LIVER-FUNCTION, CEREBRAL BLOOD-FLOW AUTOREGULATION, AND HEPATIC-ENCEPHALOPATHY IN FULMINANT HEPATIC-FAILURE

In acute liver failure, massive hepatic necrosis may result in impaire d regulation of cerebral blood flow (CBF), development of encephalopat hy, and cerebral edema. In 10 consecutive patients with fulminant hepa tic failure (FHF), CBF autoregulation was found to be absent, as trans cranial Doppler mean flow velocity (V-mean) in the middle cerebral art ery increased from 49 (27-59) to 69 (49-92) cm/s (P < .05) during a 30 - (28-34) mm Hg rise in mean arterial pressure (MAP). In 7 patients, r estoration of CBF autoregulation was shown within 48 (24-120) hours af ter spontaneous hepatic recovery or liver transplantation, before comp lete alleviation of hepatic encephalopathy (HE). The extraordinarily r apid restoration of CBF autoregulation in patients with FHF following re-establishment of liver function is unique compared with other condi tions affecting the CBF autoregulation, indicating a close connection between liver function and regulation of cerebral circulation. Because CBF autoregulation was restored after initial alleviation of HE, it d oes not appear to be of major pathophysiological importance in the med iation of HE.