Division of Anesthesiology, Department of Anesthesiology, Nihon University School of Medicine, Tokyo, Japan.
Adv Exp Med Biol. 2024;1463:147-151. doi: 10.1007/978-3-031-67458-7_25.
Combined use of a surgical mask and oxygen mask might decrease the inspired oxygen concentration and increase the risk of hypercapnia. We investigated the fraction of inspired oxygen (FiO) and end-tidal carbon dioxide (ETCO) under different combinations of masks and oxygen flows. Five healthy volunteers were administered oxygen using the following methods: oxygen mask alone (O group), oxygen mask over a surgical mask (S group), and oxygen mask over an N95 mask (N group). FiO and ETCO were measured at oxygen flow rates of 0, 5, and 8 L/min under each mask condition. At oxygen flow rates of 5 and 8 L/min, FiO was lower in the order of N group (0.32 at 5 L/min, 0.36 at 8 L/min), S group (0.45 at 5 L/min, 0.52 at 8 L/min), and O group (0.61 at 5 L/min, 0.73 at 8 L/min). ETCO was higher in the order of N, S, and O groups. In conclusion, wearing the oxygen mask over the surgical mask or N95 mask reduces FiO and increases ETCO in healthy volunteers. Since patients who have emerged from general anaesthesia are more likely to have worse respiratory conditions, they need close observation to avoid hypoxemia and hypercapnia.
在使用口罩和氧气面罩时，联合使用可能会降低吸入氧气浓度，并增加发生高碳酸血症的风险。我们研究了不同口罩和氧气流量组合下的吸入氧分数（FiO）和呼气末二氧化碳（ETCO）。对 5 名健康志愿者采用以下方法进行氧疗：单独使用氧气面罩（O 组）、氧气面罩上加手术口罩（S 组）、氧气面罩上加 N95 口罩（N 组）。在每种口罩条件下，测量氧气流量为 0、5 和 8 L/min 时的 FiO 和 ETCO。在氧气流量为 5 和 8 L/min 时，FiO 按 N 组（5 L/min 时 0.32，8 L/min 时 0.36）、S 组（5 L/min 时 0.45，8 L/min 时 0.52）和 O 组（5 L/min 时 0.61，8 L/min 时 0.73）的顺序降低。ETCO 按 N、S 和 O 组的顺序升高。总之，在健康志愿者中，在手术口罩或 N95 口罩上佩戴氧气面罩会降低 FiO 并增加 ETCO。由于全身麻醉后苏醒的患者更有可能出现呼吸状况恶化，因此需要密切观察，以避免低氧血症和高碳酸血症。
