Experimental carbon dioxide pulmonary embolization after vena cava laceration under pneumoperitoneum

The potential for pulmonary embolization following major venous laceration occurring during laparoscopic surgery has never been evaluated. Five anesthetized dogs were hemodynamically monitored with an arterial line and Swan-Ganz catheter. Observation by transesophageal echocardiography (TEE) allowed comparison with pulmonary artery pressure (PAP) recording. Under pneumoperitoneum, a 1-cm venotomy was performed in the infrarenal vena cava and a total of 11 events were evaluated upon unclamping the venotomy. These results were compared with intravenous (i.v.) bolus injections of 15 cc of CO2 (15 events) and of 100 cc of CO2 (12 events). The animals were maintained euvolemic. In 2 out of the 11 (18%) events which followed unclamping the venotomies, a few CO2 bubbles were seen in the right heart cavities. However, the quantity of gas was much less important than that seen after i.v. injection of 15 cc and 100 cc of CO2. There was no significant elevation of the PAP from pre-event values after venotomy or after i.v. injection of 15 cc of CO2. However, there was a significant difference (P < 0.05) when these results were compared to the PAP values recorded after i.v. injection of 100 cc of CO2. No dog died after these episodes of embolization. Massive i.v. injection of CO2 (> 300 cc) led to appearance of gas bubbles in the left heart cavities and death. This experiment suggests that caution should be exerted when laparoscopic surgery is performed beside large veins. Nevertheless, the observation that no gas embolism occurred in 82% of the cases after unclamping venotomies was unexpected. In contrast, many more gas bubbles were detected in the right heart after i.v. injection of only 15 cc of CO2. TEE is a more sensitive indicator of pulmonary embolization than elevation of PAP.