Necrotizing enterocolitis and gastrointestinal complications after indomethacin therapy and surgical ligation in premature infants with patent ductus arteriosus

Clinical Dilemma Involving Treatments for Very Low-Birth-Weight Infants and the Potential Risk of Necrotizing Enterocolitis: A Narrative Literature Review

Necrotizing enterocolitis (NEC) is a critical gastrointestinal emergency with substantial morbidity and mortality risks, especially for very low-birth-weight (VLBW) infants, and unclear multifactorial pathophysiology. Whether common treatments for VLBW infants increase the NEC risk remains controversial. Indomethacin (utilized for patent ductus arteriosus) offers benefits but is concerning because of its vasoconstrictive impact on NEC susceptibility. Similarly, corticosteroids used to treat bronchopulmonary dysplasia may increase vulnerability to NEC by compromising immunity and altering the mesenteric blood flow. Histamine-2 receptor blockers (used to treat gastric bleeding) may inadvertently promote NEC by affecting bacterial colonization and translocation. Doxapram (used to treat apnea) poses a risk of gastrointestinal disturbance via gastric acid hypersecretion and circulatory changes. Glycerin enemas aid meconium evacuation but disrupt microbial equilibrium and trigger stress-related effects associated with the NEC risk. Prolonged antibiotic use may unintentionally increase the NEC risk. Blood transfusions for anemia can promote NEC via interactions between the immune response and ischemia-reperfusion injury. Probiotics for NEC prevention are associated with concerns regarding sepsis and bacteremia. Amid conflicting evidence, this review unveils NEC risk factors related to treatments for VLBW infants, offers a comprehensive overview of the current research, and guides personalized management strategies, thereby elucidating this clinical dilemma.

The severity of NEC is ameliorated by prostaglandin E2 through regulating intestinal microcirculation

Prostaglandin E2 (PGE2) is implicated in intestinal inflammation and intestinal blood flow regulation with a paradoxical effect on the pathogenesis of necrotizing enterocolitis (NEC), which is not yet well understood. In the current study, we found that PGE2, EP4, and COX-2 varied at different distances from the most damaged area in the terminal ileum obtained from human infants with NEC. PGE2 administration alleviated the phenotype of experimental NEC and the intestinal microvascular features in experimental NEC, but this phenomenon was inhibited by eNOS depletion, suggesting that PGE2 promoted intestinal microcirculatory perfusion through eNOS. Furthermore, PGE2 administration increased the VEGF content in MIMECs under TNFα stress and promoted MIMEC proliferation. This response to PGE2 was involved in eNOS phosphorylation and nitric oxide (NO) production and was blocked by the EP4 antagonist in vitro, suggesting that targeting the PGE2-EP4-eNOS axis might be a potential clinical and therapeutic strategy for NEC treatment. The study is reported in accordance with ARRIVE guidelines ( https://arriveguidelines.org ).

US for Evaluation of Acute Abdominal Conditions in Neonates

US is the imaging modality of choice for evaluation of a variety of abdominal conditions, and in recent years it has also become useful and promising as a bedside technique for assessment of acute abdominal conditions in neonates. Bedside US can help, complement, and sometimes replace radiographic or contrast-enhanced studies in critically ill and labile neonates who are difficult to transport to the fluoroscopy suite. Some of the features of bedside US can be applied as point-of-care US (POCUS) of the sick neonate. Some of the abdominal conditions in neonates that can be assessed and monitored with bedside US are necrotizing enterocolitis and its complications, malrotation with a midgut volvulus, segmental volvulus, meconium peritonitis, and complicated inguinal hernia. High-resolution US with the use of 15-MHz and higher-frequency probes allows characterization of the bowel anatomy and features of intestinal abnormalities in neonates in fine detail. Color Doppler US and microvascular imaging improve accuracy in the detection and characterization of bowel vascularity, which is important in the treatment and follow-up of patients with intestinal conditions. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. The slide presentation from the RSNA Annual Meeting is available for this article.

Extracardiac Complications in Intensive Care Units after Surgical Repair for Congenital Heart Disease: Imaging Review with a Focus on Ultrasound and Radiography

Pediatric patients show various extracardiac complications after cardiovascular surgery, and radiography and ultrasound are routinely performed in the intensive care unit to detect and evaluate these complications. This review presents images of these complications, sonographic approach, and timing of occurrence that are categorized based on their extracardiac locations and include complications pertaining to the central nervous system, mediastinum, thorax and lung parenchyma, diaphragm, liver and biliary system, and kidney along with pleural effusion and iatrogenic complications. This pictorial review will make it easier for medical doctors in intensive care units to identify and manage various extracardiac complications in pediatric patients after cardiovascular surgery.

Ligation of patent ductus arteriosus in very low birth weight premature infants

BACKGROUND

Patent ductus arteriosus (PDA) is frequently encountered in premature infants. Optimal management of PDA remains undefined. We aim to assess the national trend for PDA ligation over 18 years and evaluate mortality and associated morbidities.

METHODS

We used data from the National Inpatient Sample (NIS) and KID of the Healthcare Cost and Utilization Project (HCUP) from 1998 to 2015. All infants with gestational age 24-32 weeks and birth weight <1500 g were included. Patients with PDA were classified into two groups: those who did and did not receive surgical ligation. Associated mortality and morbidities were compared.

RESULTS

A total of 429,900 neonatal admissions were identified. Of them, 149,473 (34.8%) infants had PDA. PDA-ligated infants were 27,364 (6.4%). PDA ligation was more likely in those with smaller gestational age and with birth weight <1000 g. A steady decline in PDA ligation was noticed since 2004. The mortality rate in PDA-ligated infants was less than in PDA-non-ligated infants (7.5% vs. 8.9%; OR = 0.82; 95% CI: 0.78-0.86; p < 0.001). However, the prevalence rates of pulmonary hemorrhage and necrotizing enterocolitis (NEC) were greater in PDA-ligated infants (OR = 1.58; 95% CI: 1.49-1.67; p < 0.001, and OR = 1.32; 95% CI: 1.26-1.38; p < 0.001, respectively).

