Introduction
Several fundamentals of perioperative care for shunt-dependent dual-distribution circulation (see Chapter 70 ) extend to transitional care from the intensive care unit and throughout the interstage period in an effort to preserve organ function and promote somatic growth. Conventional outpatient surveillance limited to vital signs and routine growth assessment has historically been associated with high interstage mortality rates after discharge from Norwood or stage I palliation and prior to stage II palliation. (For the purposes of this chapter, stage II palliation refers to the general concepts of a superior cavopulmonary connection, the specific type of which depends on the individual patient’s anatomy and surgical preference.) Interstage programs that leverage engagement of families and providers for vigilant monitoring of physiologic variances has led to improved interstage survival. The initial report of interstage monitoring noted a reduction of interstage death with a sustained single-center interstage survival rate for infants discharged to home of 98% over a 10-year period. Over the past 15 years, the unanticipated benefits of interstage monitoring have included improvement in somatic growth and less arbitrary timing of stage II palliation. Additional value has been the growing collaboration between numerous health care disciplines and parent advocates for the sole purpose of not only improving survival but also quality of life for infants born with hypoplastic left heart syndrome and related variants.
Rationale and Metrics for Interstage Monitoring
Rationale for Monitoring
A variety of mechanisms have been proposed for infant demise during the first interstage period. Some single-center reports have identified nonmodifiable risk factors such as anatomic subtype including aortic atresia/mitral atresia and possibly aortic atresia/mitral stenosis, although larger single-center and multicenter investigations have failed to link anatomic subtype to interstage mortality other than an independent association between aortic atresia/mitral atresia as noted in the Pediatric Heart Network Single Ventricle Reconstruction trial. Potentially modifiable cardiac risk factors linked to interstage mortality include the presence of a restrictive atrial communication, neoaortic arch obstruction, obstruction of the systemic to pulmonary artery shunt, pulmonary artery distortion, atrioventricular valve insufficiency, and the presence of arrhythmias. Interstage mortality for patients in the Pediatric Heart Network Single Ventricle Reconstruction trial was significantly higher in those patients palliated with a modified Blalock-Taussig-Thomas shunt compared with the right ventricle to pulmonary artery (Sano) conduit (18 vs. 6%, P < .001) ( Fig. 72.1 ). Noncardiac risk factors associated with interstage mortality include commonly acquired gastrointestinal losses, respiratory illnesses, and/or feeding difficulties. Any of the mentioned processes may influence systemic vascular resistance, potentially lead to progressive hypoxia and/or shock (hypovolemia or cardiogenic), and, in the presence of limited myocardial reserve inherent to shunt-dependent dual-distribution circulation after stage I palliation, place infants at greater risk for serious morbidity and death regardless of their apparent physiologic reserve early after initial palliation.
Pulse Oximetry
Monitoring within the medical home environment necessitates technology that is reliable, accessible, and easy to use, which led to the selection of pulse oximetry as the primary physiologic monitor. In infants with a dual-distribution circulation, desaturation from baseline may be indicative of limited pulmonary flow from myocardial dysfunction, shunt obstruction or outgrowth, anemia, or an acute illness leading to pulmonary venous desaturation. Alternatively, saturations higher than baseline may also be indicative of progressive disease that leads to escalation in systemic vascular resistance and hence increased pulmonary blood flow such as mild dehydration. These clinical scenarios have guided triage parameters for home monitoring of oxygen saturations ( Fig. 72.2 ). Specifically, arterial saturation less than 75% or greater than 90% warrants consideration for evolving pathology.
Weight, Nutrition, and Somatic Growth
Daily assessment of infant weight with a digital scale sensitive to 10 g was initially adopted as part of the interstage monitoring program to earlier detect mild dehydration due to inadequate oral intake (less than 100 mL/kg per day) or excessive gastrointestinal losses. Consensus-driven criteria for assessment by a health care provider was set at weight loss of 30 g or failure to gain 20 g of weight over 3 days. Interestingly, breach of weight criteria was less commonly due to dehydration from gastrointestinal losses and more commonly associated with inadequate enteral intake, with volumes less than 100 mL/kg per day in nearly half the patients who breached weight criteria.
