Margin of Safety in Positioning Double-lumen Endotracheal Tubes Using a Fiberoptic Bronchoscope in Korean Adult

Abstract

Background: The margin of safety is the length of the mainstem bronchi, over which double-lumen endotracheal tubes (DLTs) can be moved and still be correctly positioned. A negative value of margin of safety means that DLTs may not be safe. We measured the length of the left and right mainstem bronchi and margin of safety in Korean adults. Methods: One hundred and fifty-six ASA I or II adult patients undergoing an elective surgery were examined. After induction of general anesthesia, we measured the lengths from the upper incisor to the tracheal carina, to the proximal margin of the left and right upper lobe bronchial opening using a fiberoptic bronchoscope. We calculated the lengths of the left and right mainstem bronchi and margin of safety using the measured lengths. Results: In Korean adults, the average margin of safety of left-sided DLTs of males and females was 2.4 1.0 cm and 1.9 0.7 cm and right-sided DLTs of males and females was 1.0 0.9 cm and 0.8 0.3 cm, respectively. The percentage of a negative value of the margin of safety in positioning right-sided DLTs was 10.4% in males and 8.6% in females. However, all values of the margin of safety in left-sided DLTs were positive. Conclusions: Using left-sided DLTs, regardless of the operative side, is better than right-sided DLTs because left-sided DLTs have a greater margin of safety in positioning. If we use right-sided DLTs, we should confirm the proper position of tubes using a fiberoptic bronchoscope.