Peritoneal tissue-oxygen tension during a carbon dioxide pneumoperitoneum in a mouse laparoscopic model with controlled respiratory support

BACKGROUND: Previous animal studies suggested that the peritoneal environment during a carbon dioxide (CO2) pneumoperitoneum is hypoxic and that this may contribute to the formation of intra-abdominal adhesions or the growth of malignant cells. There is no study, however, that investigates the relationship between anaesthesia, ventilation and the laparoscopic peritoneal environment to the development of hypoxia. The objective of this study is to monitor the peritoneal tissue-oxygen tension (PitO(2)) under various conditions including anaesthesia alone, during a CO2 pneumoperitoneum at both low and high intraperitoneal pressure (IPP), and laparotomy, in animal models with controlled respiratory support (CRS). METHODS: C57BL6 mice were divided into eight groups (n = 5) consisting of anaesthesia alone or with CO2 pneumoperitoneum at low (2 mmHg) or high (8 mmHg) IPP or undergoing laparotomy. Groups were further subdivided into those with or without CRS with endotracheal intubation and mechanical ventilation. Over the course of the 1 h procedure, PitO(2) was continuously monitored. RESULTS: Protocol 1. The PitO(2) levels (104.2 +/- 7.8 mmHg, mean +/- SEM) in non-injured peritoneum during a CO2 pneumoperitoneum at a low IPP were elevated similar to 2-fold over the levels during laparotomy (49.8 +/- 15.0 mmHg) in ventilated mice. Protocol 2. After insufflation with CO2, the PitO(2) was immediately elevated and maintained at a higher level. Following laparotomy, it decreased immediately. This elevation was not seen with air insufflation. CONCLUSION: In mice, a significant elevation in PitO(2) occurs during a CO2 pneumoperitoneum at low IPP with CRS.