Natural evolution of ductus arteriosus with noninterventional conservative management in extremely preterm infants born at 23-28 weeks of gestation

Device Closure of Hemodynamically Significant Patent Ductus Arteriosus in Premature Infants

The patent ductus arteriosus is a very common condition in preterm infants, and a hemodynamically significant patent ductus arteriosus increases morbidity and mortality in these vulnerable patients. However, despite numerous randomized controlled trials, there is no consensus regarding management. Medical therapy is typically offered as first-line treatment, although it yields limited success and carries the potential for severe adverse events. In recent years, there has been rapid development in transcatheter patent ductus arteriosus closure primary with the use of the Amplatzer Piccolo Occluder, and this has gained widespread acceptance as a safe and effective alternative to surgical ligation in extremely low-birth-weight infants weighing over 700 g. This article aims to provide an appraisal of the patient selection process, a step-by-step procedural guide, and a comprehensive review of the outcomes associated with this approach.

Patent ductus arteriosus (also non-hemodynamically significant) correlates with poor outcomes in very low birth weight infants. A multicenter cohort study

OBJECTIVES

To standardize the diagnosis of patent ductus arteriosus (PDA) and report its association with adverse neonatal outcomes in very low birth weight infants (VLBW, birth weight < 1500 g).

STUDY DESIGN

A multicenter prospective observational study was conducted in Emilia Romagna from March 2018 to October 2019. The association between ultrasound grading of PDA and adverse neonatal outcomes was evaluated after correction for gestational age. A diagnosis of hemodynamically significant PDA (hsPDA) was established when the PDA diameter was ≥ 1.6 mm at the pulmonary end with growing or pulsatile flow pattern, and at least 2 of 3 indexes of pulmonary overcirculation and/or systemic hypoperfusion were present.

RESULTS

218 VLBW infants were included. Among infants treated for PDA closure in the first postnatal week, up to 40% did not have hsPDA on ultrasound, but experienced clinical worsening. The risk of death was 15 times higher among neonates with non-hemodynamically significant PDA (non-hsPDA) compared to neonates with no PDA. In contrast, the risk of death was similar between neonates with hsPDA and neonates with no PDA. The occurrence of BPD was 6-fold higher among neonates with hsPDA, with no apparent beneficial role of early treatment for PDA closure. The risk of IVH (grade ≥ 3) and ROP (grade ≥ 3) increased by 8.7-fold and 18-fold, respectively, when both systemic hypoperfusion and pulmonary overcirculation were present in hsPDA.

CONCLUSIONS

The increased risk of mortality in neonates with non-hsPDA underscores the potential inadequacy of criteria for defining hsPDA within the first 3 postnatal days (as they may be adversely affected by other clinically severe factors, i.e. persistent pulmonary hypertension and mechanical ventilation). Parameters such as length, diameter, and morphology may serve as more suitable ultrasound indicators during this period, to be combined with clinical data for individualized management. Additionally, BPD, IVH (grade ≥ 3) and ROP (grade ≥ 3) are associated with hsPDA. The existence of an optimal timeframe for closing PDA to minimize these adverse neonatal outcomes remains uncertain.

PDA management strategies and pulmonary hypertension in extreme preterm infants with bronchopulmonary dysplasia

BACKGROUND

Premature infants are at risk for developing pulmonary hypertension (PH) in the context of bronchopulmonary dysplasia (BPD). Studies suggest a potential link between prolonged patent ductus arteriosus (PDA) exposure and BPD-PH, though management strategies remain controversial.

METHODS

Retrospective echocardiographic evaluation of newborns <29 weeks gestational age with BPD at two distinct centers. Primary objective was to evaluate the relationship between center-specific PDA management strategies (interventional or conservative) and the prevalence of BPD-PH. BPD was defined as oxygen or respiratory support at 36 weeks post-menstrual age (PMA). The presence of PH was defined as either an estimated sPAP of ≥40 mmHg or sEI ≥1.3. Center A has a conservative PDA policy. Center B has a targeted interventional policy.

RESULTS

PH rates were similar between sites (21% vs 17%), while rates of PDA treatment was different (7% vs 81). Adjusted models did not demonstrate an association for center or PDA treatment exposure for PH and EI, although infants from Center A had echocardiography evidence of higher systolic eccentricity index (EI; 1.12 ± 0.19 vs 1.06 ± 0.15, p = 0.04). Markers of RV function (TAPSE and RV-FAC) were similar between groups.

CONCLUSION

In preterm infants <29 weeks with BPD, conservative PDA treatment policy was not associated with higher rate of pulmonary hypertension diagnosis.

IMPACT

The association between PDA-management approaches and the occurrence of BPD-associated pulmonary vascular disease in premature infants has sparsely been described. We found that a conservative policy, regarding the PDA, was not associated with an increase in pulmonary hypertension diagnosis. We identified that, in patients with BPD, echocardiographic metrics of LV performance were lower.

Impact of Early Surfactant Administration on Ductus Arteriosus Assessed at 24 h in Preterm Neonates Less than 32 Weeks of Gestational Age

BACKGROUND AND OBJECTIVES

The purpose of this study was to investigate whether early surfactant administration affects the status of ductus arteriosus (DA) in preterm infants ≤ 32 weeks of gestational age (GA) within 24 h of birth.

MATERIALS AND METHODS

It is a prospective study conducted from 1 March 2022 to 31 December 2023 in a tertiary academic center. In-born infants ≤ 32 weeks of gestation (n = 88) were enrolled. The study group was further divided into surfactant (n = 44) and non-surfactant (n = 44) subgroups.

RESULTS

A total of 76% of the preterm infants who received surfactant therapy (RRR = 0.839) recorded an increase in Kindler score at 24 h of life (1 - RR = 1 - 0.24 = 76%). Surfactant administration was significantly associated with decreased pre-ductal diastolic pressure (29.9 mmHg vs. 34.8 mmHg, p = 0.0231), post-ductal diastolic pressure (28.7 mmHg vs. 32.2 mmHg, p = 0.0178), pre-ductal MAP (41.6 mmHg vs. 46.5 mmHg, p = 0.0210), and post-ductal MAP (41.0 mmHg vs. 45.3 mmHg, p = 0.0336). There were no significant changes in ductus arteriosus parameters at 24 h of life.

CONCLUSIONS

Early surfactant administration does not affect the status of ductus arteriosus in preterm infants ≤ 32 weeks of gestational age at 24 h of life.

