Sensitivity of PalmPrint, Modified Mallampati Score and 3-3-2 Rule in Prediction of Difficult Intubation

Abstract

Background: This study evaluated the performance of modified Mallampati score, 3-3-2 rule and palm print in prediction of difficult intubation.

Methods: In a prospective descriptive study, data from 500 patients scheduled for elective surgery under general anesthesia were collected. An anesthesiologist evaluated the airway using mentioned tests and another anesthesiologist evaluated difficult intubation. Laryngoscopic views were determined by Cormack and Lehane score. Grades 3 and 4 were defined as difficult intubation. Sensitivity, specificity, positive predictive value, negative predictive value and Youden index were determined for all tests.

Results: Difficult intubation was reported in 8.9% of the patients. There was a significant correlation between body mass index and difficult intubation (P : 0.004); however, other demographic characteristics didn’t have a significant correlation with difficult intubation. Among three tests, palm print was of highest specificity (96.46%) and modified Mallampati of highest sensitivity (98.40%). In a combination of the tests, the highest specificity, sensitivity and Youden index were observed when using all three tests together.

Conclusions: Palm print has a high specificity for prediction of difficult intubation, but the best way for prediction of difficult intubation is using all three tests together.

Keywords: Difficult intubation, modified Mallampati score, palm print, 3-3-2 rule