The usefulness of point of care ultrasound (POCUS) in preanaesthetic airway assessment.

Abstract

Background and Aims:Point of care ultrasound has the potential to become reliable airway assessment tool by accurate prediction of difficult laryngoscopy. We aimed to determine the feasibility of ultrasound in preoperative airway assessment.Methods:This prospective, observational study was conducted on 200 patients requiring general anaesthesia and tracheal intubation. The thickness of anterior soft tissue neck at the level of hyoid bone (DSHB), epiglottis (DSEM), and Pre-E/E-VC[depth of the pre-epiglottic space (Pre-E)/distance from the epiglottis to the midpoint of the distance between the vocal cords (E-VC)] were measured sonographically. The hyomental distance ratio (HMDR) was measured utilising distances with head in neutral and extended position. The primary outcome was the efficacy of the parameters in predicting difficult laryngoscopy[Cormack Lehane 3,4]. The secondary outcome was to correlate the parameters to CL grading.Results:Utilising receiver operating curves, cutoff value of HMDR for predicting difficult laryngoscopy was ≤1.0870 with sensitivity of 65%, specificity of 77%. The cutoff value, sensitivity andspecificity for Pre-E/E-VC were ≥1.785, 82.8% and 83.8%., respectively. The cutoff value of DSHB was ≥0.99 with sensitivity of 48% and specificity of 82%. The cutoff, sensitivity and specificity for DSEM were ≥1.615, 89.7%, and 64.8%, respectively. There was moderate positive correlations of DSHB, DSEM, and Pre-E/E-VC (r = 0.551 and 0.701, 0.787: P = 0.00), whereas moderate negative correlation observed with HMDR (r = -.0671: P = 0.00).Conclusion:The strong positive correlation of Pre-E/E-VC, DSEM, and moderate negative correlation of HMDR makes these ultrasound parameters reliable predictors for difficult laryngoscopy.