Lung ultrasound score in the decision of patent ductus arteriosus closure in neonates

PURPOSE

We aimed to investigate the role of lung ultrasound (LUS) score in the closure of hemodynamically insignificant patent ductus arteriosus (PDA) and the clinical findings of the patients before and after closure.

METHODS

The study groups (107 preterm neonates under 34 gestational weeks) were classified as hemodynamically significant PDA (group 1), hemodynamically insignificant PDA with closure therapy (group 2), hemodynamically insignificant PDA without closure therapy (group 3), and no PDA group (group 4) based on the echocardiography. 6- and 10-region LUS scores were compared for each group.

RESULTS

There was a significant difference between groups 1 and 3 on first, third, and seventh days. In contrast, groups 1 and 2 had similar LUS scores on the first, third, and seventh days. There was a negative correlation between LUS scores on the first and third days and gestational age, birth weight, the first- and fifth-minute APGAR scores, and there was a positive correlation between aortic root to left atrium ratio, and PDA diameter/weight ratio.

CONCLUSION

We observed that LUS scores in patients with hemodynamically insignificant PDA treated with closure therapy were similar to in patients with hemodynamically significant PDA. Thus, LUS score can have role in PDA closure in preterm neonates. However, more comprehensive studies are needed.

Evaluation of the association between patent ductus arteriosus approach and neurodevelopment in extremely preterm infants

OBJECTIVE

Assess if unit-level PDA management correlates with neurodevelopmental impairment (NDI) at 18-24 months corrected postnatal age (CPA) in extremely preterm infants.

STUDY DESIGN

Retrospective analysis of infants born at <29 weeks (2014-2017) across two units having distinct PDA strategies. Site 1 utilized an echocardiography-based treatment strategy aiming for accelerated closure (control). Site 2 followed a conservative approach.

PRIMARY ENDPOINT

NDI, characterized by cerebral palsy, any Bayley-III composite score <85, sensorineural/mixed hearing loss, or at least unilateral visual impairment.

RESULTS

377 infants were evaluated. PDA treatment rates remained unchanged in Site 1 but eventually reached 0% in Site 2. Comparable rates of any/significant NDI were seen across both sites (any NDI: 38% vs 36%; significant NDI: 13% vs 10% for Site 1 and 2, respectively). After adjustments, NDI rates remained similar.

CONCLUSION

PDA management strategies in extremely preterm newborns showed no significant impact on neurodevelopment outcomes at 18-24 months CPA.

Treatment of patent ductus arteriosus and short-term outcomes among extremely preterm infants: a multicentre cohort study

Background

The optimal treatment strategy for patent ductus arteriosus (PDA) in extremely preterm infants is currently highly controversial. This study aimed to evaluate the association between PDA treatment and short-term outcomes among extremely preterm infants.

Methods

This cohort study included all extremely preterm infants (≤27 and 6/7 weeks) who were admitted to hospitals participating in the Chinese Neonatal Network from January 2019 to December 2021, and were diagnosed to have PDA by echocardiogram. PDA treatment was defined as medical treatment and/or surgical ligation of PDA during hospitalization. Short-term outcomes included death, bronchopulmonary dysplasia (BPD), death/BPD, retinopathy of prematurity, necrotizing enterocolitis, and severe brain injury. Multivariate logistic regression was used to evaluate the association between PDA treatment and outcomes. Subgroup analysis were performed among infants with different respiratory support on 3 and 7 days of life.

Findings

A total of 2494 extremely preterm infants with the diagnosis of PDA were enrolled, of which 1299 (52.1%) received PDA treatment. PDA treatment was significantly associated with lower risk of death (adjusted odds ratio, 0.48; 95% confidence interval, 0.38-0.60). The decreased risk of death was accompanied by increased risk of BPD and death/BPD. In subgroup analysis according to respiratory support, PDA treatment was associated with lower risk of death among infants who required invasive ventilation. However, the beneficial effect on death was not significant among infants who did not require invasive ventilation.

Interpretation

PDA treatment was associated with reduced mortality in extremely preterm infants, but this beneficial effect was mainly present among infants who required invasive ventilation.

Funding

This study was funded by the Shanghai Science and Technology Commission's Scientific and Technological Innovation Action Plan (21Y21900800) and the Canadian Institutes of Health Research (CTP87518).

Personalized Evidence-Based Management of Patent Ductus Arteriosus in Preterm Infants

There is no universal consensus on management of patent ductus arteriosus (PDA) in preterm infants and it varies significantly worldwide, even among the clinicians within units. The decision to treat requires a thorough understanding of the clinical status of the patient, clinical evaluation of PDA, echocardiographic diagnosis, and hemodynamic impact of ductal shunt on the pulmonary and systemic circulation. In this article, updated evidence on the efficacy and adverse effects of pharmacological treatment options and expectant management are presented, while highlighting the long-term benefits of PDA treatment remains equivocal and controversial. The authors propose a schematic targeted PDA treatment approach based on gestational and chronological age for practical clinical use, and they emphasize important future directions including advancement in PDA device closure techniques, diagnostic echo-parameters, hemodynamic evaluation to assess the impact on other organs, and understanding the long-term outcomes.

Prophylaxis of Patent Ductus Arteriosus with Paracetamol in Extremely Low Gestational Age Newborns (ELGANs): A Single-Institution Observational Study in Vietnam

INTRODUCTION

Prophylactic paracetamol for extremely low gestation age neonates (ELGAN, <27 weeks' gestation) with symptomatic patent ductus arteriosus (sPDA) in high-income countries (HIC) reduces medical and surgical interventions. Its effectiveness in low-to-middle-income countries (LMIC) remains uncertain. This study assesses prophylactic paracetamol's impact on sPDA interventions in ELGANs in an LMIC.

METHODS

This is a retrospective cohort study that compared a historical cohort of ELGANs that were treated with oral ibuprofen or intravenous paracetamol after diagnosis of sPDA (n = 104) with infants (n = 76) treated with prophylactic paracetamol (20 mg/kg loading, 7.5 mg/kg qid for 4 days), in a tertiary neonatal intensive care unit (NICU) in Vietnam. Oral ibuprofen or intravenous therapeutic paracetamol were administered if prophylactic paracetamol failed to close sPDA. Surgical ligation was conducted if targeted medical intervention failed, or the infant deteriorated from conditions attributable to sPDA.