CONCLUSIONS

Ligation of PDA has been steadily declining since 2004. Despite higher morbidities, PDA-ligated infants had less mortality.

[Abdominal surgery in premature infants with patent ductus arteriosus]

INTRODUCTION

Patent ductus arteriosus (PDA) is considered a risk factor for necrotising enterocolitis (NEC) and other gastrointestinal complications in preterm infants. The aim of this study is to determine whether there is a higher incidence of abdominal surgery and the associated morbidity and mortality in preterm infants who require treatment due to a significant PDA.

METHODS

An observational study was conducted that included preterm infants with <37 weeks of gestational age, and a diagnosis of PDA in the last 10 years. Depending on the treatment received, the patients were divided into 3 groups: medical (A), medical and surgical (B), and no treatment (C). An analysis was performed on the pre- and peri-natal variables, as well as the incidence of gastrointestinal complications (NEC, and need for surgery for this reason), and overall mortality.

RESULTS

The study included a sample of 144 patients, of whom 91 were assigned to group A, 16 to B, and 37 to C. The mean gestational age by groups was 28, 26.7, and 30.1 weeks, respectively. The mean birth weight was 1083.9 gr, 909.3 gr, and 1471.2 gr, respectively. As regards the incidence of NEC, a total of 21, 5, and 5 cases, respectively, were found in each group, with 43%, 60% and 35%, respectively requiring abdominal surgery. Mortality by groups was 12%, 19%, and 3%, respectively CONCLUSION: Patients who required treatment for a significant PDA had a higher incidence of gastrointestinal complications and higher mortality than untreated patients, with no statistically significant differences being found. In the group of patients that required treatment, lower gestational age and birth weight, could explain the increase in morbidity and mortality found in these patients.

A quality improvement initiative to reduce necrotizing enterocolitis across hospital systems

OBJECTIVE

Necrotizing enterocolitis (NEC) is a devastating intestinal disease in premature infants. Local rates of NEC were unacceptably high. We hypothesized that utilizing quality improvement methodology to standardize care and apply evidence-based practices would reduce our rate of NEC.

STUDY DESIGN

A multidisciplinary team used the model for improvement to prioritize interventions. Three neonatal intensive care units (NICUs) developed a standardized feeding protocol for very low birth weight (VLBW) infants, and employed strategies to increase the use of human milk, maximize intestinal perfusion, and promote a healthy microbiome.

RESULTS

The primary outcome measure, NEC in VLBW infants, decreased from 0.17 cases/100 VLBW patient days to 0.029, an 83% reduction, while the compliance with a standardized feeding protocol improved.

CONCLUSION

Through reliable implementation of evidence-based practices, this project reduced the regional rate of NEC by 83%. A key outcome and primary driver of success was standardization across multiple NICUs, resulting in consistent application of best practices and reduction in variation.

The nitric oxide synthase 2 pathway is targeted by both pro- and anti-inflammatory treatments in the immature human intestine

BACKGROUND AND AIM

NO synthase 2 (NOS2) was recently identified as one the most overexpressed genes in intestinal samples of premature infants with necrotizing enterocolitis (NEC). NOS2 is widely implicated in the processes of epithelial cell injury/apoptosis and host immune defense but its specific role in inflammation of the immature human intestinal mucosa remains unclear. Interestingly, factors that prevent NEC such as epidermal growth factor (EGF) attenuate the inflammatory response in the mid-gestation human small intestine using serum-free organ culture while drugs that are associated with NEC occurrence such as the non-steroidal anti-inflammatory drug, indomethacin (INDO), exert multiple detrimental effects on the immature human intestine. In this study we investigate the potential role of NOS2 in modulating the gut inflammatory response under protective and stressful conditions by determining the expression profile of NOS2 and its downstream pathways in the immature intestine.

METHODS

Gene expression profiles of cultured mid-gestation human intestinal explants were investigated in the absence or presence of a physiological concentration of EGF (50 ng/ml) or 1 μM INDO for 48 h using Illumina whole genome microarrays, Ingenuity Pathway Analysis software and quantitative PCR to investigate the expression of NOS2 and NOS2-pathway related genes.

RESULTS

In the immature intestine, NOS2 expression was found to be increased by EGF and repressed by INDO. Bioinformatic analysis identified differentially regulated pathways where NOS2 is known to play an important role including citrulline/arginine metabolism, epithelial cell junctions and oxidative stress. At the individual gene level, we identified many differentially expressed genes of the citrulline/arginine metabolism pathway such as ARG1, ARG2, GLS, OAT and OTC in response to EGF and INDO. Gene expression of tight junction components such as CLDN1, CLDN2, CLDN7 and OCN and of antioxidant markers such as DUOX2, GPX2, SOD2 were also found to be differentially modulated by EGF and INDO.

CONCLUSION

These results suggest that the protective effect of EGF and the deleterious influence of INDO on the immature intestine could be mediated via regulation of NOS2. Pathways downstream of NOS2 involved with these effects include metabolism linked to NO production, epithelial barrier permeability and antioxidant expression. These results suggest that NOS2 is a likely regulator of the inflammatory response in the immature human gut and may provide a mechanistic basis for the protective effect of EGF and the deleterious effects of INDO.

Pathogenesis of NEC: Impact of an altered intestinal microbiome

Necrotizing enterocolitis (NEC), a disease most commonly seen in preterm infants, often presents without warning and is associated with very high mortality and morbidity. Progress in the prevention and treatment of NEC has been slow. In this article, we will discuss some of the reasons as to why this progress has been slow. We will describe some of the factors that appear to be highly associated and important components in the pathophysiology of NEC. We will discuss the intestinal microbial environment of the fetus as well as the preterm infant and how interaction of dysbiosis with an immature gastrointestinal tract combined with dietary factors play a role in the pathogenesis of NEC. Testable hypotheses are discussed as well as how these may lead to not only a better understanding of the pathophysiology of the disease but also the preventative strategies.

