Comparison of upper lip bite test and ratio of height to thyromental distance with other airway assessment tests for predicting difficult endotracheal intubation

Abstract

Background and Aims:Unanticipated difficult intubation or the failed intubation in operating room and in emergency department is an imperative source of anesthesia-related patient's mortality. The aim of this study is to compare the predictive value of upper lip bite test (ULBT) and ratio of height to thyromental distance (RHTMD) with other commonly used preoperative airway assessment tests for predicting difficult intubation in Indian population.Materials and Methods:In this prospective, single-blinded observational study, 260 adult patients of either sex, belonging to American Society of Anesthesiologists physical Status I and II undergoing elective surgical procedure under general anesthesia were included in the study. ULBT, RHTMD, inter-incisor gap, modified Mallampati grade, horizontal length of the mandible, head and neck movements, sternomental distance, and TMD were assessed preoperatively and correlated with Cormack and Lehane's grading during laryngoscopy under anesthesia. Statistical analysis was done by Chi-square and Fisher's exact test.Results:ULBT and RHTMD had highest sensitivity (66.7% and 63.3%), specificity (99.1% and 89.6%), positive predictive value (90.9% and 44.2%), and negative predictive value (96.9% and 95.0%), respectively, when compared to other parameters in predicting difficult airway.Conclusion:ULBT and RHTMD may be used as a simple bedside airway assessment tools for prediction of difficult intubation.

Evaluation of different airway tests to determine difficult intubation in apparently normal adult patients undergoing surgical procedures

“…These findings are consistent with the results of Palczynski et al [ 40 ], who found a sensitivity of 60% and a PPV of 19% for SMD. A poor sensitivity and PPV for this test (8.3 and 3.4%, respectively) were observed by Khatiwada et al [ 41 ] and, in a study by Shobha et al [ 42 ], SMD sensitivity was found to be 3.3% and PPV was 6.25%.…”

“…Although repeatedly reported to be a good measure of head extension, previous studies have reported that the SMD has limited clinical value and fails to adequately and solely predict difficult intubations [ 33 , 41 , 42 ].…”

Evaluation of different airway tests to determine difficult intubation in apparently normal adult patients: A prospective observational study

“…These ndings are consistent with the results of Palczynski et al [40], who found a sensitivity of 60% and a PPV of 19% for SMD. A poor sensitivity and PPV for this test (8.3% and 3.4%, respectively) were observed by Khatiwada et al [41] and, in a study by Shobha et al [42], SMD sensitivity was found to be 3.3% and PPV was 6.25%.…”

“…Although repeatedly reported to be a good measure of head extension, previous studies have reported that the SMD has limited clinical value and fails to adequately and solely predict di cult intubations [33,41,42].…”

Sternomental distance ratio as a predictor of difficult laryngoscopy: A prospective, double-blind pilot study

“…Several tests have been proposed as prognostic factors for difficult laryngoscopy[ 7 8 10 11 14 24 25 ] however none of them seems to perform well alone, and different combinations between them have been proposed to improve accuracy. [ 18 26 27 ] This is also the case of SMD which is a factor that indirectly combines mandibular space, cervical spine mobility, and neck height. [ 10 20 21 ] Whereas retrognathia, limited cervical spine mobility and short neck have all been individually associated with difficult laryngoscopy,[ 13 14 17 ] their absence does not indicate an easy laryngoscopy and several other factors such as the Mallampati score have to be also assessed.…”