RESULTS

In the historical cohort, 57 (55%) infants died within 7 days of life compared to 18 (24%) from the prophylactic cohort (p < 0.01). Of the survivors, 21 (45%) of the historical and 23 (39.7%) of the prophylactic cohort required surgical ligation (p = 0.6). Duration of hospitalization for survivors was lower in the prophylactic cohort (mean 74 vs. 97 days, p = 0.01). In the prophylactic cohort, 24 (41%) infants did not need further treatment while 34 (59%) required further treatment including ibuprofen and/or paracetamol 28 (48%) and surgical ligation 22 (38%).

CONCLUSIONS

Prophylactic paracetamol for ELGAN in LMIC does not reduce the need for surgical ligation, sPDA rates, and other PDA-related morbidities in infants who survive beyond 7 days of age. It may reduce the risk of death and the duration of hospitalization but further study into the reasons behind this need to be determined with larger studies.

Current Trends in Invasive Closure of Patent Ductus Arteriosus in Very Low Birth Weight Infants in United States Children's Hospitals, 2016-2021

OBJECTIVE

To describe the current practices in invasive patent ductus arteriosus (PDA) closure (surgical ligation or transcatheter occlusion) in very low birth weight (VLBW) infants and changes in patient characteristics and outcomes from 2016 to 2021 among US children's hospitals.

STUDY DESIGN

We evaluated a retrospective cohort of VLBW infants (birth weight 400-1499 g and gestational age 22-31 weeks) who had invasive PDA closure within 6 months of age from 2016 to 2021 in children's hospitals in the Pediatric Health Information System. Changes in patient characteristics and outcomes over time were evaluated using generalized linear models and generalized linear mixed models.

RESULTS

2418 VLBW infants (1182 surgical ligation; 1236 transcatheter occlusion) from 42 hospitals were included. The proportion of infants receiving transcatheter occlusion increased from 17.2% in 2016 to 84.4% in 2021 (P < .001). In 2021, 28/42 (67%) hospitals had performed transcatheter occlusion in > 80% of their VLBW infants needing invasive PDA closure, compared with only 2/42 (5%) in 2016. Although median postmenstrual age (PMA) at PDA closure did not change for the overall cohort, PMA at transcatheter occlusion decreased from 38 weeks in 2016 to 31 weeks by 2020, P < .001. Among those infants not intubated prior to PDA closure, extubation within 3 days postprocedure increased over time (yearly adjusted odds ratios of 1.26 [1.08-1.48]). Length of stay and mortality did not change over time.

CONCLUSION

We report rapid adoption of transcatheter occlusion for PDA among VLBW infants in US children's hospitals over time. Transcatheter occlusions were performed at younger PMA over time.

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 Predictive Value of Lung Ultrasound Score on Hemodynamically Significant Patent Ductus Arteriosus among Neonates ≤25 Weeks

Lung ultrasound (LU) is increasingly used to diagnose and monitor neonatal pulmonary disorders; however, its role in hemodynamically significant patent ductus arteriosus (hsPDA) has not been elucidated. This prospective study investigated the predictive value of the LU score (LUS) for hsPDA in preterm infants with gestational age (GA) ≤ 25 weeks. Preterm infants with GA ≤ 25 weeks were enrolled in this study. LU was conducted on the fourth day of life (DOL). Six lung regions in every lung were scanned, with each region rated as 0-4 points. The performance of the LUS in predicting hsPDA among infants aged ≤25 weeks was analyzed by plotting the receiver operating characteristic (ROC) curve. A total of 81 infants were included in this study. GA, birth weight (BW), gender, Apgar score, delivery mode, antenatal steroids, meconium-stained amniotic fluid, premature rapture of membrane, and early-onset sepsis were not significantly different, but infants in the hsPDA group had increased LUS (38.2 ± 2.8 vs. 30.3 ± 4.3, p < 0.001) compared with non-hsPDA group. The area under the ROC curve (AUC) value of the LUS on the fourth DOL was 0.94 (95% CI: 0.93-0.99) in predicting hsPDA. The LUS threshold at 33 achieved 89% sensitivity and 83% specificity, with the positive and negative predictive values (PPV and NPV) being 87 and 86%, respectively. The LUS can predict hsPDA in extremely preterm infants at an early stage.

A Global Perspective on PDA Management in the Extremely Premature: Shifting Trend Toward Transcatheter Closure

Patent ductus arteriosus (PDA) is a frequently encountered defect in infants born extremely premature (≤26 weeks' gestation). Historically, closure of the PDA was performed using cyclooxygenase inhibitor medications or by surgical ligations. However, the benefits of PDA closure using these therapies have never been demonstrated, albeit studies have previously not focused on the extremely premature infants. Therefore, there was a worldwide trend toward conservative management of the PDA. With improved survival of extremely premature infants, comorbidities associated with the PDA has increased, resulting in finding alternate treatments such as transcatheter patent ductus arteriosus closure (TCPC) for this population. Currently, there is a renewed interest toward selective treatment of the PDA in this high-risk cohort of small infants. This Comprehensive Review article inspects the globally changing trends in the management of the PDA in premature infants, with a special focus on the rising adoption of TCPC. Moreover, this article compiles data from several neonatal networks worldwide to help understand the problem at hand. Understanding the current management of premature infants and their outcomes is fundamentally essential if pediatric cardiologists are to offer TCPC as a viable therapeutic option for this population. This article aims to serve as a guide for pediatric cardiologists on this topic by compiling the results on landmark clinical trials on PDA management and the controversies that arise from these trials. Comparative outcomes from several countries are presented, including interpretations and opinions of the data from experts globally. This is a step toward coming to a global consensus in PDA management in premature infants.

Association between gastrointestinal perforation and patent ductus arteriosus in extremely-low-birth-weight infants: a retrospective study of our decade-long experience

PURPOSE

Management of persistently patent ductus arteriosus (PDA) in extremely low-birth-weight infants (ELBWIs) requires attention due to the risk of tissue hypoperfusion. We investigated the association between PDA and gastrointestinal perforation.

METHODS

We performed a retrospective chart review from 2012 to 2021. Preterm (≤ 32 weeks) ELBWIs with PDA after birth who developed necrotizing enterocolitis (NEC), focal intestinal perforation (FIP), and idiopathic gastric perforation were included; ELBWIs with congenital heart disease were excluded. Data were analyzed using chi-squared tests with Yates; correction, and Student's t test.

