Ibuprofen-induced patent ductus arteriosus closure: physiologic, histologic, and biochemical effects on the premature lung

Prophylactic indomethacin and the risk of serious pulmonary hemorrhages in preterm infants less than 28 weeks' gestation

OBJECTIVE

To determine if prophylactic indomethacin (PINDO) decreases serious pulmonary hemorrhages in infants <28 weeks.

STUDY DESIGN

Intention-to-treat analysis of 615 consecutively admitted infants during four alternating protocol-driven epochs of PINDO or expectant patent ductus arteriosus (PDA) management.

RESULTS

41/615 (6.7%) developed serious pulmonary hemorrhage at 2 (1, 3) days (median (IQR)). In unadjusted and adjusted multivariable models, infants born in a PINDO epoch had significantly lower incidences of pulmonary hemorrhage and pulmonary hemorrhage or death before 7 days. There were less moderate/large PDA during PINDO epochs. The associations between PINDO and pulmonary hemorrhage and pulmonary hemorrhage/death were no longer significant when presence of a PDA was included in the analyses. There was no apparent association between PINDO epochs and the incidence of serious intraventricular hemorrhages.

CONCLUSION

Even though PINDO no longer appears to affect the incidence of sIVH it still is associated with a lower incidence of pulmonary hemorrhage.

Acute Kidney Injury in Neonatal Intensive Care Unit: Epidemiology, Diagnosis and Risk Factors

Acute kidney injury (AKI) is associated with long-term consequences and poor outcomes in the neonatal intensive care unit. Its precocious diagnosis represents one of the hardest challenges in clinical practice due to the lack of sensitive and specific biomarkers. Currently, neonatal AKI is defined with urinary markers and serum creatinine (sCr), with limitations in early detection and individual treatment. Biomarkers and risk factor scores were studied to predict neonatal AKI, to early identify the stage of injury and not the damage and to anticipate late increases in sCr levels, which occurred when the renal function already began to decline. Sepsis is the leading cause of AKI, and sepsis-related AKI is one of the main causes of high mortality. Moreover, preterm neonates, as well as patients with post-neonatal asphyxia or after cardiac surgery, are at a high risk for AKI. Critical patients are frequently exposed to nephrotoxic medications, representing a potentially preventable cause of AKI. This review highlights the definition of neonatal AKI, its diagnosis and new biomarkers available in clinical practice and in the near future. We analyze the risk factors involving patients with AKI, their outcomes and the risk for the transition from acute damage to chronic kidney disease.

Patent Ductus Arteriosus and Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension: A Bayesian Meta-Analysis

Importance

Bronchopulmonary dysplasia (BPD) is often associated with pulmonary vascular disease and secondary pulmonary hypertension (PH). The pathogenesis of BPD-associated PH (BPD-PH) is complex and involves prenatal and postnatal factors that disrupt pulmonary vascular development, and patent ductus arteriosus (PDA) is a factor potentially associated with risk of BPD-PH that has been identified in very recent studies.

Objective

To explore the association of PDA with BPD-PH using a bayesian model-averaged (BMA) meta-analysis of studies.

Data Sources

PubMed and Embase were searched up to April 2023. Key search terms included BPD and PH.

Study Selection

Studies examining infants with gestational age 32 weeks or less and reporting data on PDA and risk of BPD-PH.

Data Extraction and Synthesis

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Meta-Analysis of Observational Studies in Epidemiology reporting guidelines. Two independent reviewers extracted data, with a third reviewer checking for accuracy and completeness. Data pooling and effect size calculations were performed by BMA.

Main Outcomes and Measures

The primary outcome was BPD-PH. BMA was used to calculate Bayes factors (BFs). The BF10 is the ratio of the probability of the data under the alternative hypothesis (H1, association of PDA with BPD-HP) over the probability of the data under the null hypothesis (H0).

Results

A total of 32 studies (8513 infants) were included. BMA showed that the evidence in favor of H1 was weak for any PDA (BF10 = 2.90; 10 studies), moderate for hemodynamically significant PDA (BF10 = 3.77; 3 studies), and extreme for surgically ligated or catheter-occluded PDA (BF10 = 294.9; 16 studies). In contrast, the evidence in favor of H0 was weak for medically treated PDA (BF10 = 0.55; 6 studies). In addition, BMA found strong evidence in favor of H1 when prolonged exposure to PDA was analyzed as a dichotomous variable (BF10 = 11.80; 6 studies) and extreme evidence (BF10 = 113.60; 3 studies) when PDA exposure time was analyzed as a continuous variable.

Conclusions and Relevance

In this bayesian meta-analysis, the data suggest that prolonged exposure to PDA might be associated with increased risk of pulmonary vascular disease in extremely preterm infants. This highlights the need to monitor for PH in high-risk preterm infants with prolonged exposure to PDA and to incorporate PH risk into clinical decisions regarding PDA management.

Pulmonary phenotypes of bronchopulmonary dysplasia in the preterm infant

Bronchopulmonary dysplasia (BPD) remains the most common complication of premature birth, imposing a significant and potentially life-long burden on patients and their families. Despite advances in our understanding of the mechanisms that contribute to patterns of lung injury and dysfunctional repair, current therapeutic strategies remain non-specific with limited success. Contemporary definitions of BPD continue to rely on clinician prescribed respiratory support requirements at specific time points. While these criteria may be helpful in broadly identifying infants at higher risk of adverse outcomes, they do not offer any precise information regarding the degree to which each compartment of the lung is affected. In this review we will outline the different pulmonary phenotypes of BPD and discuss important features in the pathogenesis, clinical presentation, and management of these frequently overlapping scenarios.

Bronchopulmonary Dysplasia: Pathogenesis and Pathophysiology

Bronchopulmonary dysplasia (BPD), also known as chronic lung disease, is the most common respiratory morbidity in preterm infants. "Old" or "classic" BPD, as per the original description, is less common now. "New BPD", which presents with distinct clinical and pathological features, is more frequently observed in the current era of advanced neonatal care, where extremely premature infants are surviving because of medical advancements. The pathogenesis of BPD is complex and multifactorial and involves both genetic and environmental factors. This review provides an overview of the pathology of BPD and discusses the influence of several prenatal and postnatal factors on its pathogenesis, such as maternal factors, genetic susceptibility, ventilator-associated lung injury, oxygen toxicity, sepsis, patent ductus arteriosus (PDA), and nutritional deficiencies. This in-depth review draws on existing literature to explore these factors and their potential contribution to the development of BPD.

