Objective:
The aim of this study was to evaluate the effects of hypercarbia, asidosis and hypoxia due to pneumoperitoneum on healing of colonic anastomoses.
Material and Methods:
Forty Guinea pigs weighting 500-550 gr, were divided into four groups, each consisting of 10 Guinea pigs. Group 1: laparotomy plus colon anastomosis (control group), Group 2: 12 mmHg CO2 pneumoperitoneum for 30 minutes plus colon anastomosis, Group 3: 12 mmHg CO2 pneumoperitoneum for 60 minutes plus colon anastomosis, Group 4: 12 mmHg CO2 pneumoperitoneum for 30 minutes plus subcutaneous emphysema plus colon anastomosis. After pneumoperitoneum was induced as described above, arterial blood samples were withdrawn from the femoral artery for arterial blood gase analysis. Left colon resection and end-to-end anstomosis was performed on all animals after blood samples were withdrawn. All animals were killed on the postoperative day 4 and anastomosis bursting pressures were measured.
Results:
Hypercarbia, acidosis and hypoxia were all present in the pneumoperitoneum groups and these levels were statistically different compared to the control group. The degree of hypercarbia, acidosis and hypoxia correlated with the volume of CO2 absorbed which was dependent on the lenght of pneumoperitoneum and presence of subcutaneous emphysema. The highest levels of hypercarbia, acidosis and hypoxia were found in Group 4. The lowest anastomotic bursting pressure occurred in Group 4 and the difference was statistically significant when compared with control group (p<0.05).
Conclusion:
Anastomotic healing is not impaired until a critical level of hypercarbia, acidosis and hypoxia is reached. In this study pneumoperitoneum alone was not sufficient to achieve this treshold, however subcutaneous emphysema likely futher increased CO2 absorbtion which impairs anastomosis healing.
Keywords: Pneumoperitoneum, hypercarbia, acidosis, hypoxia, anastomotic healing