怀孕早期，氟烷和恩氟烷的最低肺泡浓度降低。

Minimum alveolar concentration of halothane and enflurane are decreased in early pregnancy.

作者信息

Chan M T, Mainland P, Gin T

机构信息

Department of Anaesthesia and Intensive Care, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong.

出版信息

Anesthesiology. 1996 Oct;85(4):782-6. doi: 10.1097/00000542-199610000-00013.

DOI:10.1097/00000542-199610000-00013

PMID:8873548

Abstract

BACKGROUND

Minimum alveolar concentration (MAC) of isoflurane is decreased in early pregnancy but it is not known whether this occurs to the same extent with other inhalational anesthetics. The MAC of halothane and enflurane were compared in pregnant women undergoing elective termination of pregnancy and in nonpregnant women.

METHODS

We studied 16 pregnant women scheduled for termination of pregnancy at 8 to 13 weeks gestation and 16 non-pregnant patients undergoing laparoscopic sterilization. Eight patients in each group received halothane and the others received enflurane. After inhalational induction of anesthesia and tracheal intubation, MAC was determined in each patient by observing the motor response to a 10-s, 50-Hz, 80-mA transcutaneous electric tetanic stimulus to the ulnar nerve at varying concentrations of either halothane or enflurane. The end-tidal concentration of inhalational anesthetic was kept constant for at least 15 min before each stimulus and the concentration was varied ultimately in steps of 0.05 vol% (halothane) or 0.10 vol% (enflurane) until a sequence of three alternate responses (move, not move, move) or (not move, move, not move) was obtained. Minimum alveolar concentration for each person was taken as the mean of the two concentrations just permitting and just preventing movement, and MAC for the group was the median of individual MAC values. Confidence intervals were calculated for the percentage decrease in MAC for pregnant women compared with nonpregnant women.

RESULTS

The median (range) MAC of halothane, 0.58 vol% (0.53 to 0.58), and enflurane, 1.15 vol% (0.95-1.25), in the pregnant women were less than those in the nonpregnant women, 0.75 vol% (0.70 to 0.78), P = 0.0005 and 1.65 vol% (1.45 to 1.75), P = 0.0007, respectively. The percentage decrease (95% CI) in MAC for pregnant women was 27% (20 to 27%) for halothane and 30% (24 to 36%) for enflurane.

CONCLUSIONS

The MAC of halothane and enflurane were reduced by a similar degree in pregnant women at 8 to 13 weeks gestation compared with nonpregnant women.

摘要

背景

异氟烷的最低肺泡浓度（MAC）在妊娠早期会降低，但尚不清楚其他吸入性麻醉剂是否也会出现同样程度的降低。比较了接受选择性终止妊娠的孕妇和非孕妇中氟烷和恩氟烷的MAC。

方法

我们研究了16例计划在妊娠8至13周终止妊娠的孕妇和16例接受腹腔镜绝育术的非孕妇。每组8例患者接受氟烷，其余患者接受恩氟烷。在吸入诱导麻醉和气管插管后，通过观察在不同浓度的氟烷或恩氟烷下对尺神经施加10秒、50赫兹、80毫安经皮电强直刺激的运动反应，测定每位患者的MAC。在每次刺激前，将吸入麻醉剂的呼气末浓度保持恒定至少15分钟，最终浓度以0.05体积%（氟烷）或0.10体积%（恩氟烷）的步长变化，直到获得三个交替反应序列（动、不动、动）或（不动、动、不动）。将每个人的最低肺泡浓度作为刚好允许和刚好阻止运动的两个浓度的平均值，该组的MAC为个体MAC值的中位数。计算了孕妇与非孕妇MAC降低百分比的置信区间。

结果

孕妇中氟烷的中位数（范围）MAC为0.58体积%（0.53至0.58），恩氟烷为1.15体积%（0.95 - 1.25），均低于非孕妇，非孕妇中氟烷为0.75体积%（0.70至0.78），P = 0.0005，恩氟烷为1.65体积%（1.45至1.75），P = 0.0007。孕妇中氟烷MAC降低的百分比（95%CI）为27%（20至27%），恩氟烷为30%（24至36%）。