Perinatal origins of bronchopulmonary dysplasia-deciphering normal and impaired lung development cell by cell

Bronchopulmonary dysplasia (BPD) is a multifactorial disease occurring as a consequence of premature birth, as well as antenatal and postnatal injury to the developing lung. BPD morbidity and severity depend on a complex interplay between prenatal and postnatal inflammation, mechanical ventilation, and oxygen therapy as well as associated prematurity-related complications. These initial hits result in ill-explored aberrant immune and reparative response, activation of pro-fibrotic and anti-angiogenic factors, which further perpetuate the injury. Histologically, the disease presents primarily by impaired lung development and an arrest in lung microvascular maturation. Consequently, BPD leads to respiratory complications beyond the neonatal period and may result in premature aging of the lung. While the numerous prenatal and postnatal stimuli contributing to BPD pathogenesis are relatively well known, the specific cell populations driving the injury, as well as underlying mechanisms are still not well understood. Recently, an effort to gain a more detailed insight into the cellular composition of the developing lung and its progenitor populations has unfold. Here, we provide an overview of the current knowledge regarding perinatal origin of BPD and discuss underlying mechanisms, as well as novel approaches to study the perturbed lung development.

Expectant Management or Early Ibuprofen for Patent Ductus Arteriosus

BACKGROUND

Cyclooxygenase inhibitors are commonly used in infants with patent ductus arteriosus (PDA), but the benefit of these drugs is uncertain.

METHODS

In this multicenter, noninferiority trial, we randomly assigned infants with echocardiographically confirmed PDA (diameter, >1.5 mm, with left-to-right shunting) who were extremely preterm (<28 weeks' gestational age) to receive either expectant management or early ibuprofen treatment. The composite primary outcome included necrotizing enterocolitis (Bell's stage IIa or higher), moderate to severe bronchopulmonary dysplasia, or death at 36 weeks' postmenstrual age. The noninferiority of expectant management as compared with early ibuprofen treatment was defined as an absolute risk difference with an upper boundary of the one-sided 95% confidence interval of less than 10 percentage points.

RESULTS

A total of 273 infants underwent randomization. The median gestational age was 26 weeks, and the median birth weight was 845 g. A primary-outcome event occurred in 63 of 136 infants (46.3%) in the expectant-management group and in 87 of 137 (63.5%) in the early-ibuprofen group (absolute risk difference, -17.2 percentage points; upper boundary of the one-sided 95% confidence interval [CI], -7.4; P<0.001 for noninferiority). Necrotizing enterocolitis occurred in 24 of 136 infants (17.6%) in the expectant-management group and in 21 of 137 (15.3%) in the early-ibuprofen group (absolute risk difference, 2.3 percentage points; two-sided 95% CI, -6.5 to 11.1); bronchopulmonary dysplasia occurred in 39 of 117 infants (33.3%) and in 57 of 112 (50.9%), respectively (absolute risk difference, -17.6 percentage points; two-sided 95% CI, -30.2 to -5.0). Death occurred in 19 of 136 infants (14.0%) and in 25 of 137 (18.2%), respectively (absolute risk difference, -4.3 percentage points; two-sided 95% CI, -13.0 to 4.4). Rates of other adverse outcomes were similar in the two groups.

CONCLUSIONS

Expectant management for PDA in extremely premature infants was noninferior to early ibuprofen treatment with respect to necrotizing enterocolitis, bronchopulmonary dysplasia, or death at 36 weeks' postmenstrual age. (Funded by the Netherlands Organization for Health Research and Development and the Belgian Health Care Knowledge Center; BeNeDuctus ClinicalTrials.gov number, NCT02884219; EudraCT number, 2017-001376-28.).

Patent ductus arteriosus (PDA) and pulmonary morbidity: can early targeted pharmacologic PDA treatment decrease the risk of bronchopulmonary dysplasia?

A persistent left-to-right shunt through a patent ductus arteriosus (PDA) increases the rate of pulmonary hydrostatic fluid filtration, impairs pulmonary mechanics, and prolongs the need for respiratory support. Infants with a moderate/large PDA shunt that persists for more than 7-14 days are at increased risk for developing bronchopulmonary dysplasia (BPD) if they also require invasive ventilation for more than 10 days. In contrast, infants who require invasive ventilation for less than 10 days have similar rates of BPD no matter how long they are exposed to a moderate/large PDA shunt. Although pharmacologic PDA closure decreases the risk of abnormal early alveolar development in preterm baboons that are ventilated for 2 weeks, the findings from recent randomized controlled trials, as well as a quality improvement project, suggest that routine early targeted pharmacologic treatments, as currently employed, do not appear to alter the incidence of BPD in human infants.

Vascular and pulmonary effects of ibuprofen on neonatal lung development

BACKGROUND

Ibuprofen is a nonsteroidal anti-inflammatory drug that is commonly used to stimulate closure of a patent ductus arteriosus (PDA) in very premature infants and may lead to aberrant neonatal lung development and bronchopulmonary dysplasia (BPD).

METHODS

We investigated the effect of ibuprofen on angiogenesis in human umbilical cord vein endothelial cells (HUVECs) and the therapeutic potential of daily treatment with 50 mg/kg of ibuprofen injected subcutaneously in neonatal Wistar rat pups with severe hyperoxia-induced experimental BPD. Parameters investigated included growth, survival, lung histopathology and mRNA expression.

RESULTS

Ibuprofen inhibited angiogenesis in HUVECs, as shown by reduced tube formation, migration and cell proliferation via inhibition of the cell cycle S-phase and promotion of apoptosis. Treatment of newborn rat pups with ibuprofen reduced pulmonary vessel density in the developing lung, but also attenuated experimental BPD by reducing lung inflammation, alveolar enlargement, alveolar septum thickness and small arteriolar wall thickening.

CONCLUSIONS

In conclusion, ibuprofen has dual effects on lung development: adverse effects on angiogenesis and beneficial effects on alveolarization and inflammation. Therefore, extrapolation of the beneficial effects of ibuprofen to premature infants with BPD should be done with extreme caution.

Effects of prophylactic indomethacin on morbidity and mortality in infants <25 weeks' gestation: a protocol driven intention to treat analysis

OBJECTIVE

To determine if prophylactic indomethacin (PINDO) decreases death or bronchopulmonary dysplasia-grades 2 and 3 (death/BPD) in newborns <25 weeks.

