Furosemide for symptomatic patent ductus arteriosus in indomethacin-treated infants

Closing the Gap: Investigation of Various Approaches in the Management of Patent Ductus Arteriosus

In preterm newborns with extremely low birth weights, patent ductus arteriosus (PDA), which is defined as a remnant connection between the aorta and pulmonary artery after 72 hours of birth, is frequently linked to substantial morbidity and mortality. If left untreated, a hemodynamically significant PDA (hsPDA) increases the risk for bronchopulmonary dysplasia, necrotizing enterocolitis, and intraventricular hemorrhage among other morbidities, and can even lead to death. While instances of patent ductus arteriosus (PDA) resolving on their own are frequent, the primary approach for managing PDA closure in premature infants involves pharmacological interventions, commonly utilizing indomethacin, ibuprofen, or paracetamol. However, with these pharmacological treatment options, there is an increased risk of renal toxicity, gastrointestinal bleeding, and reopening of PDA among other complications. If pharmacological interventions are not successful or contraindicated, PDA can be closed via transcatheter closure or surgical ligation. As with any medically invasive procedure, it is not without risks and can lead to long-term complications. This review explores the different management options and the benefits and outcomes of conservative management vs. active management in order to get one step closer to standardizing the treatment for PDA. With so much controversy surrounding the best management option, there is a lack of evidence to support one treatment method superior to the other in reducing overall mortality, and this needs to be explored further.

Interventions for patent ductus arteriosus (PDA) in preterm infants: an overview of Cochrane Systematic Reviews

BACKGROUND

Patent ductus arteriosus (PDA) is associated with significant morbidity and mortality in preterm infants. Several non-pharmacological, pharmacological, and surgical approaches have been explored to prevent or treat a PDA.

OBJECTIVES

To summarise Cochrane Neonatal evidence on interventions (pharmacological or surgical) for the prevention of PDA and related complications, and interventions for the management of asymptomatic and symptomatic PDA in preterm infants.

METHODS

We searched the Cochrane Database of Systematic Reviews on 20 October 2022 for ongoing and published Cochrane Reviews on the prevention and treatment of PDA in preterm (< 37 weeks' gestation) or low birthweight (< 2500 g) infants. We included all published Cochrane Reviews assessing the following categories of interventions: pharmacological therapy using prostaglandin inhibitor drugs (indomethacin, ibuprofen, and acetaminophen), adjunctive pharmacological interventions, invasive PDA closure procedures, and non-pharmacological interventions. Two overview authors independently checked the eligibility of the reviews retrieved by the search, and extracted data from the included reviews using a predefined data extraction form. Any disagreements were resolved by discussion with a third overview author. Two overview authors independently assessed the methodological quality of the included reviews using the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews) tool. We reported the GRADE certainty of evidence as assessed by the respective review authors using summary of findings tables.

