Use of Point-of-care upper airway ultrasound during preanesthetic airway assessment to predict difficult intubation in adult patients with obesity

Abstract

BackgroundUltrasound is a simple, noninvasive complementary tool for preoperative airway assessment. This study compared airway ultrasound and conventional airway assessments to predict difficult intubation. MethodsAirway assessment was performed in 99 patients scheduled for bariatric surgery using the following two parameters: El-Ganzouri score (EGS) and oblique transverse ultrasound view. The following measurements were gathered with ultrasound: pre-epiglottic space depth (pre-E), distance from the epiglottis to the mid-vocal cords (E-VC), mean distance between the skin and epiglottis (mDSE), distance between the skin and hyoid bone (DSHB), and tongue volume. After induction of anesthesia, direct laryngoscopy was performed and Cormack–Lehane (CL) classification was reported.CL grades 1 and 2 were classified as the easy laryngoscopy (EL) group, Grades 3 and 4 were classified as having a difficult laryngoscopy (DL). The crucial performance measure was the E-ability VC's to anticipate difficult intubation. Association between these factors and the CL categorization was a significant indication. ResultsIn 12.12 percent of cases, hard intubation was seen. The DL group had a lower E-VC than the EL group (0.9 ± 0.28 cm vs. 1.52 ± 0.3 cm; P -value less than0.001). The DL cutoff point was <1.22 cm, with 91.7% sensitivity and 83.9% specificity. The CL classification indicated a strongly positive association with the EGS and strongly negative association with the E-VC measurement (r = 0.700 and –0.828, consecutively; P-value less than 0.001), moderately positive correlation with mDSE and DSHB (r = 0.433 and 0.566, consecutively; P-value less than 0.001), and weakly positive correlation with pre-E and tongue volume (r = 0.331 and 0.344, respectively; P-value less than 0.001). ConclusionsUltrasound as a complementary measure to anticipate difficult intubation is beneficial with high sensitivity and low specificity in avoiding the hazards of unanticipated, difficult intraoperative laryngeal visualization.