异氟烷和氧化亚氮麻醉期间脊髓运动神经元的兴奋性

Spinal cord motoneuron excitability during isoflurane and nitrous oxide anesthesia.

作者信息

Zhou H H, Mehta M, Leis A A

机构信息

Department of Anesthesiology, New York University Medical Center, New York 10016, USA.

出版信息

Anesthesiology. 1997 Feb;86(2):302-7. doi: 10.1097/00000542-199702000-00005.

DOI:10.1097/00000542-199702000-00005

PMID:9054248

Abstract

BACKGROUND

Recent evidence suggests that the spinal cord is an important site of anesthesia that is necessary for surgical immobility, but the specific effect of anesthetics within the spinal cord is unclear. This study assessed the effect of isoflurane and nitrous oxide on spinal motoneuron excitability by monitoring the H-reflex and the F wave.

METHODS

Eight adult patients, categorized as American Society of Anesthesiologists physical status 1 or 2, who were undergoing elective orthopaedic surgery were anesthetized with 0.6, 0.8, 1.0, and 1.2 times the estimated minimum alveolar concentration (MAC) of isoflurane. Nitrous oxide was added in graded concentrations of 30%, 50%, and 70%, whereas the isoflurane concentration was decreased to maintain a total MAC of 1. The H-reflex of the soleus muscle and the F wave of the abductor hallucis muscle were measured before anesthesia and 15 min after each change of anesthetic concentration. Four or more trials of the H-reflex and 18 trials of the F wave were recorded at each concentration of anesthesia. The effect of the anesthetics on the H-reflex and F wave was analyzed using. Dunnett's test.

RESULTS

H-reflex amplitude was decreased to 48.4 +/- 18.6% of preanesthesia level at 0.6 MAC isoflurane and to 33.8 +/- 19.1% when isoflurane concentration increased from 0.6 MAC to 1.2 MAC. F wave amplitude and persistence decreased to 52.2 +/- 33.6% and 44.4 +/- 26% of baseline at 0.6 MAC isoflurane, and to 33.8 +/- 26% and 21.7 +/- 22.8% at 1.2 MAC isoflurane. Isoflurane plus nitrous oxide (total 1 MAC) decreased H-reflex amplitude to 30.4-33.3% and decreased F wave persistence to 42.8-56.3% of baseline.

CONCLUSIONS

Both isoflurane alone and isoflurane plus nitrous oxide decrease H-reflex and F-wave amplitude and F-wave persistence. These effects suggest that isoflurane and nitrous oxide decrease motoneuronal excitability in the human spinal cord. This may play an important role in producing surgical immobility.

摘要

背景

最近的证据表明，脊髓是麻醉的一个重要部位，对于手术中保持不动是必需的，但麻醉剂在脊髓内的具体作用尚不清楚。本研究通过监测H反射和F波，评估异氟烷和氧化亚氮对脊髓运动神经元兴奋性的影响。

方法

八名美国麻醉医师协会身体状况分级为1或2级、正在接受择期骨科手术的成年患者，分别用0.6、0.8、1.0和1.2倍预计最低肺泡浓度（MAC）的异氟烷进行麻醉。氧化亚氮以30%、50%和70%的梯度浓度添加，而异氟烷浓度降低以维持总MAC为1。在麻醉前以及每次麻醉浓度改变后15分钟，测量比目鱼肌的H反射和拇展肌的F波。在每个麻醉浓度下记录4次或更多次H反射试验和18次F波试验。使用Dunnett检验分析麻醉剂对H反射和F波的影响。

结果

在0.6MAC异氟烷时，H反射波幅降至麻醉前水平的48.4±18.6%，当异氟烷浓度从0.6MAC增加到1.2MAC时，降至33.8±19.1%。在0.6MAC异氟烷时，F波波幅和出现率分别降至基线的52.2±33.6%和44.4±26%，在1.2MAC异氟烷时，分别降至33.8±26%和21.7±22.8%。异氟烷加氧化亚氮（总1MAC）使H反射波幅降至基线的30.4 - 33.3%，使F波出现率降至42.8 - 56.3%。