MAIN RESULTS

We included 16 Cochrane Reviews, corresponding to 138 randomised clinical trials (RCT) and 11,856 preterm infants, on the prevention and treatment of PDA in preterm infants. One of the 16 reviews had no included studies, and therefore, did not contribute to the results. Six reviews reported on prophylactic interventions for the prevention of PDA and included pharmacological prophylaxis with prostaglandin inhibitor drugs, prophylactic surgical PDA ligation, and non-pharmacologic interventions (chest shielding during phototherapy and restriction of fluid intake); one review reported on the use of indomethacin for the management of asymptomatic PDA; nine reviews reported on interventions for the management of symptomatic PDA, and included pharmacotherapy with prostaglandin inhibitor drugs in various routes and dosages, surgical PDA ligation, and adjunct therapies (use of furosemide and dopamine in conjunction with indomethacin). The quality of reviews varied. Two reviews were assessed to be high quality, seven reviews were of moderate quality, five of low quality, while two reviews were deemed to be of critically low quality. For prevention of PDA, prophylactic indomethacin reduces severe intraventricular haemorrhage (IVH; relative risk (RR) 0.66, 95% confidence interval (CI) 0.53 to 0.82; 14 RCTs, 2588 infants), and the need for invasive PDA closure (RR 0.51, 95% CI 0.37 to 0.71; 8 RCTs, 1791 infants), but it does not appear to affect the composite outcome of death or moderate/severe neurodevelopmental disability (RR 1.02, 95% CI 0.90 to 1.15; 3 RCTs, 1491 infants). Prophylactic ibuprofen probably marginally reduces severe IVH (RR 0.67, 95% CI 0.45 to 1.00; 7 RCTs, 925 infants; moderate-certainty evidence), and the need for invasive PDA closure (RR 0.46, 95% CI 0.22 to 0.96; 7 RCTs, 925 infants; moderate-certainty evidence). The evidence is very uncertain on the effect of prophylactic acetaminophen on severe IVH (RR 1.09, 95% CI 0.07 to 16.39; 1 RCT, 48 infants). Necrotising enterocolitis (NEC) was lower with both prophylactic surgical ligation (RR 0.25, 95% CI 0.08 to 0.83; 1 RCT, 84 infants), and fluid restriction (RR 0.43, 95% CI 0.21 to 0.87; 4 RCTs, 526 infants). For treatment of asymptomatic PDA, indomethacin appears to reduce the development of symptomatic PDA post-treatment (RR 0.36, 95% CI 0.19 to 0.68; 3 RCTs, 97 infants; quality of source review: critically low). For treatment of symptomatic PDA, all available prostaglandin inhibitor drugs appear to be more effective in closing a PDA than placebo or no treatment (indomethacin: RR 0.30, 95% CI 0.23 to 0.38; 10 RCTs, 654 infants; high-certainty evidence; ibuprofen: RR 0.62, 95% CI 0.44 to 0.86; 2 RCTs, 206 infants; moderate-certainty evidence; early administration of acetaminophen: RR 0.35, 95% CI 0.23 to 0.53; 2 RCTs, 127 infants; low-certainty evidence). Oral ibuprofen appears to be more effective in PDA closure than intravenous (IV) ibuprofen (RR 0.38, 95% CI 0.26 to 0.56; 5 RCTs, 406 infants; moderate-certainty evidence). High-dose ibuprofen appears to be more effective in PDA closure than standard-dose ibuprofen (RR 0.37, 95% CI 0.22 to 0.61; 3 RCTs, 190 infants; moderate-certainty evidence). With respect to adverse outcomes, compared to indomethacin administration, NEC appears to be lower with ibuprofen (any route; RR 0.68, 95% CI 0.49 to 0.94; 18 RCTs, 1292 infants; moderate-certainty evidence), oral ibuprofen (RR 0.41, 95% CI 0.23 to 0.73; 7 RCTs, 249 infants; low-certainty evidence), and with acetaminophen (RR 0.42, 95% CI 0.19 to 0.96; 4 RCTs, 384 infants; low-certainty evidence). However, NEC appears to be increased with a prolonged course of indomethacin versus a shorter course (RR 1.87, 95% CI 1.07 to 3.27; 4 RCTs, 310 infants).

AUTHORS' CONCLUSIONS

This overview summarised the evidence from 16 Cochrane Reviews of RCTs regarding the effects of interventions for the prevention and treatment of PDA in preterm infants. Prophylactic indomethacin reduces severe IVH, but does not appear to affect the composite outcome of death or moderate/severe neurodevelopmental disability. Prophylactic ibuprofen probably marginally reduces severe IVH (moderate-certainty evidence), while the evidence is very uncertain on the effect of prophylactic acetaminophen on severe IVH. All available prostaglandin inhibitor drugs appear to be effective in symptomatic PDA closure compared to no treatment (high-certainty evidence for indomethacin; moderate-certainty evidence for ibuprofen; low-certainty evidence for early administration of acetaminophen). Oral ibuprofen appears to be more effective in PDA closure than IV ibuprofen (moderate-certainty evidence). High dose ibuprofen appears to be more effective in PDA closure than standard-dose ibuprofen (moderate-certainty evidence). There are currently two ongoing reviews, one on fluid restriction for symptomatic PDA, and the other on invasive management of PDA in preterm infants.

