Isoflurane Induced Anesthetic Preconditioning in Elective Liver Resection

Elective liver resection is performed primarily for the treatment of benign and malignant liver tumors1. In addition, with the increasing use of living donor liver transplantation to supplement the inadequate pool of cadaveric organs available, liver resection is performed also in live liver donors2.

Postoperative complications are common following liver resections. Occurrence of complications increases ICU and hospital stay, and resource utilization. The most serious postoperative complication after a liver resection is post-resectional liver failure (PLF)3. Risk factors for the development of PLF are preexisting liver disease, especially cirrhosis, excessive blood loss during liver resection, and liver ischemia and reperfusion injury4-5. Several strategies have been developed to combat excessive intra-operative blood loss including: lowering the central venous pressure6, hypoventilation7, and hepatic inflow occlusion using an atraumatic clamp8 (Pringle's maneuver)9; While inflow occlusion is the most important of these steps, hepatic ischemia and reperfusion is an important sequel to the inflow occlusion. Therefore, interventions which decrease hepatic ischemia reperfusion injury to the liver have the potential to improve outcomes following liver resection.

A strategy that directly modulates the hepatic response to ischemia is ischemic preconditioning (IPC). Classically, IPC has been induced by exposing an organ to brief periods of ischemia and reperfusion before exposing the organ to a more prolonged ischemic insult. In patients undergoing liver resection, IPC decreases postoperative aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels15. IPC is also associated with decreased histological evidence of apoptosis as well as immunohistochemical evidence of increased protective gene expression16 in the liver.

The primary disadvantage of IPC is the direct stress to the target organ as well as the mechanical trauma to major vasculature.

More recently, it has been found that inhaled volatile anesthetics such as Desflurane, Sevoflurane and Isoflurane induce similar preconditioning effects19 without causing any significant direct organ damage. While several animal studies exist, which demonstrate the hepatoprotective effect of volatile anesthetics on the liver23, there is only limited clinical data examining their effect in humans. One recent small clinical study, examining the preconditioning effect of volatile anesthetic on patients undergoing liver surgery, showed that anesthetic pre conditioning (APC) using Sevoflurane significantly decreased the several measures of liver dysfunction postoperatively24.