Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
Department of Anesthesiology, Chibaken Saiseikai Hospital, Chiba, Japan.
Physiol Rep. 2021 Dec;9(23):e15139. doi: 10.14814/phy2.15139.
Some evidence suggests that both hypothermia and anesthesia can exert similar effects on metabolism and ventilation. This study examined the synergistic effects of anesthesia and hypothermia on ventilation in spontaneously breathing adult mice under three different conditions, that is, (1) pentobarbital group (n = 7) in which mice were anesthetized with intraperitoneal pentobarbital of 80 mg/kg, (2) sevoflurane-continued group (n = 7) in which mice were anesthetized with 1 MAC sevoflurane, and (3) sevoflurane-discontinued group (n = 7) in which sevoflurane was discontinued at a body temperature below 22˚C. We cooled mice in each group until breathing ceased and followed this with artificial rewarming while measuring changes in respiratory variables and heart rate. We found that the body temperature at which respiration arrested is much lower in the sevoflurane-discontinued group (13.8 ± 2.0˚C) than that in the sevoflurane-continued group (16.7 ± 1.2˚C) and the pentobarbital group (17.0 ± 1.4˚C). Upon rewarming, all animals in all three groups spontaneously recovered from respiratory arrest. There was a considerable difference in breathing patterns between sevoflurane-anesthetized mice and pentobarbital-anesthetized mice during progressive hypothermia in terms of changes in tidal volume and respiratory frequency. The changes in the respiratory pattern during rewarming are nearly mirrored images of the changes observed during cooling in all three groups. These observations indicate that adult mice are capable of autoresuscitation from hypothermic respiratory arrest and that anesthesia and hypothermia exert synergistic effects on the occurrence of respiratory arrest while the type of anesthetic affects the breathing pattern that occurs during progressive hypothermia leading to respiratory arrest.
一些证据表明，低温和麻醉都可以对代谢和通气产生相似的影响。本研究在三种不同条件下研究了麻醉和低温对成年小鼠自主呼吸通气的协同作用，分别是：（1）戊巴比妥组（n=7），小鼠腹腔注射 80mg/kg 的戊巴比妥麻醉；（2）七氟醚持续组（n=7），小鼠以 1MAC 七氟醚麻醉；（3）七氟醚中断组（n=7），当体温低于 22°C 时停止使用七氟醚。我们在每个组中给小鼠降温，直到呼吸停止，然后在人工复温的同时测量呼吸变量和心率的变化。我们发现，七氟醚中断组（13.8±2.0°C）呼吸停止时的体温明显低于七氟醚持续组（16.7±1.2°C）和戊巴比妥组（17.0±1.4°C）。复温后，三组中的所有动物均自发地从呼吸停止中恢复过来。在逐渐降温过程中，七氟醚麻醉的小鼠和戊巴比妥麻醉的小鼠之间的呼吸模式存在很大差异，表现在潮气量和呼吸频率的变化上。三组在复温过程中呼吸模式的变化几乎与降温过程中观察到的变化的镜像。这些观察结果表明，成年小鼠能够从低温呼吸暂停中自动复苏，麻醉和低温对呼吸暂停的发生有协同作用，而麻醉类型则会影响导致呼吸暂停的逐渐降温过程中的呼吸模式。
