Objective: The expanded use of laparoscopy has led to reports of tumor dissemination and spread to laparoscopic port sites. We previously showed that carbon dioxide insufflation produced tumor dissemination compared with laparotomy. It is unknown whether the type of gas used influences this dissemination. Although carbon dioxide is commonly used during laparoscopy, helium and nitrous oxide could be used. This study was undertaken to compare the effects of carbon dioxide, helium, and nitrous oxide gas on tumor spread in an animal model to determine whether the type of gas used for the pneumoperitoneum would affect tumor spread.
Study design: Viable MATB mammary adenocarcinoma cells were injected into the peritoneal cavity of Fisher 344 rats (1 x 10(5) cells/rat). The animals were then divided into three groups. Four 18-gauge angiocaths were inserted into each of four quadrants of the peritoneal cavity, and induction of pneumoperitoneum with helium, nitrous oxide, or carbon dioxide gas was done at approximately 7 mm Hg for 2 hours. Animals were killed at 7 days and the ventral peritoneal wall and abdominal cavity were examined for evidence of tumor formation. Tumor implants were counted for each of the four quadrants on the anterior peritoneal wall and for the total abdominal cavity.
Results: A total of 39 rats were studied with 13 animals per group. The total number of implants was calculated for the groups: carbon dioxide, n = 57; helium, n = 62; nitrous oxide, n = 66. There was no significant difference in the total number of implants according to the type of gas or the size of implants. When implants that were <5 mm were analyzed, the four quadrants of the anterior peritoneum showed a random difference in tumor disbursement between one quadrant in the helium (n = 15) and one quadrant in the nitrous group (n = 23). However, when the three gasses were compared with all four quadrants, there was no statistical significance (carbon dioxide, n = 35; helium, n = 38; nitrous oxide, n = 44).
Conclusion: There is no difference in tumor implantation when with use of carbon dioxide, helium, or nitrous oxide gas in an animal model. Thus, carbon dioxide insufflation does not appear to increase tumor spread compared with other gasses.