Gasless laparoscopic surgery.

Conventional laparoscopic surgery requires pneumoperitoneum to elevate the abdominal wall for maintaining expansion in an operating field. A continuous insufflation of a noncombustible, soluble gas in a sealed environment is essential. At 15 mm Hg intra-abdominal pressure (the upper limit of intra-abdominal pressure used by most surgeons), significant cardiovascular changes have been observed. These changes are caused by diaphragm elevation and inferior vena cava compression. Elevation of the diaphragm also causes a decrease in tidal volume with resulting pulmonary dysfunction. In conventional practice where C02 is used to create pneumoperitoneum, increased absorption of the gas causes metabolic acidosis and increased intracerebral pressure. Therefore, in patients with intracranial pathology, the use of C02 pneumoperitoneum is not desirable. Compression of the vena cava by pneumoperitoneum results in venous stasis in the lower extremities. Deep venous thrombosis has not been a major problem for gynecologists because pelvic peritoneoscopy is performed in the Trendelenburg position where blood return is enhanced. More lower extremity thromboembolism would be expected when more upper abdominal laparoscopic procedures are performed with the patient positioned in a reversed Trendelenburg position.