Somatosensory evoked responses during and after graded brain ischaemia in goats.
Somatosensory evoked potentials (SEPs) were studied during graded incomplete cerebral ischaemia in eight goats and for the following 2 h. Anaesthesia was maintained with etomidate 1-1.5 mg kg-1 h-1 and 50% nitrous oxide in oxygen. Global cerebral blood flow (gCBF) was measured by a magnetic flow transducer at one internal maxillary artery after surgical occlusion of all other major extracranial cerebral arteries. CBF was reduced every 30 min by 25% with a lower limit of 15-20 ml 100 g-1 min-1. Regional cerebral blood flow (rCBF) in the brainstem and cortex was measured by the microsphere technique. The main findings were: (a) a graded decline in cortical SEP and a concurrent prolongation of the central conduction time (CCT) at gCBF values below 35 ml 100 g-1 min-1 and (b) an incomplete recovery of cortical SEP components during recirculation. Reduction of gCBF affected cortical rCBF more severely than brainstem rCBF. As a result, only cortical SEPs were changed. Our data suggest that reduced cerebral perfusion may result in altered cortical brain electrical activity that may be monitored by SEP recordings.
Kochs
E
E
Department of Anaesthesiology, University-Hospital Eppendorf, Hamburg, Germany.
Schulte am Esch
J
J
D000818:Animals; D002545:Brain Ischemia / Q000503:physiopathology*; D001933:Brain Stem / Q000098:blood supply / Q000503:physiopathology; D002540:Cerebral Cortex / Q000098:blood supply / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006041:Goats; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology