Alternative methods of exposure minimize cardiopulmonary risk in experimental animals during minimally invasive surgery.

BACKGROUND: Alternative methods of exposure are needed for minimally invasive surgery to avoid hypercarbia and acidosis associated with carbon dioxide (CO2) abdominal insufflation. The goals of this study were to determine the pulmonary and hemodynamic effects of both helium (HE) abdominal insufflation and placement of a mechanical abdominal wall-lifting device (lifter) during laparoscopy.
METHODS: Sixteen adult domestic pigs under general endotracheal anesthesia underwent baseline measurements of pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and arterial blood gas. Six pigs underwent standard CO2 abdominal insufflation, five pigs underwent abdominal insufflation with HE, and a lifter was used for exposure in five other animals. Sequential readings of PCWP, CO, and arterial blood gas were recorded at 20-min intervals for 60 min in all 16 animals.
RESULTS: No significant changes from baseline values were noted in arterial pCO2 or pH in animals who underwent placement of the lifter at any time point. After undergoing HE insufflation, animals experienced modest but significant acidosis and little change in pCO2. There was a significant rise in arterial pCO2 and decrease in pH from baseline values at all time points in animals undergoing CO2 insufflation.
CONCLUSIONS: This study shows that neither HE abdominal insufflation or the lifter have significant deleterious pulmonary or hemodynamic effects on experimental animals during laparoscopy. Gasless laparoscopy or HE insufflation may provide a safer alternative method of exposure for minimally invasive surgery in patients with pre-existing pulmonary or cardiac dysfunction. By minimizing risk in these patients, costly invasive monitoring may be avoided.