Influence of gases on intraperitoneal immunity during laparoscopy in tumor-bearing rats

Laparoscopy has been associated with metastases to abdominal wall wounds. I n addition, many recent experimental studies suggest that laparoscopy is as sociated with increased tumor dissemination. It is possible that immune or metabolic disturbances due to the use of a pneumoperitoneum could contribut e to this problem. To investigate this possibility, we studied the effect o f two insufflation gases and gasless laparoscopy on in vivo peritoneal macr ophage Function and intraperitoneal pH in an experimental model. A carcinom a was implanted into the flank of 32 experimental rats that underwent lapar oscopic surgery in one of four treatment groups: anesthesia alone, gasless laparoscopy, helium insufflation, and CO2 insufflation. Intraperitoneal pH was monitored during surgery, and peritoneal macrophage function was determ ined 3 days after surgery by harvesting peritoneal macrophages and then exa mining their ability to produce tumour necrosis factor-alpha (TNF-alpha). C O2 insufflation was associated with a consistent fall in intraperitoneal pH and a significant reduction in TNF alpha production. These findings did no t occur in the other study groups. The results of this study demonstrate th at CO2 insufflation results in depressed intraperitoneal macrophage activit y. It is possible that it is mediated by pH changes. In addition, it could be a contributing factor to the development of port-site metastases. Furthe r studies are needed to determine whether the factors identified act during clinical surgery.