Treatment of persistent patent ductus arteriosus in preterm infants: time to accept the null hypothesis?

Percutaneous closure of patent ductus arteriosus in small infants with significant lung disease may offer faster recovery of respiratory function when compared to surgical ligation

OBJECTIVES

To describe our experience with percutaneous closure of patent ductus arteriosus (PDA) in small infants and compare outcomes to matched surgical patients.

BACKGROUND

Ligation via thoracotomy has been used to close PDAs in small infants, but has been associated with respiratory and hemodynamic compromise. We hypothesized that percutaneous closure would offer faster recovery of respiratory function.

METHODS

Patients <4 kg requiring positive pressure ventilation who underwent percutaneous PDA closure between January 2000 and April 2012 were reviewed and matched to contemporary surgical patients on gestational age (GA), birth weight (BW), procedure weight (WT), and ventilation mode. Patients returned to baseline respiratory status when the product of mean airway pressure and FiO2 returned to pre-procedural levels.

RESULTS

Eight matched pairs were included. Median BW, GA, and WT were 1.43 kg (0.52-2.97), 29.8 weeks (24-39), and 2.8 kg (2.2-3.9) for catheter patients and 1.55 kg (0.48-3.04), 29 weeks (23-37), and 2.75 kg (2.3-4.2) for surgical patients. Complete PDA closure occurred in all. The median time to return to baseline respiratory status was significantly shorter in the percutaneous group (17 hr (range 0-113) vs. 53 hr (range 13-219), P < 0.05). In the percutaneous group, two patients developed mild aortic coarctation, one mild left pulmonary artery stenosis, and four femoral vascular thromboses which all resolved with medical therapy. Surgical complications included significant respiratory and cardiac compromise, rib fractures and urinary retention.

CONCLUSIONS

Percutaneous closure of PDA in small infants on respiratory support is equivalent in safety and efficacy and may offer shorter recovery time than surgical ligation.

Therapeutic strategies, including a high surgical ligation rate, for patent ductus arteriosus closure in extremely premature infants in a North American centre

OBJECTIVE

To document the rate of surgical ligation of a patent ductus arteriosus (PDA) in extremely premature infants who had received more than one course of indomethacin. Outcomes were compared among three subgroups (ligation, further indomethacin and no further treatment) of infants who received at least one course of indomethacin, and between two subgroups (one course of indomethacin and more than one course) among infants who underwent ligation.

STUDY DESIGN

A retrospective chart review of all 23 weeks+0 days to 26 weeks+6 days' gestational age infants with a PDA born between 1994 and 2005 was performed. Secondary outcomes were compared among the subgroups.

RESULTS

The final study population consisted of 196 extremely premature infants with a PDA. The rate of surgical ligation in the 88 infants who received more than one course of indomethacin was 64%. The ligation subgroup, in comparison with the no further treatment subgroup, spent a greater median time on mechanical ventilation (39 versus 29 days, P<0.001) and in hospital (115 versus 92 days P=0.002), while trending toward lower mortality (18% versus 40%, P=0.07). The PDA closed following the first course of indomethacin in only 20% of infants.

CONCLUSIONS

A majority of extremely premature infants receiving more than one course of indomethacin underwent surgical ligation. Repeated indomethacin courses were generally well tolerated, but were mostly unsuccessful. Ligation appears to have potential risks and benefits. A randomized trial should be performed after studies define a hemodynamically significant PDA that will result in morbidity and/or mortality unless treated.

