Cerebral perfusion during human liver transplantation.

During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (Vmean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients Vmean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The Vmean (40 +/- 13 cm s-1 [mean +/- SD]), thoracic electrical impedance (TI) (30 +/- 7 Ohm), heart rate (97 +/- 19 beats min-1), mean arterial pressure (84 +/- 9 mmHg) and arterial carbon dioxide tension (PaCO2, 4.5 +/- 0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6 +/- 2.7 to 5.4 +/- 1.41 min-1), stroke volume (SV, 79 +/- 26 to 56 +/- 15 ml) and PI (1.2 +/- 0.3 to 0.9 +/- 0.2) decreased (P < 0.05). During reperfusion, CO (9.9 +/- 4.01 min-1), SV (105 +/- 40 ml), PaCO2 (5.5 +/- 0.6 kPa), Vmean (57 +/- 17 cm s-1) and PI (1.2 +/- 0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension.