A PORCINE MODEL FOR EVALUATION OF CEREBRAL HEMODYNAMICS AND METABOLISM DURING INCREASED INTRACRANIAL-PRESSURE

In patients with severe head injuries raised intracranial pressure (IC P) constitutes the most important cause of mortality. Several new ther apies for increased ICP have recently been suggested and it is of impo rtance to study the physiological effects of these treatments in anima l experiments during steady state conditions. A porcine model for eval uation of cerebral haemodynamics and metabolism during increased ICP i s presented. Intracranial hypertension was induced by inflation of two tonometric gastric balloons placed extradurally covering a major part of the parietooccipital region bilaterally The distribution of the bl ood flow supplied by the carotid artery used for the cerebral blood fl ow (CBF) measurements was studied by intraarterial (i.a.) injection of Tc-99np-HMPAO. The measurements showed that following ligation of the external carotid and the occipital artery no accumulation of tracer s ubstance occurred in extracranial tissues during normal or increased I CP. Cerebral physiological variabies (CBF, Cavo(2), and ICP) were meas ured 5, 20 and 60 min after induction of intracranial hypertension. Th e results confirm that the experimental situation gives a reproducible increase in ICP (25-28 mm Hg) and that the physiologial variables rem ain stable during the period of intracranial hypertension. We conclude chat the model simulates the effects of an acute intracranial focal m ass and is well suited for the evaluation of different pharmacological therapies of increased ICP.