STUDY DESIGN

Intention-to-treat, cohort-controlled study of 106 infants admitted during three alternating epochs of PINDO or Expectant patent ductus arteriosus (PDA) management.

RESULTS

At 7-8 days 85% of Expectant Management epoch infants had a moderate/large PDA (median exposure was 23 days). Among PINDO epoch infants only 24% still had a PDA at 7-8 days. There were no significant differences in the incidence of death/BPD or of secondary outcomes (BPD, death, necrotizing enterocolitis/spontaneous perforations, or intraventricular hemorrhage (grades 3 or 4)) in either unadjusted or adjusted comparisons between infants born in a PINDO epoch and those born in the Expectant Management epoch.

CONCLUSION

Despite being at high risk for PDA-related morbidities, PINDO did not appear to alter the rates of our primary and secondary outcomes in infants <25 weeks.

Patent ductus arteriosus, tracheal ventilation, and the risk of bronchopulmonary dysplasia

BACKGROUND

An increased risk for bronchopulmonary dysplasia (BPD) exists when moderate-to-large patent ductus arteriosus shunts (hsPDA) persist beyond 14 days.

GOAL

To examine the interaction between prolonged exposures to tracheal ventilation (≥10 days) and hsPDA on the incidence of BPD in infants <28 weeks gestation.

STUDY DESIGN

Predefined definitions of prolonged ventilation (≥10 days), hsPDA (≥14 days), and BPD (room air challenge test at 36 weeks) were used to analyze deidentified data from the multicenter TRIOCAPI RCT in a secondary analysis of the trial.

RESULTS

Among 307 infants who survived >14 days, 41 died before 36 weeks. Among survivors, 93/266 had BPD. The association between BPD and hsPDA depended on the length of intubation. In multivariable analyses, prolonged hsPDA shunts were associated with increased BPD (odds ratio (OR) (95% confidence interval (CI)) = 3.00 (1.58-5.71)) when infants required intubation for ≥10 days. In contrast, there was no significant association between hsPDA exposure and BPD when infants were intubated <10 days (OR (95% CI) = 1.49 (0.98-2.26)). A similar relationship between prolonged hsPDA and length of intubation was found for BPD/death (n = 307): infants intubated ≥10 days: OR (95% CI) = 2.41 (1.47-3.95)); infants intubated <10 days: OR (95% CI) = 1.37 (0.86-2.19)).

CONCLUSIONS

Moderate-to-large PDAs were associated with increased risks of BPD and BPD/death-but only when infants required intubation ≥10 days.

IMPACT

Infants with a moderate-to-large hsPDA that persist beyond 14 days are only at risk for developing BPD if they also receive prolonged tracheal ventilation for ≥10 days. Infants who receive less ventilatory support (intubation for <10 days) have the same incidence of BPD whether the ductus closes shortly after birth or whether it persists as a moderate-to-large shunt for several weeks. Early PDA closure may be unnecessary in infants who require short durations of intubation since the PDA does not seem to alter the incidence of BPD in infants who require intubation for <10 days.

Changes in Patent Ductus Arteriosus Treatment Strategy and Respiratory Outcomes in Premature Infants

OBJECTIVE

To evaluate whether change in patent ductus arteriosus (PDA) management strategies over time had an impact on respiratory outcomes in premature infants.

STUDY DESIGN

Prospectively collected data were included from all preterm infants born at 23-30 weeks gestational age with PDA admitted to the Children's Hospital of the University of Miami/Jackson Memorial Medical Center from January 1, 2005 to December 31, 2007 (epoch 1) and January 1, 2011 to December 31, 2015 (epoch 2). The 2 epochs were compared for approach with PDA diagnosis and subsequent management strategies and respiratory outcomes.

RESULTS

Significantly fewer infants were treated for PDA in epoch 2 (54%) compared with epoch 1 (90%). Multivariable logistic regression analysis demonstrated that infants in epoch 2, with later PDA diagnosis and less frequent PDA treatment, had greater odds of bronchopulmonary dysplasia (BPD), composite of BPD or death, and more treatment with postnatal steroids than in epoch 1.

CONCLUSIONS

The change in approach to diagnosis and management of PDA, from a more proactive and aggressive approach during the earlier epoch 1 to a more expectant approach during the subsequent epoch 2, was associated with worse respiratory outcomes, including increase in BPD and in BPD or death.

Early closure mechanisms of the ductus arteriosus in immature infants

AIM

According to experimental studies, cardiopulmonary distress decreases after closure of patent ductus arteriosus. However, early closure of the ductus using ibuprofen or indomethacin has failed to increase survival without serious morbidity. We review relevant data aiming to define optimal early management strategies that promote early closure of ductus arteriosus without serious adverse effects.

METHODS

Literature in English was searched selectively focusing on the potential of using acetaminophen for early closure of the ductus.

RESULTS

Prophylactic ibuprofen or indomethacin intended to close the ductus, predisposes infants to ischaemia, bleeding and immune dysfunction. Acetaminophen appears to have a similar efficacy as indomethacin or ibuprofen, and all three dose-dependently constrict the ductus. Ibuprofen and indomethacin cause non-specific inhibition of prostaglandin synthesis, while acetaminophen predominantly inhibits prostaglandin E synthesis. Owing to low CYP450 activity in infancy, acetaminophen toxicity has been rarely evident. However, increasing the dosage increases the oxidative stress. We review prophylactic treatments that may increase the safety and efficacy of acetaminophen. These include vitamin A, cysteine and glutamine, and low-dose corticosteroid supplementation.

CONCLUSION

The current challenge is to define a safe perinatal management practice that promotes cardiorespiratory adaptation in immature infants, particularly the seamless closure of the ductus before significant cardiopulmonary distress develops.

Early Role of the Atrial-Level Communication in Premature Infants with Patent Ductus Arteriosus

BACKGROUND

High-volume systemic-to-pulmonary ductus arteriosus shunts in premature infants are associated with adverse neonatal outcomes. The role of an atrial communication (AC) in modulating the effects of a presumed hemodynamically significant patent ductus arteriosus (PDA) is poorly studied. The objective of this study was to characterize the relationship between early AC and echocardiographic indices of PDA shunt volume and clinical neonatal outcomes.