Functional echocardiography in staging for ductal disease severity : role in predicting outcomes

Equipoise persists as to the issue of assigning haemodynamic and clinical significance to a patent ductus arteriosus (PDA). The objective was to ascertain whether echocardiographic scoring of a PDA correlates with outcomes. Unit electronic data base was accessed to identify infants less than 32 weeks' gestation who received ibuprofen for medical closure of the PDA during the period June 2010-June 2012. Echocardiographic score was assigned on the day of therapy and the infants were prospectively followed up to ascertain the occurrence of chronic lung disease (CLD). Logistic regression analysis was used to estimate the association between composite score and occurrence of CLD. Fifty-two infants were identified out of which 27 (52 %) subsequently developed CLD. Echocardiographic parameters were of a significantly higher magnitude in infants who later developed CLD. The median composite score (inter-quartile range) was also significantly higher in this group 26 (24-26) vs. 19 (17-20), p < 0.001). Higher composite scores were associated with increased risk of developing CLD; for every one point increase in composite score, the odds of CLD increased by 78 % (odds ratio (95 % CI): 1.78 (1.35-2.34); p < 0.001).

CONCLUSIONS

Infants with a high composite score, assigned according to the staging criteria at the time of treatment, were noted to have a higher incidence of subsequent CLD. Whether disease stratification can be the basis of further RCT's needs prospective evaluation.

Early echocardiographic prediction of ductal closure in neonates ≤ 30 weeks gestation

OBJECTIVE

To determine the accuracy of the patent ductus arteriosus:left pulmonary artery ratio (PDA:LPA) on echocardiogram (ECHO) at 3-day postnatal in predicting spontaneous PDA closure in neonates ≤ 30 weeks gestational age (GA).

STUDY DESIGN

ECHOs were performed at 72 h to characterize PDA size as closed-to-small (PDA:LPA <0.5) or moderate-to-large (PDA:LPA ≥ 0.5) and at 10 days to determine spontaneous closure (defined as closed-to-small in the absence of medical and/or surgical treatment). Caretakers were blinded to results; treatment was based on standard care. Neonates were prospectively enrolled and stratified: <27 weeks (n=31) and 27 to 30 weeks (n=65).

RESULT

Neonates <27 weeks with closed-to-small PDAs had 60% spontaneous closure vs 9% when moderate-to-large (positive predictive value (PPV) 60%, negative predictive value (NPV) 91%). Neonates 27 to 30 weeks had 95% spontaneous closure vs 27%, respectively (PPV 95%, NPV 73%). Inter-observer variability for the initial ECHO was 0.84.

CONCLUSION

PDA size defined by PDA:LPA at 3 days postnatal in combination with GA predicts spontaneous PDA closure.

Neurodevelopmental outcomes following two different treatment approaches (early ligation and selective ligation) for patent ductus arteriosus

OBJECTIVE

To examine whether a change in the approach to managing persistent patent ductus arteriosus (PDA) from early ligation to selective ligation is associated with an increased risk of abnormal neurodevelopmental outcomes.

STUDY DESIGN

In 2005, we changed our PDA treatment protocol for infants born at ≤27 6/7 weeks' gestation from an early ligation approach, with prompt PDA ligation if the ductus failed to close after indomethacin therapy (period 1: January 1999 to December 2004), to a selective ligation approach, with PDA ligation performed only if specific criteria were met (period 2: January 2005 to May 2009). All infants in both periods received prophylactic indomethacin. Multivariate analysis was used to compare the odds of a composite abnormal neurodevelopmental outcome (Bayley Mental Developmental Index or Cognitive Score <70, cerebral palsy, blindness, and/or deafness) associated with each treatment approach at age 18-36 months (n = 224).

RESULTS

During period 1, 23% of the infants in follow-up failed indomethacin treatment, and all underwent surgical ligation. During period 2, 30% of infants failed indomethacin, and 66% underwent ligation after meeting prespecified criteria. Infants treated with the selective ligation strategy demonstrated fewer abnormal outcomes than those treated with the early ligation approach (OR, 0.07; P = .046). Infants who underwent ligation before 10 days of age had an increased incidence of abnormal neurodevelopmental outcome. The significant difference in outcomes between the 2 PDA treatment strategies could be accounted for in part by the earlier age of ligation during period 1.

CONCLUSION

A selective ligation approach for PDAs that fail to close with indomethacin therapy is not associated with worse neurodevelopmental outcomes at age 18-36 months.

