The treatment of patent ductus arteriosus in preterm infants. A review and overview of randomized trials

Patent ductus arteriosus of the preterm infant

A persistently patent ductus arteriosus (PDA) in preterm infants can have significant clinical consequences, particularly during the recovery period from respiratory distress syndrome. With improvement of ventilation and oxygenation, the pulmonary vascular resistance decreases early and rapidly, especially in very immature infants with extremely low birth weight (<1000 g). Subsequently, the left-to-right shunt through the ductus arteriosus (DA) is augmented, thereby increasing pulmonary blood flow, which leads to pulmonary edema and overall worsening of cardiopulmonary status. Prolonged ventilation, with the potential risks of volutrauma, barotrauma, and hyperoxygenation, is strongly associated with the development and severity of bronchopulmonary dysplasia/chronic lung disease. Substantial left-to-right shunting through the ductus may also increase the risk of intraventricular hemorrhage, necrotizing enterocolitis, and death. Postnatal ductal closure is regulated by exposure to oxygen and vasodilators; the ensuing vascular responses, mediated by potassium channels, voltage-gated calcium channels, mitochondrial-derived reactive oxygen species, and endothelin 1, depend on gestational age. Platelets are recruited to the luminal aspect of the DA during closure and probably promote thrombotic sealing of the constricted DA. Currently, it is unclear whether and when a conservative, pharmacologic, or surgical approach for PDA closure may be advantageous. Furthermore, it is unknown if prophylactic and/or symptomatic PDA therapy will cause substantive improvements in outcome. In this article we review the mechanisms underlying DA closure, risk factors and comorbidities of significant DA shunting, and current clinical evidence and areas of uncertainty in the diagnosis and treatment of PDA of the preterm infant.

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

Medical and surgical interventions are widely used to close a persistently patent ductus arteriosus in preterm infants. Objective evidence to support these practices is lacking, causing some to question their usage. Emerging evidence suggests that treatments that close the patent ductus may be detrimental. This review examines the history of and evidence underlying these treatments. Neither individual trials, pooled data from groups of randomized-controlled trials, nor critical examination of the immediate consequences of treatment provide evidence that medical or surgical closure of the ductus is beneficial in preterm infants. These conclusions are supported by sufficient evidence. Neither continued routine use of these treatments nor additional clinical trials using similar designs seems to be justified. A definitive trial, comparing current standard management with novel strategies not primarily intended to achieve ductal closure, may be necessary to resolve doubts regarding the quality or conduct of prior studies.

Cardiac and plasma lipid profiles in response to acute hypoxia in neonatal and young adult rats

Background

The physiological and biochemical responses to acute hypoxia have not been fully characterized in neonates. Fatty acids and lipids play an important role in most aspects of cardiac function.

Methods

We performed comprehensive lipid profiling analysis to survey the changes that occur in heart tissue and plasma of neonatal and young adult rats exposed to hypoxia for 2 h, and following 2 h of recovery from hypoxia.

Results

Cardiac and plasma concentrations of short-chain acylcarnitines, and most plasma long-chain fatty acids, were decreased in hypoxic neonates. Following recovery from hypoxia, concentrations of propionylcarnitine, palmitoylcarnitine, stearoylcarnitine were increased in neonatal hearts, while oleylcarnitine and linoleylcarnitine concentrations were increased in neonatal plasma. The concentrations of long-chain fatty acids and long-chain acylcarnitines were increased in the hearts and plasma of hypoxic young adult rats; these metabolites returned to baseline values following recovery from hypoxia.

Conclusion

There are differential effects of acute hypoxia on cardiac and plasma lipid profiles with maturation from the neonate to the young adult rat. Changes to neonatal cardiac and plasma lipid profiles during hypoxia likely allowed for greater metabolic and physiologic flexibility and increased chances for survival. Persistent alterations in the neonatal cardiac lipid profile following recovery from hypoxia may play a role in the development of rhythm disturbances.

Humanistic therapies versus other psychological therapies for depression

This is the protocol for a review and there is no abstract. The objectives are as follows: To examine the effectiveness and acceptability of all humanistic therapies compared with all other psychological therapy approaches for acute depression.To examine the effectiveness and acceptability of different humanistic therapy models (person-centred, gestalt, process-experiential, transactional analysis, existential and non-directive therapies) compared with all other psychological therapy approaches for acute depression.To examine the effectiveness and acceptability of all humanistic therapies compared with different psychological therapy approaches (psychodynamic, behavioural, humanistic, integrative, cognitive-behavioural) for acute depression.

Prevention of bronchopulmonary dysplasia

Considerable effort has been devoted to the development of strategies to reduce the incidence of bronchopulmonary dysplasia (BPD), including use of medications, nutritional therapies, and respiratory care practices. Unfortunately, most of these strategies have not been successful. To date, the only two treatments developed specifically to prevent BPD whose efficacy is supported by evidence from randomized, controlled trials are the parenteral administration of vitamin A and corticosteroids. Two other therapies, the use of caffeine for the treatment of apnea of prematurity and aggressive phototherapy for the treatment of hyperbilirubinemia, were evaluated for the improvement of other outcomes and found to reduce BPD. Cohort studies suggest that the use of continuous positive airway pressure as a strategy for avoiding mechanical ventilation might also be beneficial. Other therapies reduce lung injury in animal models but do not appear to reduce BPD in humans. The benefits of the efficacious therapies have been modest, with an absolute risk reduction in the 7-11% range. Further preventive strategies are needed to reduce the burden of this disease. However, each will need to be tested in randomized, controlled trials, and the expectations of new therapies should be modest reductions of the incidence of the disease.

