Pathophysiological and clinical aspects of carbonic dioxide pneumoperitoneum

The number of laparoscopic procedures is still rising and within the field of gastro-intestinal surgery, urology, and gynaecology the laparoscopic procedure has now become the gold standard. The prerequisite for laparoscopic surgery is a working cavity. Positive pressure carbonic dioxide pneumoperitoneum (CO 2 -PP) and positional changes of the patients are the general methods of exposing the intraperitoneal organs. Carbonic dioxide (CO 2 ) is the preferred gas, because it is inexpensive, highly soluble, and chemically stable. In addition, it suppresses combustion and is a normal product of human metabolism. There is, however, some concern in regard to CO 2 -PP, which may affect the cardiovascular and pulmonary functions. CO 2 is absorbed from the peritoneal cavity into the circulation, where it may result in hypercarbia, acid-base disturbances, and may affect the systemic response and the plasma cascade systems. As the laparoscopic procedures are also offered to patients with co-morbidity, it is mandatory to be aware of the specific, intraoperative, pathophysiological effects that are related to laparoscopic surgery, when using positive pressure CO 2 -PP and to evaluate alternative, minimally invasive methods. Based on a randomized design comparing conventional with gasless laparoscopy the effects of CO 2 - PP are investigated in regard to: ? outcome, pain, convalescence, ? coagulation and fibrinolysis ? surgical stress response ? perioperative haemodynamics and heart performance ? perioperative respiratory function The studies revealed that: ? convalescence is significantly prolonged in patients undergoing surgery with CO 2 -PP compared with gasless technique. However, no difference is registered in postoperative pain or hospital stay ?   coagulation and fibrinolysis is not enhanced by CO 2 -PP ? endocrine and metabolic response may be activated and the inflammatory response blunted by CO 2 -PP   ? mean arterial pressure and heart rate is increased during CO 2 -PP ? preload and afterload is increased, heart performance decreased, but cardiac output not affected during CO 2 -PP ? the haemodynamic effects are most pronounced in the reverse Trendelenburg position ? static lung compliance is reduced, hypercarbia and acidosis follows CO 2 -PP ? postoperative hypercarbia and acidosis may be due to hypoventilation rather than CO 2 accumulation after CO 2 -PP laparoscopy. Further studies are needed to evaluate the long time effects on cancer related survival in patients undergoing laparoscopic surgery compared with that of open fast trac surgery and different laparoscopic techniques. In addition, the evidence of the effect of CO 2 -PP on high risk cardio-pulmonary patients are insufficient.