Randomized study comparing the "sniffing position" with simple head extension for laryngoscopic view in elective surgery patients

Background: The "sniffing position" is recommended for optimization of glot tic visualization under direct laryngoscopy. However, no study to date has confirmed its superiority over simple head extension. In a prospective, ran domized study, the authors compared the sniffing position with simple head extension hi orotracheal intubation. Methods: The study included 456 consecutive patients. The sniffing position was obtained by placement of a 7-cm cushion under the head of the patient. The extension position was obtained by simple head extension. The anesthet ic procedure included two laryngoscopies without paralysis: the first was u sed for topical glottic anesthesia. During the second direct laryngoscopy, intubation of the trachea was performed. The head position was randomized a s follows: group A was in the sniffing position during the first laryngosco py and the extension position during the second, group B was in the extensi on position during the first laryngoscopy and the sniffing position during the second. Glottic exposure was assessed by the Cormack scale. Results: The sniffing position improved glottic exposure (decreased the Cor mack grade) in 18% of patients and worsened it (increased the Cormack grade ) in 11% of patients, in comparison with simple extension. The Cormack grad e distribution was not significantly modified between the two groups. Multi variate analysis showed that reduced neck mobility and obesity were Indepen dently related to improvement in laryngoscopic view with application of the sniffing position. Conclusions: Routine use of the sniffing position appears to provide no sig nificant advantage over simple head extension for tracheal intubation in th is setting. The sniffing position appears to be advantageous in obese and h ead extension-limited patients.