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

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 (N(2)O)/oxygen (O(2)) inspired mixture on the appearance time of the ISP (T(ISP)) via the modified inflation‐deflation method. METHODS: A total of 65 participants who underwent segmentectomy were randomized into three groups: 75% N(2)O (n = 24), 50% N(2)O (n = 23) or 0% N(2)O (n = 18). The 75% N(2)O group received a gas mixture of N(2)O/O(2) (Fio(2) = 0.25), the 50% N(2)O group received N(2)O/O(2) (Fio(2) = 0.5), and the 0% N(2)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: T(ISP) was significantly shorter in the 75% N(2)O group (320.2 ± 65.9 s) compared with that of the 50% N(2)O group (552.4 ± 88.9 s, p < 0.001) and the 0% N(2)O group (968.3 ± 85.5 s, p < 0.001), while the 50% N(2)O group was shorter than that of the 0% N(2)O group (p < 0.001). Arterial oxygenation was significantly improved in the 0% N(2)O group only after lung expansion, before which there were no differences in mean PaO(2) values among groups. CONCLUSIONS: The use of N(2)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.