Electroencephalographic Patterns Related to Hemodynamic Changes at the Onset of Cardio-Pulmonary Bypass Circulation.

Abstract

Electroencephalographic (EEG) changes in relation to hemodynamic changes at the onset of cardio-pulmonary (C-P) bypass circulation in 31 cases undergoing open heart surgeries were studied. Rapid and extensive changes in systemic circulation, which were followed by abnormal EEGs, appeared within the first five minutes of C-P bypass. Abnormal EEG patterns including disappearance of fast waves, slowing under 6 Hz in frequency with high voltage and flattening were observed in 64% of the cases. The relations between the appearance of these abnormal EEGs and hemodynamic factors such as mean arterial pressure (mAP), central venous pressure (CVP), rate of decrease in mAP and rate of change in CVP, were analyzed in order to elucidate causes of development of the abnormal EEGs. Only the rate of decrease in mAP at the onset of C-P bypass had a high correlation (p <0.01) with the appearance of abnormal EEGs. The findings suggest that rapid circulatory changes in the first five minutes of C-P bypass may induce disruption of cerebral autoregulation.EEG; C-P bypass circulation ; systemic circulation ; autoregulation ; hemodynamic changes Direct recording of EEGs and cerebral function monitoring (CFM) reveal that EEG patterns are extremely sensitive to changes in the systemic circulation at the onset of cardio-pulmonary (C-P) bypass circulation (Davenport et al. 1959;Brierley 1967;Wright et al. 1972;Branthwaite 1973;Witoszka et al. 1973). Among a number of factors which affect EEG patterns and CFM at the onset of C-P bypass, arterial hypotension is one of the most important.In the conscious state, cerebral blood flow is sustained within a normal range via cerebral autor-

Hemoglobin Concentration Affects Electroencephalogram During Cardiopulmonary Bypass: An Indication for Neuro‐Protective Values

“…Although an arterial pressure gradient was observed during CPB (mean value decrease from T0 to T1: 21.4 mm Hg; increase from T1 to T2: 20 mm Hg), this factor did not seem to substantially contribute in our patients and is unlikely to significantly contribute to EEG slowing in our population, in that the trend shows an opposite direction (lower arterial pressure at T1 than at T2, when major EEG slowing is observed). In the dog, a delta activity is induced by profound hypotension of 20 mm Hg (22), and brain cell death is reported at a mean arterial pressures of 25 mm Hg in monkeys (23,24), whereas very abrupt pressure dips of up to 45 mm Hg cause EEG slowing in humans (25). None of these conditions were observed in our cohort.…”

Transient electroencephalographic suppression with initiation of cardiopulmonary bypass in pigs: blood versus nonblood priming

“…Electroencephalographic (EEG) changes have been reported in 24-64% of cardiac surgical patients with the initiation of cardiopulmonary bypass (CPB). [1][2][3][4] These EEG alterations are characterized by a sudden, transient loss of cerebral electrical activity for 10-100 s, followed by resumption of normal activity within 5 min. 4 Although the exact cause is unknown, these EEG changes have been attributed to a sudden reduction in cerebral perfusion pressure from arterial hypotension 2,5,6 or venous hypertension, 4 rapid cooling, cerebral gaseous microemboli, 4,7 hypoxia 4 and the effect of nonblood bypass prime.…”

“…[1][2][3][4] These EEG alterations are characterized by a sudden, transient loss of cerebral electrical activity for 10-100 s, followed by resumption of normal activity within 5 min. 4 Although the exact cause is unknown, these EEG changes have been attributed to a sudden reduction in cerebral perfusion pressure from arterial hypotension 2,5,6 or venous hypertension, 4 rapid cooling, cerebral gaseous microemboli, 4,7 hypoxia 4 and the effect of nonblood bypass prime. 6 In particular, the effect of pump prime solutions (nonblood vs blood) on EEG activity during initiation of CPB has not been examined, but may be important owing to the absence of hemoglobin in nonblood priming solutions, which could acutely, but transiently, reduce oxygen delivery to the brain.…”