Maternal insufflation during the second trimester equivalent produces hypercapnia, acidosis, and prolonged hypoxia in fetal sheep.
BACKGROUND
Anecdotal reports suggest that the second trimester is the safest time to conduct a laparoscopic procedure on a pregnant patient, but this supposition has not been tested empirically.


METHODS
Previously instrumented preterm sheep (total n = 8) at gestational day 90 (term, 145 days) were anesthetized and then insufflated with carbon dioxide for 60 min at a pressure of 15 mmHg. Cardiovascular parameters were continuously recorded while blood gas status was determined before and at 15-min intervals during and up to 2 h after insufflation.


RESULTS
Insufflation produced minimal maternal blood gas or cardiovascular changes except for a significant reduction in uterine blood flow. The decrease in perfusion increased fetal arterial blood partial pressure of carbon dioxide and decreased fetal pH, oxygen saturation, and oxygen content; there was also progressive fetal hypotension and bradycardia. After manually deflating the ewe, uterine blood flow returned to normal, and the fetal partial pressure of carbon dioxide and pH changes resolved within 1 h. However, fetal oxygen saturation and content remained depressed, and fetal cardiovascular status continued to decline during the 2-h postinsufflation monitoring period.


CONCLUSIONS
Previous studies with near-term sheep determined that carbon dioxide pneumoperitoneum produces respiratory acidosis but does not decrease fetal oxygenation. In contrast, the current findings indicate that in the preterm fetus, insufflation-induced hypercapnia and acidosis are accompanied by prolonged fetal hypoxia and cardiovascular depression. This result suggests that additional work should be conducted to confirm the presumed safety of conducting minimally invasive procedures during the second trimester.
Uemura
Kenichiro
K
Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA.
McClaine
Rebecca J
RJ
de la Fuente
Sebastian G
SG
Manson
Roberto J
RJ
Campbell
Kurt A
KA
McClaine
Deborah J
DJ
White
William D
WD
Stamler
Jonathan S
JS
Eubanks
W Steve
WS
Reynolds
James D
JD
D000138:Acidosis / Q000139:chemically induced*; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D005315:Fetal Diseases / Q000139:chemically induced*; D005311:Fetal Hypoxia / Q000139:chemically induced*; D006340:Heart Rate, Fetal / Q000187:drug effects; D006439:Hemodynamics / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000139:chemically induced*; D007327:Insufflation; D010100:Oxygen / Q000097:blood; D011027:Pneumoperitoneum / Q000139:chemically induced / Q000503:physiopathology; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D014599:Uterus / Q000098:blood supply
D002245:Carbon Dioxide; D010100:Oxygen