Experimental Cerebral Circulatory Arrest: Effect on Electrocortical Potentials

Abstract

PONTANEOUS cerebral electrical potentials have been used clinically for prognosis following destructive cerebral lesions, and a persistently isoelectric electroencephalographic recording (EEG) has been considered one criterion of cerebral nonviability both for cessation of artificial maintenance of vital functions and for subsequent somatic organ transplantation. Prominent among causes of cerebral non-viability are those related to circulatory arrest, which include shock, arterial occlusive disease, cardiopulmonary insufficiency, and cardiac arrest. Diminution of cerebral blood flow as well as greatly increased intracranial pressure causes stagnant (ischemic) hypoxia, which in turn is reflected in profound EEG changes. These types of ischemic or anoxic cerebral insults may be reproduced experimentally and their effects on electrocortigraphic (ECoG) activity recorded. In such experiments, intrathoracic vascular occlusion causing immediate circulatory arrest has been produced to determine patterns of electrocortical silence, recovery, and the sensitivity of cortical electrical function related to survival. However, the preparation is not comparable to stepwise obliteration of the four major cervical vessels since simultaneous occlusion is difficult and a certain amount of cerebral damage can occur during experimental ligations, which make exact timing of anemia difficult. Also, a potentially large amount of collateral circulation exists. In man, for example, cases have been reported in which only minimal neurological dysfunction was caused following occlusion of all major cervical vessels, 8 although acute

Cerebral Lactate Accumulation and Glucose Exhaustion During Circulatory Arrest

“…Brockman and Jude (2) have shown that 10-12 min is the limit of canine survival applying clinical criteria in the model utilized in the present experiments. A study employing electtocortical recordings in dogs has shown that survival can be predicted by quality and timing of recurrence of activity (3). From those studies it appears that lactate accumulation recorded in the present experiment at 10 min may represent a level in dogs with which restoration of useful cerebral function becomes unlikely.…”

“…One standard experimental model (1,2) of circulatory standstill which is closely related to its clinical counterpart has been studied electrophysiologically (3). Effects of circulatory arrest on intracranial pressure and time limits of tolerance to prolonged arrest have been delineated (2,3). In the present study, this experimental model has been utilized for a timed survey of cerebral lactate accumulation and glucose disappearance.…”

“…This is a true emergency, since restoration of circulation either by artificial or natural means is imperative primarily because of cerebral (and somatic organ) intolerance to hypoxia. One standard experimental model (1,2) of circulatory standstill which is closely related to its clinical counterpart has been studied electrophysiologically (3). Effects of circulatory arrest on intracranial pressure and time limits of tolerance to prolonged arrest have been delineated (2,3).…”

“…Arterial pH and oxygen saturation were determined immediately prior to circulatory arrest and were essentially physiologic. Thoracotomy was performed through the fourth right intercostal space, and umbilical tapes were loosely applied around the roots of the ascending aorta, inferior vena cava, and superior vena cava cephalad to the azygos vein according to techniques previously described (2,3). Cessation of left ventricular cardiac output except for coronary flow was accomplished by near simultaneous occlusion of both vena cavae followed by occlusion of the ascending aorta.…”

Arrêt Circulatoire Intracrânien Dans La Mort Du Cerveau

“…De nombreux travaux montrent la grande importance et les limites de l'elecrro-encephalogramrne dans le diagnostic de la mort cerebrale, Notamment, pour la duree necessaire d'observation d'un electro-encephalogramme nul, qui merne depassant plusieurs jours peut ne pas etre suffisant dans certaines conditions etiologiques comme les intoxications (1, 3,4,5,9,21,26,27,31,40). Les enregistrements profonds donnent les memes resultats (12,38).…”