Patent ductus arteriosus ligation and adverse outcomes: causality or bias?

Observational studies have associated patent ductus arteriosus (PDA) ligation in preterm infants with increased chronic lung disease (CLD), retinopathy of prematurity, and neurodevelopmental impairment at long-term follow-up. Although the biological rationale for this association is incompletely understood, there is an emerging secular trend toward a permissive approach to the PDA. However, insufficient adjustment for postnatal, pre-ligation confounders, such as intraventricular hemorrhage and the duration and intensity of mechanical ventilation, suggests the presence of residual bias due to confounding by indication, and obliges caution in interpreting the ligation-morbidity relationship. A period of conservative management after failure of medical PDA closure may be considered to reduce the number of infants treated with surgery. Increased mortality and CLD in infants with persistent symptomatic PDA suggests that surgical ligation remains an important treatment modality for preterm infants.

Application of prostaglandin E2 improves ileal blood flow in NEC

PURPOSE

Indomethacin, a nonselective prostaglandin inhibitor used to treat patent ductus arteriosus, is associated with intestinal perforation inducing an NEC-like illness. We sought to define the contribution of prostaglandin E2 (PG E2) and its receptor EP4 to intestinal blood flow regulation in premature neonates with NEC.

METHODS

Newborn Sprague-Dawley rats were randomized by litter to undergo experimental NEC induction or to serve as a CONTROL. At 48hours of age, intestinal laser Doppler blood flow was assessed at baseline and after intraperitoneal administration of indomethacin, PG E2, EP4 antagonist, or EP4 agonist. Data were analyzed using a 2-way ANOVA with post hoc Tukey-Kramer correction.

RESULTS

At baseline, NEC animals had lower intestinal blood flow than controls. Indomethacin, PG E2 and EP4 agonist all increased ileal blood flow, but PG E2 and EP4 agonist increased blood flow the most in NEC pups. EP4 antagonist decreased intestinal perfusion in both groups.

CONCLUSION

The above evidence suggests the importance of PG E2 and EP4 in regulation of neonatal intestinal blood flow. Since indomethacin treatment of patent ductus arteriosus in the premature infant is associated with an increased risk of intestinal perforation owing to compromised blood flow, PG E2 supplementation might provide intestinal protection if administered simultaneously with indomethacin.

PDA ligation and health outcomes: a meta-analysis

BACKGROUND AND OBJECTIVE

Patent ductus arteriosus (PDA) ligation has been variably associated with neonatal morbidities and neurodevelopmental impairment (NDI). The objective was to systematically review and meta-analyze the impact of PDA ligation in preterm infants at <32 weeks' gestation on the risk of mortality, severe neonatal morbidities, and NDI in early childhood.

METHODS

Medline, Embase, Cochrane Central Register of Controlled Trials, Education Resources Information Centre (ERIC), Cumulative Index to Nursing and Allied Health (CINAHL), PsycINFO, and the Dissertation database were searched (1947 through August 2013). Risk of bias was assessed by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool. Meta-analyses were performed by using a random-effects model. Unadjusted and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were pooled when appropriate.

RESULTS

Thirty-nine cohort studies and 1 randomized controlled trial were included. Nearly all cohort studies had at least moderate risk of bias mainly due to failure to adjust for survival bias and important postnatal preligation confounders such as ventilator dependence, intraventricular hemorrhage, and sepsis. Compared with medical treatment, surgical ligation was associated with increases in NDI (aOR: 1.54; 95% CI: 1.01-2.33), chronic lung disease (aOR: 2.51; 95% CI: 1.98-3.18), and severe retinopathy of prematurity (aOR: 2.23; 95% CI: 1.62-3.08) but with a reduction in mortality (aOR: 0.54; 95% CI: 0.38-0.77). There was no difference in the composite outcome of death or NDI in early childhood (aOR: 0.95; 95% CI: 0.58-1.57).

CONCLUSIONS

Surgical ligation of PDA is associated with reduced mortality, but surviving infants are at increased risk of NDI. However, there is a lack of studies addressing survival bias and confounding by indication.

What really causes necrotising enterocolitis?

Background. One of the most serious gastrointestinal disorders occurring in neonates is necrotising enterocolitis (NEC). It is recognised as the most common intra-abdominal emergency and is the leading cause of short bowel syndrome. With extremely high mortality and morbidity, this enigmatic disease remains a challenge for neonatologists around the world as its definite aetiology has yet to be determined. As current medical knowledge stands, there is no single well-defined cause of NEC. Instead, there are nearly 20 risk factors that are proposed to increase the likelihood of developing NEC. Aims and Objectives. The aim of this project was to conduct a comprehensive literature review around the 20 or so well-documented and less well-documented risk factors for necrotising enterocolitis. Materials and Methods. Searches of the Medline, Embase, and Science direct databases were conducted using the words "necrotising enterocolitis + the risk factor in question" for example, "necrotising enterocolitis + dehydration." Search results were ordered by relevance with bias given to more recent publications. Conclusion. This literature review has demonstrated the complexity of necrotising enterocolitis and emphasised the likely multifactorial aetiology. Further research is needed to investigate the extent to which each risk factor is implicated in necrotising enterocolitis.

Repeated bowel perforations with Ibuprofen lysine: a case report

Non-steroidal anti-inflammatory drugs (NSAID) have been used to close the patent ductus arteriosus in neonates for over two decades. Ibuprofen lysine, a parenteral NSAID, is labeled for the treatment of patent ductus arteriosus in neonates who do not respond to conventional medical management. While sharing many of the same adverse effects as indomethacin, spontaneous bowel perforation has not been reported. We describe a premature infant that experienced isolated bowel perforations after treatment with ibuprofen lysine for symptomatic patent ductus arteriosus.

Treatment of patent ductus arteriosus and neonatal mortality/morbidities: adjustment for treatment selection bias

OBJECTIVE

To examine the association between treatment for patent ductus arteriosus (PDA) and neonatal outcomes in preterm infants, after adjustment for treatment selection bias.

