EFFECTS OF FENOLDOPAM ON INTRACRANIAL-PRESSURE AND HEMODYNAMIC VARIABLES AT NORMAL AND ELEVATED INTRACRANIAL-PRESSURE IN ANESTHETIZED PIGS

Fenoldopam (FE), a dopamine DA1-receptor agonist, has been introduced for treatment of arterial hypertension and heart failure and for prese rvation of renal function. Vasodilators are generally assumed to affec t all vascular beds including the cerebral circulation. We have evalua ted effects of FE-induced (4 mug . kg-1 . min-1) arterial hypotension on intracranial pressure (ICP) and intraocular pressure (IOP) under co nditions of normal and increased intracranial elastance. ICP and IOP r esponses to hypertension were tested by infusion of angiotensin II (15 mug . kg-1 . min-1), and the response to hypercapnia was tested by el imination and reintegration of soda lime canisters in the breathing ci rcuit. Intracranial elastance was increased by infusing mock cerebrosp inal fluid (CSF) into the lateral ventricle (20 +/- 3 ml . h-1). Arter ial hypotension induced with FE did not increase ICP. With increased i ntracranial elastance, the infusion rate of mock CSF had to be reduced while administering, FE to avoid a rise in ICP (p < 0.05 compared wit h preinfusion value); this indicates a shift on the volume-pressure cu rve to the right. There were no indicators that cerebral autoregulatio n or CO2 reactivity of the cerebral vasculature were affected by FE in this anesthetized porcine model, as speculated from analysis of the t ime course of DELTA ICP. There are, however, indicators of increased i ntracranial elastance, most likely caused by vasodilation. Caution sho uld hence be exercised when FE is administered to patients with increa sed intracranial elastance.