Effects of a patent ductus arteriosus on postprandial mesenteric perfusion in premature baboons

Efficacy of bowel ultrasound to diagnose necrotizing enterocolitis in extremely low birthweight infants

BACKGROUND

Bowel ultrasound (US) is one of the methods used to enhance diagnostic accuracy of necrotizing enterocolitis (NEC) and its associated complications in premature newborns.

AIM

To explore the diagnostic accuracy of BUS in extremely low birth weight (ELBW) infants with NEC.

METHODS

A single-center retrospective case-control study included 84 extremely low birth weight (ELBW) infants. The infants were divided into three groups: Group 1 -infants with NEC (n = 26); Group 2 -infants with feeding problems (n = 28); Group 3 -control group (n = 30).

RESULTS

The specific BUS findings in premature newborns with NEC (stage 3) included bowel wall thinning, complex (echogenic) ascites, and pneumoperitoneum, p <  0.05. The diagnostic effectiveness of these sonographic signs was 96.8% (sensitivity 75.0% and specificity 97.6%), p <  0.05. These findings with high specificity were associated with the need for surgical intervention, poor outcomes, or increased mortality. Stage 2 NEC which did not require surgery showed impaired differentiation of the bowel wall layers, absent or decreased bowel peristalsis, pneumatosis intestinalis, portal venous gas, or simple ascites, with a diagnostic accuracy of 82.9% (sensitivity 55.6%, specificity 91.4%, p <  0.05).

CONCLUSIONS

BUS can be used as an adjunct to abdominal radiography to aid in the diagnosis of infants with suspected NEC by providing more detailed evaluation of the intestine.

Should we "eliminate" PDA shunt in preterm infants? A narrative review

The patent ductus arteriosus frequently poses a significant morbidity in preterm infants, subjecting their immature pulmonary vascular bed to substantial volume overload. This, in turn, results in concurrent hypoperfusion to post-ductal organs, and subsequently alters cerebral blood flow. In addition, treatment has not demonstrated definitive improvements in patient outcomes. Currently, the optimal approach remains a subject of considerable debate with ongoing research controversy regarding the best approach. This article provides a comprehensive review of existing literature.

Nutrition of the preterm infant with persistent ductus arteriosus: existing evidence and practical implications

The persistence of a patent ductus arteriosus (PDA) is a common condition in preterm infants with a prevalence inversely proportional to gestational age. PDA is associated with mild-to-severe gastrointestinal complications such as feeding intolerance, gastrointestinal perforation, and necrotizing enterocolitis, which represent a major challenge for the nutritional management in preterm infants. In this context, the Section on Nutrition, Gastroenterology and Metabolism and the Circulation Section of the European Society for Pediatric Research have joined forces to review the current knowledge on nutritional issues related to PDA in preterm infants. The aim of the narrative review is to discuss the clinical implications for nutritional practice. Because there is little literature on postnatal nutrition and PDA in preterm infants, further research with well-designed studies on this topic is urgently needed. Guidelines should also be developed to clearly define the implementation and course of enteral nutrition and the target nutritional intake before, during, and after pharmacologic or surgical treatment of PDA, when indicated. IMPACT: Persistent ductus arteriosus (PDA) is associated with gastrointestinal complications such as feeding intolerance, gastrointestinal perforation, and necrotizing enterocolitis, which pose a major challenge to the nutritional management of preterm infants. In PDA infants, fluid restriction may lead to inadequate nutrient intake, which may negatively affect postnatal growth and long-term health. The presence of PDA does not appear to significantly affect mesenteric blood flow and splanchnic oxygenation after enteral feedings. Initiation or maintenance of enteral nutrition can be recommended in infants with PDA.

Measuring gut perfusion and blood flow in neonates using ultrasound Doppler of the superior mesenteric artery: a narrative review

The gut is a relatively silent organ in utero but takes on a major role after birth for the absorption and digestion of feed for adequate nutrition and growth. The neonatal circulation undergoes a transition period after birth, and gut perfusion increases rapidly to satisfy the oxygen demand and consumption. If this process is compromised at any stage, preterm and fetal growth restricted infants are at particular risk of gut tissue injury secondary to hypoxia, leading to necrotizing enterocolitis. Feeding can also be a challenge in these high-risk groups due to gut dysmotility. Superior mesenteric artery (SMA) Doppler is a safe, bedside investigation that could rapidly aid clinicians with feeding strategies and in monitoring high-risk infants. This article aims to establish normal patterns of gut blood flow velocity in neonates using SMA Doppler and reviews how it might be used clinically in pathologic states.