STUDY DESIGN

Secondary analyses were conducted using data collected by the Canadian Neonatal Network for neonates born at a gestational age ≤ 32 weeks and admitted to neonatal intensive care units in Canada between 2004 and 2008. Infants who had PDA and survived beyond 72 hours were included in multivariable logistic regression analyses that compared mortality or any severe neonatal morbidity (intraventricular hemorrhage grades ≥ 3, retinopathy of prematurity stages ≥ 3, bronchopulmonary dysplasia, or necrotizing enterocolitis stages ≥ 2) between treatment groups (conservative management, indomethacin only, surgical ligation only, or both indomethacin and ligation). Propensity scores (PS) were estimated for each pair of treatment comparisons, and used in PS-adjusted and PS-matched analyses.

RESULTS

Among 3556 eligible infants with a diagnosis of PDA, 577 (16%) were conservatively managed, 2026 (57%) received indomethacin only, 327 (9%) underwent ligation only, and 626 (18%) were treated with both indomethacin and ligation. All multivariable and PS-based analyses detected significantly higher mortality/morbidities for surgically ligated infants, irrespective of prior indomethacin treatment (OR ranged from 1.25-2.35) compared with infants managed conservatively or those who received only indomethacin. No significant differences were detected between infants treated with only indomethacin and those managed conservatively.

CONCLUSIONS

Surgical ligation of PDA in preterm neonates was associated with increased neonatal mortality/morbidity in all analyses adjusted for measured confounders that attempt to account for treatment selection bias.

Gastrointestinal complications associated with ibuprofen therapy for patent ductus arteriosus

OBJECTIVE

To review intestinal complications associated with ibuprofen treatment of patent ductus arteriosus (PDA).

STUDY DESIGN

Data from preterm infants treated with ibuprofen were retrospectively reviewed. χ(2) test and Fischer's exact test were used for univariate analyses. Multivariate analyses with logistic regression modeling were used to identify risk factors.

RESULT

One hundred and two infants were treated with ibuprofen for PDA. Nine (9/102, 8.8%) infants developed spontaneous intestinal perforation (SIP), whereas 93/102 (91.2%) did not. The mean (± s.d.) gestational age (GA) at birth in infants with and without SIP was 25.2 (± 1.3) vs 27.6 (± 2.4) weeks (P=0.02) and the median (interquartile) length of stay (LOS) was 109.5 (91.0 to 116.5) vs 75.0 (53.0 to 94.5) days (P=0.002), respectively. The mean (± s.d.) age at starting ibuprofen was 3.3 (± 1.3) vs 5.8 (± 3.5) days in infants with and without SIP, respectively (P=0.03). In logistic regression analyses, increasing GA and later initiation of ibuprofen treatment were protective against risk of SIP; odds ratio, 95% confidence interval (OR, 95% CI)=0.26 (0.09 to 0.75), P=0.01 and 0.63 (0.41 to 0.95), P=0.03, respectively.

CONCLUSION

Infants at lower GA are at risk of SIP when treated early with ibuprofen for symptomatic PDA.

The risk of necrotizing enterocolitis after indomethacin tocolysis

BACKGROUND

Postnatal indomethacin is reportedly associated with an increased incidence of necrotizing enterocolitis (NEC) in preterm infants. Because indomethacin readily crosses the placenta, we hypothesized that antenatal indomethacin (AI) would increase the risk for NEC in preterm infants.

OBJECTIVE

The goal of this study was to explore the association between AI and NEC in preterm infants.

METHODS

Medical records of preterm infants, 23 to 32 weeks' gestational age, without major congenital anomalies, were reviewed. Maternal and neonatal data were abstracted. Association of AI within 15 days before delivery (predictor variable) and classification of NEC according to modified Bell's stage 2a or higher in the first 15 days after delivery (early NEC [primary outcome variable]) was explored by using bivariate analyses, multivariate logistic regression, and propensity score analysis.

RESULTS

Of 628 eligible infants, 63 received AI and 28 developed early NEC. AI exposure was significantly associated with multiple gestation, race, antenatal corticosteroids and magnesium sulfate, lower birth weight and gestational age, umbilical arterial catheter placement, respiratory distress syndrome, postnatal vasopressors and antibiotics, patent ductus arteriosus, sepsis, NEC, intraventricular hemorrhage, and mortality. On multivariate logistic regression controlling for covariates, AI was significantly associated with early NEC (adjusted odds ratio: 7.193 [95% confidence interval: 2.514-20.575]; number needed to harm: 5). The results remained significant when analyses were repeated using AI exposure within 5 days before delivery as a predictor variable; on analyses stratified according to gestational age; and on propensity score analysis.

CONCLUSIONS

AI was associated with NEC in preterm infants in the first 15 days of life in this study, as were multiple other clinical factors.

Treatment of patent ductus arteriosus with bidirectional flow in neonates

BACKGROUND

Patent ductus arteriosus is a common occurrence among prematurely born neonates and is believed to play a role in the development of other complications of prematurity including intraventricular hemorrhage, bronchopulmonary dysplasia, and necrotizing enterocolitis. The clinical decision to treat the patent ductus arteriosus is complicated by the lack of evidence available regarding clinical conditions under which closure should be attempted.

STUDY AIMS

To compare clinical outcomes for neonates who underwent treatment of patent ductus arteriosus exhibiting bidirectional blood flow versus those with flow that was left to right.

STUDY DESIGN

Cohort study of all neonates with patent ductus arteriosus in which medical closure was attempted at the Duke University between January 2002 and October 2007.

OUTCOME MEASURES

Death and other important clinical conditions.

RESULTS

We identified 20 neonates with bidirectional flow out of 317 cases in which medical closure of patent ductus arteriosus was attempted. There was no significant increase in overall complications due to closure of a bidirectional patent ductus arteriosus [40% (8/20)] versus ones with left to right shunting [38% (111/297) p=0.82]. Death occurred in 15% (3/20) with bidirectional PDA compared to 11% (34/297) in the left to right group, p=0.72.

