Effect of Sevoflurane and Propofol on Hepato-splanchnic Pressure and Flow During Hepatobiliary Surgery

Overview

Blood loss in hepatobiliary surgery is correlated with an increase in postoperative complications (e.g. transfusion related lung injury and tumor recurrence) and reduced longterm survival. To reduce morbidity and mortality in hepatobiliary surgery, modulation of the hepato-splanchnic blood flow and pressure is used. In liver surgery pharmacological modulations are widely used to prevent blood loss. For pharmacological modulation central venous pressure is commonly used to reduce the pressure in the inferior vena cava, however little is known about pharmacological effect on blood flow in the hepatic artery and portal vein. The modulation of the hepato-splanchnic blood flow can also play an important role, not only for prevention of blood loss but also for survival of the organs (e.g. ischemic injury due to low flow). Volatile anesthetics induce a dose-dependent reduction of the hepato-splanchninc blood flow. Propofol however, increases hepatic blood flow when compared with volatile anesthetics. Pharmacological modulation of hepato-splanchnic bloodflow with anesthetics such as sevoflurane or propofol can play an important role in modulation of ischemia/reperfusion injury and survival of organs. The aim of the study is to determine and to compare the effect of sevoflurane versus propofol on hepatosplanchnic pressure and hepato-splanchnic blood flow during hepatobiliary surgery.

All patients receive standardized anesthesia care for hepato-biliary surgery according to the existing anesthesia protocol. The type of anaesthesia will be randomized : propolipid (TIV) or sevorane(inhalation). At designated times, hemodynamic variables will be recorded. These will include: * HF (/min) * CVP (mmHg), * MAP (mmHg) * CI (L/min.m2) * PPV (pulse pressure variation). Hemodynamic measurement will be done using PiCCO catheter. The hemodynamic measurements will be compared and related to hepato-splanchnic blood flow and pressure measurements performed by the surgeon: * Flow v. porta * Flow art. hepatica * Pressure v. porta * Pressure v. cava The flow measurements will be done using ultrasound transit time flow measurements TTFM (Medi-Stim AS, Oslo, Norway). At the same time pressure measurements will be obtained in portal vein and caval vein using a 25-gauge needle which is directly placed in the vein. Both flow and pressure will be simultaneously recorded (VeriQ 4122, Medi-Stim AS, Oslo, Norway). Both measurements will be done during apnea to minimize the effect of ventilation on pressure \& flow. Flow values will be expressed in ml per minute, pressure values will be expressed in mmHg.