Error associated with the choice of an aortic cannula in measuring regional cerebral blood flow with microspheres during pulsatile CPB in a neonatal piglet model

The effectiveness of an infant pulsatile cardiopulmonary by-pass (CPB) system on maintaining regional cerebral blood flow (CBF) using two different types of aortic cannulae in 3 kg piglets has been investigated. The University of Texas Neonatal Pulsatile Pump was used with either a DLP (Group I, n = 6) or an Elecath (Group II, n = 7) 10Fr aortic cannula. In all the subjects, nasopharyngeal temperature was reduced to 18°C, followed by 1 hr of deep hypothermic circulatory arrest (DHCA), then 45 min of rewarming. During cooling and rewarming, alpha-stat blood gas management was used. The radionuclide labeled microsphere technique was used to determine blood flows in the cerebellum, basal ganglia, brainstem, right and left hemispheres, as well as global CBF (ml/100 g/min). When the DLP aortic cannula was used, regional and global CBF appeared to be higher pre- and post DHCA. In both groups regional CBF was significantly decreased following DHCA. Although better pulsatile flow was attained using the DLP cannula and this may have resulted in higher regional CBF, these results must be interpreted in light of the large standard deviations noted when this cannula was chosen for the studies. These results demonstrate the importance of choosing an appropriate aortic cannula for measuring regional CBF with a pulsatile neonate-infant CPB system.