Head elevation improves laryngeal exposure with direct laryngoscopy

Abstract

Study objective: The aim of this study was to examine the effect of changing head position on the laryngeal view in the same subject.

Design: Prospective, randomized, crossover comparison of laryngeal views.

Setting: Operating suite at a university-affiliated, community hospital.

Patients: One hundred sixty-seven consenting adult patients scheduled to undergo elective surgery with general anesthesia.

Interventions: After anesthesia induction and muscle relaxation and the head in extended position, the laryngeal view was graded in 3 different head height positions. A special inflatable pillow was placed under the subject's head before induction and was deflated to produce no head elevation or inflated to produce either 6.0cm (sniffing position), or 10.0cm elevation (elevated sniffing position) in random order.

Main results: The incidence of difficult laryngoscopy (grade ≥3) was 8.38% with no head elevation, 2.39% in the sniffing position, and 1.19% in the elevated sniffing position. Head elevation was not associated with a worse grade in any single patient.

Conclusions: Sniffing position improves glottic exposure when the laryngoscopic grade is greater than 1 in the head-flat position. The elevated sniffing position improves the view to a better grade in some patients. Because head elevation was not associated with a worse grade in any subject, the elevated sniffing position should be considered as the initial head position before direct laryngoscopy when a difficult exposure is anticipated.

Keywords: Direct laryngoscopy; Sniffing position.