INTRAABDOMINAL CARBON-DIOXIDE INSUFFLATION IN THE PREGNANT EWE - UTERINE BLOOD-FLOW, INTRAAMNIOTIC PRESSURE, AND CARDIOPULMONARY EFFECTS

Background: Laparoscopic surgical procedures are being performed in pr egnant women with increasing frequency. Maternal-fetal physiologic cha nges occurring during intraabdominal carbon dioxide insufflation are p oorly understood, and maternal-fetal safety is of concern during carbo n dioxide pneumoperitoneum. A previous pilot study using end-tidal car bon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum, Using serial arterial P-CO2 to guide ventilation, this study was designed to evalua te maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insuff lation in singleton pregnant ewes between 120 and 135 days of gestatio n. Methods: In a prospective randomized cross-over study, nine ewes we re to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or rece ive no insufflation (n = 9; control group), Anesthesia was induced wit h thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guide d by serial maternal arterial blood gas analysis to maintain Pa-CO2 be tween 35 and 40 mmHg, Data from insufflated animals were collected dur ing insufflation (60 min) and after desufflation (30 min). Control gro up data were collected and matched to similar time intervals for 90 mi n. Ewes mere allowed to recover, and after a rest period (48 h) they m ere entered in the cross-over study. Results: During insufflation ther e was a significant increase (P < 0.05) in maternal Pa-CO2 to end-tida l carbon dioxide gradient and minute ventilation, with concomitant dec reases in maternal end-tidal carbon dioxide and Pa-O2. Intraamniotic p ressure increased significantly during insufflation. No significant ch anges were observed in maternal hemodynamic variables, fetal variables , or in uterine blood flow during the study. There were no fetal death s or preterm labor in any of the animals during the experiment. Conclu sions: During the 1-h insufflation, a marked increase in PaCO2-to-end- tidal carbon dioxide gradient was observed, suggesting that capnograph y may be an inadequate guide to ventilation during carbon dioxide pneu moperitoneum in the pregnant patient. No other significant circulatory changes were observed.