The Prevalence of Small for Gestational Age and Extrauterine Growth Restriction among Extremely and Very Preterm Neonates, Using Different Growth Curves, and Its Association with Clinical and Nutritional Factors

Monitoring the growth of neonates in the Neonatal Intensive Care Unit (NICU) using growth charts constitutes an essential part of preterm infant care. Preterm infants are at increased risk for extrauterine growth restriction (EUGR) due to increased energy needs and clinical complications. This retrospective study compares the prevalence of small for gestational age (SGA) at birth and EUGR at discharge in extremely and very preterm neonates hospitalized in the NICU of a tertiary hospital in Greece, using different growth curves, and it examines the associated nutritional and clinical factors. Fenton2013 and INTERGROWTH-21st growth curves were used to calculate z-scores of birth weight (BW) and weight, length, and head circumference at discharge. The study includes 462 newborns with a mean BW of 1341.5 g and mean GA of 29.6 weeks. At birth, 6.3% of neonates were classified as SGA based on Fenton2013 curves compared to 9.3% with INTERGROWTH-21st growth curves. At discharge, 45.9% of neonates were characterized as having EUGR based on the Fenton2013 weight curves and 29.2% were characterized based οn INTERGROWTH-21st curves. Nutritional factors such as the day of initiation, attainment of full enteral feeding, and the duration of parenteral nutrition were associated with EUGR by both curves. The prevalence of SGA and EUGR neonates differs between the two growth references. This shows that further evaluation of these charts is needed to determine the most appropriate way to monitor infant growth.

Combination pharmacotherapy for patent ductus arteriosus: Rationale and evidence

While cyclooxygenase inhibitors have been the most common medications used to facilitate earlier closure of patent ductus arteriosus in preterm infants, adverse effects and low efficacy in extremely low gestational age neonates (ELGANs) have highlighted a need for alternative options. Combination therapy with acetaminophen and ibuprofen is a novel strategy for PDA treatment in ELGANs, as it may facilitate higher ductal closure rates via additive action on two separate pathways inhibiting prostaglandin production. Initial small observational studies and pilot randomized clinical trials indicate potentially higher efficacy of the combination regime to induce ductal closure in comparison to treatment with ibuprofen alone. In this review, we examine the potential clinical impact of treatment failure in ELGANs with significant PDA, highlight the biological rationale in support of studying combination therapy, and review the randomized and non-randomized studies to date. With the rising number of ELGANs receiving neonatal intensive care, who are vulnerable to PDA-related morbidities, there is an urgent need for adequately powered clinical trials to systematically investigate the efficacy and safety of combination therapy for PDA treatment.

The dilemma of feeding during the treatment of patent ductus arteriosus with oral ibuprofen in preterm infants ≤30 weeks of gestation-a randomized controlled trial

OBJECTIVES

To evaluate the effect of minimal enteral feeding (MEN) versus withholding feeding on time to reach full feeds during treatment of hs-PDA with oral ibuprofen in infants ≤30 weeks.

STUDY DESIGN

We performed a single-center, randomized control trial of 126 premature infants born ≤30 weeks gestation, <7 days of age with hs-PDA comparing continuation of MEN (n = 64) vs no feeding (n = 62) during treatment. The primary outcome was time to reach a feed volume of 150 ml/kg/day. Secondary outcomes included were episodes of feed intolerance, GI bleed, NEC and other comorbidities.

RESULTS

There was no difference in the time to reach full feeds - median age of 16 days in both groups (p = 0.573). Incidence of feed intolerance, NEC and other secondary outcomes were also similar in both groups.

CONCLUSIONS

Continuing MEN during treatment of hs-PDA with oral ibuprofen does not decrease time to reach full enteral feeds in very preterm infants.

Patent ductus arteriosus and cerebral, cardiac, and gut hemodynamics in premature neonates

Patent ductus arteriosus is associated with multiple comorbidities in premature infants, however a causal link or strategy to decrease these morbidities has not been found. The association between the patent ductus arteriosus and morbidities has biologic plausibility as, like any cardiac mixing lesion, a significant systemic to pulmonic shunt may lead to pulmonary over-circulation and systemic hypoperfusion. Understanding the underlying pathophysiology of associated morbidities in the setting of a patent ductus arteriosus may aid in risk stratifying infants and offer a patient targeted approach to infants with a pathological ductal shunt. While the deleterious impact of increased pulmonary blood flow maybe easier to identify, the impact on end-organ perfusion is more challenging. In this review, we will discuss the pathophysiology of a hemodynamically significant patent ductus arteriosus in premature infants, impact on end-organ perfusion and associated morbidities, and novel modalities to assess shunt volume and effect on end-organ perfusion.

The effect of prolonged tracheal intubation on the association between patent ductus arteriosus and bronchopulmonary dysplasia (grades 2 and 3)

OBJECTIVE

To determine if the need for mechanical ventilation alters the association between prolonged patent ductus arteriosus (PDA) exposure and bronchopulmonary dysplasia (grades 2 and 3) (BPD).

STUDY DESIGN

Observational study of 407 infants (<28 weeks' gestation) with echocardiograms performed at planned intervals.