RESULTS

Five hundred thirty-five preterm ELBWIs were analyzed, including 20 with NEC, 22 with FIP, and 1 with gastric perforation. In NEC and FIP, the ductus arteriosus remained open in 40% (4/10) and 63.6% (14/22) of cases, respectively, and cyclo-oxygenase inhibitor treatment showed poor efficacy (p = 0.492 and 0.240). The incidence of perforation in NEC (4/9 vs. 6/11, p = 0.653), mortality in NEC (3/4 vs. 3/6, p = 0.895) and FIP (6/14 vs. 3/8, p = 0.838) did not differ according to whether the PDA persisted or resolved.

CONCLUSION

The presentation of PDA did not affect the mortality or morbidity of ELBWIs. However, it is essential to consider the possibility of gastrointestinal perforation due to decreased organ blood flow caused by ductal steal.

Effectiveness and safety of rectal dexibuprofen versus oral ibuprofen for closure of patent ductus arteriosus in preterm infants with gestational age<34 weeks: A pilot study

This pilot study aimed to explore the effectiveness and safety of dexibuprofen suppository in the treatment of PDA in preterm infants. Preterm infants with gestational age <34 weeks and color Doppler echocardiographic evidence of hemodynamically significant PDA (hs PDA) with systemic hypoperfusion was intended to be included into this study since January 2020. As of January 1, 2021, this trial had recruited 87 preterm infants who met the inclusion criteria. Neonates were admitted into hospital within 1 hour after birth and were randomly assigned into two groups. Group one included 44 preterm newborns administered with oral ibuprofen. Group two included 43 preterm newborns administered with dexibuprofen suppository. This preliminary study showed that rectal dexibuprofen and oral ibuprofen were both effective for the closure of PDA, and the closure rate of dexibuprofen suppository was comparable to that of oral ibuprofen after the 1st and 2nd courses of treatment. In addition, rectal dexibuprofen did not increase the incidence of adverse outcomes, including bronchopulmonary dysplasia, intraventricular hemorrhage, sepsis, and necrotising enterocolitis. This pilot study showed dexibuprofen suppository is as effective and safe as oral ibuprofen; yet, better designed, muticenter controlled studies are still needed.

The role of interleukin-1 in perinatal inflammation and its impact on transitional circulation

Preterm birth is defined as delivery at <37 weeks of gestational age (GA) and exposes 15 million infants worldwide to serious early life diseases. Lowering the age of viability to 22 weeks GA entailed provision of intensive care to a greater number of extremely premature infants. Moreover, improved survival, especially at extremes of prematurity, comes with a rising incidence of early life diseases with short- and long-term sequelae. The transition from fetal to neonatal circulation is a substantial and complex physiologic adaptation, which normally happens rapidly and in an orderly sequence. Maternal chorioamnionitis or fetal growth restriction (FGR) are two common causes of preterm birth that are associated with impaired circulatory transition. Among many cytokines contributing to the pathogenesis of chorioamnionitis-related perinatal inflammatory diseases, the potent pro-inflammatory interleukin (IL)-1 has been shown to play a central role. The effects of utero-placental insufficiency-related FGR and in-utero hypoxia may also be mediated, in part, via the inflammatory cascade. In preclinical studies, blocking such inflammation, early and effectively, holds great promise for improving the transition of circulation. In this mini-review, we outline the mechanistic pathways leading to abnormalities in transitional circulation in chorioamnionitis and FGR. In addition, we explore the therapeutic potential of targeting IL-1 and its influence on perinatal transition in the context of chorioamnionitis and FGR.

Conservative Management of Patent Ductus Arteriosus Is Feasible in the Peri-Viable Infants at 22-25 Gestational Weeks

The purpose of this study was to determine the natural course of hemodynamically significant (HS) patent ductus arteriosus (PDA) with conservative management and whether the presence or prolonged duration of HS PDA affected mortality/morbidities in infants at 22-25 weeks estimated gestational age (EGA). We retrospectively reviewed the medical records of 77 infants born at 22-25 weeks EGA, stratified into 22-23 weeks (n = 21) and 24-25 weeks EGA (n = 56). HS PDA was present in 77%, 76%, and 77%, and open ductus at discharge was 12%, 13%, and 12% in the total and at 22-23 and 24-25 weeks EGA infants, respectively. For backup rescue treatment, 7% and 5% of the infants received oral ibuprofen and device closure, respectively. A mortality rate of 9% was found in the HS PDA (+) infants, significantly lower than the 28% in HS PDA (-) infants. There are no significant differences in morbidities. In multivariate analyses, the presence and/or prolonged duration of HS PDA was not associated with increased mortality or morbidity. Spontaneous closure of HS PDA was achieved through conservative management in the peri-viable infants at 22-25 weeks EGA.

Protecting the brain of the micropreemie

Advances in perinatal care have seen substantial improvements in survival without disability for extremely preterm infants. Protecting the developing brain and reducing neurodevelopmental sequelae of extremely preterm birth are strategic priorities for both research and clinical care. A number of evidence-based interventions exist for neuroprotection in micropreemies, inclusive of prevention of preterm birth and multiple births with implantation of only one embryo during in vitro fertilisation, as well as antenatal care to optimize fetal wellbeing, strategies for supporting neonatal transition, and neuroprotective developmental care. Avoidance of complications that trigger ischemia and inflammation is vital for minimizing brain dysmaturation and injury, particularly of the white matter. Neurodevelopmental surveillance, early diagnosis of cerebral palsy and early intervention are essential for optimizing long-term outcomes and quality of life. Research priorities include further evaluation of putative neuroprotective agents, and investigation of common neonatal interventions in trials adequately powered to assess neurodevelopmental outcome.

Is early patent ductus arteriosus ligation helpful in premature neonates? A 10-year retrospective study

BACKGROUND

To compare short and long outcomes between early (≤ 28 days) (EL) and late ligation (LL) groups. To explore factors predicting early extubation (≤ 7 days) after patent ductus arteriosus (PDA) ligation.

METHODS

We conducted a single center, retrospective cohort study of preterm infants < 32 weeks who underwent surgical ligation over a 10-year period (2009-2019).