CONCLUSION

The trend in mortality is worrisome but does not contraindicate an aggressive approach to the clinically significant PDA that has bidirectional flow at the time of the echocardiogram.

Prenatal or postnatal indomethacin exposure and neonatal gut injury associated with isolated intestinal perforation and necrotizing enterocolitis

OBJECTIVE

To examine the role of indomethacin in neonatal gut injury.

STUDY DESIGN

Infants born at gestational age 23 weeks and with birth weights 400-1200 g were included in this prospective prevalence study of neonatal gut injury. Infants with isolated intestinal perforation (IIP) confirmed at laparotomy or at autopsy or with necrotizing enterocolitis (NEC) were identified. Data were abstracted bi-weekly.

RESULT

Among 992 study infants, 58 infants exposed solely to prenatal indomethacin did not show an increased rate of neonatal gut injury. Any postnatal indomethacin exposure (n=611) increased the odds of IIP (OR 4.17, CI, 1.24-14.08, P=0.02) but decreased the odds of NEC (OR 0.65, CI 0.43-0.97, P=0.04). There was a negative association between the timing of indomethacin-exposure and the odds of developing IIP (OR 0.30, CI 0.11-0.83, P=0.02). Compared with NEC, IIP occurred at an earlier age (P<0.05) and was more common (P<0.05) among infants who received early indomethacin (first dose at <12 h of age) to prevent intraventricular hemorrhage than among infants who were treated with late indomethacin for closure of a patent ductus arteriosus (PDA). Unlike the classic hemorrhagic ischemic lesions of NEC in which large areas of tissue were inflamed or necrotic, the IIP lesions were small and discrete.

CONCLUSION

Early (<12 h) postnatal indomethacin exposure was associated with an increased odds of IIP in very low birth weight infants whereas its later use for closure of a PDA appeared to provide protection against NEC. The paradoxical effect of the timing of indomethacin on IIP versus on NEC may be related to the different pathogeneses of the two diseases. Our findings also suggest that PDA may contribute to NEC.

Management of patent ductus arteriosus in term or near-term neonates with respiratory distress

BACKGROUND

Respiratory distress and patent ductus arteriosus (PDA) in neonates are mutually perpetuating. Contrary to the situation in premature infants, the recognition, clinical relevance and optimal management of PDA in full-term neonates are unclear. The present study aimed to identify PDA as a possible cause of respiratory distress in term and near-term neonates, and to examine the clinical responsiveness of PDA to different treatment modalities in mature-gestational-age neonates.

METHODS

Patients with gestational ages of over 34 weeks were included in this retrospective chart review; they had PDA as the sole recognizable cause of respiratory distress and were free of all other diseases. Clinical responsiveness to different regimens, including conservative treatment, drug therapy with preload reduction and inotropic agent with or without the addition of indomethacin, and surgical intervention were analyzed.

RESULTS

Forty-four neonates qualified for this study. Six received no treatment and their cardiorespiratory symptoms resolved within 1 week (regimen A). Symptoms in 11 neonates were relieved after use of diuretic and inotropic agents (regimen B). Twelve neonates became asymptomatic without further intervention after indomethacin treatment in addition to preload reduction and inotropes (regimen C). A total of 15 of the 44 infants underwent PDA ligation (regimen D) due to persistent heart failure following regimens B or C, but had speedy resolution of respiratory symptoms following surgery. There were significant differences in birth body weight and hemodynamic variation based on left atrium to aortic root dimensional ratio between the treatment (regimens B, C and D) and non-treatment (regimen A) groups (p < 0.05).

CONCLUSION

PDA plays an important role in prolonging respiratory distress in term or near-term neonates. Although most infants respond to noninvasive medical treatment, surgical ligation during the neonatal period is warranted in certain mature infants. Surgical treatment should be considered in patients with smaller birth body weights and those with increased left atrium to aortic root dimensional ratios.

Is there an optimal timing for surgical ligation of patent ductus arteriosus in preterm infants?

BACKGROUND

We sought to define the variables associated with hospital outcome in preterm infants with patent ductus arteriosus (PDA) and identify the optimal timing for PDA closure to improve hospital outcome.

METHODS

Included were 201 premature babies (< or = 32 weeks gestational age), from January 2001 to June 2007, with PDA who received primary medical treatment with ibuprofen. Number of ibuprofen cycles, gestational age, body weight, and presence of symptomatic hypotension requiring vasoactive/inotropic drugs were related to hospital outcome, including hospital mortality, presence of necrotizing enterocolitis, acute renal failure, intraventricular hemorrhage, retinopathy and bronchopulmonary dysplasia at week 36. Data were analyzed with a logistic regression model.

RESULTS

Medical treatment was effective in 149 patients (75%), but 52 (25%) required surgical ligation after medical treatment failed. They had younger gestational age (25 weeks [IQR, 24 to 27 weeks] vs 27 weeks [IQR, 25 to 28 weeks], p < 0.0001), lower body weight at birth (730 g [IQR, 595 to 915 g] vs 840 g [IQR, 670 to 1016], p = 0.05), and a higher incidence of symptomatic hypotension (38 of 52 [73%] vs 56 of 149 [38%], p < 0.0001) than patients who responded to ibuprofen. More than two cycles of ibuprofen was significantly associated with an increased risk for bronchopulmonary dysplasia (odds ratio [OR], 2.81; p = 0.03) and acute renal failure (OR, 3.81; p = 0.09).

CONCLUSIONS

The prolonged patency of the ductus arteriosus in preterm infants is related to an increased morbidity. Surgical ligation of PDA is a safe and effective treatment and should be done soon after two complete cycles of ibuprofen, especially in selected patients, to improve clinical outcome.