METHODS

A retrospective review of preterm infants (born at <32 weeks' gestation) who underwent echocardiography in the first postnatal week was performed. The cohort was divided into four groups on the basis of presence of a presumed hemodynamically significant PDA (≥1.5 vs <1.5 mm) and AC size (≤1 vs >1 mm), and echocardiographic measures of PDA shunt volume were then compared. Clinical outcomes, including chronic lung disease and intraventricular hemorrhage, were also compared among all four groups.

RESULTS

A total of 199 preterm infants (mean birth weight, 928 ± 632 g; mean gestational age, 26.6 ± 1.5 weeks) were identified; 159 infants had PDAs ≥ 1.5 mm, of whom 52 had ACs ≤ 1 mm and 107 had ACs > 1 mm. The remaining 40 infants had PDAs < 1.5 mm, of whom 23 had ACs ≤ 1 mm and 17 had ACs > 1 mm. Infants with PDAs ≥ 1.5 mm and ACs > 1 mm had higher pulmonary vein D-wave velocities (P < .05), higher left ventricular output (P < .005), higher PDA scores (P < .001), and increased rates of reversed diastolic flow in the descending aorta (P < .001), celiac artery (P < .001), and middle cerebral artery (P < .001) than infants with either PDAs < 1.5 mm or PDAs ≥ 1.5 mm and ACs ≤ 1 mm. There was no difference in the incidence of intraventricular hemorrhage, but infants with PDAs ≥ 1.5 mm and ACs > 1 mm had a higher risk for a composite outcome of chronic lung disease or death before hospital discharge (P < .05).

CONCLUSIONS

Echocardiographic evidence of ACs > 1 mm in patients with PDAs ≥ 1.5 mm during the first postnatal week may be a marker of a more pathologic hemodynamically significant PDA in premature infants. Future investigations should evaluate if early identification and treatment of patients with both high-volume PDAs and larger atrial-level communications may help mitigate adverse outcomes, such as chronic lung disease or death, in this high-risk patient population.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Minimally Invasive Surfactant Administration for the Treatment of Neonatal Respiratory Distress Syndrome: A Multicenter Randomized Study in China

Background/Aims: Nasal continuous positive airway pressure (nCPAP) was recommended as the initial respiratory support for spontaneous breathing in infants with very low birth weight and neonatal respiratory distress syndrome (NRDS). Less invasive surfactant administration (LISA) and minimally invasive surfactant therapy (MIST) have been reported to reduce the incidence of bronchopulmonary dysplasia (BPD). This study aimed to explore the applicability of minimally invasive surfactant administration (MISA) in China. Materials and Methods: MISA was a randomized controlled study conducted at eight level III neonatal intensive care units (NICUs) in China. Spontaneously breathing infants born at 25+0 to 31+6 weeks' gestation who progressively developed respiratory distress during the first 6 h after birth were randomly assigned to receive MISA or endotracheal intubation surfactant administration (EISA). The primary outcome was the difference in the morbidity of BPD between two groups of infants with MISA and EISA at 36 weeks corrected gestational age. Results: Demographic and clinical characteristics of the 151 infants in the MISA group were similar to the 147 infants in the EISA group. The comparison showed no clear benefits in the MISA group in the incidence of BPD, while infants from the EISA group had higher rates of patent ductus arteriosus (PDA) (60.5 vs. 41.1%, p = 0.001). The duration of surfactant infusion and the total time of surfactant administration in the MISA group were significantly longer than in the EISA group. A slightly increased heart rate was noted 1 h post surfactant administration in the EISA group. In subgroup analysis, the comparison of 51 smaller (<30 weeks) preterm infants, named MISAs (n = 31) and EISAs (n = 20), showed a significant reduction of BPD (29.0 vs. 70.0%, p = 0.004) and PDA (29.0 vs. 65.0%, p = 0.011). In the subgroup analysis of blood gas, arterial oxygen saturation (SaO₂) value at 1 and 12 h and partial pressure of arterial oxygen (PaO₂) at 12 h were all higher in the EISA group compared to the MISA group. Conclusion: MISA had no clear benefit on the incidence of BPD, but it was related to a reduction in PDA. It is an appropriate therapy for spontaneous breathing in infants with extremely low birth weight and NRDS.

Prediction of Bronchopulmonary Dysplasia in Preterm Infants Using Postnatal Risk Factors

Objective: To identify postnatal risk factors for bronchopulmonary dysplasia (BPD) development in preterm infants with gestational age ≤32 weeks. Methods: Seventy-two preterm infants(30 with BPD and 42 non-BPD controls) admitted in the neonatal intensive care unit (NICU) of the Children's Hospital of Soochow University during 2017 were enrolled in this prospective longitudinal study. Perinatal clinical data, a neonatal critical illness score (NCIS), different soluble B7-H3(sB7-H3), and interleukin-18 (IL-18) levels by days after birth were collected. An early predictive model for BPD development was established based on clinical data using multiple logistic regression analysis. And the sensitivity and specificity of the model were assesed by ROC curve. Results: Electrolyte disturbances, hemodynamically significant patent ductus arteriosus (hs-PDA), and the age that infants achieved 120 kcal/kg.d via enteral feeding ≥40 days after birth were found to be associated with the BPD pathogenesis. Serum sB7-H3, IL-18, and NCIS were significantly higher in the BPD group compared to the non-BPD group (p < 0.05). BPD group had significantly lower enteral fluid and caloric intake compared to the non-BPD group at 1, 7, 14, and 28 days after birth. The risk factors were analyzed by multiple logistic regression and a predictive model of a combination of sB7-H3 (day 7), IL-18 (day 14), NCIS, and clinical risk factors was evaluated via ROC curve with an area under the curve (AUC) of 0.960 having sensitivity of 86.7% and a specificity of 97.6%, respectively. Conclusion: The causes of BPD are multifactorial postnatal risk factors. And the combination of sB7-H3 (day 7), IL-18 (day 14), NCIS, and clinical risk factors (electrolyte disturbances, hs-PDA, and the age that infants achieved 120 kcal/kg.d via enteral feeding ≥40 days after birth) might be served as an optimal predictive model for the occurrence of BPD.

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.

PDA-TOLERATE Trial: An Exploratory Randomized Controlled Trial of Treatment of Moderate-to-Large Patent Ductus Arteriosus at 1 Week of Age

OBJECTIVE

To compare early routine pharmacologic treatment of moderate-to-large patent ductus arteriosus (PDA) at the end of week 1 with a conservative approach that requires prespecified respiratory and hemodynamic criteria before treatment can be given.

