Extracorporeal glass-wool filtration of whole blood enhances post-ischemic recovery of the cortical sensory evoked response

Abstract

In twenty dogs, anticoagulated with heparin 300 units/kg, the right cortical sensory evoked response (CSER) to contralateral median nerve stimulation was suppressed during 60 min ischemia induced by periodic infusion of 50 to 100 microliter increments of air via the right internal carotid artery. The post-ischemic recovery of the CSER was followed an additional 60 min in 19 of these animals divided into 2 groups. Ten dogs were subjected to glass-wool filtration of their blood by extracorporeal shunting from femoral artery to femoral vein for one hr prior to infusing air. Nine dogs did not receive glass-wool filtration. Post-ischemic recovery of CSER amplitude, a quantifiable electrophysiologic index of neuronal function, was significantly greater in the filtered group than in the non-filtered group. 14C-antipyrine autoradiographic blood flow studies were performed in 3 dogs. One was studied at the end of a 60 min ischemic CSER suppression period and showed severe flow disruption by air embolism. Two dogs, one from each group, were studied at the conclusion of the 60 min recovery period. In the filtered animal, cortical blood flow exceeded the threshold for CSER maintenance while cortical flow rates in the unfiltered animal fell below this threshold. The enhanced postischemic neuronal recovery in the filtered group as indicated by the CSER in attributed to the preservation of injury zone nutrient blood flow that is supported by collateral circulation.