Early experience with interstage monitoring of weight trends highlighted growth failure that was associated with functionally univentricular heart. The growth failure can be attributed to a variety of factors that lead to inadequate enteral intake such as heart failure, genetic or extracardiac anomalies, gastrointestinal dysmotility, and/or malabsorption. Although some of the contributing factors are not modifiable, ensuring adequate nutrition in the presence of these comorbidities is an essential function of interstage monitoring and important for more health maintenance and outcomes at stage II palliation, the superior cavopulmonary connection. Multiple studies have shown that poor growth velocity and lower weight-for-age z -score at stage II palliation predicts a more complex postoperative course.
Inpatient Preparation for Interstage Management
Medical Readiness
Readiness for discharge after stage I palliation includes understanding anatomic and physiologic risks specific to each patient beyond the basic principles of having a dual distribution circulation. Knowledge of anatomic variants and potential residual or recurrent lesions may not only direct prescribed medical therapies but also inform the team about follow-up frequency, diagnostic imaging, or timing of subsequent interventions. Likewise, physiologic vulnerability that is often manifested during physiologic demanding tasks such as feeding, bathing, and normal infant irritability may warrant an alteration in prescribed medical therapies or even the decision to discharge. In fact, a subset of stage I palliation survivors, specifically those with a more complicated perioperative course, may benefit from inpatient management during the interstage period. Determining medical readiness for discharge is dependent on comprehensive communication between care teams and specialists as the patient moves through the various phases of inpatient care, particularly from the intensive care unit to the acute care floor.
Pharmacologic Management
Optimizing circulatory function during the interstage period is a critical part of interstage care. Determining chronic medical support should begin in the intensive care unit while the patient is fully monitored and as he or she is liberated from vasoactive medications. Prescribed drug therapies remain variable among institutions and more commonly include chronic afterload reduction, diuretics, and/or digoxin for support of the cardiovascular system.
Angiotensin-converting enzyme inhibitor may be beneficial in patients who have high a pulmonary-to-systemic flow ratio in the early postoperative period, greater than mild atrioventricular valve insufficiency, evidence of congestive heart failure, or noninvasive evidence of elevated systemic vascular resistance. If the blood pressure is suboptimally controlled with angiotensin-converting enzyme inhibitor therapy or if the patient demonstrates high sympathetic tone (persistently elevated heart rate and/or blood pressure when calm and with normal baby activity), enteral or transdermal clonidine may be effective. Afterload reduction is titrated with caution, particularly when combined with diuretic therapy, to avoid diastolic hypotension that could result in impairment of coronary flow particularly in presence of a modified Blalock-Taussig-Thomas shunt. Chronic tachypnea due to pulmonary edema either from elevated pulmonary-to-systemic flow ratio, elevated end-diastolic pressure from myocardial dysfunction, or atrioventricular valve insufficiency generally warrants management with diuretics. However, caution should be taken to avoid intravascular volume depletion that might reduce total cardiac output, as well as increase the risk of shunt thrombosis due to changes in blood viscosity. Persistence of heart failure symptoms or excessive hypoxia during titration of afterload reduction and diuretic therapy may warrant diagnostic investigation to rule out a residual or acquired anatomic cause.
Arrhythmias have been postulated as an important mechanism for interstage mortality. The incidence of tachyarrhythmias after stage I palliation have a reported incidence as high as 34%, whereas the incidence of heart block is much lower. Although the presence of tachyarrhythmias was associated with longer ventilation and hospital length of stay, it was not associated with hospital or interstage mortality in the Pediatric Heart Network Single Ventricle Reconstruction trial. In the absence of documented arrhythmias, digoxin is commonly used during the interstage period and has been found to be protective against interstage mortality in two large multicenter cohorts—one from the Pediatric Heart Network Single Ventricle Reconstruction trial and the other from the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC). The mechanism by which digoxin is protective remains elusive but may in fact be due to its effects on the neurohormonal axis of heart failure.
