BACKGROUND In patients with fulminant hepatic failure, systemic vascular resistance and blood pressure are often reduced. OBJECTIVE To determine whether systemic vascular resistance increases during high-volume plasmapheresis, which is assumed to eliminate endogenous vasodilatory substances from the bloodstream. METHODS A prospective study. METHODS Ten patients [median age 48 (range 21-53) years] were admitted for liver transplantation. Systemic haemodynamic variables were determined using a catheter in a radial artery and a thermodilution catheter placed in a pulmonary artery. Ten (range 8-15) litres of fresh frozen plasma were exchanged, while body temperature [37.6 (range 36.6-38.4) degrees C], blood partial pressure of carbon dioxide [3.75 (range 3.30-4.50) kPa] and peak inspiratory ventilatory pressure [24 (range 20-26) mmHg] were kept constant. RESULTS Mean arterial pressure increased from 74 (range 61-110) to 96 (range 68-103) mmHg and cardiac index decreased from 5.2 (range 3.6-7.5) to 4.2 (range 3.4-6.6) l/min/m2. The systemic vascular resistance index increased from 662 (range 430-1270) to 1060 (range 621-1520) dyn s/cm5/m2. In contrast, the pulmonary vascular resistance index [42 (range 20-110) dyn s/cm5/m2) remained constant. As cardiac index decreased, oxygen delivery decreased from 939 (range 680-1496) to 745 (range 601-1189) ml/min/m2 with no effect on oxygen consumption [171 (87-231) ml/min/m2], as the arteriovenous oxygen extraction ratio increased from 17 (range 9-22) to 25 (range 8-31)% (P < 0.02). CONCLUSIONS In patients with fulminant hepatic failure, cardiac output, systemic vascular resistance and arterial blood pressure improved during high-volume plasmapheresis.