RESULTS

A total of 133 infants underwent PDA ligation, in the study period. Both groups had similar short-term outcome such as bronchopulmonary dysplasia (BPD) or death (96% vs. 98%, P = 0.64) and long-term clinical outcomes including Bayley's assessment at 2 years corrected age. Fewer infants in the EL group developed severe BPD (63% vs. 81%, P = 0.02). Age at ligation had adjusted odds ratio of 1.04 with over lapping confidence interval (95% CI 1.0-1.1, P = 0.02) for severe BPD/death. There was no difference in day of extubation between the EL and LL group (8 days vs. 7 days, P = 0.85). Left atrium/aortic root ratio of ≥ 1.75 would give sensitivity of 41% and 80% specificity for early extubation (area under the curve of 0.61). There was marginal reduction of hospital stay in the EL group [113 (105-121) days vs. 115 (107-123) days; log rank P = 0.026].

CONCLUSION

EL can be delivered safely with a clinically important lower incidence of severe BPD and shorter duration of hospital stay compared to LL.

Early N-Terminal Pro B-Type Natriuretic Peptide (NTproBNP) Plasma Values and Associations with Patent Ductus Arteriosus Closure and Treatment-An Echocardiography Study of Extremely Preterm Infants

The aim was to investigate the association of gestational age (GA), echocardiographic markers and levels of plasma N-terminal pro-B-type natriuretic peptide (NTproBNP) with the closure rate of a haemodynamically significant patent ductus arteriosus (hsPDA). Ninety-eight Swedish extremely preterm infants, mean GA 25.7 weeks (standard deviation 1.3), born in 2012–2014, were assessed with echocardiography and for levels of NTproBNP. Thirty-three (34%) infants had spontaneous ductal closure within three weeks of age. Infants having spontaneous closure at seven days or less had significantly lower NTproBNP levels on day three, median 1810 ng/L (IQR 1760–6000 ng/L) compared with: infants closing spontaneously later, 10,900 ng/L (6120–19,200 ng/L); infants treated either with ibuprofen only, 14,600 ng/L (7740–28,100 ng/L); or surgery, 32,300 ng/L (29,100–35,000 ng/L). Infants receiving PDA surgery later had significantly higher NTproBNP values on day three than other infants. Day three NTproBNP cut-off values of 15,001–18,000 ng/L, predicted later PDA surgery, with an area under the curve in ROC analysis of 0.69 (0.54–0.83). In conclusion, the spontaneous PDA closure rate is relatively high in extremely preterm infants. Early NTproBNP levels can be used with GA in the management decisions of hsPDA.

Spontaneous Closure of the Arterial Duct after Transcatheter Closure Attempt in Preterm Infants

(1) Background: Transcatheter closure of the patent arterial duct (TCPDA) in preterm infants is an emerging procedure. Patent arterial duct (PDA) spontaneous closure after failed TCPDA attempts is seen but reasons and outcomes are not reported; (2) Methods: We retrospectively included all premature infants <2 kg with abandoned TCPDA procedures from our institutional database between September 2017 and August 2021. Patients’ data and outcomes were reviewed; (3) Results: The procedure was aborted in 14/130 patients referred for TCPDA. Two patients had spasmed PDA upon arrival in the catheterization laboratory and had no intervention. One patient had ductal spasm after guidewire cross. Four patients had unsuitable PDA size/shape for closure. In seven patients, device closure was not possible without causing obstruction on adjacent vessels. Among the 12 patients with attempted TCPDA, five had surgery on a median of 3 days after TCPDA and seven had a spontaneous PDA closure within a median of 3 days after the procedure. Only the shape of the PDA differed between the surgical ligation group (short and conical) and spontaneous closure group (F-type); (4) Conclusions: In the case of TCPDA failure, mechanically induced spontaneous closure may occur early after the procedure. Surgical ligation should be postponed when clinically tolerated.

Patent ductus arteriosus: From pharmacology to surgery

Patent ductus arteriosus (PDA) may be found in 0.1-0.2% of term infants, but the average incidence is at least five-fold higher in premature infants, correlating inversely with birth weight and gestational age. While not all patients with a PDA require treatment, the deleterious effects of persistent left-to-right shunting across the ductus can have important short- and long-term consequences. Medical and interventional approaches to PDA closure have evolved greatly in the past decade and add to the decision-making pathways. This article summarizes the pathophysiology of PDA and characterizes the medical, surgical and endovascular treatment approaches.

Outcomes among preterm infants with patent ductus arteriosus: Relationship with treatment, gestational age, hemodynamic status and timing of treatment

BACKGROUND

There remains controversy regarding the outcomes resulting from treatment versus conservative management of patent ductus arteriosus (PDA) among preterm infants. The effects of extreme prematurity, hemodynamic status of the PDA, and age at treatment remain poorly defined.

STUDY DESIGN

This retrospective case-control study including infants <  1250 gm who were categorized into 3 groups: Group 1: without PDA, Group 2: with untreated PDA, and Group 3: treated PDA. Diagnosis and treatment of PDA extracted from the medical records. Demographics, clinical characteristics, and outcomes compared using chi-square and analysis of variance. Logistic regression used to estimate adjusted odds ratios.

RESULTS

The study included 734 infants, with 141(19%) in Group 1, 329 (45%) in 2, and 264 (36%) in 3. Group 3 had higher incidence of bronchopulmonary dysplasia (BPD) (aOR, 2.9; 95%CI 1.7-4.8). Infant treated for hemodynamically significant PDA (HSPDA) had higher incidence of BPD (aOR, 1.9; 95%CI 1.0-3.8) and retinopathy of prematurity (ROP) (aOR, 3.4; 95%CI 1.6-6.9). There were no differences in outcome associated with treatment among≤26 weeks gestation and the age when treated.

CONCLUSION

Infants with PDA who were treated had higher incidence of BPD. Among those who were treated, those with HSPDA had a higher incidence of BPD and ROP.

Outcomes of Extremely Premature Infants Comparing Patent Ductus Arteriosus Management Approaches

OBJECTIVE

To evaluate the change in the proportion of deaths/bronchopulmonary dysplasia (BPD) among premature infants (born <26 and 26-29 weeks of gestational age) following a policy change to a strict nonintervention approach, compared with standard treatment.