RESULTS

Twelve percent (48/407) of study infants had BPD (grades 2 and 3). In a multivariable regression model, exposure to a moderate-to-large PDA shunt for ≥7 days was associated with an increased risk of BPD (grades 2 and 3) (from 16 to 35%: aRD = 19% (6, 32%), p < 0.005) when infants required ≥10 days of intubation (n = 170). In contrast, there was no significant association between prolonged PDA exposure and BPD when infants required ≤9 days of intubation (aRD = 4%) (-1, 10%) (n = 237).

CONCLUSIONS

Moderate-to-large PDAs are associated with an increased risk of BPD-but only when infants require intubation ≥10 days.

Measurement of gut oxygenation in the neonatal population using near-infrared spectroscopy: a clinical tool?

CONTEXT

Near-infrared spectroscopy (NIRS) is a non-invasive bedside monitor of tissue oxygenation that may be a useful clinical tool in monitoring of gut oxygenation in newborn infants.

OBJECTIVE

To systematically review literature to determine whether NIRS is a reliable tool to monitor gut oxygenation on neonatal units.

DATA SOURCES

PubMed and Embase databases were searched using the terms 'neonate', 'preterm infants', 'NIRS' and 'gut oxygenation' (2001-2018).

STUDY SELECTION

Studies were included if they met inclusion criteria (clinical trial, observational studies, neonatal population, articles in English and reviewing regional gut oxygen saturations) and exclusion criteria (not evaluating abdominal NIRS or regional oxygen saturations).

DATA EXTRACTION

Two authors independently searched PubMed and Embase using the predefined terms, appraised study quality and extracted from 30 studies the study design and outcome data.

LIMITATIONS

Potential for publication bias, majority of studies were prospective cohort studies and small sample sizes.

RESULTS

Thirty studies were reviewed assessing the validity of abdominal NIRS and potential application in neonates. Studies reviewed assessed abdominal NIRS in different settings including normal neonates, bolus and continuous feeding, during feed intolerance, necrotising enterocolitis and transfusion with packed red cells. Several observational studies demonstrated how NIRS could be used in clinical practice.

CONCLUSIONS

NIRS may prove to be a useful bedside tool on the neonatal unit, working alongside current clinical tools in the monitoring of newborn infants (preterm and term) and inform clinical management. We recommend further studies including randomised controlled trials looking at specific measurements and cut-offs for abdominal NIRS for use in further clinical practice.

To Feed or Not to Feed: A Critical Overview of Enteral Feeding Management and Gastrointestinal Complications in Preterm Neonates with a Patent Ductus Arteriosus

The management of enteral feeds in preterm infants with a hemodynamically significant patent ductus arteriosus (hs-PDA) is a major challenge for neonatologists due to the fear of gastrointestinal (GI) complications. This review aims to analyze the available evidence on the complex relation between the presence and management of PDA, enteral feeding practices, and GI outcomes in the preterm population. There is limited evidence, based on small and heterogeneous trials, that hs-PDA may affect the splanchnic hemodynamic response to enteral feeds. While the presence of PDA seems a risk factor for adverse GI outcomes, the benefits of feeding withholding during pharmacological PDA treatment are controversial. The lack of robust evidence in support of or against a timely feeding introduction or feeding withholding during pharmacological PDA closure in preterm neonates does not allow to draw any related recommendation. While waiting for further data, the feeding management of this population should be carefully evaluated and possibly individualized on the basis of the infants’ hemodynamic and clinical characteristics. Large, multicentric trials would help to better clarify the physiological mechanisms underlying the development of gut hypoperfusion, and to evaluate the impact of enteral feeds on splanchnic hemodynamics in relation to PDA features and treatment.

Effect of Patent Ductus Arteriosus on Splanchnic Oxygenation at Enteral Feeding Introduction in Very Preterm Infants

Because of its possible effect on mesenteric blood flow, the presence of a hemodynamically significant patent ductus arteriosus (PDA) is often of concern for the introduction of enteral feeds in preterm neonates. Near-infrared spectroscopy allows a continuous monitoring of splanchnic oxygenation (SrSO2) and may provide useful hemodynamic information. This observational study evaluated SrSO2 patterns in response to first feed administration in 50 preterm infants <32 weeks' gestation with different ductal status. According to their echocardiographic characteristics, the enrolled infants were divided into the following groups: pulsatile PDA with hemodynamically significant features, restrictive PDA, and no evidence of PDA. The presence of PDA, either with restrictive or hemodynamically significant characteristics, does not significantly affect SrSO2 response to enteral feeding introduction and is not associated with increased rates of gut complications. This finding may provide encouraging evidence in support of early enteral nutrition in very preterm infants with PDA.

[Splanchnic oximetry in small for gestational age neonates in relation to prenatal doppler study]

INTRODUCTION

Among small for gestational age neonates, foetal Doppler enables the identification of placental insufficency aetiology and the classification of severity in small for gestational age neonates. There are studies that associate the Doppler data with alterations in the intestinal flow of the newborn, but its relationship with intestinal oximetry has been little studied.