Anomalous left coronary artery from the pulmonary artery in a preterm infant: presentation after ligation of ductus arteriosus

Surgical or medical closure of a patent ductus arteriosus (PDA) is a very common practice in premature infants in the neonatal intensive care unit, but often the coronary arteries are not delineated prior to closure. In this report, a 32-week gestational age premature infant who underwent surgical ligation of a PDA developed new-onset left ventricular systolic dysfunction. A repeat echocardiogram noted an anomalous left coronary artery from the pulmonary artery. Successful left coronary artery reimplantation with rapid normalization of left ventricular systolic function occurred. As previously not reported, ligation of a PDA in a premature infant can unmask anomalous left coronary artery from the pulmonary artery. Surgical left coronary artery reimplantation is the mainstay of therapy and should be performed to establish normal coronary blood flow, even in a premature, low birth weight infant.

Retinopathy of prematurity

This article briefly reviews the history of ROP followed by a discussion of the pathogenesis of this complex disorder. We describe the International Classification System for ROP and identify risk factors and screening recommendations. Finally, we discuss some of the measures that have been used in an attempt to both prevent and treat ROP.

Renal impairment associated with indomethacin treatment for patent ductus arteriosus in extremely preterm neonates—is postnatal age at start of treatment important?

OBJECTIVE

To study serum creatinine (SCr) levels following indomethacin for patent ductus arteriosus (PDA) closure in extremely preterm neonates in relation to postnatal age at the start of treatment.

METHODS

This was a retrospective (January 2000-December 2002) analysis of data on preterm neonates (gestation <29 weeks) who received indomethacin for PDA. Pre-existing renal malformation and/or impairment and high serum levels of nephrotoxic drugs were criteria for exclusion.

RESULTS

Indomethacin was commenced at postnatal age <7 days and >or=7 days in 60 (group 1) and 30 (group 2) neonates, respectively. The median (Q1, Q3) gestational age and birth weight for group 1 and group 2 neonates were 25 (23, 27) vs. 25 (24, 26) weeks and 740 (620, 909) vs. 780 (663, 966) grams, respectively. Postnatal age <7 days at start of indomethacin was associated with higher baseline (0.083 (0.074, 0.090) vs. 0.073 (0.054, 0.083) mmol/L, p=0.001) and peak SCr levels (0.099 (0.089,0.109) vs. 0.090 (0.064, 0.104) mmol/L, p=0.015). Logistic regression analysis controlling for gestational age and baseline SCr level indicated that postnatal age >or=7 days was a risk factor for elevated SCr after indomethacin (OR=13.4, 95% CI: 3.8-46.6, p < 0.001).

CONCLUSION

Postnatal age >or=7 days at the start of indomethacin is a predictor of a significant rise in SCr in extremely preterm neonates.

Renal effects of ibuprofen for the treatment of patent ductus arteriosus in premature infants

In recent years ibuprofen has been proposed for the treatment of patent ductus arteriosus (PDA) as it has been proved to be equally as effective as indomethacin and shows fewer cerebral blood flow, intestinal and renal hemodynamic effects. A number of studies and several meta-analyses comparing both drugs are now available that debate whether indomethacin or ibuprofen should be used for PDA prophylaxis or closure. This review examines the available knowledge on the specific issue of the effects of ibuprofen on kidney function, as improved renal tolerance is a major argument in favor of its use in the routine treatment of PDA. There is sufficient evidence to consider that ibuprofen, at the currently proposed dosing regimen, has a similar efficacy to indomethacin but is better tolerated by the neonatal kidney when employed for the treatment of established PDA. However, adverse effects of ibuprofen have been evidenced both in trials on the use of ibuprofen for the prevention of PDA and of intraventricular hemorrhage-periventricular hemorrhage (IVH-PVH), and in experimental studies on a neonatal, anesthetized animal model. Thus ibuprofen, as with other cyclooxygenase (COX) inhibitors, may not be exempt from causing renal adverse effects, especially in circumstances when renal prostaglandin activation is maximal (i.e., when administrated early after birth, in more immature patients and in certain situations such as in the anesthetized rabbit). However, although the issue has been addressed extensively in the last decades, there is insufficient evidence that therapeutic intervention in PDA is beneficial in terms of mortality or clinically significant morbidity outcomes. Studies aimed at resolving this key issue are still needed.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Furosemide in preterm infants treated with indomethacin for patent ductus arteriosus

OBJECTIVE

To evaluate the effect of furosemide on renal function and water balance in preterm infants treated with indomethacin (3 x 0.2 mg/kg at 12-h intervals) for symptomatic patent ductus arteriosus.

PATIENTS AND METHODS

We performed a retrospective multi-centre double cohort study in preterm infants <32 weeks of gestational age. Thirty-two infants treated with furosemide (1 mg/kg i.v.) before each indomethacin dose (furosemide group) were matched with 32 infants with indomethacin treatment alone (control-group). Renal effects (urine output, weight gain, serum creatinine, sodium concentration) were registered.

RESULTS

The study groups were comparable for gestational age, birth weight and day of therapy. Pretreatment differences were observed for urine output, weight and serum sodium. However, no differences were noticed in day-to-day urine output change or weight gain between the groups. A significant increase in serum creatinine concentration (50% vs. control, 18%; p < 0.05) and a concomitant significant decrease in serum sodium (-9 vs. control, -3 mmoL/L; p < 0.05) in the furosemide group was observed 72-96 h after starting therapy.

CONCLUSION

Furosemide before each indomethacin dose resulted in a significant increase in serum creatinine and hyponatremia, without increasing urine output.

The management of patent ductus arteriosus in Australia and New Zealand

AIM

This study aimed to establish current management practice for patent ductus arteriosus (PDA) among individual consultant neonatologists in Australia and New Zealand, to examine the influences that drives practice and highlight the importance of future randomised controlled trials in the region.

