Haemodynamic conditions enhancing gas embolism after venous injury during laparoscopy: a study in pigs.

This study was designed to determine the conditions that promote carbon dioxide embolism after venous injury during laparoscopy in pigs. Injury to an iliac vein was filmed during laparoscopy in the presence of a pneumoperitoneum created at increasing pressures from 0 to 30 mm Hg in 5-mm Hg increments. At intraperitoneal pressures less than 20 mm Hg, there was a parallel increase in femoral venous pressures, resulting in haemorrhage, with persistent blood flow to the inferior vena cava. At intraperitoneal pressures of 20-30 mm Hg, there was collapse of the femoral vein, occurring earlier in the presence of hypovolaemia. Between these two states (haemorrhage and collapse), there was a point of equilibrium which allowed retrograde venous penetration of carbon dioxide bubbles. During release of the pneumoperitoneum, these bubbles were exteriorized through the area of the injury, but some passed into the inferior vena cava where their presence was detected by an oesophageal Doppler probe.