The incidence of a difficult laryngoscopy or intubation varies from 1.
5% to 13%, and failed intubation has been identified as one of the ana
esthesia-related causes of death or permanent brain damage. Problems i
n the airway management can be predicted based on previous anaesthesia
records, the medical history of the patient and a physical examinatio
n. Several radiological measurements have been reported to be associat
ed with a difficult intubation. The sensitivities of the commonly used
bedside tests i.e. the Mallampati classification and the thyromental
distance have been reported to be from 42% to 81%, and from 62% to 91%
, respectively. The figures for the specificity have varied from 66% t
o 84% and from 25% to 82%, respectively. The other subjective assessme
nts and objective measurements employed for the prediction of a diffic
ult intubation reach comparable sensitivities and specificities. Evide
ntly, the positive predictive value is improved, if combinations of te
sts are used. (C) Acta Anesthesiol Scandinavica 40 (1996).