METHODS

Eligible subjects were identified from the Directory of Neonatal Intensive Care Units in Australia and New Zealand, 2007. A questionnaire was sent online to each consultant and was followed up with a letter and telephone call. Seven questions addressed management approach, the drug used and the treatment regimen, threshold for referral for surgical ligation and the literature influencing practice. Data were collected from 22 August 2007 to 22 November 2007.

RESULTS

The overall response rate was 95%. For infants < or =28 weeks or < or =1000 g, all consultants treat PDA by one of four distinct management approaches. Expectant management was favoured by 35%, echocardiographic targeted prophylaxis 32%, presymptomatic treatment 16% and prophylaxis by 17%. There were marked regional variations in practice. Within individual units, more than one approach is used in 14 out of 24 units. Long courses of indomethacin are used to treat PDA by 86%. For 22% of consultants, management is not influenced by published literature.

CONCLUSIONS

Differences of opinion in the literature are reflected by the heterogeneity in clinical practice across regions and within units. Crucial questions undergoing evaluation are whether data extrapolated from a previous area are relevant to PDA in modern neonatology and whether targeting treatment early can translate to improved clinical outcome.

Therapeutic management of patent ductus arteriosus

Management of patent ductus arteriosus (PDA) in premature neonates has always been a challenge to the neonatologist and continues to be a controversial topic. Indications for treatment are not clear. Approximately 40% of ductus arteriosus close spontaneously even in extremely-low-birth-weight neonates. Prophylactic or early pre-symptomatic treatment may unnecessarily expose these babies, in whom the ductus might close spontaneously, to pharmacologic agents and their adverse effects. On the other hand, with advancing postnatal age, delaying treatment could potentially decrease successful medical closure thereby increasing the rate of surgical ligation and the complications associated with surgery. We tried to develop some clinical guidelines for management of PDA in premature neonates based on evidence, or lack thereof, and experience.

Clinical and echocardiographic diagnosis of patent ductus arteriosus in premature neonates

The ductus arteriosus frequently fails to close in premature neonates. Considerable difference in opinion exists around what signifies a hemodynamically significant patent ductus arteriosus (PDA) and how reliable clinical signs are in determining the degree of the left-to-right shunting. Although reliance on clinical signs alone could delay the diagnosis of a PDA, there is insufficient evidence to suggest that early treatment improves outcome. Echocardiography is often used as the gold standard for diagnosing a PDA. A combination of echocardiographic measurements may assist in the early diagnosis of a PDA with a hemodynamically significant degree of left-to-right shunting, especially in extremely premature babies, where closure can be significantly delayed. Decision to treat PDA should be based on a combination of clinical signs and echocardiographic parameters. Monitoring B-type natriuretic peptide may be useful in the diagnosing neonates with symptomatic PDA.

Hypotension in preterm infants with significant patent ductus arteriosus: effects of dopamine

OBJECTIVE

To study the effects of dopamine on systemic arterial pressure (SAP) and systemic blood flow (SBF) (estimated with the superior vena cava [SVC] flow) in preterm infants with hypotension and patent ductus arteriosus (PDA).

STUDY DESIGN

Clinical and echocardiographic variables were measured before and 2 hours after starting dopamine in premature infants <32 weeks gestational age with PDA and systemic hypotension.

RESULTS

Seventeen premature infants were included (gestational age, 28+/-2 weeks; birth weight, 1030 +/- 400 g). A mean rate of 8 +/- 2 microg/kg/min of dopamine raised SAP from 30 +/- 3 to 41 +/- 5 mm Hg (P < .05), and the pulmonary artery pressures from 25 +/- 5 to 32 +/- 8 mm Hg (P < .05). The SVC flow increased by 30% (from 130 +/- 40 to 170 +/- 44 mL/kg/min; P < .05). The left ventricular output and the end-diastolic and mean left pulmonary artery blood flow velocities did not change despite the increase in pulmonary artery pressure.

CONCLUSION

In preterm infants with hypotension and PDA, dopamine (<10 microg/kg/min) increases the systemic blood pressure and the systemic blood flow. Our results suggest that dopamine decreases left-to-right shunting across ductus arteriosus, caused by a rise in pulmonary vascular resistances.

Development of the ACTH and corticosterone response to acute hypoxia in the neonatal rat

Acute episodes of severe hypoxia are among the most common stressors in neonates. An understanding of the development of the physiological response to acute hypoxia will help improve clinical interventions. The present study measured ACTH and corticosterone responses to acute, severe hypoxia (8% inspired O(2) for 4 h) in neonatal rats at postnatal days (PD) 2, 5, and 8. Expression of specific hypothalamic, anterior pituitary, and adrenocortical mRNAs was assessed by real-time PCR, and expression of specific proteins in isolated adrenal mitochondria from adrenal zona fascisulata/reticularis was assessed by immunoblot analyses. Oxygen saturation, heart rate, and body temperature were also measured. Exposure to 8% O(2) for as little as 1 h elicited an increase in plasma corticosterone in all age groups studied, with PD2 pups showing the greatest response ( approximately 3 times greater than PD8 pups). Interestingly, the ACTH response to hypoxia was absent in PD2 pups, while plasma ACTH nearly tripled in PD8 pups. Analysis of adrenal mRNA expression revealed a hypoxia-induced increase in Ldlr mRNA at PD2, while both Ldlr and Star mRNA were increased at PD8. Acute hypoxia decreased arterial O(2) saturation (SPo(2)) to approximately 80% and also decreased body temperature by 5-6 degrees C. The hypoxic thermal response may contribute to the ACTH and corticosterone response to decreases in oxygen. The present data describe a developmentally regulated, differential corticosterone response to acute hypoxia, shifting from ACTH independence in early life (PD2) to ACTH dependence less than 1 wk later (PD8).

Acute hemodynamic decompensation following patent ductus arteriosus ligation in premature infants

INTRODUCTION

Patent ductus arteriosus (PDA) ligation can lead to postoperative hemodynamic instability requiring inotropic support, termed hemodynamic decompensation. The purpose of this study was to prospectively determine the incidence, predictors, and clinical impact of hemodynamic decompensation after PDA ligation in preterm infants.