OBJECTIVE

To assess whether there is a relationship between prenatal Doppler data and abdominal oximetry in small for gestational age neonates MATERIAL AND METHODS: A prospective observational study carried out on neonates>32 weeks with a birth weight<P10. The severity of placental insufficiency was classified according to prenatal Doppler criteria. Splanchnic oximetry was monitored during the first three days of life and a comparative analysis of the oximetry data was performed according to the prenatal Doppler alteration severity.

RESULTS

A total of 53 patients were evaluated. Significant differences were observed in the mean regional oximetry (rSO₂) between patients with moderate or severe placental failure and those with normal or slightly altered prenatal Doppler: 42±10 vs. 71.3±10 (P<.001). These differences were maintained during the first 3 days of life. Standard patterns of splanchnic oximetry were identified depending on the degree of placental insufficiency.

CONCLUSIONS

There is a correlation between the foetal Doppler and the splanchnic oximetry pattern during the first days of life. Neonates with moderate or severe placental insufficiency have more altered abdominal oximetry patterns, making it a useful technique to evaluate the degree of placental insufficiency and the risk of oral intolerance in small for gestational age neonates.

Circulatory Insufficiency and Hypotension Related to the Ductus Arteriosus in Neonates

The biological role of the ductus arteriosus (DA) in neonates varies from an innocent bystander role during normal postnatal transition, to a supportive role when there is compromise to either systemic or pulmonary blood flow, to a pathological state in the presence of hemodynamically significant systemic to pulmonary shunts, as occurs in low birth weight infants. Among a wide array of clinical manifestations arising due to the ductal entity, systemic circulatory insufficiency and hypotension are of significant concern as they are particularly challenging to manage. An understanding of the physiologic interplay between the DA and the circulatory system is the key to developing appropriate targeted therapeutic strategies. In this review, we discuss the relationship of systemic hypotension to the DA, emphasizing the importance of critical thinking and a precise individual approach to intensive care support. We particularly focus on the variable states of hypotension arising directly due to a hemodynamically significant DA or seen in the period following successful surgical ligation. In addition, we explore the mechanistic contributions of the ductus to circulatory insufficiency that may manifest during the transitional period, states of maladapted transition (such as acute pulmonary hypertension of the newborn), and congenital heart disease (both ductal dependent and non-ductal dependent lesions). Understanding the dynamic modulator role of the ductus according to the ambient physiology enables a more precise approach to management. We review the pathophysiology, clinical manifestations, diagnosis, monitoring, and therapeutic intervention for the spectrum of DA-related circulatory compromise.

Enteral feeding during indomethacin treatment for patent ductus arteriosus: association with gastrointestinal outcomes

OBJECTIVE

Enteral feeds are often discontinued or reduced during indomethacin treatment for patent ductus arteriosus (PDA) in preterm neonates, but the clinical impact of this practice is unknown. The objective of this study was to study the associations between enteral feed volume at the time of indomethacin therapy in preterm neonates with PDA and subsequent gastrointestinal outcomes.

STUDY DESIGN

Retrospective cohort study. Single-center level III Neonatal Intensive Care Unit.

RESULTS

All consecutive preterm neonates who had received treatment with indomethacin for PDA over a 5-year period were included and categorized based on enteral feed volume exposure during treatment (Group A: nil per oral (NPO, N=229); Group B: ⩽60 ml kg(-1) day(-1) (N=142); Group C:>60 ml kg(-1) day(-1) (N=44)). Baseline characteristics and clinical outcomes were compared between the three groups. The primary outcome was necrotizing enterocolitis (NEC) ⩾stage IIa, while secondary outcomes included other gastrointestinal complications and common prematurity-related morbidities. Group C had a higher gestational age (mean±s.d.; A: 26.3±1.8; B: 26.1±1.8; C: 27.0±2.0 weeks), birth weight (A: 864±239; B: 847±202; C: 932±234 g) and postnatal age at the time of indomethacin treatment (A: 5.3±2.9; B: 7.2±4.9; C: 15.4±6.6 days). All groups had similar rates of the primary outcome NEC (A: 6.1%, B: 7.8% and C: 4.6%, respectively). They also had similar rates of the secondary outcomes with the exception of days to reach enteral feeds of 120 ml kg(-1) day(-1) (A: 22.8±8.5; B: 20.5±8.6; C: 16.8±7.7; P<0.05 for all inter-group comparisons). Secondary analysis including only those neonates who were not already NPO before indomethacin treatment (N=261) and categorized based on preemptive management (made NPO; enteral feed volume reduced; enteral feed volume unchanged/increased) also showed similar results.

