THE AIRWAY - PROBLEMS AND PREDICTIONS IN 18,500 PATIENTS

The purpose of this study was to describe methods, risk factors, and outcomes of airway management in all patients (obstetrics excluded) attended by anaesthetists over 27 months. Preoperatively, anaesthetists recorded patient factors and assessed four airway characteristics. Methods of tracheal intubation and ease of direct laryngoscopy following general anaesthesia (easy, awkward, difficult) were noted. Factors predictive of poor outcome and the value of the preoperative airway examination M ere determined. For 18,205 patients following a direct laryngoscopy (GA), tracheal intubation was difficult (>2 laryngoscopies) in 1.8% and awkward (less than or equal to 2 laryngoscopies) in 2.5%. This approach was a failure in 0.3%, and surgery was postponed in 0.05%. However an alternative approach to direct laryngoscopy (GA) war the first choice in 353 patients. Risk factors for difficult tracheal intubation included male sex, age 40-59 yr and obesity (p less than or equal to 0.01). For direct laryngoscopy, (GA), airway characteristics predictive of difficult tracheal intubation were decreased mouth opening (relative risk 10.3), shortened thyromental distance (9.7), poor visualization of the hypopharynx (4.5), and limited neck extension (3.2), any two (7.6) and more than two (9.4) (P < 0.01). For 1,856 patients (10.0%) where at least one airway characteristic was abnormal, a direct laryngoscopy, (GA) resulted in 8.3% awkward and 6.0% difficult tracheal intubations.