Comparative analysis of intubating conditions using channeled and non-channeled video laryngoscopes in supine and 25 degree back-up positions

When administering general anesthesia, tracheal intubation is crucial for maintaining patency of the airway. The ideal head and neck posture for direct laryngoscopy has long been considered to be the "sniffing" position. Endotracheal intubation using video laryngoscopes (VLSs) has become more common due to its ability to reduce the stress response while simultaneously improving laryngeal exposure. But there is still a dearth of information in the literature on the proper head and neck positioning for video-laryngoscopy. The clinical practice makes use of a variety of postures, including the 25° backup position and the supine (neutral or sniffing) position.

Recently published study aimed to compare intubating conditions in the supine (sniffing) and 25º back-up positions using King Vision and McGrath video laryngoscopes. The primary objective was to compare intubating conditions in terms of the modified Intubation Difficulty Scale (mIDS), with secondary comparisons of intubation time, number of attempts, vital parameters, and airway complications in both positions.

Study Procedure and Patient Enrollment The study, conducted at a tertiary healthcare center, enrolled 100 adult patients and randomized them into two groups using computer-generated random numbers. The patients were intubated using either King Vision or McGrath VLS in the supine (sniffing) or 25° back-up positions. The primary outcome measured was the ease of intubation using mIDS, while secondary outcomes included intubation time, number of attempts, vital parameters, and complications.

Study Findings The study found that the 25° back-up position resulted in significantly lower mIDS compared to the supine position when using both King Vision and McGrath VLS. Intubation time was also shorter in the 25° back-up position for both VLSs. Additionally, fewer patients required ancillary maneuvers during intubation in the 25° back-up position compared to the supine position. The study concluded that the 25° back-up position provided easier intubation using both channelled and non-channelled VLS, with less requirement for ancillary maneuvers and shorter intubation time, without complications. The authors also noted that the results cannot be generalized to patients with difficult airways, obese and pregnant patients, or those requiring emergency surgeries, and cautioned that the same results cannot be extrapolated to VLSs other than King Vision and McGrath. They also offered to share de-identified data upon request and confirmed no conflicts of interest. In summary, the study demonstrated the advantages of the 25° back-up position over the supine position for intubating conditions, providing valuable insights for anesthesiologists and researchers in the field.

Reference –

Desai, Devyani; Sompura, Riddhi; Yadav, Sudarshan. Comparison of intubating conditions in supine (sniffing) and 25° back-up position using channelled and non-channelled video laryngoscopes - A randomised controlled study. Indian Journal of Anaesthesia 67(12):p 1090-1095, December 2023. | DOI: 10.4103/ija.ija_662_23