONCLUSIONS: In addition to the increased volume of pharyngeal soft tissue structures, direct fat deposits within the tongue may contribute to airway compromise in obesity. Pharyngeal airway dilation during inspiration in NZO mice compared with narrowing in NZW mice suggests that airway compromise in obese mice may lead to muscle activation to defend upper airway patency during inspiration.
コメント: Dynamic MRI検査。正常マウスに比べ、肥満マウスでは、咽頭周囲脂肪組織が有意に増加した（P < 0.0001）。上気道内構造では、舌（P=0.003）と咽頭側壁（P＝0.01）と軟口蓋（P=0.02）の容積が増加し、咽頭気道径が減少した。さらに、吸気時に、正常マウスの咽頭は咽頭気道径が縮小したのに対し、肥満マウスは咽頭気道が拡張した。肥満マウスでは、上気道開存を維持するため、上気道開大筋活動によって代償している(犬・猫の呼吸器科 城下幸仁-2018.11.28）。
Kim AM, Keenan BT, Jackson N, et al. Tongue fat and its relationship to obstructive sleep apnea. Sleep2014;37:1639-1648.
STUDY OBJECTIVES: The objective of this study was to determine whether tongue fat is increased in obese sleep apneics compared to obese subjects without sleep apnea. We hypothesized that excess fat is deposited in the tongue in obese patients with sleep apnea. DESIGN: Case-control design. SETTING: Academic medical center. PATIENTS: We examined tongue fat in 31 obese controls (apnea-hypopnea index, 4.1 +/- 2.7 events/h) and 90 obese apneics (apnea-hypopnea index, 43.2 +/- 27.3 events/h). Analyses were repeated in a subsample of 18 gender-, race-, age-, and BMI-matched case-control pairs. INTERVENTIONS: All subjects underwent a MRI with three-point Dixon magnetic resonance imaging. We used sophisticated volumetric reconstruction algorithms to study the size and distribution of upper airway fat deposits in the tongue and masseter muscles within apneics and obese controls. MEASUREMENTS AND RESULTS: The data supported our a priori hypotheses that after adjustment for age, BMI, gender, and race, the tongue in apneics was significantly larger (P = 0.001) and had an increased amount of fat (P = 0.002) compared to controls. Similar results were seen in our matched sample. Our data also demonstrate that within the apneic and normal tongue, there are regional differences in fat distribution, with larger fat deposits at the base of the tongue. CONCLUSIONS: There is increased tongue volume and deposition of fat at the base of tongue in apneics compared to controls. Increased tongue fat may begin to explain the relationship between obesity and obstructive sleep apnea.
Upper Airway, fat deposits: 12 refs
Upper Airway, fat deposits, dog: 0 refs
Upper Airway, fat deposits, veterinary: 0 refs
Hawkins EC. Pulmonary parenchymal diseases In: Ettinger SJ,Feldman EC, eds. Textbok of Veterinary Internal Medicine. 5th ed. Philadelphia, 2000;1061-1091.
”The benefical effects of weight reduction in animals with chronic bronchial or pulmonary disease can be dramatic.”
コメント：人の「肥満低換気症候群（obesity-hypoventilation syndrome, OHS）=Pickwickian Syndrome」と関連付けて、肺実質疾患と肥満との関連について経験的に記載していた（犬・猫の呼吸器科 城下幸仁-2018.11.28）。
Wolfsheimer KJ. Obesity In: Ettinger SJ,Feldman EC, eds. Textbok of Veterinary Internal Medicine. 5th ed. Philadelphia, 2000;70-72.
Kuehn NF. Chronic Bronchitis in Dogs In: King LG, ed. Textbook of Respiratory Disease in Dogs and Cats. St.Louis: SAUNDERS, 2004;379-387.
Mason RA. Tracheal hypoplasia In: King LG, ed. Textbook of Respiratory Diseases in Dogs and Cats. St.Louis: SAUNDERS, 2004;356-359.
Hendrick JC. Sleep Disorders In: Ettinger SJ,Feldman EC, eds. Textbook of Veterinary Internal Medicine. 6th ed. St. Louis, MO: Elsevier Saunders, 2005;176-181.
Similar signs as BAS associated sleep apnea have been described by owners of Shar Peis, pugs, beagles, and an obese, hypothyroid miniature poodle with obvious upper airway narrowing due to fat accumulation. This anecdotal evidence suggests that sleep apnea exists in several canine breeds.