STUDY DESIGN

We examined 1249 infants (341 born <26 weeks of gestational age) at 2 comparable sites. Site 1 (control) continued medical treatment/ligation, and site 2 (exposed) changed to a nonintervention policy in late 2013. Using the difference-in-differences approach, which accounts for time-invariant differences between sites and secular trends, we assessed changes in death or BPD separately among infants born 26-29 weeks and <26 weeks of gestational age in 2 epochs (epoch 1: 2011-2013; epoch 2: 2014-2017).

RESULTS

Baseline characteristics were similar across sites and epochs. Medical treatment/ligation use remained stable at site 1 but declined progressively to 0% at site 2, indicating adherence to policy. We saw no difference in death/BPD among infants born at 26-29 weeks of gestational age (12%, 95% CI -1% to 24%). However, incidence of death/BPD increased by 31% among infants born <26 weeks of gestational age (95% CI 10%-51%) in site 2, whereas there was no change in outcomes in site 1. The Score for Neonatal Acute Physiology-Version II, used as a control outcome, did not change in either site, suggesting that our findings were not due to changes in patients' severity.

CONCLUSIONS

Adherence to a strict conservative policy did not impact death or BPD among 26 weeks but was associated with a significant rise in infants born <26 weeks.

Patent ductus arteriosus treatment trends and associated morbidities in neonates

To evaluate national epidemiologic data on infants treated for patent ductus arteriosus (PDA) in Korea and analyze outcomes associated with different PDA treatments. We retrospectively evaluated data on 12,336 patients diagnosed with PDA (International Classification of Diseases-10 code: Q250) between 2015 and 2018 from the Health Insurance Review and Assessment database. Among them, 1623 patients underwent surgical ligation (code: O1671). We used birth certificate data from Statistics Korea to estimate the prevalence, diagnosis, and treatment of PDA. The prevalence of infants with PDA was 81 infants per 10,000 live births and 45.2% in very low birth weight (VLBW) infants, which increased from 2015 to 2018. PDA ligation was performed in 2571 infants and 22% VLBW infants. Medical treatment was administered to 4202 infants, which decreased significantly, especially in VLBW infants (62% to 53%). The proportion of treatment was as follows: conservative treatment (53.1%), intravenous ibuprofen (24.4%), surgery (20.4%), and oral ibuprofen (10.7%); that among 4854 VLBW infants was as follows: intravenous ibuprofen (46.3%), conservative treatment (33.2%), surgery (22.2%), and oral ibuprofen (14.2%). Surgical treatment had a significantly higher risk (odds ratio 1.36) of mortality than conservative treatment. Surgical and/or medical treatments were associated with a higher risk of morbidity. Recently, increased use of conservative management of PDA has contributed to improved neonatal outcomes in VLBW infants. Select patients may still benefit from surgical ligation following careful consideration.

Evidence for the Management of Bronchopulmonary Dysplasia in Very Preterm Infants

BACKGROUND

Very preterm birth often results in the development of bronchopulmonary dysplasia (BPD) with an inverse correlation of gestational age and birthweight. This very preterm population is especially exposed to interventions, which affect the development of BPD.

OBJECTIVE

The goal of our review is to summarize the evidence on these daily procedures and provide evidence-based recommendations for the management of BPD.

METHODS

We conducted a systematic literature research using MEDLINE/PubMed on antenatal corticosteroids, surfactant-replacement therapy, caffeine, ventilation strategies, postnatal corticosteroids, inhaled nitric oxide, inhaled bronchodilators, macrolides, patent ductus arteriosus, fluid management, vitamin A, treatment of pulmonary hypertension and stem cell therapy.

RESULTS

Evidence provided by meta-analyses, systematic reviews, randomized controlled trials (RCTs) and large observational studies are summarized as a narrative review.

DISCUSSION

There is strong evidence for the use of antenatal corticosteroids, surfactant-replacement therapy, especially in combination with noninvasive ventilation strategies, caffeine and lung-protective ventilation strategies. A more differentiated approach has to be applied to corticosteroid treatment, the management of patent ductus arteriosus (PDA), fluid-intake and vitamin A supplementation, as well as the treatment of BPD-associated pulmonary hypertension. There is no evidence for the routine use of inhaled bronchodilators and prophylactic inhaled nitric oxide. Stem cell therapy is promising, but should be used in RCTs only.

Objective Assessment of Physiologic Alterations Associated With Hemodynamically Significant Patent Ductus Arteriosus in Extremely Premature Neonates

Delay in closure of ductus arteriosus in postnatal life may lead to serious consequences and complications in an extremely premature neonate secondary to hemodynamic alterations in regional blood flow pattern in various organs. Despite the widespread recognition amongst neonatologists to identify a hemodynamically significant patent ductus arteriosus (hsPDA) early in the postnatal course, there is lack of consensus in its definition and thus the threshold to initiate treatment. Echocardiographic assessment of PDA shunt size and volume combined with neonatologists' impression of clinical significance is most frequently used to determine the need for treatment of PDA. Common clinical signs of hsPDA utilized as surrogate for decreased tissue perfusion may lag behind early echocardiographic signs. Although echocardiogram allows direct assessment of PDA shunt and hemodynamic alterations in the heart, it is limited by dependence on pediatric cardiologist availability, interobserver variation and isolated time point assessment. Electrical cardiometry (EC) is a non-invasive continuous real time measurement of cardiac output by applying changes in thoracic electrical impedance. EC has been validated in preterm newborns by concomitant transthoracic echocardiogram assessments and may be beneficial in studying changes in cardiac output in premature newborns with hsPDA. Alterations in perfusion index derived from continuous pulse oximetry monitoring has been used to study changes in cardiac performance and tissue perfusion in infants with PDA. Near infrared spectroscopy (NIRS) has been used to objectively and continuously assess variations in renal, mesenteric, and cerebral oxygen saturation and thus perfusion changes due to diastolic vascular steal from hsPDA in preterm neonates. Doppler ultrasound studies measuring resistive indices in cerebral circulation indicate disturbance in cerebral perfusion secondary to ductal steal. With recent trends of change in practice toward less intervention in care of preterm newborn, treatment strategy needs to be targeted for select preterm population most vulnerable to adverse hemodynamic effects of PDA. Integration of these novel ways of hemodynamic and tissue perfusion assessment in routine clinical care may help mitigate the challenges in defining and targeting treatment of hsPDA thereby improving outcomes in extremely premature neonates.