Prolonged persistent patent ductus arteriosus: potential perdurable anomalies in premature infants

OBJECTIVE

Patent ductus arteriosus (PDA) is a common condition among preterm infants. Controversy exists regarding the risk-benefit ratio of early closure of PDAs by either medical or surgical treatments. On the other hand, potential morbidities associated with no or delayed closure has not been well studied. The objective of the study was to determine if there is an association of prolonged persistent PDA (PP-PDA) with various morbidities in infants ≤28 weeks or 1250 g.

STUDY DESIGN

This matched case-control analysis includes preterm infants with a diagnosis of PDA over a period of 28 months in a single level III center in the USA. The predictive variable was the presence of a PP-PDA (PDA>3 weeks). Cases were infants with PP-PDA and controls were those with PDA but not PP-PDA (two controls for each case). Outcome variables included days on mechanical ventilation and with oxygen treatment, length of hospital stay, bronchopulmonary dysplasia (BPD), retinopathy of prematurity stage III-V (ROP) necrotizing enterocolitis grade II or more (NEC), delayed growth, direct hyperbilirubinemia >4 mg dl(-1) and osteopenia of prematurity. Data was obtained from database collected prospectively and from the review of clinical records when necessary. Statistics included ANOVA, Kaplan-Meier curves and χ (2). Significance was set at P<0.05.

RESULT

PP-PDA was associated with a significant increase in the number of days of mechanical ventilation, oxygen treatment and length of hospital stay, and in the rates of BPD (60% vs 4.5%), NEC (29% vs 5%), ROP (43% vs 5%), direct hyperbilirubinemia (41% vs 3%), osteopenia (44% vs 6%), parenteral nutrition for >40 days (70% vs 21%), tracheostomy during the hospitalization (15% vs 0%) and delayed growth (70% vs 21%), were also significantly higher in babies with PP-PDA.

CONCLUSION

A prolonged exposure to PDA does not seem to be inconsequential for some infants and is associated with an increase prevalence of severe morbidities with potential long lasting effects.

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.

Predictors of bronchopulmonary dysplasia

Although significant advances in respiratory care have been made in neonatal medicine, bronchopulmonary dysplasia (BPD) remains the most common serious pulmonary morbidity in premature infants. The development of BPD is the result of the complex interactions between multiple perinatal and postnatal factors. Early identification of infants at the most risk of developing BPD through the use of estimators and models may allow a targeted approach at reducing BPD in the future.

Preterm patent ductus arteriosus: should we treat it?

Debate about the importance of the preterm patent ductus arteriosus (PDA) remains unresolved. Ultrasound studies of PDA have suggested that the haemodynamic impact may be much earlier after birth than previously thought, but we still do not know when to treat a PDA. Studies that have tested symptomatic or pre-symptomatic treatment are mainly historical and have not tested the effect of no treatment. Prophylactic treatment is the best studied regimen, but improvements in some short-term outcomes do not translate to any difference in longer term outcomes. Neonatologists have been reluctant to engage in trials that test treatment against not treating at all or very rarely. Targeting treatment on the basis of the early post-natal constrictive response of the duct is currently being tested as a possible strategy.

Patent ductus arteriosus in premature neonates

Persistent patency of the ductus arteriosus is a major cause of morbidity and mortality in premature infants. In infants born prior to 28 weeks of gestation, a haemodynamically significant patent ductus arteriosus (PDA) can cause cardiovascular instability, exacerbate respiratory distress syndrome, prolong the need for assisted ventilation and increase the risk of bronchopulmonary dysplasia, intraventricular haemorrhage, renal dysfunction, cerebral palsy and mortality. We review the pathophysiology, clinical features and assessment of haemodynamic significance, and provide a rigorous appraisal of the quality of evidence to support current medical and surgical management of PDA of prematurity. Cyclo-oxygenase inhibitors such as indomethacin and ibuprofen remain the mainstay of medical therapy for PDA, and can be used both for prophylaxis as well as for rescue therapy to achieve PDA closure. Surgical ligation is also effective and is used in infants who do not respond to medical management. Although both medical and surgical treatment have proven efficacy in closing the ductus, both modalities are associated with significant adverse effects. Because the ductus does undergo spontaneous closure in some premature infants, improved and early identification of infants most likely to develop a symptomatic PDA could help in directing treatment to the at-risk infants and allow others to receive expectant management.

