Preoperative ultrasonographic airway assessment and indirect laryngoscopy as a predictor of difficult laryngeal view: Pilot study
Demet Altun, Hakan Kara, Tuğçe Dinç, Erol Bozbora, Emre Çamcı,
1department Of Anesthesiology, Istanbul Faculty Of Medicine, Istanbul University, Istanbul, Turkey
2 Department Of Ear Nose Throat Surgery, Istanbul Faculty Of Medicine, Istanbul University, Istanbul, Turkey
Background Ultrasonographic airway assessment (UAS) and indirect laryngoscopic (IL) examination have been shown to be useful adjuncts whereas there is no accurate method that can predict the possibility of a difficult laryngeal view (DL). The aim of this feasibility study was to test the ability of UAS and IL to predict DL. Methods This was a prospective observational study on 77 patients undergoing elective surgery under general anesthesia. Preoperative clinical examination [Body mass index(BMI), mallampati classification(MP), thyromental distance (TMD), sternomental distance (SMD), neck circumference (NC)], ultrasonographic assessment of the airway [epiglottis-skin distance (ESD), hyoid bone-skin distance (HSD), the root of tongue thickness (RoTT), anterior commissure-skin distance (ACSD)] and IL with the rigid 70-degree laryngoscope (Visible anterior commissure=I, posterior part of vocal cords=II, posterior commissure and epiglottis=III, epiglottis tip and posterior pharyngeal wall=IV) were performed to predict DL (Cormack-Lehane (CL) 3 and 4). CL scores were assessed during direct laryngoscopy using Macintosch blade. The sensitivity (Sn), specificity (Sp), positive predictive value (PP), and negative predictive values (NP) of the parameters were assessed. ROC curve was drawn for ultrasonographic measurements and the cut-off point to determine the DL for each parameter was described. Also, the correlation between IL and USG measurements in prediction of DL were assessed. Results Twelve of 77 (15%) patients were diagnosed with DL. Our results are shown in table 1. Among the clinical predictors, Mallampati classification had the maximum sensitivity and specificity, and among the sonographic parameters, HSD had the maximum sensitivity and ESD had the maximum specificity (table 2). ESDykrk312.14 cm, HSDykrk310.835 cm, RoTTykrk313.44 cm, ACSDykrk310.545 cm and BMIykrk3126.84, respectively can be used to predict DL. Area under curve values were 0.88, 0.863, 0.868, 0.545 and 0.824 in the same order. Good correlation was found between IL and ESD, HSD, and RoTT(p= 0.002, 0.001 and 0.012, respectively). Conclusion: Our study shows that both IL and UAS (ESD, HSD and RoTT) can be used to predict DL in adult patients.
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