Neck Circumference as Sole Predictor of Cormack-Lehane Score and Difficult Intubation

Objective: To determine if higher neck circumference correlates with greater Cormack-Lehane score and difficulty in intubation among patients undergoing orthopaedic surgery under general anaesthesia. Study Design: Prospective longitudinal study Place and Duration of Study: Combined Military Hospital, Rawalpindi, Pakistan from April to July, 2021. Methodology: ASA I and II adult patients undergoing elective orthopaedic surgery planned under general anaesthesia who had a neck circumference greater than 40 cm were included in the study. Non-randomized, consecutive sampling was used and all eligible patients during the study period were included. Neck circumference at the level of the thyroid cartilage was measured by the resident during pre-anaesthesia assessment. Modified Cormack-Lehane Score (MCLS) for each patient was determined either by the senior (third or fourth year) resident or the consultant on duty. All intubations were performed either by a senior resident or the consultant. Intubation Difficulty Scale (IDS) score of 5 or more was considered a difficult intubation. Results: 55 patients, of which 28(50.9%) were female, were included in the study. Mean age was 36.89±14.08 years. Mean neck circumference was 43.14±1.63 cm. 37(67.3%) had MCLS grade 2b or higher while 20(36.4%) had IDS score of 5 or higher. Greater neck circumference was found to be significantly associated with a higher MCLS grade (p=0.012) but not with a higher IDS score (p=0.055). Conclusion: Neck circumference could have predictive value for MCLS grade but not directly for IDS score. Further studies are needed to determine utility of NC as sole predictor of difficult intubation.