Cerebral autoregulation in neonates with a hemodynamically significant patent ductus arteriosus

OBJECTIVE

Very low birth weight (VLBW) preterm infants are at risk for impaired cerebral autoregulation with pressure passive blood flow. Fluctuations in cerebral perfusion may occur in infants with a hemodynamically significant patent ductus arteriosus (hsPDA), especially during ductal closure. Our goal was to compare cerebral autoregulation using near-infrared spectroscopy in VLBW infants treated for an hsPDA.

STUDY DESIGN

This prospective observational study enrolled 28 VLBW infants with an hsPDA diagnosed by echocardiography and 12 control VLBW infants without an hsPDA. Near-infrared spectroscopy cerebral monitoring was applied during conservative treatment, indomethacin treatment, or surgical ligation. A cerebral pressure passivity index (PPI) was calculated, and PPI differences were compared using a mixed-effects regression model. Cranial ultrasound and magnetic resonance imaging data were also assessed.

RESULTS

Infants with surgically ligated hsPDAs were more likely to have had a greater PPI within 2 hours following ligation than were those treated with conservative management (P=.04) or indomethacin (P=.0007). These differences resolved by 6 hours after treatment.

CONCLUSIONS

Cerebral autoregulation was better preserved after indomethacin treatment of an hsPDA compared with surgical ligation. Infants requiring surgical hsPDA ligation may be at increased risk for cerebral pressure passivity in the 6 hours following surgery.

Timing of patent ductus arteriosus treatment and respiratory outcome in premature infants: a double-blind randomized controlled trial

OBJECTIVE

To determine whether "early" ibuprofen treatment, at the onset of subtle patent ductus arteriosus (PDA) symptoms, would improve respiratory outcome in premature infants compared with "expectant" management, with ibuprofen treatment only when the PDA becomes hemodynamically significant (HS).

STUDY DESIGN

We conducted a randomized double-blind controlled trial of infants with gestational ages 23 to 32 weeks and birth weights 500 to 1250 g who had echocardiography for subtle PDA symptoms (metabolic acidosis, murmur, bounding pulses). Infants were then randomized to "early" treatment (blinded ibuprofen; n = 54) or "expectant management" (blinded placebo, n = 51). If the PDA became HS (pulmonary hemorrhage, hypotension, respiratory deterioration), infants received open label ibuprofen. Infants with HS PDA at enrollment were excluded from the study. Respiratory outcomes and mortality and major morbidities were determined.

RESULTS

"Early" treatment infants received ibuprofen at median age of 3 days; infants in the "expectant group" in whom HS symptoms developed (20%) received ibuprofen at median of 11 days. A total of 49% of "expectant" infants never required ibuprofen or ligation. No significant differences were found in the primary outcome (days on oxygen [O(2)] during the first 28 days), death, O(2) at 36 weeks, death or O(2) at 36 weeks, intestinal perforation, surgical necrotizing enterocolitis, grades III and IV intracranial hemorrhage, periventricular leukomalacia, sepsis or retinopathy of prematurity.

CONCLUSION

Infants with mild signs of PDA do not benefit from early PDA treatment compared with delayed treatment.

What happens when the patent ductus arteriosus is treated less aggressively in very low birth weight infants?

OBJECTIVE

It remains unclear whether indomethacin (INDO) and/or surgical ligation (LIGATE) are necessary to improve outcomes in premature infants with a patent ductus arteriosus (PDA). We have adopted a conservative approach to PDA management that emphasizes waiting for spontaneous closure unless certain cardiorespiratory distress criteria are met.