Conservative Management of Patent Ductus Arteriosus in Preterm Infants-A Systematic Review and Meta-Analyses Assessing Differences in Outcome Measures Between Randomized Controlled Trials and Cohort Studies

Objective: This study aims to evaluate outcome after conservative management (no pharmacological/surgical intervention other than fluid restriction, diuretics, or ventilator adjustments) compared with active (pharmacological and/or surgical) treatment for patent ductus arteriosus (PDA) in preterm infants and analyze differences in outcome between randomized controlled trials (RCTs) and cohort studies. Study Design: This is a systematic literature review using PubMed, EMBASE, and Cochrane library. RCTs and cohort studies comparing conservative management with active treatment were included. Meta-analysis was used to compare conservative management with any active (pharmacological and/or surgical), any pharmacological (non-prophylactic and prophylactic), and/or surgical treatment for mortality as primary and major neonatal morbidity as secondary outcome measure. Fixed-effect analysis was used, unless heterogeneity (I ²) was >50%. Outcome is presented as relative risk (RR) with 95% confidence interval. Results: Twelve cohort studies and four RCTs were included, encompassing 41,804 and 720 patients, respectively. In cohort studies, conservative management for PDA was associated with a significantly higher risk for mortality (RR, 1.34 [1.12-1.62]) but a significantly lower risk for bronchopulmonary dysplasia (RR, 0.55 [0.46-0.65]), necrotizing enterocolitis (RR, 0.85 [0.77-0.93]), intraventricular hemorrhage (RR, 0.88 [0.83-0.95]), and retinopathy of prematurity (RR, 0.47 [0.28-0.79]) compared with any active PDA treatment. Meta-analysis of the RCTs revealed no significant differences in outcome between conservative management and active treatment. Conclusion: No differences in mortality or morbidity for conservative management compared with active treatment regimens were observed in RCTs. Findings from cohort studies mainly highlight the lack of high-quality evidence for conservative management for PDA in preterm infants.

Conservative Treatment Without Any Intervention Compared With Other Therapeutic Strategies for Symptomatic Patent Ductus Arteriosus in Extremely Preterm Infants: A Nationwide Cohort Study in Korea

Objective: Although symptomatic treatment is the most preferred treatment strategy for proven symptomatic patent ductus arteriosus (PDA), a considerable number of infants only received conservative treatment without any pharmacological or surgical interventions in the lower gestational age and lower birth weight group in Korea. We compared in-hospital outcomes of infants treated conservatively without any intervention and those of infants managed by other therapeutic strategies in extremely preterm infants with symptomatic PDA. Methods: A prospectively collected cohort study for 2,303 infants with gestational ages <28 weeks from the Korean Neonatal Network database. These infants were classified into four groups according to the presence of PDA-related symptoms and therapeutic treatment strategy: prophylactic treatment group, pre-symptomatic treatment (PST) group, symptomatic treatment (ST) group, and conservative treatment (CT) without any intervention group. Results: In multivariable logistic regression analysis, the risk of death was significantly decreased in the PST group (adjusted odds ratio [aOR] = 0.507; 95% confidence interval [CI] 0.311-0.826) and ST group (aOR = 0.349; 95% CI: 0.230-0.529) compared with the CT group. However, the risk of composite outcome of severe bronchopulmonary dysplasia or death had not increased in the PST group and ST group. Neonatal death due to pulmonary hemorrhage or neurological disease was significantly higher in the CT group than in the PST group or ST group. Conclusion: In extremely preterm infants, who are at highest risk of PDA-related morbidities and mortality, even less interventional approach for PDA can be allowed; the rescued pharmacological or surgical interventions are necessary if they met the criteria for hemodynamically significant PDA.

PATENT DUCTUS ARTERIOSUS CLOSURE: EXPERIENCE FROM A TERTIARY REFERRAL CENTER

Objective:

To characterize the number and methods of closure of Persistent Ductus Arteriosus (PDA) over a span of 16 years in a third level maternity hospital.

Methods:

Retrospective study of neonates born between January 2003 and Deccember 2018, who underwent ductus arteriosus closure by pharmacological, surgical and/or transcatheter methods. Gestational age, birth weight, number and methods of closures per year were evaluated. The success rate of the pharmacologic method was calculated, as well as the mortality rate. The association between mortality and birthweight, treatment used and treatment failure was explored.

Results:

There were 47,198 births, 5,156 were preterm, 325 presented PDA and 106 were eligible for closure (median gestational age - 27 weeks, birthweight <1000 g - 61%). Frequency of PDA closure decreased during the study period, especially starting in 2010. Success rate with pharmacologic treatment was 62% after the first cycle and 74% after the second. After drug failure, 12 underwent surgical ligation and two underwent transcatheter closure. Exclusive surgical ligation was indicated in four infants. Ibuprofen replaced indomethacin in 2010, and acetaminophen was used in three infants. Among the 106 infants, hospital mortality was 12% and it was associated with birthweight <1000 g (13/65 <1000 vs. 0/41 >1000 g; p=0.002) and with failure in the first pharmacologic treatment cycle (13/27 with failure, vs. 0/75 without failure; p<0.001).

Conclusions:

The national consensus published in 2010 for the diagnosis and treatment of PDA in preterm infants led to a decrease in the indication for closure. Pharmacological closure was the method of choice, followed by surgical ligation. Birthweight <1000 g and first cycle of pharmacologic treatment failure were associated with higher mortality.

Patent Ductus Arteriosus of the Preterm Infant

Postnatal ductal closure is stimulated by rising oxygen tension and withdrawal of vasodilatory mediators (prostaglandins, nitric oxide, adenosine) and by vasoconstrictors (endothelin-1, catecholamines, contractile prostanoids), ion channels, calcium flux, platelets, morphologic maturity, and a favorable genetic predisposition. A persistently patent ductus arteriosus (PDA) in preterm infants can have clinical consequences. Decreasing pulmonary vascular resistance, especially in extremely low gestational age newborns, increases left-to-right shunting through the ductus and increases pulmonary blood flow further, leading to interstitial pulmonary edema and volume load to the left heart. Potential consequences of left-to-right shunting via a hemodynamically significant patent ductus arteriosus (hsPDA) include increased risk for prolonged ventilation, bronchopulmonary dysplasia, necrotizing enterocolitis or focal intestinal perforation, intraventricular hemorrhage, and death. In the last decade, there has been a trend toward less aggressive treatment of PDA in preterm infants. However, there is a subgroup of infants who will likely benefit from intervention, be it pharmacologic, interventional, or surgical: (1) prophylactic intravenous indomethacin in highly selected extremely low gestational age newborns with PDA (<26 + 0/7 weeks' gestation, <750 g birth weight), (2) early targeted therapy of PDA in selected preterm infants at particular high risk for PDA-associated complications, and (3) PDA ligation, catheter intervention, or oral paracetamol may be considered as rescue options for hsPDA closure. The impact of catheter-based closure of hsPDA on clinical outcomes should be determined in future prospective studies. Finally, we provide a novel treatment algorithm for PDA in preterm infants that integrates the several treatment modalities in a staged approach.

