Diagnostic Value of Neck Circumference and Sternomental Distance for Difficult Intubation in Patients Undergoing Cesarean Section

Introduction: Airway safety for difficult intubation or failure to intubate is important during anesthesia. This study assessed the airway before anesthesia, and the diagnostic value of neck circumference (NC) and sternomental distance (SMD) tests was investigated in predicting difficult tracheal intubation during cesarean section.Methods: In a cross-sectional study, ۱۰۱ women who were candidates for cesarean section were selected through the convenience and non-random sampling method. The modified Mallampati test (MMT), upper lip bite (ULBT), thyromental distance (TMD), neck circumference (NC), and sternomental distance (SMD) tests were performed to estimate the laryngoscopy problem. The success rate of airway assessment by SMD and NC was evaluated using the Cormack-Lehane score. Data analysis was performed using the software SPSS version ۱۶.۰.Results: TMD (p=۰.۰۳۴) and NC (p<۰.۰۰۱) indicated substantial association with laryngoscopy grades. The sensitivity was ۳۵.۲۹% and ۵۸.۸۲%, and the specificity was ۹۳.۹۳% and ۵۹.۰۹% for NC and SMD. The accuracy, NPV, and PPV of NC was higher than the SMD test (۷۴% vs. ۵۹%, ۷۳.۸۰% vs. ۷۳.۵۸, and ۷۵% vs. ۴۲.۵۵%). The PPV and NPV were ۴۳.۶۳% and ۷۷.۷۷% for TMD. MMT, with high sensitivity (۷۳.۵۲%) and specificity (۹۰.۹۰%), increased the risk of difficult laryngoscopy up to ۲۴-fold when adjusted for TMD, SMD, and NC [p<۰.۰۰۱; OR=۲۴.۳۸ (۶.۳۱-۹۴.۲۵)]. Although NC indicated low sensitivity, it had maximum specificity (۹۳.۹۳%) in predicting difficult intubation.Conclusion: High Mallampati grades increase the risk of difficult laryngoscopy. NC presented low predictive values, and SMD and TMD lack predictive values for difficult intubation.

Keywords:

Cesarean , Neck Circumference , Mallampati , Sternomental distance