Comparison of lung ultrasound technique versus clinical method to evaluate the accuracy of size and placement of left endobronchial double lumen tube in patients undergoing elective thoracic surgery: a prospective observational study

Anthropometric measurements like height and gender have been frequently found to be inaccurate in the prediction of the size of double lumen tube (DLT). Tracheal ultrasonography is a technique that can be used to predict the size of DLT and its correct placement for lung isolation. We aim to check the accuracy of ultrasound over clinical methods. This prospective study included 68 patients undergoing elective thoracic surgery requiring one-lung ventilation with DLT. The groups were assessed for the size of DLT by either anthropometric measurement using height and gender (group C) or ultrasound method (group U). Further, the accuracy of placement of DLT was assessed through either lung auscultation in group C or various ultrasonographic and ventilatory parameters such as lung isolation in the first attempt (lung sliding and lung pulse sign), oxygenation status, and peak airway pressure in group U. Surgeon satisfaction score was also compared in both groups. The accuracy of predicted DLT size between group C and group U was statistically significant (p=0.044). In group C, 56% of patients showed a mismatch between the predicted DLT size and the actual size required, while in group U, the mismatch was only 32.4%. The accuracy of DLT placement through group C was 41% as compared to 79% in group U. The surgeon satisfaction score was also significantly higher in group U as compared to group C (p=0.0028). Thus, our study suggests that tracheal and chest ultrasonography for DLT size selection and placement for lung isolation is superior to clinical methods.