Most anesthesiologists universally recommend the sniffing position and consider it to be essential for improving the performance of orotracheal intubation. However, a recent investigation reported that the sniffing position does not aid the laryngoscope except under specific circumstances (i.e., obesity). Therefore, this study examined the impact of the BMI (body mass index) on the effectiveness of the sniffing position in improving the laryngeal view.

A video laryngoscopy imaging system and POGO (the percentage of glottic opening) scoring system were used to assess the laryngeal view in 79 adult patients undergoing a laryngoscopy. In each patient, the laryngeal view was videotaped continuously from simple head extension to the sniffing position by inflating a pressure bag as a pillow to obtain approximately 15° of flexion of the lower cervical spine on the chest. The variables assessed included the BMI, the POGO score in each position and the change in the POGO score.

The POGO scores improved with the sniffing position (18.1 ± 14.3%). However, the sniffing position did not improve the POGO score in 16/79 (20.3%) patients. The sniffing position did not worsen the POGO score in any patient. No significant correlation was found between the BMI and the change in the POGO score in the sniffing position (Pearson's correlation coefficient r = 0.075).

The sniffing position has the potential to improve the laryngeal view in all intubations without needing to consider the BMI. Therefore, the sniffing position appears to be advantageous for orotracheal intubation compared with a simple head extension.