Prophylactic antiplatelet therapy with low-dose aspirin, usually 20.25 mg to 40.5 mg daily, is the most commonly administered antithrombotic agent during the interstage period. Increasing awareness of aspirin resistance and the ease in which its effect can be tested has led to increased surveillance with platelet aggregation studies for aspirin dosing. If evidence of atrial or venous clot is found, subcutaneous low-molecular-weight heparin may also be warranted.
Understanding the Family Needs
Successful interstage management relies on family involvement as well as understanding of program rationale and goals. Providers must develop a clear understanding of individualized needs for each family and tailor discharge preparation to promote success. Parenting stress is prominent in families caring for children with all forms of congenital heart disease and even increased for parents caring for children with a functionally univentricular heart. Thus barriers for successful implementation of an interstage home monitoring program are ideally identified prior to discharge. Families of children with a functionally univentricular heart report varying levels of stress, particularly at time of discharge to the home. Parental challenges and stressors may include language barriers, educational level, family support, socioeconomic burdens, and emotional distress, including feelings of fear, depression, or fatigue. Any of these issues may affect a family’s readiness to learn and their ability to successfully carry out home monitoring and interstage cares. Identified barriers warrant additional support from the cardiac team, social workers, psychologists, or parent support organizations, as available. Ethnicity and socioeconomic factors have been associated with interstage mortality. Enrollment in a home monitoring program has effectively reduced interstage mortality across varying sociodemographic populations.
Iterative parent education throughout the stage I palliation hospital stay is important for retention and mastery of skills, as well as anticipatory preparation for commonly encountered infant challenges that may in fact destabilize those infants with a dual-distribution circulation. Tools such as discharge-teaching checklists for parents and providers or visual diagrams depicting learning needs and referred to as “stepping stones” or “journey boards” ( Fig. 72.3 ) provide a family-friendly, coordinated, and standardized means of tracking the discharge planning process. The strategy of having parents participate in an extended period of “rooming-in without monitors” or “24- to 48-hour care” is a valuable strategy often used just prior to discharge. This exercise affords parents the opportunity to confirm a level of comfort performing daily tasks and mimic life at home while still having providers available for consultation. In addition, this experience can ensure the provider team of parent competence and/or identify areas of care with which parents need additional reassurance or training.
Transitional Care
Care coordination from the inpatient to outpatient setting is vital to continued well-being during the interstage period. This transition of care requires clear communication between providers, including referring cardiologists, primary care providers, and other subspecialists such as gastroenterologists. The absence of comprehensive and effective communication between health care providers can negatively impact patient outcomes.
Identification of a discharge coordinator who takes primary responsibility for overseeing the discharge process minimizes practice variation and aids in the care coordination efforts necessary to ensure a safe transition to home. This responsibility often falls on advance practice providers whose roles overlap inpatient and outpatient care. Vital components for transitional care are outlined as follows:
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Identification of a specific team member to coordinate the discharge process.
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Use of a standard discharge checklist to ensure completion of tasks ( Fig. 72.4 ).
Fig. 72.4
Standardized interstage discharge checklist.
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Assessment of outpatient pharmacy capability for compounding pediatric medications.
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Confirmation of home monitoring equipment (infant scale, pulse oximeter) and home nursing services in place prior to discharge.
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Coordination of a predischarge conference call between interstage care team, referring cardiologist, primary care provider, and parents.
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Scheduling necessary outpatient follow-up visits prior to discharge (referring cardiologist, interstage clinic, primary care, and other subspecialties as needed).
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Identify outpatient emergency centers and action plan to contact primary cardiology team should need arise for acute evaluation.
Additional helpful discharge activities are included in the NPC-QIC Care Transition Bundle ( Table 72.1 ).
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