Pulsatile low-flow perfusion for enhanced cerebral protection.

We examined the oxygen tension, carbon dioxide tension, and pH in canine brains under profound hypothermia to evaluate the effects of perfusion (circulatory arrest for 1 hour; 25 and 50 mL.kg-1 x min-1 for 2 hours) with and without pulsatile assistance. The effects of pulsatile flow on cerebral blood flow and metabolism were also evaluated in dogs supported by low-flow perfusion (25 mL.kg-1 x min-1) for 2 hours. Profound hypoxia occurred in the brain after 20 to 60 minutes of circulatory arrest. Brain tissue acidosis with hypercapnia was moderated by perfusion at a rate of flow of 50 mL.kg-1 x min-1. Pulsatile low-flow perfusion (25 mL.kg-1 x min-1) moderated cerebral hypercapnia and made the cerebral metabolism aerobic without affecting the total cerebral blood flow and consumption of oxygen.