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 °C body temperature without (n = 6) or with either 10 °C (n = 6), 20 °C (n = 7) or 30 °C (n = 7) of SACP. Haemodynamics, metabolics and neurophysiology (EEG, SSEP, ICP, sagittal sinus saturation) were monitored. Animals were sacrified 4 h 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 °C group (p ≪ 0.05) and remained high during the entire experiment. In the 10 °C group the rise in ICP was postponed, but increased during reperfusion. The 20 °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 °C (p ≪ 0.05). EEG recovery was most complete in the 20 °C group (p ≪ 0.05). RT-PCR analysis of brain tissue revealed a reduction for heat shock protein (HSP-72) in 20 °C (p ≪ 0.05) and 10 °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 °C provides adequate brain protection in comparison to the potential detrimental effects of moderate (30 °C) and profound (10 °C) temperatures.