CONCLUSIONS

This large retrospective study did not identify any association between enteral feed volumes during indomethacin treatment or preemptive reduction in enteral feeds and subsequent incidence of adverse gastrointestinal outcomes in preterm neonates. Preemptive reduction in enteral feed volume was associated with longer time to reach full enteral feeds.

Packed red blood cell transfusion (PRBC) attenuates intestinal blood flow responses to feedings in pre-term neonates with normalization at 24 hours

OBJECTIVE

To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.

DESIGN/METHODS

VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3 h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45 min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15 ml/kg of PRBC transfusion was given over 3 h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48 h after the transfusion.

RESULTS

Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48 h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.

CONCLUSIONS

PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24 h post-transfusion.

Diethylstilbestrol decreased adrenal cholesterol and corticosterone in rats

The synthetic oestrogen diethylstilbestrol (DES), which is known to bind oestrogen receptors (ERs), has been reported to have adverse effects on endocrine homeostasis; however, the molecular mechanisms underlying these effects are poorly understood. In this study, we treated rats with DES and found high levels of this compound in the liver, adrenal glands and pituitary gland, as compared with other tissues. We have also detected early adverse effects of DES in the adrenal glands. The adrenal glands of rats treated with DES (340 μg/kg body weight every 2 days) for 2 weeks showed increased weight and size and a decreased fat droplet size. Following 1 week of treatment with DES, the blood and adrenal corticosterone levels were substantially decreased without any histological alterations. The levels of the precursors for corticosteroid biosynthesis in the adrenal glands were also decreased, as determined using mass spectroscopy. Cholesterol, the principal material of corticosteroid biosynthesis, decreased substantially in the adrenal glands after only 1 week of treatment with DES. In conclusion, cholesterol insufficiency results in a reduction in adrenal corticosterone biosynthesis, which may lead to endocrine dysfunction, such as reproductive toxicity.

Antenatal corticosteroids alter insulin signaling pathways in fetal baboon skeletal muscle

We hypothesize that prenatal exposure to glucocorticoids (GCs) negatively alters the insulin signal transduction pathway and has differing effects on the fetus according to gestational age (GA) at exposure. Twenty-three fetal baboons were delivered from 23 healthy, nondiabetic mothers. Twelve preterm (0.67 GA) and 11 near-term (0.95 GA) baboons were killed immediately after delivery. Half of the pregnant baboons at each gestation received two doses of i.m. betamethasone 24 h apart (170 μg/kg) before delivery, while the other half received no intervention. Vastus lateralis muscle was obtained from postnatal animals to measure the protein content and gene expression of insulin receptor β (IRβ; INSR), IRβ Tyr 1361 phosphorylation (pIRβ), IR substrate 1 (IRS1), IRS1 tyrosine phosphorylation (pIRS1), p85 subunit of PI3-kinase, AKT (protein kinase B), phospho-AKT Ser473 (pAKT), AKT1, AKT2, and glucose transporters (GLUT1 and GLUT4). Skeletal muscle from preterm baboons exposed to GCs had markedly reduced protein content of AKT and AKT1 (respectively, 73 and 72% from 0.67 GA control, P<0.001); IRβ and pIRβ were also decreased (respectively, 94 and 85%, P<0.01) in the muscle of premature GC-exposed fetuses but not in term fetuses. GLUT1 and GLUT4 tended to increase with GC exposure in preterm animals (P=0.09), while GLUT4 increased sixfold in term animals after exposure to GC (P<0.05). In conclusion, exposure to a single course of antenatal GCs during fetal life alters the insulin signaling pathway in fetal muscle in a manner dependent on the stage of gestation.

Superior mesenteric artery blood flow velocities following medical treatment of a patent ductus arteriosus

We examined superior mesenteric artery blood flow velocity in response to feeding in infants randomized to trophic feeds (n = 16) or nil per os (n = 18) during previous treatment for patent ductus arteriosus. Blood flow velocity increased earlier in the fed infants, but was similar in the 2 groups at 30 minutes after feeding.

Enteral feeding during indomethacin and ibuprofen treatment of a patent ductus arteriosus

OBJECTIVE

To test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive "trophic" (15 mL/kg/d) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus.

STUDY DESIGN

Infants were eligible for the study if they were 23(1/7)-30(6/7) weeks' gestation, weighed 401-1250 g at birth, received maximum enteral volumes ≤60 mL/kg/d, and were about to be treated with indomethacin or ibuprofen. A standardized "feeding advance regimen" and guidelines for managing feeding intolerance were followed at each site (N = 13).

RESULTS

Infants (N = 177, 26.3 ± 1.9 weeks' mean ± SD gestation) were randomized at 6.5 ± 3.9 days to receive "trophic" feeds ("feeding" group, n = 81: indomethacin 80%, ibuprofen 20%) or no feeds ("fasting [nil per os]" group, n = 96: indomethacin 75%, ibuprofen 25%) during the drug administration period. Maximum daily enteral volumes before study entry were 14 ± 15 mL/kg/d. After drug treatment, infants randomized to the "feeding" arm required fewer days to reach the study's feeding volume end point (120 mL/kg/d). Although the enteral feeding end point was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the 2 groups. There were no differences between the 2 groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation, or other neonatal morbidities.

