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A low cardiac output state with reduced systemic oxygen delivery can complicate the early postoperative recovery early after surgery for congenital heart disease (CHD). All patients undergoing surgery on cardiopulmonary bypass (CPB) are at risk for a low cardiac output state, but the risk is greatest for younger patients undergoing more complex surgery. Although the clinical manifestations of a reduced cardiac output are generally transient and reversible, this can result in increased intensive care stay, and contributes to the long term morbidity and mortality associated with surgery for CHD.
The circulatory management of children with CHD should routinely be aimed at optimising systemic oxygen delivery according to the underlying diagnosis and physiology. This article will begin with a review of the pathophysiology of circulatory insufficiency, focusing on the period early after surgery for CHD. This background will provide a template for the ensuing discussions of a range of strategies for manipulating the circulation and optimising systemic oxygen delivery of infants and children with CHD, focusing mainly on postoperative management.
RECOGNISING IMPAIRED SYSTEMIC OXYGEN DELIVERY EARLY AFTER SURGERY
An evolving or established low cardiac output state should always be suspected in infants and children who are not progressing as would be expected early after cardiac surgery. The low cardiac output state may have one or more of the following manifestations: increased heart rate, worsening acidosis, organ dysfunction, elevated atrial pressures, elevated central temperature, systemic hypertension or hypotension, or cardiac arrest. In a landmark study of infants early after the arterial switch operation, Wernovsky identified a typical time course for the low cardiac output state when related to cardiopulmonary bypass itself, with the nadir of cardiac output predictably occurring between 9–12 h after surgery, with a return to “normal” by 24 h. Concomitant with this fall was an increase in calculated systemic and pulmonary resistances.1
Clinicians caring for patients …