unit to confirm plans, have necessary equipment available, and provide closedloop communication Invasive and Noninvasive Monitoring The monitoring considerations for the postoperative SCPC patient are similar to those described following initial palliation Once again, the goal of monitoring is the early detection of an evolving imbalance in DO2 and VO2 In addition, as pleural effusions are common following the SCPC, trends in the noninvasive continuous monitoring of respiratory rate, heart rate, and pulse oximetry may be the first signs of a developing effusion Postoperative Management Following the Superior Cavopulmonary Connection With transition from a multidistribution circulation to the SCPC, the volume load, CO requirement, and myocardial VO2 are reduced The acute decrease in ventricular volume creates a mismatch between the ventricular volume and muscle mass, causing diastolic dysfunction (see Fig 71.3) Qp is primarily determined by the volume of brachiocephalic outflow, cerebral metabolism, and the pressure developed within the cerebral venous circulation and superior caval vein (see also Chapter 70, Fig 70.4) Cerebral blood flow/DO2 is tightly coupled to metabolism and remains constant with changes in systemic arterial blood pressure as long as the pressure oscillates within the range of pressure autoregulation Uncoupling of cerebral blood flow from metabolism increases cerebral DO2 and therefore Qp, as occurs with permissive hypercapnia Arterial hypoxemia following the SCPC may be due to pulmonary venous admixture resulting from alveolar disease or arteriovenous malformations (AVMs) Hypoxemia may be due to a decrease in Qp, which may result from an obstruction to flow at the superior vena cava–pulmonary artery anastomosis or from an increase in PVR, but only in the presence of decompressing venovenous collaterals In the absence of venovenous collaterals, cerebral venous return will be obligate into the pulmonary vascular bed, resulting in an increase in SVC pressure Over time, which is variable from patient to patient, elevated SVC pressure may lead to the formation of decompressive venovenous collaterals between the superior vena cava and inferior vena cava system or right atrium (See Chapter 70 for a more complete description of these anatomic connections.) In addition to causing arterial hypoxemia, a decrease in Qp will increase the arterial-to-end tidal CO2 gradient Contrast echocardiography (agitated saline injected into an upper extremity venous catheter) will establish the diagnosis of pulmonary AVMs and venovenous collaterals that may be present in the anterior venous compartment Posterior venovenous collaterals through the nonvalved cerebrospinal circulation and Batson plexus will not be visible with saline contrast echocardiography and may be visible only by MRI of the venous drainage of the head Treatment strategies for improving oxygenation can vary considerably and depend on the underlying mechanisms Inadequate lung volume responds to positive airway pressure; but, as discussed previously, PPV may have an adverse effect on systemic venous return and selective cerebral venous return through anterior and posterior venous systems as well as PVR An increase in ITP decreases the effective compliance of the SVC–pulmonary artery confluence, increasing the pressure within, which represents the downstream pressure for systemic venous return from the head and neck vessels A rise in the downstream pressure must be compensated for by an increase in cerebral venous/SVC pressure or Qp will fall Conversely, minimizing ITP or transitioning to spontaneous ventilation increases the pressure gradient for systemic venous return, lowering venous pressure, decreasing flow through venovenous collaterals, and increasing Qp In the event that the transpulmonary vascular pressure is elevated (>5 to 10 mm Hg, SVC pressure–common atrial pressure), consideration should be given to the use of pulmonary vasodilators such as inhaled nitric oxide and evaluation for anatomic substrates for obstruction to flow such as narrowing at the cavopulmonary anastomosis (requiring an interventional catheterization) Another measure to increase Qp is the uncoupling of cerebral blood flow from cerebral metabolism with permissive hypercapnia Hypercapnia and acidosis also increase PVR; however, studies have demonstrated that the net effect is an increase in Qp.231 This strategy requires the use of muscle relaxants and the realization that the effect wanes over hours due to normalization of the pH in the perivascular space of the blood-brain barrier Common Postoperative Findings Systemic hypertension is observed in the majority of infants who undergo an SCPC Although the exact etiology of hypertension is unknown, the most likely etiology is an increase in systemic blood pressure to maintain cerebral perfusion when there is an increase with cerebral venous pressure Other mechanisms include an increase in catecholamines related to pain and increases in neurohormones including angiotensin II and aldosterone.232,233 Unless there is mediastinal bleeding, aggressive treatment of hypertension early after the SCPC is generally avoided, as it may reduce cerebral blood flow, which will then lead to reduced pulmonary blood flow and hypoxemia Following the SCPC, many infants are routinely treated with milrinone following and in some (e.g., those who are bleeding or have other reasons to avoid systemic hypertension, such as important AV valve regurgitation), hypertension may also be treated with sodium nitroprusside; this strategy has been shown to decrease systemic blood pressure without changing cerebral blood flow or systemic oxygen content following the SCPC.232 Many infants are quite irritable for 2 to 4 days following the SCPC, which appears to be temporally related to the common finding of upper extremity edema and plethora, producing the appearance of “SVC syndrome.” The raised intracranial pressure associated with the elevation in venous pressure in the upper body can cause headache and cough in older patients, and this is likely to be present in infants as well.234,235 Judicious use of pharmacologic analgesics and the extensive use of nonpharmacologic measure are typically sufficient during these early days after surgery Sinus Node Dysfunction/Arrhythmia Early postoperative arrhythmias are infrequent unless there are secondary interventions on the atrial septum or AV valve at the time of surgery When arrhythmias occur, they are most commonly atrial in origin External pacing maneuvers or pharmacologic strategies should be used to provide arteriovenous synchrony in the early postoperative period Late postoperative rhythm abnormalities are most common in patients with tricuspid atresia, with the majority having atrial tachycardia or sinus node dysfunction Pleural Effusions and Chylothorax Chylothorax, requiring chest tubes for longer than 1 week, can occur in up to 15% of patients following a SCPC.236 The lymphatic vessels coalesce to form