Combination of nitrous oxide and the modified inflation-deflation method for identifying the intersegmental plane in segmentectomy: A randomized controlled trial.

ABSTRACT

BACKGROUND: During thoracoscopic segmentectomy, accurately and rapidly identifying the intersegmental plane (ISP) is of great importance. This study aimed to investigate the effect and safety of a nitrous oxide (N2 O)/oxygen (O2 ) inspired mixture on the appearance time of the ISP (TISP ) via the modified inflation-deflation method. METHODS: A total of 65 participants who underwent segmentectomy were randomized into three groups 75% N2 O (n = 24), 50% N2 O (n = 23) or 0% N2 O (n = 18). The 75% N2 O group received a gas mixture of N2 O/O2 (Fio2 = 0.25), the 50% N2 O group received N2 O/O2 (Fio2 = 0.5), and the 0% N2 O group received 100% oxygen during lung expansion. The appearance time of satisfactory and ideal planes was recorded. Furthermore, arterial blood gas at breathing room air, one-lung ventilation (OLV) before lung expansion, 5 and 15 min after lung expansion were also recorded. RESULTS: TISP was significantly shorter in the 75% N2 O group (320.2 ± 65.9 s) compared with that of the 50% N2 O group (552.4 ± 88.9 s, p < 0.001) and the 0% N2 O group (968.3 ± 85.5 s, p < 0.001), while the 50% N2 O group was shorter than that of the 0% N2 O group (p < 0.001). Arterial oxygenation was significantly improved in the 0% N2 O group only after lung expansion, before which there were no differences in mean PaO2 values among groups. CONCLUSIONS: The use of N2 O in the inspired gas mixture during lung expansion is an applicable strategy to rapidly identify the ISP via the modified inflation-deflation method without any adverse effect on OLV related arterial oxygenation during segmentectomy.