Antegrade cerebral perfusion reduces cerebral edema formation in a porcine model of hypothermic circulatory arrest

Objectives: Thoracic aortic surgery using hypothermic circulatory arrest (HCA) is still associated with significant morbidity and mortality due to neurological complications. Recently, a number of clinical studies showed that antegrade cerebral perfusion (ACP) as an adjunctive seems to be superior to HCA alone. Despite this fact, experimental data on the pathophysiological background can be rarely found. Therefore, this study was undertaken to evaluate the effects of ACP using multimodal neuromonitoring in a porcine model.

Material and Methods: 12 juvenile, female pigs were randomly assigned to 100min HCA with (n=6) and without SACP (n=6). Haemodynamics, metabolics and neurophysiology (EEG, SSEP, ICP, spectroscopy, cerebral tissue monitoring, sagittal sinus saturation) were monitored continously. Animals were sacrified 4h after reperfusion and the brains were selectively perfused for further histopathological and molecular genetic assessment.

Results: Hemodynamic data showed no differences between groups. During reperfusion, EEG and SSEP recovery was significantly faster in the ACP group (p<0.05). The rise in ICP during reperfusion was markedly reduced in the ACP group (p<0.01 for the trend). 3h after reperfusion, median ICP was 128% compared to baseline in the ACP group and 243% in the HCA group (p<0.01). Invasive as well as non invasive cerebral monitoring indirectly indicates the occurrence of marked tissue acidosis in the HCA group.

Conclusions: Data indicate that SACP reduces cerebral edema formation and is associated with better neurophysiological recovery compared to HCA alone. Neurophysiological recovery correlated well with the rise in ICP. HCA alone was associated with marked acidosis in the brain tissue during reperfusion, probably caused by vasospasm.