A prospective comparative study to evaluate the utility of lung ultrasonography to improve the accuracy of traditional clinical methods to confirm position of left sided double lumen tube in elective thoracic surgeries

BACKGROUND AND AIMS: Traditional clinical methods like auscultation or inspection have been found to be inaccurate in confirmation of double-lumen tube (DLT) position. Lung ultrasonography (USG) reliably identifies the tidal movement (lung sliding) and the collapse of the lung (lung pulse). We intended to check whether the accuracy of clinical methods can be improved by the addition of USG in confirmation of left DLT (LDLT) position. METHODS: A single centred, prospective, comparative study was conducted involving 70 patients undergoing thoracic surgeries requiring the use of LDLT. The patients were assigned to Group A - where LDLT position was assessed by using clinical methods alone, and Group B - where LDLT position was assessed by USG and clinical methods. The correct position was predicted when USG demonstrated the absence of lung sliding and the presence of lung pulse on the operative side, the presence of lung sliding on non-operative side, along with normal airway pressures and oxygenation. The final verification of LDLT position was done by direct observation of lung isolation by one surgeon who was blinded to the method of confirmation. Contingency tables were drawn to calculate sensitivity, specificity, positive predictive value, negative predictive value and accuracy of each method. RESULTS: Compared to clinical methods alone, addition of lung USG improved sensitivity (75% vs. 88%), specificity (18% vs. 75%) and accuracy (57% vs. 85%) for correct prediction of LDLT position. CONCLUSION: USG is a useful addition to the armamentarium of anaesthesiologist for the confirmation of LDLT position.