STUDY DESIGN

A total of 202 neonates of <28 weeks of gestation age (mean, 25.8 ± 1.1 weeks) with moderate-to-large PDA shunts were enrolled between age 6 and 14 days (mean, 8.1 ± 2.2 days) into an exploratory randomized controlled trial.

RESULTS

At enrollment, 49% of the patients were intubated and 48% required nasal ventilation or continuous positive airway pressure. There were no differences between the groups in either our primary outcome of ligation or presence of a PDA at discharge (early routine treatment [ERT], 32%; conservative treatment [CT], 39%) or any of our prespecified secondary outcomes of necrotizing enterocolitis (ERT, 16%; CT, 19%), bronchopulmonary dysplasia (BPD) (ERT, 49%; CT, 53%), BPD/death (ERT, 58%; CT, 57%), death (ERT,19%; CT, 10%), and weekly need for respiratory support. Fewer infants in the ERT group met the rescue criteria (ERT, 31%; CT, 62%). In secondary exploratory analyses, infants receiving ERT had significantly less need for inotropic support (ERT, 13%; CT, 25%). However, among infants who were ≥26 weeks gestational age, those receiving ERT took significantly longer to achieve enteral feeding of 120 mL/kg/day (median: ERT, 14 days [range, 4.5-19 days]; CT, 6 days [range, 3-14 days]), and had significantly higher incidences of late-onset non-coagulase-negative Staphylococcus bacteremia (ERT, 24%; CT,6%) and death (ERT, 16%; CT, 2%).

CONCLUSIONS

In preterm infants age <28 weeks with moderate-to-large PDAs who were receiving respiratory support after the first week, ERT did not reduce PDA ligations or the presence of a PDA at discharge and did not improve any of the prespecified secondary outcomes, but delayed full feeding and was associated with higher rates of late-onset sepsis and death in infants born at ≥26 weeks of gestation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01958320.

Bronchopulmonary Dysplasia: 50 Years after the Original Description

Bronchopulmonary dysplasia (BPD) is one of the few diseases in neonatal medicine that has continued to evolve since its first description about 50 years ago. Over these years, advancements in neonatal medicine such as antenatal steroids and exogenous surfactant therapy have significantly reduced neonatal mortality and lowered the limits of viability for preterm infants. Although the incidence of BPD continues to be high, especially in extremely low birth weight infants, the clinical picture has evolved into a milder disease with low mortality or significant morbidities. This new BPD is the result of complex interactions between altered alveolar and vascular development, injury by ante- and postnatal pathogenic factors, and reparative processes in the lung. There has been significant progress in our understanding of risk factors for BPD, but challenges persist in its definition, and in finding effective preventive strategies. There are promising developments with newer preventive interventions such as mesenchymal stem cells, exosomes, immunomodulators, and growth factors, but they are still in preclinical stage. The future challenges include finding ways to define BPD based on the severity of lung pathology, which can better predict long-term outcomes, development of early predictors of lung disease, and finding innovative and evidence-based preventive and management strategies.

Late oral acetaminophen versus immediate surgical ligation in preterm infants with persistent large patent ductus arteriosus

OBJECTIVE

The study objective was to evaluate the association of oral acetaminophen therapy versus immediate surgical ligation with neonatal outcomes in infants with persistent patent ductus arteriosus.

METHODS

We performed a retrospective cohort study of preterm infants born 28⁺⁶ weeks or less gestational age with persistent large patent ductus arteriosus being considered for surgical ligation after unsuccessful medical therapy. Infants in epoch 1 (July 2009 to June 2012) were immediately referred for ligation, and infants in epoch 2 (July 2012 to June 2015) were treated with oral acetaminophen and referred for ligation in the absence of improvement. The primary outcome was a composite of death or chronic lung disease.

RESULTS

A total of 92 infants with median (interquartile range) gestational age 25.2 weeks (24.4-26.3) had persistent large patent ductus arteriosus (43 in epoch 1, 49 in epoch 2). Infants in epoch 2 had decreased surgical ligation (26 [53%] vs 31 [72%]; adjusted odds ratio [aOR], 0.32; 95% confidence interval [CI], 0.12-0.89) but increased chronic lung disease (36 [73%] vs 25 [58%]; aOR, 3.34; 95% CI, 1.05-10.58) and increased death/chronic lung disease of borderline significance (39 [80%] vs 29 [67%]; aOR, 3.09; 95% CI, 0.99-9.63). Infants in epoch 2 took longer to wean off of positive pressure ventilation (28.5 vs 24 days after enrollment; aOR, 0.52; 95% CI, 0.31-0.85).

CONCLUSIONS

Late oral acetaminophen therapy for infants with persistent patent ductus arteriosus is associated with reduced surgical ligation but increased chronic lung disease. In light of a lack of improvement in clinical outcomes, the individual contributory effects of acetaminophen, surgical ligation, and prolonged exposure to patent ductus arteriosus require further study to define the optimal approach.

Patent ductus arteriosus, its treatments, and the risks of pulmonary morbidity

A persistent left-to-right shunt through a patent ductus arteriosus (PDA) increases the rate of hydrostatic fluid filtration into the lung's interstitium, impairs pulmonary mechanics, and prolongs the need for mechanical ventilation. In preclinical trials, pharmacologic PDA closure leads to improved alveolarization and minimizes the impaired postnatal alveolar development that is the pathologic hallmark of bronchopulmonary dysplasia (BPD). Although routine prophylactic treatment of a PDA on the day of birth does not appear to offer any more protection against BPD than delaying treatment for 2-3 days, recent evidence from quality improvement trials suggests that early pharmacologic treatment decreases the incidence of BPD compared with a treatment approach that exposes infants to a moderate-to-large PDA shunt for the first 7-10 days after birth. After the first week, routine pharmacologic treatment (compared with continued PDA exposure) no longer appears to alter the course of BPD development. Evidence from epidemiologic, preclinical, and randomized controlled trials demonstrate that early ductus ligation is an independent risk factor for the development of BPD.

Circulatory Insufficiency and Hypotension Related to the Ductus Arteriosus in Neonates

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

Mandatory Closure Versus Nonintervention for Patent Ductus Arteriosus in Very Preterm Infants

OBJECTIVE

To determine whether a nonintervention approach for treating hemodynamically significant patent ductus arteriosus (PDA) is associated with decreased mortality and/or morbidity compared with a mandatory closure approach in extremely low birth weight infants.

