Comparison of the effects of sevoflurane and isoflurane anesthesia on the maternal-fetal unit in sheep.
OBJECTIVE
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.


CONCLUSIONS
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.
Okutomi
Toshiyuki
T
Departments of Anesthesiology and Obstetrics/Gynecology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Whittington
Robert A
RA
Stein
Deborah J
DJ
Morishima
Hisayo O
HO
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005333:Fetus / Q000187:drug effects*; D006340:Heart Rate, Fetal / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007530:Isoflurane; D008738:Methyl Ethers; D010100:Oxygen / Q000097:blood; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects; D000077149:Sevoflurane; D012756:Sheep; D014599:Uterus / Q000098:blood supply
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D002245:Carbon Dioxide; D000077149:Sevoflurane; D007530:Isoflurane; D010100:Oxygen
Anesth Analg. 1995 Jul;81(1):90-5
7598289
Can Anaesth Soc J. 1983 Jan;30(1):24-7
6402281
Acta Anaesthesiol Belg. 2007;58(2):97-9
17710896
Anesthesiology. 1987 Mar;66(3):301-3
3826687
Am J Obstet Gynecol. 1970 Aug 15;107(8):1241-9
4989838
J Cereb Blood Flow Metab. 2005 Aug;25(8):1060-9
15758947
Can J Anaesth. 1988 Mar;35(2):153-6
3356052
J Obstet Gynaecol Br Commonw. 1969 Jan;76(1):27-33
5764764
Anesth Analg. 2007 Feb;104(2):397-406
17242098
J Pharmacol Exp Ther. 1984 Dec;231(3):640-8
6502517
Anesthesiology. 1979 May;50(5):431-6
453562
Am J Obstet Gynecol. 1966 Sep 1;96(1):41-7
5950264
Anesthesiology. 1975 Apr;42(4):458-63
1119712
J Anesth. 1990 Jan;4(1):66-72
15236019
Anesth Analg. 1992 Feb;74(2):241-5
1731544
Anesthesiology. 1974 Nov;41(5):462-72
4429215
Anesth Analg. 1983 May;62(5):489-92
6837960
Anesthesiology. 1980 Oct;53(4):315-34
6107067
J Vet Med Sci. 2003 Oct;65(10):1075-81
14600344
Anesthesiology. 1997 Feb;86(2):277-84
9054245
Br J Anaesth. 1991 Oct;67(4):387-9
1931394
Anesthesiology. 1989 Jul;71(1):110-5
2751122
J Clin Anesth. 2001 Aug;13(5):387-91
11498323
Anesthesiology. 1977 Jan;46(1):15-9
831588
Clin Obstet Gynecol. 2003 Sep;46(3):679-87
12972749
Anesth Analg. 1997 May;84(5):1150-3
9141951
Anesthesiology. 1977 Jan;46(1):11-4
831587
Anesth Analg. 1983 Jan;62(1):9-14
6849513
J Anesth. 1995 Dec;9(4):363-5
23839890
J Pediatr Surg. 2004 Mar;39(3):375-80; discussion 375-80
15017555
Am J Obstet Gynecol. 2007 Oct;197(4):414.e1-6
17904983
Can Anaesth Soc J. 1983 Nov;30(6):581-6
6640394
Int J Obstet Anesth. 2004 Jul;13(3):178-82
15321398