Elevated PEEP without effect upon gas embolism frequency or severity in experimental laparoscopic liver resection

Abstract

Carbon dioxide (CO(2)) embolism is a potential complication in laparoscopic liver surgery. Gas embolism (GE) is thought to occur when central venous pressure (CVP) is lower than the intra-abdominal pressure (IAP). This study aimed to investigate whether an increased CVP due to induction of PEEP could influence the frequency and severity of GE during laparoscopic liver resection. Twenty anaesthetized piglets underwent laparoscopic left liver lobe resection and were randomly assigned to either 5 or 15 cm H(2)O PEEP (n=10 per group). During resection, a standardized injury to the left hepatic vein [venous cut (VC)] was created to increase the risk of GE. Haemodynamic and respiratory variables were monitored, and online arterial blood gas monitoring and transoesophageal echocardiography (TOE) were used. The occurrence and severity of embolism was graded as 0 (none), 1 (minor), or 2 (major), depending on the TOE results. No differences were found between the two groups regarding the frequency or severity of GE, during either the VC (P=0.65) or the rest of the surgery (P=0.24). GE occurred irrespective of the CVP-IAP gradient. Mechanisms other than the CVP-IAP gradient seemed during laparoscopic liver surgery to contribute to the formation of CO(2) embolism. This is of clinical importance to the anaesthetists.