Sniff to see. Comparing sniffing position versus simple head extension position for glottic exposure - A prospective, randomized cross over study

Abstract

Background: Traditional teaching dictates that direct laryngoscopy is best performed with the patient's head in the sniffing position. However, of late, many authors have challenged this concept. In a recent meta-analysis, based on studies involving 2759 participants researchers have found that sniffing position affords no added advantage over simple head extension. Our study highlights an important scientific fact overlooked in all previously done studies on the subject. Aim: We aimed to compare sniffing position and simple head extension position for ease of laryngoscopic intubation using an interval scale. Materials and Methods: A prospective single-blind crossover study of 200 patients, where glottic exposure in both positions was compared in the same patient using Cormack-Lehane (CL) grading and percentage of glottic opening (POGO) score. Intubation difficulty was compared using the intubation difficulty score. Results: In every study, CL grading, an ordinal scale, has been used for comparison of glottic exposure. In our set of patients, CL grading showed 'no change' in glottic exposure quality in 85% of the laryngoscopies. When we used POGO system of classification which is an interval scale, for the same laryngoscopies in the same patients, sniffing position improved exposure in 106 patients, whereas simple head extension position improved exposure in 76 patients. Only 18 patients showed no glottic exposure. Statistical Analysis: Two-sample Wilcoxon rank-sum (Mann-Whitney) test and Chi-square tests showed sniffing position to be significantly better position for glottic exposure and for ease of intubation. Conclusion: Sniffing position provides better glottis exposure and it is easier to intubate a patient in the sniffing position as compared to simple head extension position. Sniffing position should therefore be used as initial position when attempting intubation.