METHODS

All infants undergoing PDA ligation were eligible for this prospective cohort study. After undergoing ligation, patients were followed until 30 days after successful extubation, discharge from the NICU, or death. Data collection included perinatal and preoperative clinical information, operative details, postoperative course, and outcome.

RESULTS

Ninety-six preterm infants were enrolled and underwent PDA ligation. Hemodynamic decompensation occurred in 27 patients (28%). Overall in-hospital mortality rate was 18%. Mortality was significantly higher among infants that developed hemodynamic decompensation (33% vs 11%, p = .012). Hemodynamic decompensation was associated with an adjusted odds ratio (OR) for death of 3.1 (95% confidence interval: 1.0-9.5, p = .05). Lower estimated gestational age, lower corrected age, and higher rate of preoperative mechanical ventilation were significant predictors of hemodynamic decompensation.

CONCLUSION

Hemodynamic decompensation occurred in 28% of patients after PDA ligation, resulting in a significantly higher mortality. Younger patients requiring higher ventilator support are most likely to develop hemodynamic decompensation.

Risk factors for acute retinopathy of prematurity

We prospectively studied the risk factors and the incidence of retinopathy of prematurity (ROP) in 195 consecutive preterm infants. Birth weight and duration of mechanical ventilation were the only factors that were significantly associated with the incidence of ROP. While indomethacin increases the risk of developing ROP, maternal antenatal steroids have a protective effect against the development of severe stages of ROP. The presence of intraventricular hemorrhage increases the risk of severe ROP.

Patent ductus arteriosus: lack of evidence for common treatments

Patent ductus arteriosus (PDA) is a common diagnosis among extremely premature infants, especially in those with lung disease. Treatments are often used to close the PDA. Despite nearly three decades of research, the question of whether the benefits of treatments to prevent ductal patency or promote closure outweigh the risks of these treatments remains unanswered. The authors rarely use treatments designed to close the PDA. This article reviews three considerations in support of this restrained approach: rates of spontaneous closure of the ductus arteriosus; adverse effect of persistent ductal patency; and benefits and risks of treatments for closure.

European consensus guidelines on the management of neonatal respiratory distress syndrome

Despite recent advances in the perinatal management of neonatal respiratory distress syndrome (RDS), controversies still exist. We report the recommendations of a European panel of expert neonatologists who developed consensus guidelines after critical examination of the most up-to-date evidence in 2007. Strong evidence exists for the role of antenatal steroids in RDS prevention, but it is not clear if repeated courses are safe. Many practices involved in preterm neonatal stabilization at birth are not evidence based, including oxygen administration and positive pressure lung inflation, and they may at times be harmful. Surfactant replacement therapy is crucial in management of RDS but the best preparation, optimal dose and timing of administration at different gestations is not always clear. Respiratory support in the form of mechanical ventilation may also be life saving but can cause lung injury, and protocols should be directed to avoiding mechanical ventilation where possible by using nasal continuous positive airways pressure. For babies with RDS to have the best outcome, it is essential that they have optimal supportive care, including maintenance of a normal body temperature, proper fluid management, good nutritional support, management of the ductus arteriosus and support of the circulation to maintain adequate blood pressure.

Conservative treatment for patent ductus arteriosus in the preterm

BACKGROUND

A patent ductus arteriosus (PDA) is common among preterms, and prophylactic medical treatment has been advocated as the first-line approach. Conservative treatment may result in similar outcome, but without exposure to the harmful side effects of medication. A retrospective analysis revealed a ductal closure rate of 94% after conservative treatment with adjustment of ventilation (lowering the inspiratory time and increasing positive end expiratory pressure) and fluid restriction.

OBJECTIVE

To study prospectively over one year the rate of PDA closure, and morbidity and mortality following conservative treatment.

METHOD

Prospective study (1 January 2005 - 31 December 2005) including 30 newborns <or=30 weeks' gestation, all of whom were being ventilated and required surfactant. Echocardiography was performed 48-72 h after birth. Clinically important PDA was conservatively treated as described above. The percentage of children with PDA, ductal ligation and major complications was determined.

RESULTS

Ten neonates (33%) developed a clinical important PDA. Following conservative treatment the duct closed in all neonates (100%), and none required ductal ligation or medical treatment. The rates of major complications were no higher than those reported by the Vermont Oxford Network and in the literature.

CONCLUSION

The managed care plan resulted in an overall ductal closure rate of 100%. These results suggest that conservative treatment of PDA is a worthy alternative to prophylactic medical treatment.

Clinical considerations for the pharmacologic management of patent ductus arteriosus with cyclooxygenase inhibitors in premature infants

When medical management is warranted for closure of a persistent patent ductus arteriosus (PDA) in premature infants, treatment with a cyclooxygenase (COX) inhibitor is indicated. Indomethacin, available since 1976, has been the conventional pharmacologic treatment for PDA, but its use is associated with vasoconstrictive effects that impair renal, mesenteric and cerebral blood flow. Intravenous (IV) ibuprofen lysine, approved in the United States in 2006, has less severe vasoconstrictive effects on these vital organs than IV indomethacin. Clinical trials have shown both of these COX inhibitors to be equally effective in closing the PDA in approximately 70%-80% of treated infants, with less vasoconstrictive and adverse renal effects occurring with IV ibuprofen lysine.1,2 Several clinical considerations are important in the process of medical decision-making when faced with the need for PDA treatment with one of these pharmacologic agents in the premature infant. This paper focuses on these clinical considerations, including cerebral, renal and mesenteric blood flow, renal function, pulmonary effects, protein-binding capacity as it relates to hyperbilirubinemia, and platelet aggregation. No differences in chronic lung disease, pulmonary hypertension, hyperbilirubinemia and coagulopathy were observed in clinical trials when comparing these 2 COX inhibitors; however, significant differences have been observed in arterial blood flow to the cerebral, renal and mesenteric organs, suggesting that IV ibuprofen lysine may be the more favorable agent.