STUDY DESIGN

This was a before-after observational study in infants born 501 to 1,500 g in two distinct epochs. Era 1 (January 2005 to December 2007) featured traditional management with INDO and LIGATE used early to close all moderate and large PDAs in infants receiving any respiratory support. Era 2 (January 2008 to June 2009) emphasized modest fluid restriction, watchful waiting and limited INDO and LIGATE to only those infants with large PDAs who met certain cardiorespiratory distress criteria.

RESULT

Era 1 included 139 infants with a PDA, mean (s.d.) gestational age 27.5 (2) weeks; Era 2 72 infants, mean (s.d.) gestational age 27.5 (2) weeks. In Era 2, INDO use significantly decreased (79% of infants to 26%, P<0.001), and 28 day total fluids decreased (140 vs. 130  ml kg(-1) day(-1), P<0.001). LIGATE rate was 45% in Era 1, 33% in Era 2 (P=0.11). There were no significant differences in supplemental oxygen, nasal continuous positive airway pressure, or mechanical ventilation days. There were no significant differences in mortality or individual morbidities. The combined outcome of chronic lung disease (CLD) or mortality after Day 7 significantly increased (Era 1, 40%, Era 2, 54%, P=0.04). More infants were discharged home with a PDA in Era 2, but most resolved spontaneously and the need for closure therapy after discharge from the neonatal intensive care unit (NICU) did not increase. Multiple regression analysis demonstrated Era 2 management did not predict an increased risk of one or more interlinked morbidities.

CONCLUSION

Tolerance of the PDA with watchful waiting for spontaneous closure, modest fluid reduction, and less INDO use is a reasonable treatment strategy that is not associated with significant changes in NICU mortality or individual morbidities. We did note an increase in the combined outcome of CLD or mortality after Day 7, thus our investigation supports the urgency of a randomized controlled trial comparing traditional PDA management with a true control group similar to our Era 2 management to answer important questions of short and long-term outcomes.

Pros and cons of patent ductus arteriosus ligation: hemodynamic changes and other morbidities after patent ductus arteriosus ligation

Although surgical ligation of a persistent patent ductus arteriosus resolves the adverse hemodynamic consequences of the systemic-to-pulmonary shunt and may confer some long-term benefits, it is also associated with both immediate and long-term negative effects. The population that benefits from or is harmed by the procedure is not clearly defined. Although indiscriminate ligation of the patent ductus arteriosus in all patients is not supported by the available information, the recent suggestion declaring the ductus harmless is not supported either. As we await the results of appropriately designed randomized control studies to define the indications for ligation, we must use clinical and echocardiographic indicators of a hemodynamically significant ductus arteriosus and thoughtful assessment of each individual patient to help guide us in addressing this complex problem.

Patent ductus arteriosus: are current neonatal treatment options better or worse than no treatment at all?

Although a moderate-sized patent ductus arteriosus (PDA) needs to be closed by the time a child is 1-2 years old, there is great uncertainty about whether it needs to be closed during the neonatal period. Although 95% of neonatologists believe that a moderate-sized PDA should be closed if it persists in infants (born before 28 weeks) who still require mechanical ventilation, the number of neonatologists who treat a PDA when it occurs in infants who do not require mechanical ventilation varies widely. Both the high likelihood of spontaneous ductus closure and the absence of randomized controlled trials, specifically addressing the risks and benefits of neonatal ductus closure, add to the current uncertainty. New information suggests that early pharmacologic treatment has several important short-term benefits for the preterm newborn. By contrast, ductus ligation, while eliminating the detrimental effects of a PDA on lung development, may create its own set of morbidities that counteract many of the benefits derived from ductus closure.

Diagnosis of the preterm patent ductus arteriosus: clinical signs, biomarkers, or ultrasound?

