Reshaping the Macintosh blade using biomechanical modelling - A prospective comparative study in patients

It has been demonstrated that during routine use of the Macintosh blade, great forces are exerted on the maxillary incisors. The aim of this study was, by using biomechanical modelling, to modify a standard Macintosh blade in order to reduce these forces. This resulted in a Macintosh blade with a reduced proximal flange. Five anaesthetists performed tracheal intubation in 46 patients using the modified (n = 24) or the standard blade (n = 22). The mean (SD) maximal forces exerted on the maxillary incisors were 12.7 (8.8) N in patients in the modified Macintosh group compared to 25.5 (17.8) N in the standard Macintosh group (p = 0.008). These results demonstrate that reducing the proximal step of the Macintosh laryngoscope results in a reduction of the forces exerted on the teeth and suggest that laryngoscope blades with a high proximal step might be more traumatic than blades in which the proximal step is reduced.