Risk factors for acute retinopathy of prematurity

We prospectively studied the risk factors and the incidence of retinopathy of prematurity (ROP) in 195 consecutive preterm infants. Birth weight and duration of mechanical ventilation were the only factors significantly associated with the incidence of ROP. While indomethacin increases the risk of developing ROP, maternal antenatal steroids have a protective effect against the development of severe stages of ROP. The presence of intraventricular hemorrhage increases the risk of severe ROP.

Effect of indomethacin on closure of ductus arteriosus in very-low-birthweight neonates

AIM

To identify factors related to indomethacin non-responsiveness for patent ductus arteriosus (PDA) closure in very-low-birthweight (VLBW) neonates.

METHODS

A chart review of 107 VLBW neonates with a clinical diagnosis of PDA who received indomethacin, admitted to a tertiary neonatal intensive care unit in Toronto, Canada, was conducted (study period November 2001 to October 2003). Positive responders were those with no clinical evidence of PDA for 72 h after indomethacin.

RESULTS

Response to the first course of indomethacin was 75%, and to the second course 67% among initial responders. Higher CRIB score (OR 1.15, 95% CI 1.02-1.31) and early surfactant administration (OR 3.74, 95% CI 1.04-13.47) were associated with non-responsiveness to indomethacin.

CONCLUSION

Indomethacin is effective for PDA closure. The response rate diminished with subsequent courses. Early surfactant and severity of illness at admission were associated with non-responsiveness to indomethacin.

Management of the neonate with patent ductus arteriosus

Care of the preterm infant with a suspected or confirmed diagnosis of patent ductus arteriosus (PDA) is a frequent challenge for the neonatal nurse. Management of term infants with cardiac lesions dependent upon a PDA can be even more challenging. It is vital for neonatal nurses to understand the normal cardiovascular and pulmonary changes that occur at birth so they can anticipate pathological processes influencing the clinical course of an infant with a PDA. In addition, knowledge of current and effective treatment approaches is essential to providing optimal care for these vulnerable infants, as well as in guiding their parents. The purpose of this article is to review current information about PDA, including physiology, pathophysiology, pharmacological approaches, surgical considerations, complications and outcomes, parental support, and areas for future research.

Outcome following patent ductus arteriosus ligation in premature infants: a retrospective cohort analysis

Background

The patent ductus arteriosus (PDA) is an important problem in premature infants. Surgical PDA ligation is usually only be considered when medical treatment has either failed or was contraindicated. The aims of our study were to determine the mortality and morbidity following patent ductus arteriosus ligation in premature infants, and whether prostaglandin synthetase inhibitor (PSI) use prior to ligation affects outcome.

Methods

A retrospective case note review study to determine the outcome of premature infants undergoing patent ductus arteriosus ligation in one tertiary neonatal intensive care unit and two paediatric cardiothoracic centres.

Results

We had follow-up data on 87 infants. Cumulative mortality rates at 7 days, 30 days and at hospital discharge were 2%, 8% and 20% respectively. The incidence of chronic lung disease, intraventricular haemorrhage, necrotising enterocolitis and retinopathy of prematurity were 77%, 39%, 26% and 28% respectively. There was no difference in mortality, incidence of chronic lung disease or duration of oxygen dependence between those who had and those who had not received a PSI prior to surgical ligation. In those who had received 2 or more courses of PSI prior to surgical ligation, there was a trend to increase in the duration of oxygen therapy and chronic lung disease, but no difference in mortality.

Conclusion

This study shows that patent ductus arteriosus ligation is a relatively safe procedure (30 day survival 92%) but there is substantial late mortality and a high incidence of morbidity in the survivors. 2 or more courses of PSI prior to surgical ligation trends to increased oxygen dependence and chronic lung disease. This high risk population requires careful follow-up. A definitive prospective cohort study is lacking.

Echocardiographic and Doppler characteristics of postoperative ductal aneurysm in a dog

A patent ductus arteriosus (PDA) was detected in a 10-month-old Pyrenean Shepherd. The PDA was occluded with hemostatic clips. One month after surgery, an aneurysmal dilatation of the ductus was diagnosed using Doppler echocardiography. The authors present the echo-Doppler findings and the follow-up of the ductus aneurysm. The pathogenesis and significance of such an aneurysm are discussed.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Cerebral hemodynamic change and intraventricular hemorrhage in very low birth weight infants with patent ductus arteriosus

The aims of this study were to assess the hemodynamics of the cerebral arteries and intraventricular hemorrhage in very-low-birthweight (VLBW) infants with and without patent ductus arteriosus (PDA) by cranial Doppler sonography. VLBW infants with significant PDA were recruited into the study (sPDA) group. Arterial blood gas analysis and complete blood counts were done near the time of the cranial sonography examination. Mechanical ventilator settings and daily fluid intake were recorded. The cranial Doppler sonographic examinations were repeated after PDA closure by indomethacin therapy and/or surgical ligation. A total of 40 preterm infants fulfilled the criteria of the study group. Another 37 preterm infants were recruited into a control group. Mean birth weight and gestational age did not differ significantly between the two groups. Differences in heart rate, blood pH, pCO2, pO2, use of surfactant therapy, mean airway pressure, ventilation index and FiO2 were statistically significant. In the sPDA group before closure of the PDA, the left atrial diameter/aorta diameter ratio demonstrated a positive relationship with resistance index (RI) and an inverse relationship with end diastolic velocities (Vd). After closure of the PDA, these changes neared those of the control group. The overall incidence of intraventricular hemorrhage (IVH) was higher in the sPDA than in the control group. There was no statistical difference in the grading and severity of IVH between the two groups. However, all preterm infants with severe IVH were found in the sPDA group, and their RIs were all higher than 0.80. Cranial Doppler sonography can be a useful tool to evaluate cerebral hemodynamic changes in VLBW infants with sPDA. Increased RI and decreased Vd of the cerebral artery may indicate a probable sPDA, and normalization of the RI and Vd may suggest closure of the sPDA.

