The fraction of nitrous oxide in oxygen for facilitating lung collapse during one-lung ventilation with double lumen tube
Chao Liang, Yuechang Lv, Yu Shi, Jing Cang, Changhong Miao
Abstract
Abstract Background The ideal fraction of nitrous oxide (N 2 O) in oxygen (O 2 ) for rapid lung collapse remains unclear. Accordingly, this prospective trial aimed to determine the 50% effective concentration (EC 50 ) and 95% effective concentration (EC 95 ) of N 2 O in O 2 for rapid lung collapse. Methods This study included 38 consecutive patients undergoing video-assisted thoracoscopic surgery (VATS). The lung collapse score (LCS) of each patient during one-lung ventilation was evaluated by the same surgeon. The first patient received 30% N 2 O in O 2 , and the subsequent N 2 O fraction in O 2 was determined by the LCS of the previous patient using the Dixon up-and-down method. The testing interval was set at 10%, and the lowest concentration was 10% (10, 20, 30, 40%, or 50%). The EC 50 and EC 95 of N 2 O in O 2 for rapid lung collapse were analyzed using a probit test. Results According to the up-and-down method, the N 2 O fraction in O 2 at which all patients exhibited successful lung collapse was 50%. The EC 50 and EC 95 of N 2 O in O 2 for rapid lung collapse were 27.7% (95% confidence interval 19.9–35.7%) and 48.7% (95% confidence interval 39.0–96.3%), respectively. Conclusions In patients undergoing VATS, the EC 50 and EC 95 of N 2 O in O 2 for rapid lung collapse were 27.7 and 48.7%, respectively. Trial registration http://www.chictr.org/cn/ Identifier ChiCTR19 00021474 , registered on 22 February 2019.