Circulation
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We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL.100 g-1.min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB. ⋯ This information, along with our previous data shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.
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The use of the extracorporeal membrane oxygenator (ECMO) for postoperative cardiac patients has not resulted in the same high success rate as when ECMO is used for neonates with pulmonary hypertension or pulmonary failure. The reason for this is poorly understood. ⋯ This review suggests that the diagnosis of single ventricle, initiation of ECMO in the operating room or > 50 hours after surgery, and ECMO for > 208 hours are associated with patient nonsurvival. Noncardiac complications more frequently led to discontinuation of ECMO than did failure of the return of cardiac function.
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A transient increase in pulmonary vascular resistance can result in hemodynamic compromise after a Fontan operation. An interatrial fenestration is designed to maintain cardiac output in these circumstances but may result in severe hypoxemia and a vicious circle due to hypoxemia induced pulmonary vasoconstriction. Our aim was to determine whether inhaled nitric oxide (iNO), a selective pulmonary vasodilator, could be used to reduce pulmonary vascular resistance in desaturated patients (SaO2 < or = 85%) after a fenestrated Fontan operation. ⋯ iNO improved both oxygenation and TPG in desaturated patients after the fenestrated Fontan operation, possibly by counteracting hypoxemia-induced pulmonary vasoconstriction. A trial of iNO should be considered in clinically unstable desaturated patients after the fenestrated Fontan operation.
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A low cardiac output state can complicate the postoperative course of patients undergoing Fontan-type operations and tetralogy of Fallot repair. ⋯ Negative-pressure ventilation improves cardiac output in children after total cavopulmonary connection and tetralogy of Fallot repair and may prove to be an important therapeutic option in children with the low cardiac output state.
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Continuous whole-body perfusion for > 3 hours with a cold asanguineous blood substitute, hypothermosol (HTS) solution, has been reported to preserve organ function. We used this solution in a survival animal model to evaluate its possible application in extending the safe duration of deep hypothermic circulatory arrest (DHCA). ⋯ Intermittent whole-body asanguineous perfusion with hypothermosol solution does not extend cerebral protection in a porcine survivor model of DHCA. Neurobehavioral and histological outcomes are improved in animals receiving intermittent blood perfusion during prolonged DHCA.