Tissue-engineered small intestine and stomach form from autologous tissue in a preclinical large animal model

BACKGROUND

Tissue-engineered small intestine, stomach, large intestine, esophagus, and gastroesophageal (GE) junction have been successfully formed from syngeneic cells, and employed as a rescue therapy in a small animal model. The purpose of this study is to determine if engineered intestine and stomach could be generated in an autologous, preclinical large animal model, and to identify if the tissue-engineered intestine retained features of an intact stem cell niche.

METHODS

A short segment of jejunum or stomach was resected from 6-wk-old Yorkshire swine. Organoid units, multicellular clusters with predominantly epithelial content, were generated and loaded onto biodegradable scaffold tubes. The constructs were then implanted intraperitoneally in the autologous host. Seven wk later, all implants were harvested and analyzed using histology and immunohistochemistry techniques.

RESULTS

Autologous engineered small intestine and stomach formed. Tissue-engineered intestinal architecture replicated that of native intestine. Histology revealed tissue-engineered small intestinal mucosa composed of a columnar epithelium with all differentiated intestinal cell types adjacent to an innervated muscularis mucosae. Intestinal subepithelial myofibroblasts, specialized cells that participate in the stem cell niche formation, were identified. Moreover, cells positive for the putative intestinal stem cell marker, doublecortin and CaM kinase-like-1 (DCAMKL-1) expression were identified at the base of the crypts. Finally, tissue-engineered stomach also formed with antral-type mucosa (mucus cells and surface foveolar cells) and a muscularis.

CONCLUSION

We successfully generated tissue-engineered intestine with correct architecture, including features of an intact stem cell niche, in the pig model. To our knowledge, this is the first demonstration in which tissue-engineered intestine was successfully generated in an autologous manner in an animal model, which may better emulate a human host and the intended therapeutic pathway for humans.

Association of Escherichia coli O157:H7 with necrotizing enterocolitis in a full-term infant

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of the neonate. NEC is predominantly seen in premature infants; however, in rare instances it can affect full-term infants as well. Although the pathogenesis of NEC remains elusive, it is well established that bacterial colonization is required for development of this disease. In this report, we present a case of a full-term infant, who developed a very aggressive form of NEC and was found to have Escherichia coli (E. coli) O157:H7 both in stool and blood cultures. Unfortunately, despite aggressive surgical and intensive care management, this infant suffered pan-intestinal necrosis and expired. We were not able to establish the route of transmission. To our knowledge, this is the first report of the association of E. coli O157:H7 with NEC.

Patent ductus arteriosus therapy: impact on neonatal and 18-month outcome

OBJECTIVE

The purpose of this work was to evaluate therapy for patent ductus arteriosus as a risk factor for death or neurodevelopmental impairment at 18 to 22 months, bronchopulmonary dysplasia, or necrotizing enterocolitis in extremely low birth weight infants.

METHODS

We studied infants in the National Institute of Child Health and Human Development Neonatal Research Network Generic Data Base born between 2000 and 2004 at 23 to 28 weeks' gestation and at <1000-g birth weight with patent ductus arteriosus. Patent ductus arteriosus therapy was evaluated as a risk factor for outcomes in bivariable and multivariable analyses.

RESULTS

Treatment for subjects with patent ductus arteriosus (n = 2838) included 403 receiving supportive treatment only, 1525 treated with indomethacin only, 775 with indomethacin followed by secondary surgical closure, and 135 treated with primary surgery. Patients who received supportive therapy for patent ductus arteriosus did not differ from subjects treated with indomethacin only for any of the outcomes of interest. Compared with indomethacin treatment only, patients undergoing primary or secondary surgery were smaller and more premature. When compared with indomethacin alone, primary surgery was associated with increased adjusted odds for neurodevelopmental impairment and bronchopulmonary dysplasia in multivariable logistic regression. Secondary surgical closure was associated with increased odds for neurodevelopmental impairment and increased adjusted odds for bronchopulmonary dysplasia but decreased adjusted odds for death. Risk of necrotizing enterocolitis did not differ among treatments. Indomethacin prophylaxis did not significantly modify these results.

CONCLUSIONS

Our results suggest that infants treated with primary or secondary surgery for patent ductus arteriosus may be at increased risk for poor short- and long-term outcomes compared with those treated with indomethacin. Prophylaxis with indomethacin in the first 24 hours of life did not modify the subsequent outcomes of patent ductus arteriosus therapy.

Necrotizing enterocolitis--bench to bedside: novel and emerging strategies

Necrotizing enterocolitis (NEC) is a devastating illness that predominantly affects premature neonates. The mortality associated with this disease has changed very little during the last two decades. Neonates with NEC fall into two categories: those who respond to medical management alone and those who require surgical treatment. The disease distribution may be focal, multifocal, or panintestinal. Surgical treatment should therefore be based on disease presentation. Recent studies have added significant insight into our understanding of the pathogenesis of NEC. Several groups have shown that upregulation of nitric oxide plays an integral role in the development of epithelial injury in NEC. As a result, some treatment strategies have been aimed at abrogating the toxic effects of nitric oxide. In addition, several investigators have reported the cytoprotective effect of epidermal growth factor, which is found in high levels in breast milk, on the intestinal epithelium. Thus, fortification of infant formula with specific growth factors could soon become a preferred strategy to accelerate intestinal maturation in the premature neonate to prevent the development of NEC. One of the most devastating complications of NEC is the development of short bowel syndrome (SBS). The current treatment of SBS involves intestinal lengthening procedures or bowel transplantation. A novel emerging method for treating SBS involves the use of tissue-engineered intestine. In laboratory animals, tissue-engineered small intestine has been shown to be successful in treating intestinal failure. This article examines recent data regarding surgical treatment options for NEC as well as emerging treatment modalities.

Factors affecting successful closure of hemodynamically significant patent ductus arteriosus with indomethacin in extremely low birth weight infants

BACKGROUND

The incidence of patent ductus arteriosus (PDA) is high in extremely low birth weight (ELBW) infants. Indomethacin has been widely used in the prophylaxis and treatment of hemodynamically significant PDA. This retrospective study was undertaken to identify factors such as birth weight, gestational age, gender, fetal growth retardation, ductal size, timing of the first dose of indomethacin and side effects of indomethacin, which may affect the successful closure of the PDA with indomethacin in ELBW infants.

