Is hyomental distance ratio a good predictor of the difficult intubation?

There is a wide range of complications connected to failed intubation. The major concerns for airway assesment methods are low predictability and high interobserver variabilities. Point-of-care ultrasound is gaining popularity in anaesthesiology.The procedure of sonographic measurment of hyomental distance is easy to learn and fast to perform. In this study we were aiming to find the sensitivity and specificity of hyomental distance ratio (HMDR) <1.2 as a predictor for difficult intubation (DI). In our prospective cohort study were included patients scheduled for elective surgery requiring general anesthesia and tracheal intubation in The Riga East clinical hospital Gailezers. Before the operation a sonographic measurement of hyomental distance in neutral (HMDn) and extreme head extension (HMDe) positions was performed. Then the HMDR calculation was produced by dividing hyomental distance in extreme head extension by hyomental distance in neutral head position.The efficacy of HMDR for predicting the difficult laryngoscopy (Cormack Lehane (CL) grade 3,4) was defined as primary outcome. Experienced anaesthesiologist evaluated the CL grade. Statistical analysis was performed, using IBM SPSS Statistics v.23. 56 patients met inclusion criteria, 28(50%) were males, 28(50%)-females. DL was present in 15(27%) patients. In DL group mean age was 51.3 (±11.3), in EL -53,9 (±14.5), BMI in DL goup was 34.3(±9.1), in El group 28.5(±5.7). Mean HMDn in DL group was 5.28±0.57cm, in EL group 5.04±0.5cm, mean HMDe in DL group was 5.9±0.56cm, in El group 6.26±0.0.59cm, HMDR in DL group was 1.12±0.04, in EL group – 1.24±0.06. There was no statistically signifficant difference between the groups except for BMI and HMDR. In DL group 6 (40%) patients required 1 attempt, 6 (40%) - 2 attempts and 3(20%) required 3 attempts for successful intubation. Modified Mallampati score had sensitivity 66,7% and specificity 53,7%(p>0.05).HMDR had sensitivity 86.7% and specificity 85.4%(p<0.01). HMDR is a good predictor of difficult laryngoscopy.