Perinatal and postnatal factors in very preterm infants and subsequent cognitive and motor abilities

BACKGROUND

Many children born very preterm have cognitive and minor motor problems later, even if attending mainstream schools.

OBJECTIVE

To examine associations between this suboptimal performance and perinatal and postnatal clinical factors.

PARTICIPANTS AND METHODS

A geographically determined cohort of 280 infants born at less than 32 weeks gestation in 1991-92 in Liverpool, free of major disability and attending mainstream school at 7 years of age. A perinatal and postnatal data set were obtained from the clinical records retrospectively. Measurements of height, weight, and head circumference at 7 years were made, together with assessments of intelligence (Wechsler intelligence scale for children, IQ) and motor impairment (Movement assessment battery for children, MABC).

RESULTS

Multiple regression analysis showed IQ at 7 years to be independently significantly related to gestation, persistence of the arterial duct (PDA), and head circumference at 7 years. MABC was only significantly related to gestation. PDA was related to periventricular haemorrhage (OR 2.7, 95% confidence interval (CI) 1.3 to 5.8) and parenchymal lesions including ventriculomegaly (OR 4.1, 95% CI 1.5 to 11.4).

CONCLUSION

Cognitive ability in children born preterm is significantly related to gestation, but may also be related to the effects of PDA on early brain development, through either periventricular haemorrhage/ventriculomegaly or other disturbance of early brain growth.

Prophylactic ibuprofen versus placebo in very premature infants: a randomised, double-blind, placebo-controlled trial

BACKGROUND

Patent ductus arteriosus is a common complication of prematurity that frequently requires surgical or medical treatment. The benefit of prophylactic treatment by indometacin, a cyclo-oxygenase inhibitor, remains uncertain compared with curative treatment. This benefit could be improved with ibuprofen, another cyclo-oxygenase inhibitor with fewer adverse effects than indometacin on renal, mesenteric, and cerebral perfusion. We aimed to compare prophylactic and curative ibuprofen in the treatment of this abnormality in very premature infants.

METHODS

We did a randomised controlled trial in infants younger than 28 weeks of gestation, who were randomly assigned to receive either three doses of ibuprofen or placebo within 6 h of birth. After day 3, symptomatic patent ductus arteriosus was treated first by open curative ibuprofen, then back-up indometacin, surgery, or both. The primary endpoint was need for surgical ligation. Analysis was per protocol.

FINDINGS

The study was stopped prematurely after 135 enrollments because of three cases of severe pulmonary hypertension in the prophylactic group. 65 infants received prophylactic ibuprofen, and 66 received placebo. Prophylaxis reduced the need for surgical ligation from six (9%) to zero (p=0.03), and decreased the rate of severe intraventricular haemorrhage from 15 (23%) to seven (11%) (p=0.10). However, survival was not improved (47 [71%] placebo vs 47 [72%] treatment, p=1.00), because of high frequency of adverse respiratory, renal, and digestive events.

INTERPRETATION

In premature infants, prophylactic ibuprofen reduces the need for surgical ligation of patent ductus arteriosus, but does not reduce mortality or morbidity. Therefore, it should not be preferred to early curative ibuprofen.

Patency of the ductus arteriosus in the premature infant: is it pathologic? Should it be treated?

PURPOSE OF REVIEW

The ductus arteriosus is a vessel that connects the pulmonary artery to the aorta and provides a pulmonary-to-systemic diversion during fetal life. In the vast majority of infants, the ductus arteriosus closes by 3 days of life. In some infants, especially preterm infants with lung disease, there is delayed closure of the ductus arteriosus. There has been controversy as to whether or when the ductus arteriosus should be closed by either pharmacologic or surgical methods.

RECENT FINDINGS

There have been several epidemiologic studies describing an association between a patent ductus arteriosus and the development of morbidities, such as chronic lung disease. These associations have suggested to some that a causal relationship exists between patency of the ductus arteriosus and chronic lung disease and other morbidities. However, recent metaanalyses of randomized, controlled trials of the use of indomethacin for the prevention and treatment of the patent ductus arteriosus have not documented a decrease in the incidence of these morbidities after treatment, despite success in closure of the patent ductus arteriosus.

SUMMARY

In preterm infants, patency of the ductus arteriosus may represent a normal physiologic adaptation to allow shunting from either systemic-to-pulmonary circulation (eg, in the first day of life) or from pulmonary-to-systemic circulation (eg, in the presence of severe lung disease). Therapies designed to close the ductus arteriosus are contraindicated in some settings and should not be considered a standard of care at any time until these therapies are proven to decrease long-term clinical morbidities in randomized, placebo-controlled trials.

Necrosis of the epididymis in a premature infant with patent ductus arteriosus and diastolic aortic steal: ischemia or torsion?

We describe a case of isolated ischemic necrosis of the epididymis in a premature newborn with aortic steal syndrome, secondary to a large patent ductus arteriosus (PDA). Neither this finding nor the possible underlying pathogenesis has been previously described.

CONCLUSION

In this report our knowledge of the potential complications of PDA in the premature neonate is extended.