METHODS

A cohort of 139 ELBW infants who had received indomethacin treatment for PDA during a consecutive period of more than three years (September 2000 to December 2003) was retrospectively analyzed. Administration

RESULTS

of indomethacin was associated with closure of PDA in 108 (77.7%) of 139 ELBW infants, and only 19.4% of infants required surgical ligation of the ductus eventually. There was no significant relationship between closure of PDA with gestational age, gender, fetal growth retardation, and ductal size. A higher birth weight and early use of indomethacin after birth could significantly increase the closure rate of PDA (P<0.05). Side effects of indomethacin such as transient oliguria and hyponatremia during indomethacin therapy did not affect PDA closure.

CONCLUSIONS

Indomethacin is effective for the treatment of PDA in ELBW infants. A higher rate of ductal closure is related to the increase of birth weight. PDA closure with indomethacin is age-related, and early administration of indomethacin could increase PDA closure and reduce the incidence of hyponatremia. There is no significant difference in major morbidities such as bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), and retinopathy of prematurity (ROP) after early treatment. Early screening for hemodynamically significant PDA in ELBW infants and early treatment with indomethacin are recommended.

Predictors of ductal closure and intestinal complications in very low birth weight infants treated with indomethacin

OBJECTIVE

To describe factors associated with failure of patent ductus arteriosus closure and development of gastrointestinal complications in subjects treated with indomethacin.

STUDY DESIGN

Infants <or=30 weeks and <1,500 g delivered between 1997-2003 with patent ductus arteriosus treated with indomethacin were included in this single-center retrospective study. Risk factors for failed ductal closure rates and gastrointestinal complications were identified with uni- and multivariable analyses.

RESULTS

Among 210 subjects treated with indomethacin, ductal closure increased from 43% at 23 weeks to 87% at 27 weeks (OR 1.51 per week gestation, 95% CI 1.14-2.01, p = 0.004) and was unchanged thereafter. Gastrointestinal complications decreased with increasing gestational age (OR 0.67/week, 95% CI 0.52-0.84) but increased with male gender (OR 2.41, 95% CI 1.07-5.45). SNAP-II (Score for Neonatal Acute Physiology-II) scores at birth and at the time of first indomethacin therapy were not associated with likelihood of closure or with gastrointestinal complications. Duration of ductal patency was not associated with risk of necrotizing enterocolitis or intestinal perforation after adjusting for gestational age and gender.

CONCLUSIONS

Ductal closure with indomethacin is linearly associated with gestational age in infants <or=27 weeks. Illness severity at the time of treatment is not predictive of treatment outcome or gastrointestinal complications. The duration of ductal patency is not associated with an increase in adjusted risk of necrotizing enterocolitis or intestinal perforation in patients treated with indomethacin.

Safety and efficacy of ibuprofen versus indomethacin for the treatment of patent ductus arteriosus in the preterm infant: reviewing the evidence

THE DUCTUS ARTERIOSUS IS a vascular shunt that exists before birth to enable blood flow to bypass the lungs, which are not yet functional, and direct it instead to the systemic circulation and to vital organs such as the kidney and the gastrointestinal (GI) tract. In the term infant, this shunt should start to close within the first few hours after birth; it should close functionally within 72 hours and anatomically within 2 weeks after birth.1 In the preterm infant, functional and subsequent anatomic closure frequently does not take place. Failure of ductal closure occurs in as many as 60 percent of all infants who are less than 28 weeks gestation at birth.1 Causes for patency of the ductus arteriosus in preterm infants include decreased smooth muscle fibers in the duct and continued responsiveness of the ductus arteriosus to prostaglandins produced within it.

Indomethacin prophylaxis or expectant treatment of patent ductus arteriosus in extremely low birth weight infants?

BACKGROUND

Indomethacin prophylaxis or expectant treatment are common strategies for the prevention or management of symptomatic patent ductus arteriosus (sPDA).

OBJECTIVE

To compare the clinical responses of extremely low birth weight (ELBW) infants to indomethacin prophylaxis with that of other infants who were managed expectantly by being treated with indomethacin or surgically only after an sPDA was detected.

METHODS

Retrospective cohort investigation of 167 ELBW infants who received indomethacin prophylaxis (study) and 167 ELBW infants (control) treated expectantly who were matched by year of birth (1999 to 2006), birth weight, gestational age (GA) and gender.

RESULTS

Mothers of the two groups of infants were comparable demographically and on the history of preterm labor, pre-eclampsia, antepartum steroids and cesarean delivery. Study and control infants were similar in birth weight, GA, low 5 min Apgar scores, surfactant administration, the need for arterial blood pressure control, bronchopulmonary dysplasia and neonatal mortality. Necrotizing enterocolitis, spontaneous intestinal perforations, intraventricular hemorrhage grade III to IV, periventricular leukomalacia and stage 3 to 5 retinopathy of prematurity occurred also with similar frequency in both groups of infants. In the indomethacin prophylaxis group, 29% of the infants developed sPDA, and of them 38% responded to indomethacin treatment. In the expectantly treated group, 37% developed sPDA, and of them 59% responded to indomethacin treatment. Overall, surgical ligation rate for sPDA was similar between both groups of patients.

CONCLUSION

In our experience, indomethacin prophylaxis does not show any advantages over expectant early treatment on the management of sPDA in ELBW infants. Although no deleterious effects were observed, prophylaxis exposed a significant number of infants who may have never developed sPDA, to potential indomethacin-related complications.