CONCLUSION

Infants required less time to reach the feeding volume end point if they were given "trophic" enteral feedings when they received indomethacin or ibuprofen treatments.

Hyperglycemia increases the risk of death in extremely preterm baboons

BACKGROUND

Transient neonatal hyperglycemia (HG) has been reported in up to 80% of extremely preterm human infants. We hypothesize that severe HG is associated with increased morbidity and mortality in preterm baboons.

METHODS

Sixty-six baboons born at 67% of gestation were studied. HG was defined as serum glucose level ≥150 mg/dl during the first week of life. Animals were stratified into two groups: severe HG (≥8 events) and nonsevere HG (<8 events).

RESULTS

HG developed in 65 of the 66 (98%) baboons that were included. A total of 3,386 glucose measurements were obtained. The mean serum glucose level was 159 ± 69 mg/dl for the severe HG group and 130 ± 48 mg/dl for the nonsevere HG group during the first week of life. No differences were found in gender, birth weight, sepsis, patent ductus arteriosus, or oxygenation/ventilation indexes between groups. Severe HG was associated with early death even after controlling for sepsis, postnatal steroid exposure, and catecholamine utilization.

CONCLUSION

HG is common in preterm baboons and is not associated with short-term morbidity. Severe HG occurring in the first week of life is associated with early death in preterm baboons.

Impact of patient selection on outcomes of PDA in very low birth weight infants

AIM

The aim of this study was to observe whether our patient selection maximized the benefits of PDA ligation by comparing the outcomes in a surgically ligated group of PDA to a medically closed group.

STUDY DESIGN

If a hemodynamically significant ductus arteriosus (HSDA) was found to meet both clinical and echocardiographic criteria (stage≥3), as proposed by NcNamara and Hellman, medical treatment was initiated with oral ibuprofen (maximum 2 courses). If the PDA of these patients failed to close medically, timed surgical closure was performed.

RESULT

Medical treatment was effective in 75 (72%) cases, and 29 (28%) patients required surgical ligation. The mean gestational age and birth weight were each significantly lower and the initial PDA shunt size was significantly larger in the surgically treated group. Additionally, the mean durations of mechanical ventilation, oxygen dependence and hospital admission were significantly longer in the surgically ligated group. However, our logistic regression analysis demonstrated no statistically significant difference in the outcomes of hospitalization (CLD, NEC, ARF, sepsis, IVH, ROP, PVL and death) between the two groups.

CONCLUSION

Comprehensive HSDA patient selection may maximize the benefits of timed PDA ligation without adverse outcomes in very low birth weight infants.

Does treatment of patent ductus arteriosus with cyclooxygenase inhibitors affect neonatal regional tissue oxygenation?

The effect of patent ductus arteriosus (PDA) treatment with cyclooxygenase (COX) inhibitors (indomethacin [INDO] and ibuprofen [IBU]) on regional oxygenation requires further clarification. The authors hypothesized that both INDO and IBU reduce regional tissue oxygenation in preterm neonates with PDA but that the risk is not uniform for different tissues and other factors may contribute. Regional cerebral (rSO(2-C)), renal (rSO(2-R)), and mesenteric (rSO(2-M)) tissue oxygenation measured by near-infrared spectroscopy and peripheral arterial oxygen saturation measured by pulse oximetry were recorded simultaneously before, during, and after treatment with the first dose of INDO or IBU in very preterm-born infants with PDA. Tissue-specific fractional oxygen extraction (FOE) was calculated using the rSO(2-C), rSO(2-R), rSO(2-M), and corresponding SpO(2) measurements. The findings showed a significant reduction in rSO(2-C), rSO(2-R), and rSO(2-M) and an increase in regional FOE after treatment with COX inhibitors in approximately one third of the 38 enrolled infants, which were associated with increased baseline regional tissue oxygen saturation (p < 0.01). However, the infants with posttreatment reduction of tissue oxygenation had significantly lower baseline rSO(2-C) (66.7 ± 8.1 vs 69.7 ± 8.1 %), rSO(2-R) (55.2 ± 10.8 vs 62.7 ± 11.8 %) and especially rSO(2-M) (37.8 ± 11.4 vs 46.7 ± 16.0 %) than the neonates with unchanged or increased tissue oxygenation. The two groups did not differ in terms of the risk for posttreatment reduction in regional tissue oxygenation with respect to either INDO or IBU treatment and their respective blood levels. Treatment of PDA with either INDO or IBU is associated with a 30-40 % risk for a reduction in regional tissue oxygenation, which is more pronounced in mesenteric tissue than in cerebral or renal tissue. Despite the inconsistency, reduction of regional tissue oxygenation in preterm infants with PDA is more likely associated with the administration of INDO than with the administration of IBU.