Nonsteroidal anti-inflammatory agents in neonates

The use of NSAIDs has become routine for adults and children in the management of pain. NSAIDs (other than aspirin [acetylsalicylic acid]) are also enjoying greater popularity as antipyretics since the recognition of Reye's syndrome's putative association with aspirin. In neonates, NSAIDs have been used for many years in an attempt to pharmacologically close the ductus arteriosus. This review examines the various NSAIDs and their potential and real applications in the neonatal population. For completeness, acetaminophen (paracetamol), which has weak NSAID activity and is a widely used analgesic and antipyretic in this patient group, was also included. The prostaglandin system is important for healthy development, and conversely there are unique risks posed by pharmacologic interference with this system in the neonatal period. The prostanoid system in neonates has the capacity to modulate nociception, but comes at the expense of interfering with nearly every organ system. Physiologic effects of inhibition of prostaglandin synthesis applicable to neonates include disruption of the sleep cycle, increased risk of pulmonary hypertension, alterations in cerebral blood flow, decreased renal function, disrupted thermoregulation, and alterations in hemostasis balance, among others. Prostaglandins are also important for the normal development of the central nervous, cardiovascular, and renal systems, and there is evidence that the proper genesis of these systems may be adversely effected by NSAID exposure in utero and in the neonatal period. Gastrointestinal adverse effects have provided the impetus for the development and marketing of selective cyclo-oxygenase type 2 (COX-2) inhibitors. These agents' reputation for safety in adults may not be applicable to neonates. COX-2 is involved in the development of several organ systems, and its inhibition may induce a prothrombotic state. The advent of parenteral formulations of cyclo-oxygenase inhibitors, including COX-2-selective agents, increases the therapeutic flexibility of NSAIDs. However, objective data on the safety of these agents have not kept pace with their clinical availability.

Tolerance to early human milk feeding is not compromised by indomethacin in preterm infants with persistent ductus arteriosus

AIM

Early human milk feeding is beneficial for gut and brain development. Persistent ductus arteriosus (PDA) and indomethacin may compromise enteral function in preterm infants. For many years enteral milk feedings have continued in preterm infants receiving indomethacin for PDA. The aim of this study was to investigate whether this strategy is efficient in terms of risks and tolerance to early enteral feeding.

METHODS

This retrospective study included 64 inborn infants of <29 wk gestational age (GA), 32 infants who received indomethacin for symptomatic PDA (case infants) and 32 matched controls. Case infants had a mean (SD) GA of 26.3 wk (1.3) and body weight 839 g (203) versus controls GA 26.4 wk (1.2) and body weight 896 g (213) (p = 0.82 and 0.27, respectively). Case infants had higher respiratory morbidity; 90.6% versus 50% of controls needed mechanical ventilation (p = 0.000).

RESULTS

Case infants received human milk from a median (range) age of 4.0 h (1.5-27.5), and controls from 5.3 h (2.0-38.0) (p = 0.092). The first dose of indomethacin was given at a mean age of 1.7 d (1.0). There were no differences between the two groups in feeding volumes or gastric residuals on days 1 to 7. Mean (SD) feeding volume on day 7 was 64 ml/kg (31) in case infants and 76 ml/kg (30) in controls (p = 0.23). Four infants developed necrotizing enterocolitis: two case infants and two controls (p = 1.00).

CONCLUSION

Early enteral feeding with human milk, starting within the first hours of life, seems to be as well tolerated in preterm infants treated with indomethacin for PDA as in their matched controls.

Indomethacin responsiveness of patent ductus arteriosus and renal abnormalities in preterm infants treated with indomethacin

OBJECTIVES

We evaluated the factors related to indomethacin responsiveness of the patent ductus arteriosus (PDA) and subsequent renal and electrolyte abnormalities in a large number of low birth weight infants.

METHODS

The ductus was evaluated by Doppler echocardiogram or clinical signs after the last administration of indomethacin for 2538 low birth weight infants, through the use of postmarketing surveillance data.

RESULTS

Multivariate logistic regression analyses demonstrated that clinical closure of PDA was significantly associated with pregnancy-induced hypertension and respiratory distress syndrome. In contrast, a 1-point increase of cardiovascular dysfunction score or a 1-day increase in postnatal age at the first indomethacin treatment decreased the responsiveness of the ductus to indomethacin. Clinical ductal reopening was significantly less likely to occur for each week of increased gestational age. Ductal reopening was more likely for each day of postnatal life at the first administration of indomethacin. Infants with preexisting renal and electrolyte abnormalities and infants whose mothers had received indomethacin tocolysis or who had chorioamnionitis were at increased risk of development of renal impairment.

CONCLUSIONS

Both antenatal and postnatal factors predict good or poor response to indomethacin therapy for PDA.

CURRENT CONTROVERSIES IN THE DIAGNOSIS AND TREATMENT OF PATENT DUCTUS ARTERIOSUS IN PRETERM INFANTS

This article presents common misconceptions about the physiologic significance of early ductal shunting and reviews the evidence regarding the preferential use of echocardiography rather than reliance on clinical signs to diagnose patent ductus arteriosus. The rationale for the treatment of symptomatic versus presymptomatic versus prophylactic is compared and contrasted. Finally, a novel but untested treatment approach, using early echocardiographic findings to direct treatment decisions, is proposed as a direction for future research.

Indomethacin for asymptomatic patent ductus arteriosus in preterm infants

BACKGROUND

Patent Ductus Arteriosus (PDA remains a significant cause of mortality and morbidity in premature infants. Indomethacin is an effective treatment to close a PDA, and has been used for many years with several treatment regimes, including prophylactic use in all at risk premature infants. There are however concerns regarding adverse side effects of indomethacin. By targeting a group of infants with an asymptomatic PDA, rather than treating all VLBW infants prophylactically, indomethacin use would be restricted, limiting the possibility of significant side effects to those with greater chance of benefit.

OBJECTIVES

To assess whether in premature neonates with asymptomatic PDA, treatment with indomethacin improves short and long term outcomes; in particular: incidence of symptomatic PDA, mortality, chronic neonatal lung disease (CLD), intraventricular haemorrhage (IVH), retinopathy of prematurity (ROP), neurodevelopmental outcome, length of ventilation.