Neonatal necrotizing enterocolitis: diagnosis, management, and pathogenesis

The diagnosis of neonatal necrotizing enterocolitis is one of great concern to pediatric and neonatal clinicians. Intravenous access remains an integral part of the medical and surgical management of infants with this diagnosis, and the infusion nurse is intimately involved in the care of these patients. This article discusses the definition of necrotizing enterocolitis, presents current knowledge regarding its basic pathophysiology, and identifies common and rare sequelae of this oftentimes devastating disease of premature infants. Medical and surgical management goals of therapy are described. This overview will aid the infusion nurse in caring for these patients.

The pharmacologic closure of the patent ductus arteriosus

The ductus arteriosus is a fetal vessel that allows most of the blood leaving the right ventricle of the heart to bypass the lungs. Fetal patency of the ductus, and its spontaneous closure after birth, is the result of a balanced interaction of locally produced and circulating mediators (of which prostaglandins seem to be the most important), and the unique structure of the vessel wall. Persistent patency of the ductus occurs in almost 60% of very low birthweight infants. A significant left-to-right shunt through the ductus increases morbidity and mortality in premature infants. As prostaglandins play a major role in patency of the ductus, cyclooxygenase inhibitors are conventionally used to induce its closure. This chapter focuses on some of the basic mechanisms underlying ductal patency and the clinical attempts to diminish side effects associated with indomethacin, including the alternative use of ibuprofen.

Platelet transfusions in infants with necrotizing enterocolitis do not lower mortality but may increase morbidity

OBJECTIVE

Necrotizing enterocolitis (NEC), a serious multisystemic inflammatory disease most commonly seen in premature neonates, is often associated with thrombocytopenia. Infants with severe forms of NEC commonly have platelet counts of less than 50,000/mm(3), occasionally less than 10,000/mm(3). Despite an absence of data to support the practice, platelet transfusions are commonly used to maintain a certain arbitrary platelet count in an effort to prevent bleeding. As platelet transfusions contain a variety of bioactive factors including pro-inflammatory cytokines, we hypothesized that a higher number and volume of platelet transfusions would not be associated with an improvement in mortality or morbidity.

STUDY DESIGN

A retrospective cohort analysis was conducted of the medical records of all infants between 1997 and 2001 with Bell's Stage 2 or 3 NEC associated with platelet counts of <100,000/mm(3). The medical records were evaluated for the following variables: platelet counts, number and volume of platelet transfusions, symptoms of bleeding, and hospital course. Mortality and development of short bowel syndrome and/or cholestasis were correlated to the total number and volume (total ml and ml/kg) of platelet transfusions. Differences between the outcome groups were compared using the independent t-test, Fisher's exact test and Mann-Whitney tests.

RESULTS

A total of 46 infants met the study criteria (gestational age 28+/-4 weeks and birth weight 1166+/-756 g, mean+/-SD). There were a total of 406 platelet transfusions administered to the study population. Of these, 151 (37.2%) were given in the presence of active bleeding, with 62% of these resulting in the cessation of bleeding within 24 hours. Other listed indications for platelet transfusions were hypovolemia and severe thrombocytopenia. On analysis of the entire cohort, there was no statistical improvement in either mortality or morbidity (short bowel syndrome and cholestasis) with greater number and/or volume of platelet transfusions. Furthermore, we found that infants who developed short bowel syndrome and/or cholestasis had been given a significantly higher number and volume of platelet transfusions when compared to those who did not have these adverse outcomes [median (minimum - maximum) - number of transfusions : 9 (0 to 33) vs 1.5 (0 to 20), p=0.010; volume of transfusions (ml/kg): 121.5 (0 to 476.6) vs 33.2 (0 to 224.3), p=0.013].

CONCLUSION

This retrospective analysis suggests that greater number and volume of platelet transfusions in infants with necrotizing enterocolitis are associated with greater morbidity in the form of short bowel syndrome and/or cholestasis without the benefit of lower mortality.

Patent ductus arteriosus, indomethacin and necrotizing enterocolitis in very low birth weight infants: a population-based study

BACKGROUND

Patent ductus arteriosus is a risk factor for the development of necrotizing enterocolitis. The use of indomethacin to treat patent ductus arteriosus in preterm infants may either decrease the incidence of necrotizing enterocolitis by stabilizing or closing the ductus arteriosus or increase its incidence by a direct constricting effect on mesenteric blood vessels. The authors sought to evaluate the interrelationship between patent ductus arteriosus, treatment with indomethacin and the risk of necrotizing enterocolitis in very low birth weight infants.

METHOD

The Israel National database includes prospectively collected data on 99% of all very low birth weight infants in Israel. The study population comprised 6146 infants of 24-34 weeks' gestation born between 1995 and 2000. The effect of patent ductus arteriosus on necrotizing enterocolitis was assessed using multiple regression analysis.

RESULTS

Necrotizing enterocolitis occurred in 5.5% (n = 343) of all infants, in 9.4% of infants with patent ductus arteriosus and in 8.9% of infants who received indomethacin. The occurrence of necrotizing enterocolitis was independently associated with the presence of patent ductus arteriosus among infants not treated with indomethacin (odds ratio, 1.85) and those who received indomethacin therapy (odds ratio, 1.53). Indomethacin therapy in absence of patent ductus arteriosus was not associated with an increased risk of necrotizing enterocolitis (odds ratio, 0.72).

CONCLUSIONS

Patent ductus arteriosus is an independent risk factor for the development of necrotizing enterocolitis in very low birth weight infants. Therapy with indomethacin did not have a significant effect on the risk for necrotizing enterocolitis.

Necrotizing enterocolitis: preventative strategies

Necrotizing enterocolitis (NEC) remains a major cause of morbidity and mortality in premature infants. Although the pathogenesis of NEC is unclear, prevention strategies have been developed based on clinical observations and epidemiologic and experimental data. Most current strategies have centered on feeding practices (eg, institution of feeds, advancement of feeds, composition of feeds, and standardization of feeding practices). Emerging strategies include amino acid supplementation, the use of platelet-activating factor(PAF) antagonists or PAF-acetylhydrolase administration, polyunsaturated fatty acid administration, epidermal growth factor administration, and the use of pre- and probiotics.