Reduction of pump flow during cardiopulmonary bypass (CPB) reduces theformation of microemboli and trauma to the blood components, reduces bothrewarming of the heart and the noncoronary collateral flow, and improvessurgical exposure. Recent studies indicate that a reduction in pump flow, even at normothermia, does not increase the incidence of postoperativecerebral dysfunction. We examined the cerebral consequences of 2 h ofnormothermic CPB in pigs carried out at pump flows of either 70 ml/kg permin or 50 ml/kg per min, and compared the results with those of anonperfused control group. We measured the regional cerebral glucosemetabolism and the regional capillary diffusion capacity simultaneously inten different brain regions. Brain morphology, the blood-brain barrierpermeability to serum proteins and the regional cerebral water content werealso determined in the same animals. Glucose metabolism decreasedsignificantly in both CPB groups (P < 0.001), and significantdifferences were found between the capillary diffusion capacities of thethree groups (P < 0.05), with decreases in eight out of ten brainregions examined in the 50 ml/kg per min group. The results indicate that areduction of pump flows from 70 ml/kg per min to 50 ml/kg per min isdeleterious to the brain, and that a pump flow of 70 ml/kg per min itselfhas an injurious effect, when normothermic CPB is carried out for 2 hwithout the use of vasoactive drugs to maintain the blood pressure. Meanarterial blood pressure (MAP) rather than pump flow seemed to determine theadequacy of the cerebral perfusion.
- Cardiopulmonary bypass
- Regional capillary diffusion capacity
- Regional cerebral glucose metabolism
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cardiology and Cardiovascular Medicine