SEARCH STRATEGY

Standard strategies of the Cochrane Neonatal Review Group were used. Searches were made of the Oxford Database of Perinatal Trials, MEDLINE and EMBASE from 1966 to September 2002, CINAHL from 1982 to September 2002, and the Cochrane Controlled Trials Register (CENTRAL/CCTR) in The Cochrane Library, Issue 3, 2002. Searches were also made of previous reviews including cross-referencing, abstracts, and conference and symposia proceedings published in Pediatric Research.

SELECTION CRITERIA

All randomised controlled trials of indomethacin compared with placebo or no intervention for the treatment of asymptomatic PDA in premature infants were eligible.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Neonatal Review Group were used. Trials identified by the search strategy were independently reviewed by each author and assessed for eligibility and trial quality. Data were then extracted independently by each author and compared, with any differences resolved following discussion. Any additional information required was requested from trial authors. Only published data was available for review. Results are expressed as typical relative risk and typical risk difference for dichotomous outcomes, and weighted mean difference for continuous variables.

MAIN RESULTS

Three small trials involving a total of 97 infants were included. Meta analysis of combined data was possible for seven outcomes. Treatment of an asymptomatic PDA with indomethacin significantly reduced the incidence of symptomatic PDA (RR 0.36, 95% CI 0.19, 0.68) and duration of supplemental oxygen (WMD -12.5, 95% CI -23.8, -1.26). There was no evidence of effect on mortality (RR 1.32, 95% CI 0.45, 3.86), CLD (RR 0.91, 95% CI 0.62, 1.35), IVH (RR 1.21, 95% CI 0.62, 2.37), ROP (RR 0.68, 95% CI 0.26, 1.78), or length of ventilation (WMD -7.00 days, 95%CI -17.33, 3.34). Long term neurodevelopmental outcomes were not reported. One trial reported a significant reduction in the duration of supplemental oxygen following treatment with indomethacin in the subgroup of infants with birth weight less than 1000g.

REVIEWER'S CONCLUSIONS

This review demonstrates a significant decrease in the incidence of symptomatic PDA following treatment of an asymptomatic PDA with indomethacin. There is also a small but statistically significant decrease in the duration of requirement for supplemental oxygen. There are no reported long term outcomes in the included trials, and so it is not possible to comment on possible long term effects. Further studies are required to determine the long term benefits or harms of closing a PDA prior to the onset of symptoms.

Reported adverse drug events in infants and children under 2 years of age

OBJECTIVE

To characterize risks to infants and young children from drugs and biological products that were identified in spontaneous adverse event reports submitted to the US Food and Drug Administration.

METHODS

Of >500 000 MedWatch adverse event reports received by the Food and Drug Administration from November 1997 through December 2000, we identified 7111 reports about infants and children younger than age 2. The reports were analyzed for health outcome (eg, death, hospitalization, congenital anomaly), principal suspect drug, and whether the route of drug exposure was direct administration or through the mother in the perinatal period.

RESULTS

Drug therapy was associated with an average of 243 reported deaths annually over the 38-month study period, with 100 (41%) occurring during the first month of life and 204 (84%) during the first year. In 1432 (24%) reported adverse event cases of all levels of severity, exposure to the drug was from the mother during pregnancy, delivery, or lactation. Although 1902 different drugs, biological products, and other chemicals were identified in the reports, only 17 drugs or biological products were a suspect in 54% of all serious and fatal adverse events in drugs administered directly.

CONCLUSION

Adverse reactions to drug therapy are a significant cause of death and injury in infants and children under 2 years of age. Drugs administered to the mother in the perinatal period constituted a major route of exposure to adverse drug advents. These results underscore the need for additional drug testing in the youngest pediatric patients and for carefully weighing the risks versus benefits of medication.

COX-1 and COX-2 contributions to basal and IL-1 beta-stimulated prostanoid synthesis in human neonatal cerebral microvascular endothelial cells

Mechanisms of endothelium-dependent regulation of cerebral circulation in human neonates are poorly understood owing to the lack of experimental data. Prostanoids, the products of the cyclooxygenase (COX) pathway, appear to be important regulators of blood flow in neonates. COX activity in cultured endothelial cells from small (60-300 microm) and large (>300 microm) microvessels from the autopsy specimens of neonatal human cerebral cortex and cerebellum (22-26 wk gestational age) was detected as production of vasodilator prostanoids, prostacyclin [as 6-keto-prostaglandin (PG) F(1 alpha)] and PGE(2) from arachidonic acid. Treatment of neonatal human cerebral microvascular endothelial cells (hCMVEC) with IL-1 beta (50 ng/mL, 17 h) stimulated COX activity 5- to 20-fold. Basal and IL-1 beta-stimulated COX activities were inhibited by NS-398, indicating substantial COX-2 contribution to endothelial prostanoid synthesis in neonatal human brain cortex and cerebellum at rest and when mimicking the inflammatory conditions. Increased COX-2-linked activity in response to IL-1 beta was observed in hCMVEC from both cerebrum and cerebellum (5- to 20-fold), while under the same conditions elevated COX-1-linked activity was detected only in hCMVEC from cerebellum (5- to 10-fold). In IL-1 beta-treated hCMVEC, a shift toward PGE(2) as the major vasodilator product of the COX pathway was observed. Acute treatment with the protein tyrosine kinase inhibitor, tyrphostin 25, inhibited basal and IL-1 beta-induced COX activities, suggesting the importance of posttranslational modifications in endothelial COX-2 activation in human brain. Altogether, these data indicate that both COX-1 and COX-2 contribute to endothelial prostanoid synthesis in the neonatal human brain under basal conditions and in response to proinflammatory cytokine IL-1 beta.