Prediction of the Difficult Laryngoscopy with Ultrasound Measurements of Hyomental Distance

Abstract

Ultrasound measurement of hyomental distance is promising as a predictor for difficult laryngo-scopy in cases of difficult airway management. The aim of the study was to evaluate the prognos-tic value of ultrasound measurement of hyomental distance (HMD) for prediction of difficultlaryngoscopy. Hyomental distance was sonographically measured in neutral (HMDn) and extremehead extension (HMDe) positions for fifty-six patients scheduled for elective surgery requiring tra-cheal intubation. Then the hyomental distance ratio (HMDR) was calculated. According to pres-ence of difficult laryngoscopy assessed by the Cormack–Lehane (CL) score, patients weredivided into a difficult laryngoscopy group (DL, n = 15) and easy laryngoscopy group (EL, n = 41).We calculated the sensitivity and specificity of HMDn, HMDe, and HMDR for difficult laryngo-scopy. DL was present in 15 (27%) patients. We found a significant intergroup difference inHMDR between the DL and EL groups (1.12 ± 0.04 vs. 1.24 ± 0.06, respectively;p< 0.001). Incontrast, we were not able to find a significant difference for HMDn and HMDr. HMDR had thehighest sensitivity 86.7% and specificity 85.4% (p< 0.01) to predict difficult laryngoscopy, wherethe area under the curve was 0.939;p< 0.01 for HDMR < 1.2 cm. Moreover, we found that diffi-cult laryngoscopy was associated with higher body mass index (BMI), with higher values in theDL group compared to EL patients (34.3 ± 9.1 vs. 28.5 ± 5.7 kg/m2, respectively;p= 0.035).HMDR < 1.2 cm measured by ultrasound might have a good predictive value for prediction of diffi-cult laryngoscopy.