BACKGROUND: For @entity1 cardiac surgery, recent studies suggest improved neurological outcome after deep hypothermic @entity1167 when pH-stat cardiopulmonary bypass is used compared with alpha-stat cardiopulmonary bypass. The pH-stat method is hypothesized to protect the brain through improved cooling and/or rewarming. We examined brain cooling and rewarming during pH-stat and alpha-stat cardiopulmonary bypass in 12 newborn @entity1707 . METHODS AND RESULTS: Microthermistors were inserted into the caudate and cortical gray and white matter, and a cranial window was created to map neocortical temperature gradients by using infrared imaging. Piglets were cooled with pH-stat or alpha-stat cardiopulmonary bypass until all brain regions were less than 20 degrees C; then they were subjected to 60 minutes of @entity1167 , and afterward, rewarmed with cardiopulmonary bypass. During cardiopulmonary bypass cooling, cortical gray and white matter and caudate temperatures were up to 5 degrees C less in pH-stat than in alpha-stat (P<.05), although after 10 minutes of cooling, only cortical white matter temperature remained significantly less in pH-stat. Neocortical thermal gradients during cardiopulmonary bypass cooling were greater in pH-stat versus alpha-stat during the initial 8 minutes (4 degrees C to 5 degrees C versus 2 degrees C to 3 degrees C, P<.01) but were less by 18 to 20 minutes (0.9 degrees C versus 1.7 degrees C, P<.01). Cardiopulmonary bypass cooling time to less than 20 degrees C was shorter for pH-stat than for alpha-stat in cortical gray matter (14 versus 17 minutes, P<.05) and cortical white matter (17 versus 23 minutes, P<.001) but not in caudate (13 versus 16 minutes, P=NS). Cooling time to less than 1 degrees C neocortical thermal gradient was shorter in pH-stat than in alpha-stat (15 versus 23 minutes, P<.001). During rewarming, regional brain temperatures and neocortical thermal gradients were not different between groups. CONCLUSIONS: pH-stat improves brain cooling efficiency during cardiopulmonary bypass because all regions cooled more rapidly, especially cortical white matter, and less time was required to achieve uniform cerebral @entity2332 . pH-stat and alpha-stat cardiopulmonary bypass rewarm the brain similarly after @entity1167 .

Brain cooling efficiency with pH-stat and alpha-stat cardiopulmonary bypass in newborn XXXX .

@entity1 :: ('9606', 'Species') :: ['infant'] @entity1707 :: ('9823', 'Species') :: ['pigs'] @entity2332 :: ('MESH:D007035', 'Disease') :: ['deep hypothermia'] @entity1167 :: ('MESH:D006323', 'Disease') :: ['deep hypothermic arrest', 'circulatory arrest']
@entity1707 :: (9823,Species) :: ['pigs']
