Hypothermic circulatory arrest with and without cold selective antegrade cerebral perfusion: impact on neurological recovery and tissue metabolism in an acute porcine model.

OBJECTIVE

Clinically, selective antegrade cerebral perfusion (SACP) seems to be associated with a better neurological outcome compared to hypothermic circulatory arrest (HCA) alone, but the pathophysiological mechanisms are not well understood. Therefore, this study was undertaken to assess the effects of HCA with and without SACP on the cerebral integrity using multimodal neurophysiological monitoring.

METHODS

12 pigs were randomly assigned to 100 min HCA at 20 degrees C brain temperature with (n = 6) and without (n = 6) SACP. Haemodynamics, metabolics and neurophysiology (EEG, SSEP, ICP, spectroscopy, cerebral tissue monitoring) were monitored. Animals were sacrified 4 h after reperfusion and the brains perfused for histopathological assessment.

RESULTS

There were no clinically relevant differences in hemodynamics between groups. During reperfusion, EEG and SSEP recovery was significantly faster in the SACP group (P < 0.05). The rise in ICP during reperfusion was markedly reduced in the SACP group (P < 0.01) for the trend). Three hours after reperfusion, median ICP was 130% compared to baseline in the SACP group and 225% in the HCA group (P < 0.01). Invasive as well as noninvasive cerebral monitoring indirectly indicates the occurrence of tissue acidosis in the HCA group even 4 h after HCA.

CONCLUSIONS

Cold SACP is associated with better neurophysiological recovery and less cerebral edema, indicated by lower intracranial pressures during reperfusion. Neurophysiological recovery correlated well with the rise in ICP. HCA alone causes prolonged acidosis in the brain tissue during reperfusion. From these data, SACP appears to be superior to HCA alone, but further studies have to elucidate the optimal regimes for SACP.