Remillard RL. Obesity In: Ettinger SJ,Feldman EC, eds. Textbook of Veterinary Internal Medicine. 6th ed. St. Louis, MO: Elsevier Saunders, 2005;76-78.
コメント：肥満動物では、呼吸困難やうっ血性心不全がよく認められる。BCS 4-5/9の犬は、同じように生活し同じ食事を食べているBCS 6-7/9の犬より、15％長生きした、と記載していた（犬・猫の呼吸器科 城下幸仁-2018.11.28）
城下幸仁. 短頭種気道症候群の治療 病態生理に基づく周術期管理と術式選択. 日本獣医麻酔外科学雑誌 2016;47:104-107.
Stern-Bertholtz W, Sjostrom L, Hakanson NW. Primary secretory otitis media in the Cavalier King Charles spaniel: a review of 61 cases. J Small Anim Pract2003;44:253-256.
Sixty-one episodes of primary secretory otitis media (PSOM) were diagnosed in 43 Cavalier King Charles spaniels over a 10-year period. The principal findings were signs of moderate to severe pain localised to the head or cervical area, and/or neurological signs. Diagnosis was made by examination of the tympanic membrane and middle ear with the aid of an operating microscope under general anaesthesia. A bulging, but intact, tympanic membrane was found in most cases. Following myringotomy, a highly viscous mucus plug was found filling the middle ear. Treatment, consisting of removal of the mucus plug, flushing of the middle ear, and local and systemic medical therapy, had to be repeated between one and five times. The prognosis was good in all cases. PSOM is an important differential diagnosis in Cavalier King Charles spaniels with signs of pain involving the head and neck, and/or neurological signs.
Hayes GM, Friend EJ, Jeffery ND. Relationship between pharyngeal conformation and otitis media with effusion in Cavalier King Charles spaniels. Vet Rec2010;167:55-58.
Otitis media with effusion (OME) is a common incidental finding in otherwise normal Cavalier King Charles spaniels (CKCS). In this study, measurements made on MRI were used to determine whether there was an association between OME and brachycephalic conformation. The results confirm that association and also demonstrate that, in CKCS, greater thickness of the soft palate and reduced nasopharyngeal aperture are significantly associated with OME. These results suggest that auditory tube dysfunction and OME may represent a previously overlooked consequence of brachycephalic conformation in dogs.
Harcourt-Brown TR, Parker JE, Granger N, et al. Effect of middle ear effusion on the brain-stem auditory evoked response of Cavalier King Charles Spaniels. Vet J2011;188:341-345.
Brain-stem auditory evoked responses (BAER) were assessed in 23 Cavalier King Charles Spaniels with and without middle ear effusion at sound intensities ranging from 10 to 100 dB nHL. Significant differences were found between the median BAER threshold for ears where effusions were present (60 dB nHL), compared to those without (30 dB nHL) (P=0.001). The slopes of latency-intensity functions from both groups did not differ, but the y-axis intercept when the x value was zero was greater in dogs with effusions (P=0.009), consistent with conductive hearing loss. Analysis of latency-intensity functions suggested the degree of hearing loss due to middle ear effusion was 21 dB (95% confidence between 10 and 33 dB). Waves I-V inter-wave latency at 90 dB nHL was not significantly different between the two groups. These findings demonstrate that middle ear effusion is associated with a conductive hearing loss of 10-33 dB in affected dogs despite the fact that all animals studied were considered to have normal hearing by their owners.
青木忍. 外耳・中耳からみた短頭種気道症候群. 動物臨床医学会年次大会プロシーディングno.1. 2018 :23-26.
Harvey CE, O’Brien JA. Tracheostomy in the dog and cat: analysis of 89 episodes in 79 animals. J Am Anim Hosp Assoc 1982;18:563-566. （PDFあり）
Tracheotomy was performed 89 times on 79 dogs and cats at VHUP from 1970 to 1980. Curved metal tubes were placed through a transverse incision between tracheal rings. The most common indication was upper airway obstruction or surgery for upper airway disease. Tube plugging or displacement, gagging, vomiting, and coughing were the most frequent complications. One of two dogs which developed partial tracheal stenosis subsequently died of respiratory obstruction.
Nicholson I, Baines S. Complications associated with temporary tracheostomy tubes in 42 dogs (1998 to 2007). J Small Anim Pract 2012;53:108-114.
