Effect of sniffing position versus left head rotation (LeHeR) manoeuvre on glottic visualisation during videolaryngoscopy in patients undergoing elective surgery under general endotracheal anaesthesia- A prospective randomised cross-over study

This thesis aims to compare the effects of the conventional sniffing position versus the left head rotation (LeHeR) manoeuvre on glottic visualization during videolaryngoscopy in patients undergoing elective surgery under general endotracheal anesthesia. The primary objective is to assess and compare the percentage of glottic opening (POGO) score between the two techniques in the same patient, while the secondary objective is to calculate the proportion of patients requiring optimal external laryngeal manipulation (OELM) to achieve a POGO score of at least 50% in each technique.

This will be a randomized, crossover study conducted over 18 months at the Department of Anaesthesia, All India Institute of Medical Sciences (AIIMS), Bathinda, Punjab. The study will involve adult patients aged 18 to 65 years, with a BMI between 18.5 and 35 kg/m², and American Society of Anaesthesiologists (ASA) physical status class I or II, who are undergoing elective surgical procedures requiring general endotracheal intubation. Patients with a variety of exclusion criteria, including significant airway or neck abnormalities, will not be included in the study. The sample size was calculated based on a non-inferiority design, with 192 patients included to account for a 10% dropout rate.

Participants will be randomly assigned to one of two groups using a computer-generated randomization sequence, with each patient undergoing both techniques in a crossover manner, ensuring a washout period between the two procedures to minimize bias. Both techniques will be performed following standard anesthetic induction, which includes the administration of midazolam, lignocaine, propofol, fentanyl, and vecuronium, with pre-oxygenation prior to videolaryngoscopy. In the sniffing position, the patient will be placed in the supine position with a pillow under the occiput to flex the neck and extend the head, while in the LeHeR technique, the patient’s head will be rotated to the left by 45°.

During each laryngoscopy sequence, the POGO score will be recorded, and if the score is less than 50%, optimal external laryngeal manipulation will be applied, with improvements in the POGO score noted. After completing both sequences, endotracheal intubation will be performed, and anesthesia will be maintained with titrated doses of propofol to maintain a Bispectral Index (BIS) between 40 and 60. Data will be collected on the POGO scores and the need for OELM, and analyzed using statistical software (SPSS, version 29) to compare the outcomes of the two techniques.

The results of this study will contribute to a better understanding of how different head positioning techniques affect glottic visualization during videolaryngoscopy and could have implications for improving airway management in clinical practice.

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