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| Optimal Flow Rate For Antegrade Cerebral Perfusion | |
Takashi Sasaki, Shoichi Tsuda, Robert K. Riemer, Vadiyala Mohan Reddy, Frank L. Hanley; Cardiothoracic Surgery, Stanford University, Stanford, CA
Methods: Nine 7-day old piglets (3.5-4.4 kg) were anesthetized and total body cardiopulmonary bypass was established via innominate artery and right atrial cannulation. The piglets were cooled to a nasopharyngeal temperature of 18°C using pH stat at an initial perfusion rate of 200 ml/kg/min and hematocrit maintained between 25% and 30%. At the cooling target, total body perfusion rate was reduced to 100 ml/kg/min (Baseline) for 15 minutes, the aorta was cross-clamped and cardioplegia (30 ml/kg) was administered via the aortic root. CBF was then measured under these conditions using 15-micron microspheres injected into the pump outflow line, and this value was used as the standard baseline CBF. The proximal innominate, left carotid, and left subclavian arteries were then clamped and ACP was initiated at each of three randomly selected perfusion rates (10, 30, or 50 ml/kg/min), microspheres of different colors were injected, and perfusion was continued for 15 minutes before switching perfusion rate. The piglets were then euthanized, the brains were dissected and microsphere-derived CBF was expressed as ml flow/100gm tissue/min. CBF at each of the ACP rates was then compared to the baseline cerebral flow at total body perfusion (100 ml/kg/min). Bihemispheric regional cerebral oxygen saturation (rSO2, NIRS) was monitored. Results: CBF at an ACP rate of 50 matched the CBF achieved during baseline, (73±24 vs 72±24 ml/100gm/min, p= 0.93, n= 9, 8; ANOVA), but ACP at 30 only provides about 60% of baseline CBF (44±11 ml/100gm/min, p= 0.003 vs baseline, n= 9). NIRS data revealed that ACP at 50 produces a higher rSO2 than baseline: 90±4 vs 79±13%, n= 9, 8, p= 0.035. However, jugular vein saturation was not different from baseline at ACP rates of 30 or 50. The distribution of CBF and rSO2 were equal in each brain hemisphere at all ACP rates. Conclusion: This study demonstrates that delivery of oxygen to the brain increases with ACP rate. We conclude that an optimal ACP rate is about 50 ml/kg/min because it matches baseline CBF rates while an ACP rate of 30 provides only 60% of baseline CBF. Back to 2009 Annual Meeting Back to Program Outline Back to Main Program |
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