OBJECTIVE: To identify the type and frequency of tracheostomy tube complications, and to determine factors associated with these complications, and with poor outcome. METHODS: A database search for dogs undergoing temporary tube tracheostomy was performed. The medical records were scrutinised. The signalment, respiratory disease history, diagnosis, surgery, type and frequency of tube care procedures, type of complications and outcome were recorded. RESULTS: Forty-two records were found. Complications occurred in 36 of 42 (86%) cases. Bulldogs were more likely to dislodge the tube than other breeds (P=0.0376), and cases with three or more complication types underwent more routine care procedures than those with fewer complications (P=0.0370). Thirty-four of 42 (81%) dogs had a successfully managed tracheostomy tube and survived until tube removal, or elective euthanasia without significant tube complications. Bulldogs were also significantly (P=0.0376) more likely to have an unsuccessful tube outcome, as were dogs experiencing severe bradycardia during treatment (P=0.0176). Dogs with unsuccessful tube outcome were significantly (P=0.0331) younger than dogs with successful tube outcome. CLINICAL SIGNIFICANCE: Tracheostomy tubes in dogs have a high complication rate but a good outcome in most dogs. Careful management may improve the outcome of dogs with tracheostomy tubes, especially bulldogs and dogs exhibiting bradycardia during treatment.
Hedlund CS, Tangner CH, Montgomery DL, et al. A Procedure for Permanent Tracheostomy and Its Effects on Tracheal Mucosa. Vet Surg 1982;11:13-17. (PDFあり）
Permanent tracheostomies were performed on six dogs which were evaluated clinically and histologically. One dog had abnormal tracheal cartilages and died following tracheal collapse three days postoperatively. Problems with coughing, swallowing, and infection were not noted in the remaining five dogs. The exposed tracheal epithelium temporarily underwent squamous metaplasia but returned to a relatively normal appearance within 16 weeks.
Gobbetti M, Romussi S, Buracco P, et al. Long-term outcome of permanent tracheostomy in 15 dogs with severe laryngeal collapse secondary to brachycephalic airway obstructive syndrome. Vet Surg 2018;47:648-653. doi: 10.1111/vsu.12903
OBJECTIVE: To report the long-term outcome of permanent tracheostomy for the management of severe laryngeal collapse secondary to brachycephalic airway obstructive syndrome. STUDY DESIGN: Retrospective case series. ANIMALS: Fifteen brachycephalic dogs with severe laryngeal collapse treated with permanent tracheostomy. METHODS: Follow-up data were obtained from medical records or via telephone conversation with the owners. The Kaplan-Meier estimator was used to calculate median survival time. Death was classified as related or unrelated to tracheostomy surgery. Complications were classified as major when they were life-threatening or required revision surgery. Owners were asked to classify the postoperative quality of life as improved, unchanged, or worse and the management of the stoma as simple or demanding. RESULTS: The median survival time was 100 days. Major complications were diagnosed in 12 of 15 (80%) dogs, resulting in death in 8 (median survival time 15 days) and revision surgery in 4 dogs. Seven of 15 (47%) dogs died of unrelated causes or were alive at the end of the study (median survival time 1982 days). The postoperative quality of life of 9 dogs was judged as markedly improved. Stoma management was defined as simple in 8 dogs and demanding in 4. CONCLUSION: Permanent tracheostomy was associated with a high risk of complications and postoperative death in brachycephalic dogs. However, long-term survival (exceeding 5 years) with a good quality of life was documented in 5 of 15 dogs. CLINICAL SIGNIFICANCE: Permanent tracheostomy is a suitable salvage option in brachycephalic dogs with severe laryngeal collapse that did not improve following more conservative surgeries.
コメント；BAOSによる喉頭虚脱グレード3の犬15頭に対して永久気管切開を実施した回顧的研究。標準的外科手術（軟口蓋切除、外鼻孔切除、喉頭小嚢切除）で改善しなかった症例に対して適応。粘液プラグや皮膚皺による閉塞などの重大な合併症が80％で発生し死亡率も高いが、術後20週以内に集中し、その期間を乗り越えた症例の長期予後は良好（いいのペットクリニック 飯野 亮太-2019.2.7）。
Edens ET, Venker-van Haagen AJ. Experiences with the silicone T-tube in man and dog. Vet Q 1986;8:334-338. （PDFあり）
Silicone T-tubes are particularly useful for long-term stenting of the laryngotracheal airway. Silicone is useful when non-autogenous non-reactive soft material is wanted for use in the human and animal body. Two case reports illustrate the use of the silicone T-tube.