Comparison of Inter-Incisor Distance as a Predictor of Difficult Intubation in Men and Women-A Prospective Observational Study.

Background: Most of the studies on difficult intubation and laryngoscopy focused on American and European populations. However, Indians have distinct anthropometric characteristics compared to these populations. This study aims to determine the gender difference in inter-incisor distance (IID) cut-off marks to assess the ease of intubation in the Indian population.

Methods: A prospective observational study was conducted on 516 patients scheduled for elective surgery under general anesthesia with endotracheal intubation. Preoperative assessments included IID, thyromental distance, neck circumference, sternomental distance (SMD), thyrohyoid distance, mentohyoid distance, and modified mallampatti grading. Intubation difficulty scores (IDSs) were assessed during intubation. The optimal cut-off values of inter incisor gap and difficult intubation were analyzed by receiver operating characteristic curve analysis.

Results: The total cohort was grouped into males (Group 1 [n = 258]) and females (Group 2 [n = 258]). Males had a significantly higher mean age (P = 0.04) and weight (P = 0.00) than females. Difficult intubation incidence was 16.3% of males and 6.2% of females. Increased IID (P = 0.039), decreased SMD (P = 0.046), and males (P = 0.002) are identified as predictors of difficult intubation.IID and IDS showed greater specificity than sensitivity, with significant cut-off values of 4.25 and 1.50, respectively.

Conclusion: The cut-off value of IID did not show a significant difference in gender variation. Despite the low IID in females, intubation difficulties were not observed compared to males.