title: Evaluating the difficult airway. An epidemiological study.
abstract: The epidemiological characteristics of 359 difficult intubations resulted from retrospectively collected data in a series of 4.742 individual anaesthetic case records of consecutive adult patients (2392 men, 2350 women) undergoing general anaesthesia for routine surgery. The preoperative assessment of each patient's airway was performed using standardized guidelines. Mandibular length, body weight and mobility of jaw, head and neck were evaluated with simple measurements. The presence of protruding maxilla or upper teeth, tongue tumor or cyst, long narrow mouth, short muscular neck and deviation of larynx or trachea was based on clinical and/or radiological examination. Severity of difficulty in intubation was estimated on a five-point scale grades (0-4) according to the view obtained at laryngoscopy and the final outcome of airway management. Difficult intubation (grades 1-4) was confirmed in 359 cases (7.6%) of which 208 were anticipated (57.2%). The effectiveness of preoperative evaluation had a positive correlation with the level of difficulty since, the greater the grade of difficulty the greater the sensitivity. The prevalence of failed intubation (grade 4) was 0.5%. Risk factors which had been correlated with the relative size of the tongue proved to have low probability and level of difficulty of intubation. The most important risk factor was limited jaw movement (median grade of difficulty: 4, positive predictive value: 75.0%). Large endemic goitre and thalassaemia constitute RFs contributing occasionally to difficult airway. The positive predictive value was 61.5% and 40.9% respectively. The combination of risk-factors had a cumulative impact contributing to the high level of difficulty.
authors.affiliation: Department of Anesthesiology, University of Athens, Greece.
authors.forename: G S
authors.initials: GS
authors.lastname: Voyagis
authors.forename: K P
authors.initials: KP
authors.lastname: Kyriakis
authors.forename: K
authors.initials: K
authors.lastname: Roussaki-Danou
authors.forename: E A
authors.initials: EA
authors.lastname: Bastounis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000776:Anesthesiology / Q000379:methods*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000453:epidemiology*; D007442:Intubation, Intratracheal; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged