Effects of helium pneumoperitoneum in pregnant ewes

Background: Previous animal studies have demonstrated that a carbon dioxide (CO2) pneumoperitoneum in pregnant ewes causes maternal and fetal acidosis , decreased uterine blood flow (UtBF), and fetal hypertension. This study w as undertaken to determine whether helium (He) produces these same effects when used as an insufflating gas. Methods: Six, gravid ewes, at 116 to 120 days gestation, underwent catheter ization of the maternal femoral artery and vein and the fetal hindlimb arte ry and vein, as well as insertion of a uterine artery flow probe. After a S -day recovery period, the animals were anesthetized; a Hasson trocar was pl aced; and an He pneumoperitoneum was established (IO mmHg for 30 min follow ed by 15 mmHg for 30 min). The following parameters were recorded at baseli ne and at preset time points: maternal and fetal heart rate (HR), blood pre ssure (BP), arterial blood gasses, maternal endtidal CO2 (EtCO2), and UtBF. The percentage of change over time was determined for each variable. The r esults were compared with results previously obtained in control animals an d in animals undergoing CO2 pneumoperitoneum. Statistical significance was determined by repeated measures analysis of variance (ANOVA). Results: The following statistically significant changes were found. Conclusions: Like CO2, He used for pneumoperitoneum resulted in decreased U tBF and fetal hypertension because of increased intra-abdominal pressure. U nlike a CO2, He used for pneumoperitoneum does not cause maternal or fetal acidosis, indicating that the metabolic effects seen with CO2 are the resul t of the specific gas used. Therefore, He may be a safer gas than CO2 to us e for laparoscopic procedures in pregnant patients.