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A 3-year-old, 13-kg male with a history of an atrial septal defect (ASD) presents for surgical repair with cardiopulmonary bypass (CPB). The patient is asymptomatic and is otherwise healthy.
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Physical exam: II/VI systolic murmur, fixed split second heart sound
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ECG: Right axis deviation, prolonged PR interval
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Echocardiogram: Large ostium secundum ASD
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PREOPERATIVE CONSIDERATIONS
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An ASD is a common congenital cardiac lesion that requires surgical repair with CPB if it is large. CPB is managed differently in children from the way it is managed in adults because of their different physiology, and it can have different physiologic consequences. The patient’s age and the specific lesion, as well as the planned surgical repair, dictate many of the principles of CPB management in children. Some notable differences include:
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Priming solution: Whole blood or packed red blood cells (PRBCs), fresh frozen plasma, and heparin for neonates and infants; PRBCs, crystalloid, albumin, and heparin for children 10-15 kg; crystalloid and heparin for children >15 kg.
Priming volume: May exceed the blood volume of neonates and infants by 100-200%; more marked effects of hemodilution (eg, decreased hematocrit, reduction in drug levels, coagulopathy).
Pump flow rates: Wide variation in pediatric patients, from 100-200 mL/kg/min (higher metabolic rate and oxygen demand) to 25-50 mL/kg/min (deep hypothermia).
Perfusion pressure: 20-50 mm Hg in infants and young children versus 50-80 mm Hg in adults.
Temperature: Frequent use of deep hypothermic circulatory arrest in pediatric patients (15-20 degrees).
Glucose: Can have hyperglycemia on CPB from addition of blood products to priming solution, and/or from pre-CPB IV steroid administration; hypoglycemia may also be seen in neonates and infants.
Cannulation: Increased likelihood of venous obstruction from venous cannula insertion; aortic cannulation complicated by frequent presence of aortopulmonary collaterals, patent ductus arteriosus, and aortic arch abnormalities.
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Although surgical repair of an uncomplicated ASD tends to be uneventful and amenable to extubation in the operating room (OR), preoperative discussion with the parents should include the possibility of invasive line placement (and associated complications), postoperative intubation, transfusion of exogenous blood products, neurologic injury, dysrhythmias, need for postoperative pressors and/or pacing, and even death. Premedication with oral midazolam is warranted in anxious children. Lines can be placed after inhalational induction of general anesthesia (GA).
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ANESTHETIC MANAGEMENT
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Oral midazolam premedication as needed for anxiety, with or without parental presence in the OR. GA usually is induced via inhalation induction.
Tailor anesthetic for possible extubation in the OR.
Arterial line for assessment of blood pressure (BP) on CPB (nonpulsatile flow) and for measurement of activated clotting time (ACT), arterial blood gases (ABGs), hematocrit, and electrolytes. The arterial line generally is placed after induction of GA.
Either a central venous pressure (CVP) line placed percutaneously (internal jugular [IJ], subclavian, ...