Managing the patent ductus arteriosus in the premature neonate: a new look at what we thought we knew

Over recent years, the clinical approach to patency of the ductus arteriosus in the premature neonate has been the subject of intensive reevaluation. What had once been considered inherently obvious is no longer to be taken for granted. In this review we will focus on some of the controversies surrounding various aspects of the pharmacologic treatment regimens for patent ductus arteriosus closure. The pros and cons of prophylactic vs therapeutic indomethacin, of early vs late therapy, of high- vs low-dose indomethacin, of single vs multiple courses of treatment, and of ibuprofen vs indomethacin will be considered. In addition, the possibility that patency of the ductus arteriosus is merely a physiological manifestation of extreme prematurity, and thus does not necessarily need to be therapeutically closed, has become a viable approach in some cases. As such, we will examine echocardiographic and biochemical criteria aimed at determining the clinical and hemodynamic significance of ductal shunting, and thereby of the need to treat. Finally, we speculate on potential therapeutic directions for the future, including individualized treatment regimens and multidrug treatment cocktails for those who fail initial monodrug therapy.

Learning to live with patency of the ductus arteriosus in preterm infants

Treatment of persistent patency of the ductus arteriosus in preterm infants remains heterogeneous and controversial. Routine early treatment to induce ductal closure is not beneficial, but the potential criteria for, timing of, methods for and benefits of later ductal closure have not been determined. Management strategies for infants awaiting spontaneous closure or meeting criteria for treatment may be based on pathophysiological considerations but require evaluation in clinical trials. Better diagnostic tools allowing the identification of infants who might benefit from ductal closure, supplemented by data from clinical trials confirming realization of that potential, are urgently needed.

Spectral Doppler waveforms in systemic arteries and physiological significance of a patent ductus arteriosus

Patent ductus arteriosus in extremely premature babies is associated with major neonatal morbidities, such as necrotizing enterocolitis and intraventricular hemorrhage. This may be attributable, at least in part, to systemic hypoperfusion secondary to ductal steal. A hemodynamically significant ductus arteriosus (HSDA) is known to be associated with altered systemic blood flow and end-organ hypoperfusion. Although descending aorta blood flow profiles may show abnormal diastolic retrograde flow, Doppler studies of blood flow in the systemic arteries may help improve our understanding of the relationship of a HSDA with these morbidities. In this article, we discuss aspects of diastolic blood flow reversal in the systemic arteries in premature infants with a hemodynamically significant duct. Whether these hemodynamic effects are significant enough to form the basis for initiating treatment is still unclear; these should form the basis for prospective studies.

Patterns of gene expression in the ductus arteriosus are related to environmental and genetic risk factors for persistent ductus patency

Three independent risk factors (immature gestation, absence of antenatal glucocorticoid exposure, and presence of the rs2817399(A) allele of the gene TFAP2B) are associated with patent ductus arteriosus (PDAs) that fail to close during prostaglandin inhibition. We hypothesized that these three factors may affect a common set of genes that increase the risk of persistent PDA after birth. We studied baboon ductus from term, preterm, and glucocorticoid-treated preterm fetuses and found that both immature gestation and absence of antenatal glucocorticoid exposure decreased RNA expression of calcium- and potassium-channel genes involved in oxygen-induced constriction, and phosphodiesterase genes (that modulate cAMP/cGMP signaling). Ductus obtained from second trimester human pregnancies were genotyped for TFAP2B polymorphisms. When present, the rs2817399(A) allele also was associated with decreased expression of calcium- and potassium-channel genes. In contrast, alleles of two other TFAP2B polymorphisms, rs2817419(G) and rs2635727(T), which are not related to the incidence of PDA after birth, had no effect on RNA expression. In conclusion, three calcium- and potassium-channel genes (CACNA1G/ alpha1G, CACNB 2/CaL-beta2, and KCNA2/ Kv1.2) were similarly affected by each of the PDA risk factors. We speculate that these channels may play a significant role in closing the preterm ductus during prostaglandin inhibition and may be potential targets for future pharmacologic manipulations.

Patent ductus arteriosus in the preterm infant: to treat or not to treat?

Pharmacological and/or surgical closure of a hemodynamically significant patent ductus arteriosus (PDA) in the very preterm infant has been the standard of care over the past few decades. However, the rationale for closure of PDA has recently been challenged. In this article, the factors that have fueled the controversy of the approach to the management of PDA and the gap in our knowledge are reviewed in detail. In addition, the pros and cons of the different treatment strategies applied in clinical care are evaluated with a focus on discussing the available evidence in the literature.

Noninvasive evaluation of splanchnic tissue oxygenation using near-infrared spectroscopy in preterm neonates

BACKGROUND

Diagnosis of necrotizing enterocolitis (NEC) in preterm neonates is challenging. We hypothesized that regional splanchnic oxygen saturation (rsSO₂) measured by near-infrared spectroscopy (NIRS) is a biomarker for mesenteric perfusion.