The current uncertainty in relation to treatment of the preterm patent ductus arteriosus reflects limitations to our understanding of the pathophysiology of ductal shunting, most particularly which ducts matter to which babies and when they matter. Doppler ultrasound offers a pragmatic tool with which to assess ductal patency and shunt significance and to allow prediction of spontaneous and therapeutic closure. Biomarkers, such as B-type natriuretic peptide, and clinical signs may have a diagnostic role where ultrasound is not available and also possibly as an adjunct to echocardiography in determining the pathophysiological impact of a ductal shunt in an individual baby.

The ductus arteriosus: a refined approach!

Although ongoing patency of the ductus arteriosus is common in small extremely preterm infants, consensus is lacking regarding its clinical significance and treatment strategies. Literature regarding likelihood of spontaneous closure, impact on neonatal morbidity and long-term outcomes, and adverse effects of intervention has led to uncertainty as to the best course of action. Enhancing the determination of hemodynamic significance and refining patient selection for therapeutic intervention will streamline the decision-making process. Targeted neonatal echocardiography performed by the clinician has gained popularity worldwide, and preliminary data show that it has the potential to optimize patient outcomes. We review the arguments for and against medical and surgical therapy, explore how targeted neonatal echocardiography used in conjunction with biomarkers may refine the treatment approach, and consider future directions in the field.

The definition of a haemodynamic significant duct in randomized controlled trials: a systematic literature review

AIM

A patent ductus arteriosus (PDA) is associated with morbidity in preterm infants. Treatment is prescribed for a haemodynamically significant duct (HSDA), but its definition varies. We systematically reviewed the clinical and ultrasound criteria used for the definition of an HSDA.

METHODS

PubMed and the Cochrane library were searched for randomized trials evaluating ductal treatment. The included studies were explored, and we categorized clinical and ultrasound criteria used to define an HSDA.

RESULTS

Sixty-seven trials were included in our review. Forty-two were placebo-controlled trials, and 25 were comparative trials. The diagnosis of the PDA was made by clinical examination, followed by ultrasound in most trials. Most trials used clinical and ultrasound criteria to define an HSDA, but there was a wide variety in criteria and cut-offs used. Of the clinical criteria, a murmur or hyperdynamic circulation was most used, and of the ultrasound criteria, the left-atrium-to-aorta ratio (LA/Ao ratio) was most used.

CONCLUSION

We found a wide variety in the definition of an HSDA. This finding implies that comparison of studies is difficult. International consensus should be reached on the definition of an HSDA, which will make future studies more comparable.

Evidence-based use of indomethacin and ibuprofen in the neonatal intensive care unit

Indomethacin and ibuprofen are potent inhibitors of prostaglandin synthesis. Neonates have been exposed to these compounds for more than 3 decades. Indomethacin is commonly used to prevent intraventricular hemorrhage (IVH), and both drugs are prescribed for the treatment or prevention of patent ductus arteriosus (PDA). This review examines the basis for indomethacin and ibuprofen use in the neonatal intensive care population. Despite the call for restrained use of each drug, the most immature infants are likely to need pharmacologic approaches to reduce high-grade IVH, avoid the need for PDA ligation, and preserve the opportunity for an optimal outcome.

Plasma C-terminal pro-endothelin-1 and the natriuretic pro-peptides NT-proBNP and MR-proANP in very preterm infants with patent ductus arteriosus

BACKGROUND

In very preterm infants, clinical decision-making, such as closing a patent ductus arteriosus (PDA), may be aided by measuring circulating natriuretic and endothelial pro-peptides.

OBJECTIVES

To investigate the association between perinatal characteristics, PDA echocardiography and plasma concentrations of stable pro-peptides of B-type natriuretic peptide (NT-proBNP), atrial natriuretic peptide (MR-proANP) and endothelin-1 (CT-proET-1).

METHODS

A prospective, cross-sectional, single-center study was performed in 66 infants who were less than 32 weeks of gestational age. Pro-peptide concentrations were determined at birth and at day 2-3 of life.

