Constantinides Christakis, Mean Richard, Janssen Ben J
Address correspondence and reprint requests to Dr. Christakis Constantinides, Department of Mechanical and Manufacturing Engineering at the School of Engineering of the University of Cyprus, 75 Kalipoleos Avenue, 1678 Nicosia, Cyprus or email
ILAR J. 2011;52(3):e21-31.
Isoflurane (ISO) is the most commonly used inhalational anesthetic for experimental interventions in mice and is preferred for imaging technologies that require the mouse to remain anesthetized for relatively long time periods. This study compares the stability of mean arterial pressure (MAP), heart rate (HR), and body temperature under ISO concentrations of 1%, 1.5%, and 2% (volume-to-volume, v/v) for up to 90 minutes postinduction. At all three levels of anesthesia, we examined evoked physiological responses to fractional inspiratory ratio variations of oxygen (FiO2) and nitrous oxide (N2O). In addition, we determined the hemodynamic effects of anesthesia on pH, glucose, insulin, glucocorticoids, and partial pressure of oxygen and of carbon dioxide in the blood (paO2, paCO2). The results indicate that the most appropriate ISO dose level was 1.5% v/v, yielding stable MAP and HR values comparable to those observed in the animal's conscious state, with a minute-to-minute variability in MAP and HR of .11%. Based on such recordings, the optimal FiO2 appeared to be 50%. The additional use of N2O was associated with higher and more stable values of MAP and HR. Arterial pH values were within the physiological range and varied between 7.20 and 7.43. ISO anesthesia at 1.5% v/v was also associated with mild hyperglycemia (+47%), whereas insulin levels and corticosteroids remained unaltered. We conclude that the application of isoflurane as an inhalational anesthetic in the mouse can be optimized to attain stable hemodynamics by administering it at 1.5% v/v and by supplementing it with N2O.
异氟烷（ISO）是小鼠实验干预中最常用的吸入性麻醉剂，对于需要小鼠长时间保持麻醉状态的成像技术而言是首选。本研究比较了诱导后长达90分钟内，在1%、1.5%和2%（体积比，v/v）的ISO浓度下平均动脉压（MAP）、心率（HR）和体温的稳定性。在所有三个麻醉水平下，我们检测了对氧气（FiO2）和一氧化二氮（N2O）的分数吸气比变化的诱发生理反应。此外，我们还测定了麻醉对血液中pH值、葡萄糖、胰岛素、糖皮质激素以及氧气和二氧化碳分压（paO2、paCO2）的血流动力学影响。结果表明，最合适的ISO剂量水平为1.5% v/v，产生的稳定MAP和HR值与动物清醒状态下观察到的值相当，MAP和HR的每分钟变化率为0.11%。基于这些记录，最佳FiO2似乎为50%。额外使用N2O与更高且更稳定的MAP和HR值相关。动脉pH值在生理范围内，在7.20至7.43之间变化。1.5% v/v的ISO麻醉还与轻度高血糖（+47%）相关，而胰岛素水平和皮质类固醇保持不变。我们得出结论，通过以1.5% v/v的剂量施用异氟烷并补充N2O，可以优化其作为小鼠吸入性麻醉剂的应用，以实现稳定的血流动力学。
