Hemodynamic and tissue blood flow responses to long-term pneumoperitoneum and hypercapnia in the pig

Background Increased peritoneal blood flow may influence the ability of cancer cells to adhere to and survive on the peritoneal surface during and after laparoscopic cancer surgery. Carbon dioxide (CO₂) pneumoperitoneum is associated with a marked blood flow increase in the peritoneum. However, it is not clear whether the vasodilatory effect in the peritoneum is related to a local or systemic effect of CO_2. Methods In this study, 21 pigs were exposed to pneumoperitoneum produced with either CO₂ (n = 7) or helium (He) (n = 7) insufflation at 10 mmHg for 4 h, or to two consecutive levels of hypercapnia (7 and 11 kPa) (n = 7) produced by the addition of CO₂ to the inhalational gas mixture. Tissue blood flow measurements were performed using the colored microsphere technique. Results Blood flow in peritoneal tissue increased during CO₂, but not He, pneumoperitoneum, whereas it did not change at any level of hypercapnia alone. There was no change in blood flow in most organs at the partial pressure of CO₂ (PaCO₂) level of 7 kPa. However, at a PaCO₂ of 11 kPa, blood flow was increased in the central nervous system, myocardium, and some gastrointestinal organs. The blood flow decreased markedly in all striated muscular tissues during both levels of hypercapnia. Conclusion The effect of CO₂ on peritoneal blood flow during laparoscopic surgery is a local effect, and not attributable to central hemodynamic effects of CO₂ pneumoperitoneum or high systemic levels of CO₂.