Hypothermic circulatory arrest with moderate, deep or profound hypothermic selective antegrade cerebral perfusion: which temperature provides best brain protection?

OBJECTIVE

Selective antegrade cerebral perfusion (SACP) seems to be associated with a better outcome compared to hypothermic circulatory arrest (HCA) alone. This study was undertaken to evaluate the influence of different SACP temperatures on the neurological integrity.

METHODS

Twenty-six pigs were included in the study and assigned to 100 min HCA at 20 degrees C body temperature without (n = 6) or with either 10 degrees C (n = 6), 20 degrees C (n = 7) or 30 degrees C (n = 7) of SACP. Haemodynamics, metabolics and neurophysiology (EEG, SSEP, ICP, sagittal sinus saturation) were monitored. Animals were sacrified 4h after reperfusion and brains perfused for histological and molecular genetic assessment.

RESULTS

There were no clinically relevant differences in haemodynamics between groups. The rise in ICP during SACP was significantly more marked in the 30 degrees C group (p < 0.05) and remained high during the entire experiment. In the 10 degrees C group the rise in ICP was postponed, but increased during reperfusion. The 20 degrees C group showed a slight increase of ICP over time, but remained significantly lower compared to HCA (p < 0.05). Sagittal sinus saturation decreased during SACP at 30 degrees C (p < 0.05). EEG recovery was most complete in the 20 degrees C group (p < 0.05). RT-PCR analysis of brain tissue revealed a reduction for heat shock protein (HSP-72) in 20 degrees C (p < 0.05) and 10 degrees C animals (p = 0.095). Histopathological evaluation showed a reduction of edema and eosinophilic cells in the groups treated with SACP.

CONCLUSION

In this model, SACP is superior to HCA alone. Regarding the optimal temperature for SACP, it seems that 20 degrees C provides adequate brain protection in comparison to the potential detrimental effects of moderate (30 degrees C) and profound (10 degrees C) temperatures.