Transverse forces exerted on the maxillary incisors during laryngoscopy

Abstract

Purpose: In this study the effect of level of experience of the incubator on the forces applied by the Macintosh laryngoscope on the maxillary incisors in both the axial and transverse direction were investigated. Methods: Five groups of different levels of experience (15 per group), staff anaesthetists, residents, nurse anaesthetists, surgeons and students, performed one laryngoscopy and subsequent intubation on an intubation manikin equipped with sensors to measure these forces. Results: Maximal transverse forces oriented toward the base of the skull (Fmtpmax) were between 0 and 10 N in 46 cases (61%), between 10 and 20 N in 21 (28%) and ≤20 N (maximum 46.5 N) in eight cases (11%). The maximal values of the transverse forces oriented toward the incubator (Fmtnmax) were between 0 and 10 N in 69 cases (92%), between 10 and 20 N in 3 (4%) and ≤20 N (maximum 36.4 N) in 3 (4%). Level of experience was related to Fmtpmax (Spearman: P = 0.04, r = 0.24). In addition, Fmtnmax was less in experienced incubators (anaesthetist and residents) than in inexperienced incubators (all other groups) (Student's t test: P = 0.04). Conclusion: In contrast to the effect on forces exerted in the axial direction, experience proved to have a beneficial effect on the forces in the transverse direction.