New formula for selection of an appropriate left-sided double-lumen tube size in thoracic anaesthesiology

Abstract

BackgroundIn thoracic anaesthesiology, double-lumen endobronchial tubes are used to provide one-lung ventilation. However, selecting the appropriate double-lumen endobronchial tube size to provide the most suitable ventilation with minimal damage is a challenging task for anaesthesiologists. There is no standardised approach to this issue. The present study aimed to develop a standardised mathematical formula for determining the appropriate size of the left-sided double-lumen endobronchial tube in thoracic anaesthesiology. MethodsThis retrospective study included 192 patients who were intubated with a left-sided double-lumen endobronchial tube for one-lung ventilation in our centre and underwent thoracic surgery between 2015 and 2020. Generalised multiple linear regression models were constructed, and five indicators were used as factorial features: sex, height, weight, diameter of the left main bronchus, and age. ResultsA stepwise method with an entrance threshold of P<0.1 and removal threshold of P>0.2 was used to select factors significantly related to tube size. This method identified the following three factors: sex, height, and the diameter of the left main bronchus (DLMB). The size of the tube increased (p<0.001) by 0.121 per cm of patient height (p<0.001) and by 7.22 per cm of DLMB. In addition, the increase was greater in men than in women (by 1.27; p<0.001). When the size of the tube corresponded to that calculated by formula, pulmonary complications were observed in 10.0% of patients. In contrast, when the size did not match, complications were noted in 31.2% of patients. ConclusionsWe developed a standardised mathematical formula for determining the appropriate size of a left-sided double-lumen endobronchial tube. Further prospective studies are required to confirm the accuracy of the formula for use in thoracic anaesthesiology.