RESULTS

Plasma concentrations of all 3 pro-peptides increased on average 2- to 5-fold from birth to day 2-3 of life. NT-proBNP and MR-proANP were closely related at birth and at day 2-3 (Rs 0.902 and 0.897, respectively, p < 0.001), whereas CT-proET-1 was related to NT-proBNP and MR-proANP at birth (Rs 0.478 and 0.460, respectively, p < 0.001) but not at day 2-3. Birth weight was negatively related to all 3 pro-peptides at birth (p < 0.01); however, preeclampsia and compromised placental perfusion were associated with elevated NT-proBNP and MR-proANP concentrations at birth. At day 2-3, MR-proANP and NT-proBNP correlated significantly with the ductal diameter (Rs 0.416 and 0.415, respectively, both p = 0.011), whereas CT-proET-1 correlated with the left atrium/aorta ratio (Rs 0.506, p = 0.027). CT-proET-1 was elevated in infants with treated compared to untreated PDA [median (5-95% range) 388 (272-723) vs. 303 (152-422) pmol/l, p = 0.011], but not NT-proBNP or MR-proANP.

CONCLUSION

CT-proET-1 is a promising predictor in determining the need for PDA intervention.

Current Perspectives on Pathobiology of the Ductus Arteriosus

The ductus arteriosus (DA) shunts blood away from the lungs during fetal life, but at birth this shunt is no longer needed and the vessel rapidly constricts. Postnatal persistence of the DA, patent ductus arteriosus (PDA), is predominantly a detrimental condition for preterm infants but is simultaneously a condition required to maintain systemic blood flow for infants born with certain severe congenital heart defects. Although PDA in preterm infants is associated with significant morbidities, there is controversy regarding whether PDA is truly causative. Despite advances in our understanding of the pathobiology of PDA, the optimal treatment strategy for PDA in preterm infants is unclear. Here we review recent studies that have continued to elucidate the fundamental mechanisms of DA development and pathogenesis.

Neonatal drug development

Drug development is crucial to improving the care given to neonates through new and existing medicines. Pressure from regulatory agencies has improved the way in which pharmaceutical companies work with neonates. This provides new opportunities for the neonatal community. This paper describes the issues that arise during the development of new drugs and considers how the contemporary approach to new drugs can inform research on existing drugs.

Early NT-proBNP is able to predict spontaneous closure of patent ductus arteriosus in preterm neonates, but not the need of its treatment

The objective of this study was to establish the potential utility of N-terminal pro-brain natriuretic peptide (NT-proBNP) in the management of patent ductus arteriosus (PDA). This was a monocentric prospective blind study that was conducted in a referral neonatal intensive care unit. The patients were very low-birth-weight/gestational-age neonates. Babies with cardiac congenital anomaly other than PDA, life-threatening congenital malformation, severe asphyxia at birth, persistent pulmonary hypertension, and death within the first week of life were excluded. Plasma NT-proBNP concentrations were determined on days 2, 4, and 7 of life. Echocardiography was performed on days 4 and 7. Results were blinded to clinicians. Only echographic results were available upon request. Thirty-one infants were included. NT-proBNP levels were significantly correlated to ductal size and to left atrial-to-aortic diameter ratio. The median NT-proBNP on both days 2 and 4 was significantly higher in neonates with later treated or persistent PDA. A level above 10.000 pg/mL at 48 h of age yielded a 100% positive and a 87% negative predictive value to exclude spontaneous ductal closure. However, no NT-proBNP threshold could predict which PDA would be judged necessary to treat. It was concluded that early low NT-proBNP values can be used as a reliable independent marker to predict spontaneous ductal closure in preterm neonates. Yet, high NT-proBNP levels should not be used to guide the decision to treat PDA, the risk being of treating many bystanding PDAs.

Effects of prophylactic indomethacin in extremely low-birth-weight infants with and without adequate exposure to antenatal corticosteroids

OBJECTIVE

To examine whether treatment with antenatal corticosteroids modifies the immediate and long-term effects of prophylactic indomethacin sodium trihydrate in extremely low-birth-weight infants.

