FEEDING STRATEGIES IN NEONATES WITH SEVERE CONGENITAL HEART DISEASE WITH COMMENTS ON NECROTIZING ENTEROCOLITIS

GIRIJA NATARAJAN, MD

Introduction

Growth failure is increasingly recognized as a common occurrence in neonates with severe congenital heart disease (CHD). Growth failure in this population is multifactorial and may be due to inadequate intake or excessive energy expenditure, which, in turn, relate to abnormal hemodynamics, congestive heart failure (CHF), need for fluid restriction, pulmonary hypertension, tachypnea, hypermetabolism, malabsorption, and coexistent morbidities.¹ In addition, postoperative complications such as sepsis, chylous effusions, vocal cord injury, and prolonged intubation may limit oral feeding and impair nutrient delivery.¹ Growth failure may also delay surgical intervention and is associated with postoperative infections and impaired wound healing.^1,2 Putative associations between poor nutrition and long-term growth, neurodevelopment, and oromotor skills have made the nutritional management of neonates with CHD a priority.¹ This chapter focuses on enteral nutritional strategies in neonates with CHD, before and after surgical repair. The issues related to necrotizing enterocolitis (NEC) will also be explored.

Preoperative Feeding Strategies

Early enteral nutrition has beneficial effects on feeding patterns and mechanics, intestinal secretion, motility and translocation, and immune function.^3,4 The European consensus guidelines recommend enteral nutrition as the preferred method of feeding the critically ill patient and counteracting catabolism.⁵ Based on adult and limited pediatric data,^5–8 early (within 24–48 hours of ICU admission) enteral feeds are recommended for hemodynamically stable, critically ill patients who have a functioning gastrointestinal tract. In a review of 15 randomized controlled trials, rates of infections and length of hospital stay are reduced in critically ill adults who receive early enteral nutrition.⁷ Despite the putative benefits of enteral feeding in neonates, there continues a wide variation in the practice of enteral feeding in neonates with ductal-dependent CHD prior to surgical repair. In an international survey of 200 caregivers, 56% of United States (US) respondents and 93% of respondents outside the US routinely provided preoperative enteral feeds to prostaglandin (PG)-dependent infants.⁹ Reasons cited for withholding feeds included concern for bowel hypoperfusion, inflammation, “published literature”, and umbilical catheters.⁹ The decision to feed was dependent on the cardiac defect, clinical condition, and attending preference. The direction of ductal flow was a factor in one-third of the cases, with more respondents believing that it was safer to feed in the presence of a left-to-right duct.⁹ The majority of providers were willing to feed in the presence of umbilical catheters, with a greater proportion (71% vs 55%) of careproviders outside the US and neonatologists rather than cardiologists (73% vs 48%) subscribing to such a philosophy.⁹ Feeding readiness in PG-dependent infants was assessed using a variety of parameters including clinical assessment, arterial blood gas, serum lactate, diastolic blood pressure, abdominal x-rays, and echocardiograms.⁹ Published data on the safety and benefits of enteral feeding in infants with ductal-dependent CHD are limited. In one single-center study, enteral feeds of up to 100 ml/kg/day were achieved in 75% of 52 infants at a median (range) age of 5 (1–20) days.¹⁰ One infant with hypoplastic left heart syndrome (HLHS) developed medical NEC.¹⁰ In another study, among 34 late preterm and term (>35 weeks gestational age) PG-dependent infants who were enterally fed, only one developed clinical and radiologic signs of feeding intolerance.¹¹ The nutritional guidelines of the Feeding Work Group of the Neonatal Pediatric Cardiology Quality Improvement Collaborative recommend enteral feeding in hemodynamically stable infants with single-ventricle physiology under appropriate level of monitoring on an individual patient basis with a level of evidence II³ (Table 27.1). Feeding with an umbilical arterial catheter and while on PG infusion was strongly recommended by the work group, with levels of evidence of IV and III, respectively.³ Early enteral feeding in hemodynamically stable infants with other lower-risk, ductal-dependent congenital heart lesions should be strongly considered.