STUDY DESIGN

We reviewed the medical records of 178 infants of 23-26 weeks' gestational age with PDA, requiring ventilator treatment, and with hemodynamically significant PDA ≥2 mm in size. Mandatory closure was used during period I (July 2009 to December 2011, n = 81), and nonintervention was used during period II (January 2012 to June 2014, n = 97).

RESULTS

During period I, 64% of infants were first treated with indomethacin, and 82% were ultimately ligated surgically. During period II, no infant was treated with indomethacin and/or ligation. The average postnatal day of PDA closure was day 13 and day 44 during periods I and II, respectively. There was significantly more use of diuretics and fluid restriction during period II compared with period I. There was no difference in mortality or morbidities such as necrotizing enterocolitis or intraventricular hemorrhage. The incidence of bronchopulmonary dysplasia (BPD) and the propensity score adjusted OR of BPD were significantly lower during period II compared with period I.

CONCLUSIONS

Despite longer PDA exposure, nonintervention was associated with significantly less BPD compared with mandatory closure. Additional study is warranted to determine the benefits and risks of non-intervention for the hemodynamically significant PDA in extremely low birth weight infants.

Utility of large-animal models of BPD: chronically ventilated preterm lambs

This paper is focused on unique insights provided by the preterm lamb physiological model of bronchopulmonary dysplasia (BPD). Connections are also made to insights provided by the former preterm baboon model of BPD, as well as to rodent models of lung injury to the immature, postnatal lung. The preterm lamb and baboon models recapitulate the clinical setting of preterm birth and respiratory failure that require prolonged ventilation support for days or weeks with oxygen-rich gas. An advantage of the preterm lamb model is the large size of preterm lambs, which facilitates physiological studies for days or weeks during the evolution of neonatal chronic lung disease (CLD). To this advantage is linked an integrated array of morphological, biochemical, and molecular analyses that are identifying the role of individual genes in the pathogenesis of neonatal CLD. Results indicate that the mode of ventilation, invasive mechanical ventilation vs. less invasive high-frequency nasal ventilation, is related to outcomes. Our approach also includes pharmacological interventions that test causality of specific molecular players, such as vitamin A supplementation in the pathogenesis of neonatal CLD. The new insights that are being gained from our preterm lamb model may have important translational implications about the pathogenesis and treatment of BPD in preterm human infants.

Animal models of bronchopulmonary dysplasia. The preterm baboon models

Much of the progress in improved neonatal care, particularly management of underdeveloped preterm lungs, has been aided by investigations of multiple animal models, including the neonatal baboon (Papio species). In this article we highlight how the preterm baboon model at both 140 and 125 days gestation (term equivalent 185 days) has advanced our understanding and management of the immature human infant with neonatal lung disease. Not only is the 125-day baboon model extremely relevant to the condition of bronchopulmonary dysplasia but there are also critical neurodevelopmental and other end-organ pathological features associated with this model not fully discussed in this limited forum. We also describe efforts to incorporate perinatal infection into these preterm models, both fetal and neonatal, and particularly associated with Ureaplasma/Mycoplasma organisms. Efforts to rekindle the preterm primate model for future evaluations of therapies such as stem cell replacement, early lung recruitment interventions coupled with noninvasive surfactant and high-frequency nasal ventilation, and surfactant therapy coupled with antioxidant or anti-inflammatory medications, to name a few, should be undertaken.

Cyclooxygenase-2 inhibition partially protects against 60% O2 -mediated lung injury in neonatal rats

RATIONALE

Use of the anti-inflammatory agent dexamethasone in premature infants with bronchopulmonary dysplasia has been curtailed, and no alternative anti-inflammatory agents are approved for this use. Our objective was to use a neonatal rat model of bronchopulmonary dysplasia to determine if an highly selective cyclooxygenase-2 inhibitor, 5,5-dimethyl-3-(3-fluorophenyl)4-(4-methylsulfonyl)phenyl-2(5H)-furanone (DFU; 10 µg/g body weight), could prevent inflammatory cell influx and protect against lung injury.

METHODS

Neonatal rats exposed to air or 60% O2 for 14 days from birth either received daily i.p. injections of (i) vehicle or DFU or (ii) vehicle or an EP(1) receptor antagonist, SC-19220.

RESULTS

DFU attenuated the lung macrophage and neutrophil influx, prevented interstitial thickening and prevented the loss of peripheral blood vessels induced by 60% O2 , but did not protect against the variance in alveolar diameter induced by 60% O2 . Exposure to 60% O2 caused both an increase in lung prostaglandin E2 content and a reduction in lung mesenchymal cell mass which was reversed by DFU. Prostaglandin E2 binding to the EP(1) receptor inhibited DNA synthesis in cultures of lung fibroblasts in a dose dependent fashion. Treatment with SC-19220 attenuated the reduction in lung mesenchymal mass observed following exposure of rat pups to 60% O2 .

CONCLUSIONS

An highly selective cyclooxygenase-2 inhibitor is an effective anti-inflammatory substitute for dexamethasone for preventing phagocyte influx into the neonatal lung during 60% O2 -mediated lung injury, and can modify the severity of that injury.

Managing the patent ductus arteriosus: current treatment options

Optimal management of the patent ductus arteriosus (PDA) in the premature infant remains controversial. Despite considerable historical and physiological data indicating that a persistent PDA may be harmful, robust evidence of long-term benefits or harms from treatment is lacking. This has been equated to a lack of benefit but is also a reflection of the fact that most clinical trials were designed to assess the effects of short-term (2-8 days) rather than prolonged exposure to a PDA. No clinical trials have been designed to assess the effects of prolonged exposure of persistent PDA on morbidity and mortality of very premature infants in the era of antenatal corticosteroids, surfactant and non-invasive respiratory support. Further research is required, but new insights and novel therapies are evolving, which will allow greater individual patient assessment, understanding of risk and optimisation of treatment. In this paper, we review the current literature, evidence for treatment options, including a non-interventional approach, and research directions for infants <28 weeks' gestational age.

