Effects of helium pneumoperitoneum in pregnant ewes

Previous animal studies have demonstrated that a carbon dioxide (CO(2)) pneumoperitoneum in pregnant ewes causes maternal and fetal acidosis, decreased uterine blood flow (UtBF), and fetal hypertension. This study was undertaken to determine whether helium (He) produces these same effects when used as an insufflating gas.

Six gravid ewes, at 116 to 120 days gestation, underwent catheterization of the maternal femoral artery and vein and the fetal hindlimb artery and vein, as well as insertion of a uterine artery flow probe. After a 6-day recovery period, the animals were anesthetized; a Hasson trocar was placed; and an He pneumoperitoneum was established (10 mmHg for 30 min followed by 15 mmHg for 30 min). The following parameters were recorded at baseline and at preset time points: maternal and fetal heart rate (HR), blood pressure (BP), arterial blood gasses, maternal end-tidal CO(2) (EtCO2), and UtBF. The percentage of change over time was determined for each variable. The results were compared with results previously obtained in control animals and in animals undergoing CO(2) pneumoperitoneum. Statistical significance was determined by repeated measures analysis of variance (ANOVA).

The following statistically significant changes were found.

Like CO(2), He used for pneumoperitoneum resulted in decreased UtBF and fetal hypertension because of increased intra-abdominal pressure. Unlike a CO(2), He used for pneumoperitoneum does not cause maternal or fetal acidosis, indicating that the metabolic effects seen with CO(2) are the result of the specific gas used. Therefore, He may be a safer gas than CO(2) to use for laparoscopic procedures in pregnant patients.