Table 27.1. The level of evidence categories used by the Feeding Work Group of the Neonatal Pediatric Cardiology Quality Improvement Collaborative, based on the modified delphi methodology

The use of nasogastric (NG) feeds for infants with CHD in the preoperative period is frequent, although without rigorous evaluation of safety or benefits.10–13 Reported rates vary from 21% to 45% in studies, with 25% of respondents of a multinational survey stating that they used tube feedings “always or frequently” in the preoperative period in infants with HLHS.^10,11,13 NG feeding may be the only available delivery modality for intubated infants; however, this route precludes assessment of oral feeding behavior as a sign of clinical well-being. Only oral feeding is allowed in the preoperative period in some centers, without the goal of achieving full feeds.¹⁴ The Feeding Work Group makes no recommendations on NG tube feeding in infants with single-ventricle physiology but does include it as an option.³

The Feeding Work Group recommends human milk as the preferred option for initiation of feeds (level of evidence III), based on the numerous benefits of breast milk.³ If breast milk is unavailable, donor milk or standard formulae are recommended, appropriate for the gestational age of the infant. Caloric fortification of feeds to achieve optimal energy intakes is required in the preoperative period in a subset (17%–24%) of infants.^10,11 Standardized feeding guidelines (Table 27.2) to ensure consistent monitoring and reduce variation in practice have been shown to be beneficial in other populations at high risk for gastrointestinal complications.¹⁵

Table 27.2. Elements of a standardized preoperative feeding regimen for infants with CHD

The Feeding Work Group nutritional algorithm for infants with single-ventricle physiology strongly recommends (level of evidence II) initiation of enteral feeds as soon as the infant is hemodynamically stable following surgical repair at a volume of about 20 ml/kg/day.3 Breast milk, donor milk, or standard gestational-age appropriate formulae are considered as the options.³ Elemental formula has been used when breast milk is unavailable in some centers.¹⁶ Steady advancement of volume of feeds from 120 to 140 mL/kg/day at a rate of 20 or 1 mL/kg/day q 4 to 6 hours in case of continuous feeds, followed by advancement of calories to achieve target caloric intake of 120 to 150 cal/kg and target weight gain of 20 to 30 g/day is recommended.^3,17 Higher caloric intake of up to 175 cal/kg/day may be required in certain cardiac lesions and for catch-up growth.¹ Caloric fortification of 24 to 30 cal/oz to achieve caloric goals was required in 72% of infants at discharge home from one center.¹⁰ Especially in infants in whom fluid restriction is necessary, caloric fortification may be necessary for optimal weight gain and is a routine practice at some institutions.¹⁴

Poor weight gain following cardiac surgery is well described in the literature, most extensively in infants with HLHS. In one study, the median duration to reach maximal energy concentration was 11 days among 28 infants who underwent Stage I Norwood procedure for HLHS, with 32% not achieving adequate energy intake at discharge from the hospital and 58% of survivors not regaining their birth weights.¹⁸ The same investigators confirmed their findings of insufficient energy intake until discharge and poor weight gain after cardiac surgery in infants with other heart defects.^18,19 More recently, among 100 patients who underwent cardiac surgery for a variety of defects, 100 cal/kg/day was achieved for less than half (48%) of patient days and 120 cal/kg for only 20% of patient days.²⁰ Median weight actually decreased during the period of enteral feeding [−20 (range, −775–1485 g)].²⁰ In one study, infants less than one year of age who underwent nonpalliative cardiac surgical repair were randomized to rapid (3 vs. 5 days) advancement of feeds to a higher formula concentration (4200 vs. 3800 kJ/L) or to usual care.²¹ The intervention group had a higher energy intake, greater weight gain, and earlier discharge from hospital.²¹

Standardized feeding algorithms for infants following cardiac surgery (Table 27.3) have been investigated in a few studies and found to be safe and to improve growth outcomes.^12,16 One retrospective chart review included infants with HLHS who underwent a Blalock—Taussig (BT) shunt or Sano conduit before (n = 52) and after (n = 46) institution of a postoperative feeding protocol.¹⁶ NEC rates dropped significantly from 27% to 6.5%; enteral feeds were initiated later and full feeds were achieved later following implementation of the protocol, while hospital length of stay was unchanged (21.5 vs. 28 days).¹⁶ Braudis and colleagues implemented an enteral feeding algorithm in infants (>35 weeks gestational age) with HLHS following Stage I palliation and reported that the median duration of total parenteral nutrition and time to achieve the target of 108 cal/kg/day were significantly reduced.¹² There was no case of NEC, compared with 11% in the control group.¹² In a systematic review of 3 studies that used feeding algorithms or standardized management following Norwood procedure, the average length of stay decreased from 31 days in the preprotocol groups to 24.3 days following implementation of the protocols.²²

Table 27.3.

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