Cold retrograde cerebral perfusion improves cerebral protection during moderate hypothermic circulatory arrest: A long-term study in a porcine model

Background: Deep hypothermic circulatory arrest is an effective method of c erebral protection, but it is associated with long cardiopulmonary bypass t imes and coagulation disturbances. Previous studies have shown that retrogr ade cerebral perfusion can improve neurologic outcomes after prolonged hypo thermic circulatory arrest. We tested the hypothesis that deep hypothermic retrograde cerebral perfusion could improve cerebral outcome during moderat e hypothermic circulatory arrest. Methods: Twelve pigs (23-29 kg) were rand omly assigned to undergo either retrograde cerebral perfusion (15 degrees C ) at 25 degrees C or hypothermic circulatory arrest with the head packed in ice at 25 degrees C for 45 minutes. Flow was adjusted to maintain superior vena cava pressure at 20 mm Hg throughout retrograde cerebral perfusion, H emodynamic, electrophysiologic, metabolic, and temperature monitoring were carried out until 4 hours after the start of rewarming. Daily behavioral as sessment was performed until elective death on day 7. A postmortem histolog ic analysis of the brain was carried out on all animals. Results: In the re trograde cerebral perfusion group, 5 (83%) of 6 animals survived 7 days com pared with 2 (33%) of 6 in the hypothermic circulatory arrest group. Comple te behavioral recovery was seen in 4 (67%) animals after retrograde cerebra l perfusion but only in 1 (17%) animal after hypothermic circulatory arrest . Postoperative levels of serum lactate were higher, and blood pH was lower in the hypothermic circulatory arrest group. There were no significant hem odynamic differences between the study groups. Conclusions: Cold hypothermi c retrograde cerebral perfusion during moderate hypothermic circulatory an est seems to improve neurologic outcome compared with moderate hypothermic circulatory arrest with the head packed in ice.