DESIGN

Post hoc subgroup analysis of data from the Trial of Indomethacin Prophylaxis in Preterms.

SETTING

Thirty-two neonatal intensive care units in Canada, the United States, Australia, New Zealand, and Hong Kong.

PARTICIPANTS

A total of 1195 infants with birth weights of 500 to 999 g and known exposure to antenatal corticosteroids. We defined as adequate any exposure to antenatal corticosteroids that occurred at least 24 hours before delivery.

INTERVENTION

Indomethacin or placebo intravenously once daily for the first 3 days.

OUTCOME MEASURES

Death or survival to 18 months with cerebral palsy, cognitive delay, severe hearing loss, or bilateral blindness; severe periventricular and intraventricular hemorrhage; patent ductus arteriosus; and surgical closure of a patent ductus arteriosus.

RESULTS

Of the 1195 infants in this analysis cohort, 670 had adequate and 525 had inadequate exposure to antenatal corticosteroids. There was little statistical evidence of heterogeneity in the effects of prophylactic indomethacin between the subgroups for any of the outcomes. The adjusted P values for interaction were as low as .15 for the outcome of death or impairment at 18 months and as high as .80 for the outcome of surgical duct closure.

CONCLUSION

We find little evidence that the effects of prophylactic indomethacin vary in extremely low-birth-weight infants with and without adequate exposure to antenatal corticosteroids. Trial Registration clinicaltrials.gov Identifier: NCT00009646.

Patent ductus arteriosus in preterm infants

Patent ductus arteriosus (PDA) is a major morbidity in preterm infants, especially in extremely premature infants less than 28 weeks. The clinical signs and symptoms of PDA in preterm infants are non specific and insensitive for making an early diagnosis of significant ductal shunting. Functional echocardiography is emerging as a new valuable bedside tool for early diagnosis of hemodynamically significant ductus, even though there are no universally accepted criteria for grading the hemodynamic significance. Echocardiography has also been used for early targeted treatment of ductus arteriosus, though the long term benefits of such strategy are debatable. The biomarkers like BNP and N terminal pro BNP are currently under research as diagnostic marker of PDA. The primary mode of treatment for PDA is pharmacological closure using cyclo-oxygenase inhibitors with closure rate of 70-80%. Oral ibuprofen is emerging as a better alternative especially in Indian scenario where parenteral preparations of indomethacin are unavailable and side effects are comparatively lesser. Though pharmacological closure of PDA is an established treatment modality, there is still lack of evidence for long term benefits of such therapy as well as there is some evidence for the possible adverse effects like increased ROP and BPD rates, especially if treated prophylactically. Hence, it is prudent to reserve treatment of PDA to infants with clinically significant ductus on the basis of gestation, birth weight, serial echocardiography and clinical status to individualize the decision to treat.

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 new bronchopulmonary dysplasia

PURPOSE OF REVIEW

Bronchopulmonary dysplasia (BPD) remains the most common severe complication of preterm birth. A number of recent animal models and clinical studies provide new information about pathophysiology and treatment.

RECENT FINDINGS

The epidemiology of BPD continues to demonstrate that birth weight and gestational age are most predictive of BPD. Correlations of BPD with chorioamnionitis are clouded by the complexity of the fetal exposures to inflammation. Excessive oxygen use in preterm infants can increase the risk of BPD but low saturation targets may increase death. Numerous recent trials demonstrate that many preterm infants can be initially stabilized after delivery with continuous positive airway response (CPAP) and then be selectively treated with surfactant for respiratory distress syndrome. The growth of the lungs of the infant with BPD through childhood remains poorly characterized.

SUMMARY

Recent experiences in neonatology suggest that combining less invasive care strategies that avoid excessive oxygen and ventilation, decrease postnatal infections, and optimize nutrition may decrease the incidence and severity of BPD.

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.

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.