Paradoxical carbon dioxide embolism during laparoscopic surgery without intracardiac right-to-left shunt: two case reports and a brief review of the literature

We herein report two cases of paradoxical carbon dioxide (CO 2 ) embolism during laparoscopic nephrectomy and hepatic left lateral lobectomy without evidence of a right-to-left shunt or obvious rupture of blood vessels. Transesophageal echocardiography detected paradoxical CO 2 embolism before the end-tidal CO 2 partial pressure (P ET CO 2 ) dropped from baseline. The pneumoperitoneum was reduced or stopped immediately after detection of the embolism. One patient developed a postoperative epileptiform seizure. In the other patient, many gas bubbles were drawn out from the central venous line. We speculate that rapid introduction of pneumoperitoneum pushed a large amount of CO 2 into the abdominal blood vessels, exceeding the gas exchange capacity of the lung and causing CO 2 bubble formation in the left-side cardiac system. These two cases indicate that intraoperative transesophageal echocardiography can reduce the influence of CO 2 embolism during laparoscopic tumor surgery by early diagnosis of the embolism and provide helpful information to establish a list of differential diagnoses of postoperative complications.