[Prediction of difficult laryngoscopy in the patients undergone cesarean section]

ABSTRACT

Unsuccessful intubations is important cause of anesthetic-related maternal mortality. Therefore, the purpose of this study was to determine the ability to predict difficult visualization of the larynx [DVL] from the following preoperative airway predictive indices modified Mallampati test [MMT], the ratio of height to thyromental distance [RHTMD], and the upper- Lip-Bite test [ULBT]. This prospective and double-blind study was conducted on the patients undergone elective cesarean section under general anesthesia requiring endotracheal intubations. RHTMD, MMT and ULBT tests were used for them prior to the operation. An experienced anesthesiologist, not apprised of the recorded preoperative airway assessment, performed the laryngoscopy and grading [as per Cormack and Lehane's classification]. Then, sensitivity, specificity, positive and negative predictive value, and false negative value for each airway predictor in isolation and in combination were determined. T and Mann Whitney tests were used for comparing of demographic data and comparing among the tests, respectively. Difficult laryngoscopy [Grade 3 or 4] was observed in 35 patients [8.75%]. RHTMD had a higher sensitivity, positive predictive value, and fewer false negatives than the other variables tested. A RHTMD=21.24 provided the best cutoff point for predicting subsequent difficult laryngoscopy. The odds ratio [95% confidence interval] of the RHTMD, Mallampati class, and ULBT were 7.8 [1.21-21.21], 2.1 [1.11-5.60], and 1.5 [0.6-4.1], respectively. The RHTMD may prove a useful screening test for predicting difficult laryngoscopy in obstetric population