The impact of carbon dioxide and helium insufflation on experimental liver metastases, macrophages, and cell adhesion molecules

Background: Laparoscopic insufflation, proposed to reduce hepatic perfusion, may enhance hepatic tumor spread. It is unknown whether intraabdominal pressure or the gas itself influences hepatic tumor growth. In contrast to carbon dioxide, the alternative gas helium is believed to reduce malignant cell growth. Methods: For this study, 36 WAG/Rij rats were randomized in two experimental groups. The animals were laparoscopically insufflated with carbon dioxide (n = 19) or helium gas (n = 17). Liver metastases were induced by laparoscopic injection of 50,000 CC531 cells into the portal vein. Macroscopic and microscopic analyses of CC531 tumor cell growth, macrophages, and CD44v5, v6 were performed. Data were analyzed by Kruskal-Wallis, Dunn, and Holm tests. Results: No significant differences in macroscopic and microscopic analyses were found between carbon dioxide and helium gas insufflations (p > 0.05). Conclusions: Recent studies have shown that insufflation with carbon dioxide may result in increased hepatic tumor growth. The current study comparing carbon dioxide and helium insufflations could show for the first time either oncologic nor immunologic differences in relation to the liver between two different gases. In conclusion, elevated intraabdominal pressure during gas insufflation is responsible for hepatic disadvantages during pneumoperitoneum, not carbon dioxide gas itself.