Patent Ductus Arteriosus-Time for a Definitive Trial

More than 70 randomized controlled trials have been conducted on the management of patent ductus arteriosus (PDA) in preterm infants. Yet, clinicians are unsure if treating a PDA improves clinically important outcomes. Earlier clinical trials have primarily explored which pharmacotherapeutic agent effectively closes the PDA. Because many of these trials included older infants, had widely varying PDA definitions, and provided open-label treatment, it is difficult to draw inferences on clinical outcomes based on the results of these trials. These flaws in trial design might have contributed to the growing notion that "no treatment" is a feasible option irrespective of the clinical characteristics of the infant and the PDA shunt volume.

Effect of Nonintervention vs Oral Ibuprofen in Patent Ductus Arteriosus in Preterm Infants: A Randomized Clinical Trial

IMPORTANCE

Persistent patent ductus arteriosus (PDA) in preterm infants is associated with increased mortality and respiratory morbidities, including bronchopulmonary dysplasia (BPD). Despite recent increasing use of noninterventional approaches, no study to our knowledge has yet directly compared the nonintervention vs pharmacologic treatment for mediating PDA closure for decreasing mortality and preventing BPD.

OBJECTIVE

To determine the noninferiority of nonintervention vs oral ibuprofen treatment for PDA in decreasing BPD incidence or death in very preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

A randomized, double-blind, placebo-controlled, noninferiority clinical trial was conducted on preterm infants (gestational age [GA] 23-30 weeks) with hemodynamically significant PDA (ductal size >1.5 mm plus respiratory support) diagnosed between postnatal days 6 and 14. Participants included 383 infants screened between July 24, 2014, and March 15, 2019.

INTERVENTIONS

Infants were stratified by GA and randomly assigned (1:1) to receive either oral ibuprofen (initial dose of 10 mg/kg followed by a 5-mg/kg dose after 24 hours and a second 5-mg/kg dose after 48 hours) or placebo.

MAIN OUTCOMES AND MEASURES

The primary outcome was BPD or death; the secondary outcomes included major morbidities and ductal closure rates. Per-protocol analysis was used.

RESULTS

Among 383 infants screened for participation, 146 infants were randomly assigned, with 72 in the nonintervention and 70 in the ibuprofen treatment group in the final analyses. The PDA closure rate at 1 week after randomization was significantly higher with ibuprofen (11 [34%]) than nonintervention (2 [7%]) in infants at GA 27 to 30 weeks (P = .007); however, the findings were not significant at GA 23 to 26 weeks (ibuprofen, 3 [8%] vs nonintervention, 1 [2%], P = .34). In addition, the ductal closure rates before hospital discharge (ibuprofen, 62 [89%] vs nonintervention, 59 [82%], P = .27) and device closure (ibuprofen, 2 [3%] vs nonintervention, 4 [6%], P = .40) were not significantly different between the 2 groups. The nonintervention approach was noninferior to ibuprofen treatment in terms of BPD incidence or death (nonintervention, 44%; ibuprofen, 50%; 95% CI, -0.11 to 0.22; noninferiority margin -0.2; P = .51). One infant in the ibuprofen arm received oral ibuprofen backup rescue treatment owing to cardiopulmonary compromise refractory to conservative management, and another infant in the ibuprofen group received surgical ligation; none of the infants in the placebo group received backup treatment.

CONCLUSIONS AND RELEVANCE

Nonintervention showed noninferiority compared with ibuprofen treatment in closing of hemodynamically significant PDA and reduction of BPD or death. The noninferiority of nonintervention over ibuprofen might be attributable to the low efficacy of oral ibuprofen for closing PDA, especially in infants born at 23 to 26 weeks' gestation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02128191.

Changes in Serum Creatinine Levels and Natural Evolution of Acute Kidney Injury with Conservative Management of Hemodynamically Significant Patent Ductus Arteriosus in Extremely Preterm Infants at 23-26 Weeks of Gestation

Changes in kidney function in extremely preterm infants (EPT) with conservatively managed hemodynamically significant (HS) patent ductus arteriosus (PDA) are not known well. We aimed to present the postnatal course in serum creatinine levels (sCr), prevalence of acute kidney injury (AKI), then relevance between AKI and adverse outcomes in EPT with conservatively managed HS PDA. By review of medical records, we analyzed the postnatal course of sCr and prevalence of stage 3 AKI defined by the modified Kidney Disease Improving Global Outcome (KDIGO) in EPT at gestational age of 23 to 26 weeks with conservatively treated HS PDA. We investigated if the presence and/or prolonged duration of stage 3 AKI elevated the risk of adverse outcomes. The results showed that, neither factor was associated with adverse outcomes. While the average PDA closure date was at postnatal day (P) 41 and 53, sCr peaked at P 10 and 14 and the cumulative prevalence of stage 3 AKI was 57% and 72% in the EPT of 25–26 and 23–24 weeks’ gestation, respectively. The high prevalence of stage 3 AKI without adverse outcomes in EPT with conservatively managed HS PDA suggests that it might reflect renal immaturity rather than pathologic conditions.

Conservative Non-intervention Approach for Hemodynamically Significant Patent Ductus Arteriosus in Extremely Preterm Infants

While persistent patent ductus arteriosus (PDA) in preterm infants has been known to be associated with increased mortality and morbidities including bronchopulmonary dysplasia, and necrotizing enterocolitis, there is minimal evidence supporting their causal relationships, and most traditional medical and/or surgical treatments have failed to show improvements in these outcomes. As such, the pendulum has swung toward the conservative non-intervention approach for the management of persistent PDA during the last decade; however, the benefits and risks of this approach are unclear. In this mini review, we focused on whom, when, and how to apply the conservative non-intervention approach for persistent PDA, especially in extremely preterm infants.