Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
, 23 (3), 392-8

Comparison of the Effects of Sevoflurane and Isoflurane Anesthesia on the Maternal-Fetal Unit in Sheep

Comparative Study

Comparison of the Effects of Sevoflurane and Isoflurane Anesthesia on the Maternal-Fetal Unit in Sheep

Toshiyuki Okutomi et al. J Anesth.


Purpose: The aim of this study was to determine the hemodynamic and blood gas effects of inhalational anesthetics on the maternal-fetal sheep unit. The principal hypothesis, tested in chronically instrumented near-term pregnant ewes, was that sevoflurane anesthesia may be safe and useful for the mother and fetus during pregnancy, compared with isoflurane.

Methods: Six chronically instrumented pregnant and 3 nonpregnant ewes were tested repeatedly to establish the minimum alveolar concentration (MAC) for sevoflurane and isoflurane to be used in the hemodynamic and blood gas studies. Progressively increasing concentrations of sevoflurane or isoflurane in oxygen were administered to 12 pregnant ewes. Uterine blood flow, maternal and fetal heart rates, blood pressure, arterial blood gases, and intra-amniotic pressure were subsequently measured.

Results: The MAC of sevoflurane was 1.52 +/- 0.1 15% and 1.92 +/- 0.17% in pregnant and nonpregnant ewes, respectively; while the MAC of isoflurane in the pregnant and nonpregnant sheep was 1.02 +/- 0.12% and 1.42 +/- 0.19%, respectively. In both the sevoflurane and isoflurane groups, changes in maternal and fetal blood gases were minimal during exposure to low-dose (0.5-1.0 MAC) inhaled concentrations. Although uterine blood flow was maintained and the fetus remained well oxygenated at higher concentrations of both agents (2.0 MAC of either agent), the agents produced decreases in maternal and fetal arterial pressure.

Conclusion: A "low-dose" concentration (0.5-1.0 MAC) of sevoflurane may be safe and useful for both mother and fetus during near-term pregnancy. However, a high concentration (1.5-2.0 MAC) of sevoflurane or isoflurane may induce hemodynamic instability in the mother and fetus when administered.

Similar articles

See all similar articles

Cited by 12 articles

See all "Cited by" articles


    1. Int J Obstet Anesth. 2004 Jul;13(3):178-82 - PubMed
    1. Br J Anaesth. 1991 Oct;67(4):387-9 - PubMed
    1. J Obstet Gynaecol Br Commonw. 1969 Jan;76(1):27-33 - PubMed
    1. J Clin Anesth. 2001 Aug;13(5):387-91 - PubMed
    1. J Cereb Blood Flow Metab. 2005 Aug;25(8):1060-9 - PubMed

Publication types

MeSH terms

LinkOut - more resources