Transitory cerebral microvascular blockade after cardiopulmonary bypass.

Abstract

. (1976). Thorax, 31,[736][737][738][739][740][741]. Transitory cerebral microvascular blockade after cardiopulmonary bypass. Dogs were submitted to cardiopulmonary bypass (CPB) carried out under conditions calculated to generate large numbers of microbubbles and microemboli. On the day following the procedure the dogs showed evidence of neurological damage including impaired consciousness and ataxia. These abnormalities largely cleared within a week. When the animals were sacrificed at intervals after the procedure, the cerebral microvasculature was demonstrated by injecting a suspension of lamp black into the carotid artery. This revealed that multiple filling defects were present in the microcirculation of the brain immediately after CPB and f6r two days thereafter. However, by seven days the microvascular blockade had disappeared, and the vascular pattern of the brain had returned to normal. Neuropathological findings were sparse and restricted to the cerebellum.This study suggests that the transient neurological syndromes that sometimes follow cardiopulmonary bypass for heart surgery may be due to a transient microvascular blockade, perhaps by microbubbles and microparticles.

Longer Duration of Cardiopulmonary Bypass Is Associated With Greater Numbers of Cerebral Microemboli

“…16,20 The rapid decline in microemboli found in this study is consistent with observations in dogs showing that after CPB, most microvascular occlusions had disappeared within 7 days, 32,33 and with the observations of Blauth et al 34 that vascular occlusions in the retinas of CPB patients were more numerous during CPB than after CPB.…”

Does hypothermia or hyperventilation affect enflurane MAC reduction following partial cardiopulmonary bypass in dogs?

“…Activation of the complement system with disruption of cell membranes may occur as a result of CPB. , [6][7][8][9][10][11][12][13][14][15][16][17][18][19] In a group of dogs undergoing hypothermic CPB, Johnston et al , 4 found that cerebral blood flow (CBF) was markedly reduced during 150 min of hypothermic CPB and remained so even after rewarming. They saw a small, but significant, rise in intracranial pressure (ICP) but could demonstrate no evidence of brain oedema on the basis of cerebral water content.…”

The Pathophysiology of Cerebral Arterial Gas Embolism

“…This fall was abolished in filtered CPB, and Doppler counting confirmed the efficacy of the filter in reducing bubble exposure. Patterson et al (61) subjected dogs to 2 hours of CPB using a bubble oxygenator operated in such a way as to produce numerous microbubbles. Groups of dogs were sacrificed after progressively longer periods of recovery.…”