PULSATILE PERFUSION IMPROVES CEREBRAL AND RENAL BLOOD FLOW DURING AND AFTER CARDIOPULMONARY BYPASS WITH DEEP HYPOTHERMIC CIRCULATORY ARREST IN A NEONATAL PIGLET MODEL

Abstract

Purpose: To date, controversy over the benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) still continues. Our objectives of this study were 1) to quantify the pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and 2) to investigate the effects of pulsatile versus nonpulsatile flow on cerebral and renal blood flow during and after CPB with deep hypothermic circulatory arrest (DHCA) in a neonatal piglet model. Methods: Fourteen piglets (mean weight of 3kg) underwent perfusion with either the hydraulically driven dual-chamber physiologic pulsatile pump (n = 7) or a conventional nonpulsatile pump (n = 7). After initiation (if CPB, all animals were subjected to 25 minutes of core cooling (18°C), followed by 60 minutes of DHCA, 10 minutes of cold reperfusion, and 40 minutes of rewarming. Mean arterial pressures (MAP) were maintained at 45 to 50 mmHg in both groups. Radiolabelled microsphere technique was used to determine the cerebral and renal blood flow. Results: Pulsatile pump produced significantly higher hemodynamic energy (from MAP to EEP) compared to the nonpulsatile pump during normothermic CPB (12.9%±3.2% vs. 0.7%±0.5%, p < 0.0001), hypothermic CPB (15.3%±4% vs. 0.9%±0.9%, p < 0.0001), and after rewarming (16.3%±4.5% vs. 0.7%±0.5%, p < 0.0001). Global cerebral blood flow was significantly higher in the pulsatile group compared to the nonpulsatile group during CPB (104±12 ml/100gm/min vs. 70±8 ml/100gm/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brain stem, blood flow resembled the global cerebral blood flow. Pulsatile pump improves renal blood flow (94±20 ml/100gm/min vs. 22±20 ml/l00gm/min, p < 0.05) after CPB. Conclusions: Pulsatile flow generates significantly higher hemodynamic energy, enhancing cerebral, and renal blood flow during and after CPB with DHCA in this model.