Identification of the difficult airway

Abstract

A difficult airway is one in which the standard procedures and equipment are of reduced effectiveness. Most patients who present serious difficulty have obvious pathology. There are well known causes of difficulty, which are largely due to stiffness, deformity or swelling of the tissues and joints of the head and neck. Difficulty is more often encountered in the old than in the young. Two associated risk factors are a full stomach and heart and lung disease, which limit options and aggravate the hypoxaemia caused by airway difficulty. Identification of obstructing upper airways can be delayed by the common misconceptions that stridor is a constant feature and normal oxygen saturation excludes serious stenosis. Identification of the few normal-looking patients who present difficulty is likely to remain an inaccurate enterprise. The limitations of all ‘screening’ processes must be appreciated. Pathological ranges of movement of the craniocervical junction and temporomandibular joint are hard to identify without generating large numbers of false-positive results. Craniocervical junction extension is a component of mouth opening, so craniocervical rigidity should be suspected in patients with limited mouth opening. The vital questions are: can a seal be achieved with a face mask; will head tilt and jaw thrust be successful; will positive pressure result in lung inflation; what is the interdental distance; is mandibular protrusion possible; is there restricted craniocervical extension?