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Transverse forces exerted on the maxillary incisors during laryngoscopy

Abstract

Purpose

In this study the effect of level of experience of the intubator 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 intubator (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 intubators (anaesthetist and residents) than in inexperienced intubators (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.

Résumé

Objectif

Vérifier l’influence de l’expérience de l’intubateur sur les forces appliquées par le laryngoscope Macintosh sur les incisives maxillaires tant dans la direction transversale qu’axiale.

Méthodes

Cinq groupes possédant des degrés variés d’expérience (15 par groupe) anesthésistes, résidents, infirmières anesthésistes, chirurgiens et étudiants ont effectué une laryngoscopie suivie de l’intubation sur un mannequin d’intubation équipé de senseurs capables de mesurer ces forces.

Résultats

Les forces transversales maximales orientées vers la base du crâne (Fmtpmax) se situaient entre 0 et 10 N dans 46 cas (61%), entre 10 et 20 N dans 21 (28%) et ≥ 20 N (maximum 46,5 N) dans huit cas (11%). Les valeurs maximales des forces orientées vers l’intubateur (Fmtnmax) se situaient entre 0 et 10 N dans 69 cas (92%), entre 10 et 20 N dans 3 (4%) et ≥ 20 N (maximum 26,4 N) dans 3 (4%). Le degré d’expérience était en rapport avec Fmtpmax (Spearman: P = 0,04, r = 0,24). De plus, Fmtnmax était plus bas chez les intubateurs expérimentés (anesthésistes et résidents) que chez les intubateurs inexpérimentés (tous les autres groupes) (test t de Student: P = 0,04).

Conclusion

Contrairement aux forces exercées en direction axiale, l’expérience a une influence bénéfique sur les forces exercées en direction transversale.

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Author information

Correspondence to Martin J. L. Bucx.

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Bucx, M.J.L., van der Vegt, M.H., Snijders, C.J. et al. Transverse forces exerted on the maxillary incisors during laryngoscopy. Can J Anesth 43, 665 (1996). https://doi.org/10.1007/BF03017948

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Key words

  • anaesthetic techniques: laryngoscopy
  • equipment: laryngoscopes
  • intubation, tracheal: technique
  • larynx: laryngoscopy