OBJECTIVE

To evaluate feasibility and safety of continuous rsSO₂ monitoring in preterm infants in the first 14 days of life.

METHODS

Preterm neonates ≤30 weeks' gestation had a NIRS sensor placed in the left paraumbilical region within 48 h of birth. rsSO₂ was recorded every 30 s. Clinical data including pulse oximetry (SaO₂) were recorded. Fractional tissue oxygen extraction (FTOE) was computed as follows: (SaO₂ - rsSO₂) × 100/SaO₂.

RESULTS

Of 21 infants enrolled, 2 were excluded because of skin breakdown and missing data. Daily mean rsSO₂ values decreased over the first 9 days (p < 0.0001) followed by an increase from day 10 (D10) to D14 (p = 0.0061). rsSO(2) was lower and FTOE was higher in infants with feeding intolerance compared to those without feeding intolerance (p = 0.0043). rsSO₂ accounted for ≥99.5% of the variance in FTOE. Two neonates with NEC had persistently low rsSO₂ with loss of variability preceded or followed by very high rsSO₂.

CONCLUSIONS

We have reported feasibility, safety and ranges for rsSO₂ for a small number of preterm infants in the first 2 weeks of life.

Early surgical ligation versus a conservative approach for management of patent ductus arteriosus that fails to close after indomethacin treatment

OBJECTIVE

To examine whether a more conservative approach to treating patent ductus arteriosus (PDA) is associated with an increase or decrease in morbidity compared with an approach involving early PDA ligation.

STUDY DESIGN

In January 2005, we changed our approach to infants born at age

RESULTS

The 2 periods had similar rates of perinatal/neonatal risk factors and indomethacin failure (24%), as well as ventilator management and feeding advance protocols. The conservative approach (period 2) was associated with decreased rates of duct ligation (72% vs 100%; P<.05). Even though infants subjected to this approach were exposed to larger PDA shunts for longer durations, the rates of bronchopulmonary dysplasia, sepsis, retinopathy of prematurity, neurologic injury, and death were similar to those in period 1. The overall rate of necrotizing enterocolitis was significantly lower in period 2 compared with period 1.

CONCLUSIONS

These findings support the need for new controlled, randomized trials to reexamine the benefits and risks of different approaches to PDA treatment.

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Key Words

• surgery
• ductus ligation
• indomethacin
• patent ductus arteriosus

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MESH Headings

• Ductus Arteriosus, Patent/drug therapy
• Ductus Arteriosus, Patent/surgery
• Female
• Humans
• Indomethacin/therapeutic use
• Infant, Newborn
• Ligation
• Male
• Prospective Studies
• Time Factors
• Treatment Failure

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Grants

• R01 HL046691 NHLBI NIH HHS
• R01 HL046691-16 NHLBI NIH HHS
• UL1 RR024131 NCRR NIH HHS
• HL46691 NHLBI NIH HHS

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Affiliation(s)

Nami Jhaveri Department of Pediatrics, University of California, San Francisco, CA 94143-0544, USA
Anita Moon-Grady
Ronald I Clyman

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Analysis of pulmonary inflammation and function in the mouse and baboon after exposure to Mycoplasma pneumoniae CARDS toxin

Mycoplasma pneumoniae produces an ADP-ribosylating and vacuolating toxin known as the CARDS (Community Acquired Respiratory Distress Syndrome) toxin that has been shown to be cytotoxic to mammalian cells in tissue and organ culture. In this study we tested the ability of recombinant CARDS (rCARDS) toxin to elicit changes within the pulmonary compartment in both mice and baboons. Animals responded to a respiratory exposure to rCARDS toxin in a dose and activity-dependent manner by increasing the expression of the pro-inflammatory cytokines IL-1α, 1β, 6, 12, 17, TNF-α and IFN-γ. There was also a dose-dependent increase in several growth factors and chemokines following toxin exposure including KC, IL-8, RANTES, and G-CSF. Increased expression of IFN-γ was observed only in the baboon; otherwise, mice and baboons responded to CARDS toxin in a very similar manner. Introduction of rCARDS toxin to the airways of mice or baboons resulted in a cellular inflammatory response characterized by a dose-dependent early vacuolization and cytotoxicity of the bronchiolar epithelium followed by a robust peribronchial and perivascular lymphocytic infiltration. In mice, rCARDS toxin caused airway hyper-reactivity two days after toxin exposure as well as prolonged airway obstruction. The changes in airway function, cytokine expression, and cellular inflammation correlate temporally and are consistent with what has been reported for M. pneumoniae infection. Altogether, these data suggest that the CARDS toxin interacts extensively with the pulmonary compartment and that the CARDS toxin is sufficient to cause prolonged inflammatory responses and airway dysfunction.