Altered lung development in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the main respiratory sequela of extreme prematurity. Its pathophysiology is complex, involving interactions between host and environment, likely to be significantly influenced by genetic factors. Thus, the clinical presentation and histological lesions have evolved over time, along with the reduction in neonatal injuries, and the care of more immature children. Impaired alveolar growth, however, is a lesion consistently observed in BPD, such that it is a key feature in BPD, and is even the dominant characteristic of the so-called "new" forms of BPD. This review describes the key molecular pathways that are believed to be involved in the genesis of BPD. Much of our understanding is based on animal models, but this is increasingly being enriched by genetic approaches, and long-term respiratory functional studies.

Bronchopulmonary dysplasia: clinical perspective

Since Northway's original description of BPD almost 45 years ago, the clinical presentation of BPD has evolved into a disease process, which mostly involves extremely premature infants. This new form of BPD is the result of multiple antenatal and postnatal factors that can cause injury to the developing lung leading to altered alveolar and vascular development. Over the years, there has been considerable increase in knowledge of factors that contribute to the development of BPD. This has led to different strategies for prevention as well as management of BPD. Some of these strategies have been successful and have withstood the test of clinical trials, such as vitamin A supplementation, post-natal steroids, caffeine, and volume targeted ventilation. The evidence for other interventions has been weak or negative. With better understanding of the complex and multifactorial pathogenesis of BPD, it is quite clear that any single therapy is very unlikely to eliminate this problem unless it reduces prematurity. Further development in prevention and treatment of BPD will likely need a multi-pronged strategy with novel therapeutic agents acting at various stages of the disease process.

Morbidity and mortality in preterm neonates with patent ductus arteriosus on day 3

OBJECTIVE

To assess the association between a patent ductus arteriosus (PDA) on day 3 of life and severe morbidity and mortality.

DESIGN

Cohort study.

SETTING

Neonatal Intensive Care Unit, Aarhus University Hospital, Denmark.

PATIENTS

All neonates with a gestational age less than 32 weeks admitted from 2010 to 2012.

INTERVENTIONS

All neonates (n=183) were routinely screened with echocardiography for PDA on day 3 of life. Information on baseline characteristics and outcome was collected by structured coding sheets and medical records.

MAIN OUTCOME MEASURES

The association among PDA diameter and pulmonary haemorrhage, intraventricular haemorrhage (IVH), necrotising enterocolitis, bronchopulmonary dysplasia (BPD), death, and the composite outcome of death or severe morbidity was assessed.

RESULTS

In neonates, born prior to 28 gestational weeks, a PDA on day 3 of life was associated with a threefold increase in odds of death or severe morbidity compared with neonates without PDA (OR=3.4; CI 1.1 to 11). The odds were highest in neonates with a large PDA (diameter ≥1.5 mm). Neonates with a large PDA were also found to have increased odds of IVH (OR 4.2; CI 1.3 to 14) and BPD (OR 3.7; CI 1.0 to 14) compared with neonates with no PDA.

CONCLUSIONS

In neonates born with a gestational age below 28 weeks the presence of a PDA on day 3 of life was associated with adverse outcome; this association was even more pronounced with a large PDA. Thus, early echocardiography may facilitate the identification of neonates suitable for a targeted approach to intervention in future randomised controlled trials.

The role of patent ductus arteriosus and its treatments in the development of bronchopulmonary dysplasia

A persistent left-to-right shunt through a patent ductus arteriosus (PDA) increases the rate of hydrostatic fluid filtration into the lung's interstitium, impairs pulmonary mechanics, and prolongs the need for mechanical ventilation. In preclinical trials, pharmacologic PDA closure leads to improved alveolarization and minimizes the impaired postnatal alveolar development that is the pathologic hallmark of the "new bronchopulmonary dysplasia (BPD)". Although early pharmacologic closure of the PDA decreases the incidence of pulmonary hemorrhage, intraventricular hemorrhage, and the need for PDA ligation, there is little evidence from controlled, clinical trials to support or refute a causal role for the PDA in the development of BPD. However, evidence from epidemiologic, preclinical, and randomized controlled clinical trials demonstrate that early ductus ligation is an independent risk factor for the development of BPD and may directly contribute to the neonatal morbidities it is trying to prevent.

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.

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.

Anesthesia and analgesia in the NICU

Painful procedures in the neonatal intensive care unit are common, undertreated, and lead to adverse consequences. A stepwise approach to treatment should include pain recognition, assessment, and treatment, starting with nonpharmacologic and progressing to pharmacologic methods for increasing pain. The most common nonpharmacologic techniques include nonnutritive sucking with and without sucrose, kangaroo care, swaddling, and massage therapy. Drugs used to treat neonatal pain include the opiates, benzodiazepines, barbiturates, ketamine, propofol, acetaminophen, and local and topical anesthetics. The indications, advantages, and disadvantages of the commonly used analgesic drugs are discussed. Guidance and references for drugs and dosing for specific neonatal procedures are provided.

MR imaging correlates of white-matter pathology in a preterm baboon model

INTRODUCTION

Cerebral white-matter (WM) abnormalities on magnetic resonance imaging (MRI) correlate with neurodevelopmental disability in infants born prematurely.

RESULTS

Quantitative histological measures of WM and ventricular volumes correlated with qualitative MRI scores of WM volume loss and ventriculomegaly. Diffuse astrocytosis was associated with signal abnormality on T(2)-weighted imaging and higher apparent diffusion coefficient in WM. Loss of oligodendrocytes was associated with lower relative anisotropy characterized by higher radial diffusivity values. The relationship between histopathology and MRI abnormalities was more pronounced in animals in the 28 d model, equivalent to the term human infant.

DISCUSSION

MRI reflects microstructural and anatomical abnormalities that are characteristic of WM injury in the preterm brain, and these changes are more evident on MRI at term-equivalent postmenstrual age.

METHODS

We assessed the histopathological correlates of MRI abnormalities in a baboon model of premature birth. Baboons were delivered at 125 d of gestation (dg, term ~185 dg) and maintained in an animal intensive care unit for 14 (n = 26) or 28 d (n = 17). Gestational control animals were delivered at 140 dg (n = 9) or 153 dg (n = 4). Cerebral WM in fixed brains was evaluated using MRI, diffusion tensor imaging (DTI), and histopathology.

Cardiovascular phenotype in extremely low birth weight infants: long-term consequences

Low birth weight, a possible consequence of prematurity at birth or intrauterine growth restriction, has been recently recognized as an emerging risk factor to develop cardiovascular (CV) future adverse events. Our aim was to perform a short review about the studies conducted in order to evaluate the CV risk profile of a specific subpopulation of infants suffering from low birth weight, that is those having a birth weight less than 1,000 g, called extremely low birth weight.

