Boston - American Association for Thoracic Surgery

AMERICAN ASSOCIATION FOR THORACIC SURGERYF8. Optimal Flow Rate for Antegrade Cerebral PerfusionTakashi Sasaki, Shoichi Tsuda, Robert K. Riemer, Vadiyala Mohan Reddy, *Frank L. Hanley *Cardiothoracic Surgery, Stanford University, Stanford, CA, USAInvited Discussant: Randall B. GrieppOBJECTIVE: Antegrade cerebral perfusion (ACP) is widely used yet perceivedideal flow rates vary significantly among centers and have never been standardized.We compared cerebral blood flow (CBF) at different ACP rates to establish theirrelation.METHODS: Nine 7-day old piglets (3.5–4.4 kg) were anesthetized and total bodycardiopulmonary bypass was established via innominate artery and right atrialcannulation. The piglets were cooled to a nasopharyngeal temperature of 18°Cusing pH stat at an initial perfusion rate of 200 ml/kg/min and hematocrit maintainedbetween 25% and 30%. At the cooling target, total body perfusion rate wasreduced to 100 ml/kg/min (Baseline) for 15 minutes, the aorta was cross-clampedand cardioplegia (30 ml/kg) was administered via the aortic root. CBF was thenmeasured under these conditions using 15-micron microspheres injected into thepump outflow line, and this value was used as the standard baseline CBF. Theproximal innominate, left carotid, and left subclavian arteries were then clampedand ACP was initiated at each of three randomly selected perfusion rates (10, 30, or50 ml/kg/min), microspheres of different colors were injected, and perfusion wascontinued for 15 minutes before switching perfusion rate. The piglets were theneuthanized, the brains were dissected and microsphere-derived CBF was expressedas ml flow/100gm tissue/min. CBF at each of the ACP rates was then compared tothe baseline cerebral flow at total body perfusion (100 ml/kg/min). Bihemisphericregional cerebral oxygen saturation (rSO2, NIRS) was monitored.TUESDAYMorningRESULTS: 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 onlyprovides 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 differentfrom baseline at ACP rates of 30 or 50. The distribution of CBF and rSO2were equal in each brain hemisphere at all ACP rates.CONCLUSION: This study demonstrates that delivery of oxygen to the brainincreases 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 only60% of baseline CBF.* AATS Member133