Relationship between circulating platelet counts and ductus arteriosus patency after indomethacin treatment

OBJECTIVE

To determine whether low platelet counts are related to the incidence of patent ductus arteriosus (PDA) after indomethacin treatment in preterm human infants.

STUDY DESIGN

Multivariable logistic regression modeling was used for a cohort of 497 infants, who received indomethacin (within 15 hours of birth).

RESULTS

Platelet counts were not related to the incidence of permanent closure after indomethacin constriction. There was a relationship between platelet counts and the initial degree of constriction; however, this relationship appeared to be primarily influenced by the high end of the platelet distribution curve. PDA incidence was similar in infants with platelet counts < 50 × 10⁹/L and those with platelet counts above this range. Only when platelet counts were consistently >230 ×10⁹/L was there a decrease in PDA incidence.

CONCLUSION

In contrast to the evidence in mice, low circulating platelet counts do not affect permanent ductus closure (or ductus reopening) in human preterm infants.

Patent ductus arteriosus ligation alters pulmonary gene expression in preterm baboons

Ibuprofen-induced ductus closure improves pulmonary mechanics and increases alveolar surface area in premature baboons compared with baboons with a persistent patent ductus arteriosus (PDA). Ibuprofen-treatment has no effect on the expression of genes that regulate pulmonary inflammation but does increase the expression of alpha-ENaC (the transepithelial sodium channel that is critical for alveolar water clearance). Although ligation eliminates the PDA, it does not improve pulmonary mechanics or increase alveolar surface area. We used preterm baboons (delivered at 67% of term gestation and ventilated for 14 d) to study whether the lack of beneficial effects, after PDA ligation, might be due to alterations in pulmonary gene expression. We found no differences in ventilation or oxygenation indices between animals that were ligated (n = 7) on day of life 6 and those that had a persistent PDA (n = 12) during the entire 14 d study. In contrast with no intervention, PDA ligation produced a significant increase in the expression of genes involved with pulmonary inflammation (COX-2, TNF-α, and CD14) and a significant decrease in alpha-ENaC sodium channel expression. We speculate that these changes may decrease the rate of alveolar fluid clearance and contribute to the lack of improvement in pulmonary mechanics after PDA ligation.

The effects of postnatal estrogen therapy on brain development in preterm baboons

OBJECTIVE

Estrogen receptors are present within the fetal brain, suggesting that estrogens may exert an influence on cerebral development. Loss of placentally derived estrogen in preterm birth may impair development.

STUDY DESIGN

Baboons were delivered at 125 days of gestation (term approximately 185 days), randomly allocated to receive estradiol (n = 10) or placebo (n = 8), and ventilated for 14 days. Brains were assessed for developmental and neuropathological parameters.

RESULTS

Body and brain weights were not different between groups, but the brain/body weight ratio was increased (P < .05) in estradiol-treated animals. There were no differences (P > .05) between groups in any neuropathological measure in either the forebrain or cerebellum. There were no intraventricular hemorrhages; 1 estradiol animal displayed ectactic vessels in the subarachnoid space.

CONCLUSION

Brief postnatal estradiol administration to primates does not pose an increased risk of injury or impaired brain development.

Risk factors for bronchopulmonary dysplasia in five Portuguese neonatal intensive care units

The pathogenesis of bronchopulmonary dysplasia (BPD) is clearly multifactorial. Specific pathogenic risk factors are prematurity, respiratory distress, oxygen supplementation, mechanical ventilation (MV), inflammation, patent ductus arteriosus (PDA), etc.

AIM

To evaluate BPD prevalence and to identify risk factors for BPD in five Portuguese Neonatal Intensive Care Units in order to develop better practices the management of these newborns.

MATERIAL AND METHODS

256 very low birth weight infants with gestational age (GA) <30 weeks and/or birthweight (BW) <1250 g admitted in five Portuguese NICUs, between 2004 and 2006 were studied. A protocol was filled in based on clinical information registered in the hospital charts. BPD was defined as oxygen dependency at 36 weeks of postconceptional age.

RESULTS

BPD prevalence was 12.9% (33/256). BPD risk decreased 46% per GA week and of 39% per 100g BW. BPD risk was significantly higher among newborns with low BW (adj OR= 0.73, 95% CI=0.57- 0.95), severe hyaline membrane disease (adj OR= 9.85, 95% CI=1.05-92.35), and those with sepsis (adj OR=6.22, 95% CI=1.68-23.02), those with longer duration on ventilatory support (42 vs 3 days, respectively in BPD and no BPD patients, p <0.001) and longer duration of FiO2>0.30 (85 vs 5 days, respectively in BPD and no BPD patients, p <0.001).

COMMENTS

The most relevant risk factors were low birth weight, severe hyaline membrane disease, duration of respiratory support and oxygen therapy, and nosocomial sepsis. The implementation of potentially better practices to reduce lung injury in neonates must be addressed to improve practices to decrease these risk factors.

Ibuprofen treatment for closure of patent ductus arteriosus is not associated with increased risk of neuropathology

Ibuprofen is an effective pharmacological intervention for closure of a patent ductus arteriosus (PDA) in preterm infants and is an alternative to surgical ligation; however, it is not certain whether ibuprofen treatment is associated with adverse effects on the brain. Therefore, this study examined neuropathological outcomes of ibuprofen therapy for a PDA. Fetal baboons were delivered at 125 d of gestation (dg; term ∼185 dg) by caesarean section, given surfactant, and ventilated for 14 d with positive pressure ventilation (PPV). Baboons were randomly allocated to receive either ibuprofen (PPV+ ibuprofen, n = 8) or no therapy (PPV, n = 5). Animals were killed on day 14 and brains assessed for cerebral growth, development, and neuropathology. Body and brain weights, the total volume of the brain, and the surface folding index (measure of brain growth) were not different (p > 0.05) between PPV+ ibuprofen-treated and PPV animals. There was no difference (p > 0.05) in the number of myelin basic protein-immunoreactive (IR) oligodendrocytes, glial fibrillary acid protein-IR astrocytes, or Iba1-IR macrophages/microglia in the forebrain. No overt cerebellar alterations were observed in either group. Ibuprofen treatment for PDA closure in the preterm baboon neonate is not associated with any increased risk of neuropathology or alterations to brain growth and development.

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.