Relative effectiveness and safety of pharmacotherapeutic agents for patent ductus arteriosus (PDA) in preterm infants: a protocol for a multicentre comparative effectiveness study (CANRxPDA)

INTRODUCTION

Patent ductus arteriosus (PDA) is the most common cardiovascular problem that develops in preterm infants and evidence regarding the best treatment approach is lacking. Currently available medical options to treat a PDA include indomethacin, ibuprofen or acetaminophen. Wide variation exists in PDA treatment practices across Canada. In view of this large practice variation across Canadian neonatal intensive care units (NICUs), we plan to conduct a comparative effectiveness study of the different pharmacotherapeutic agents used to treat the PDA in preterm infants.

METHODS AND ANALYSIS

A multicentre prospective observational comparative-effectiveness research study of extremely preterm infants born <29 weeks gestational age with an echocardiography confirmed PDA will be conducted. All participating sites will self-select and adhere to one of the following primary pharmacotherapy protocols for all preterm babies who are deemed to require treatment.Standard dose ibuprofen (10 mg/kg followed by two doses of 5 mg/kg at 24 hours intervals) irrespective of postnatal age (oral/intravenous).Adjustable dose ibuprofen (oral/intravenous) (10 mg/kg followed by two doses of 5 mg/kg at 24 hours intervals if treated within the first 7 days after birth. Higher doses of ibuprofen up to 20 mg/kg followed by two doses of 10 mg/kg at 24 hours intervals if treated after the postnatal age cut-off for lower dose as per the local centre policy).Acetaminophen (oral/intravenous) (15 mg/kg every 6 hours) for 3-7 days.Intravenous indomethacin (0.1-0.3 mg/kg intravenous every 12-24 hours for a total of three doses).

OUTCOMES

The primary outcome is failure of primary pharmacotherapy (defined as need for further medical and/or surgical/interventional treatment following an initial course of pharmacotherapy). The secondary outcomes include components of the primary outcome as well as clinical outcomes related to response to treatment or adverse effects of treatment.

SITES AND SAMPLE SIZE

The study will be conducted in 22 NICUs across Canada with an anticipated enrollment of 1350 extremely preterm infants over 3 years.

ANALYSIS

To examine the relative effectiveness of the four treatment strategies, the primary outcome will be compared pairwise between the treatment groups using χ² test. Secondary outcomes will be compared pairwise between the treatment groups using χ² test, Student's t-test or Wilcoxon rank sum test as appropriate. To further examine differences in the primary and secondary outcomes between the four groups, multiple logistic or linear regression models will be applied for each outcome on the treatment groups, adjusted for potential confounders using generalised estimating equations to account for within-unit-clustering. As a sensitivity analysis, the difference in the primary and secondary outcomes between the treatment groups will also be examined using propensity score method with inverse probability weighting approach.

ETHICS AND DISSEMINATION

The study has been approved by the IWK Research Ethics Board (#1025627) as well as the respective institutional review boards of the participating centres.

TRIAL REGISTRATION NUMBER

NCT04347720.

Nephrotoxic medications and acute kidney injury risk factors in the neonatal intensive care unit: clinical challenges for neonatologists and nephrologists

Neonatal acute kidney injury (AKI) is common. Critically ill neonates are at risk for AKI for many reasons including the severity of their underlying illnesses, prematurity, and nephrotoxic medications. In this educational review, we highlight four clinical scenarios in which both the illness itself and the medications indicated for their treatment are risk factors for AKI: sepsis, perinatal asphyxia, patent ductus arteriosus, and necrotizing enterocolitis. We review the available evidence regarding medications commonly used in the neonatal period with known nephrotoxic potential, including gentamicin, acyclovir, indomethacin, vancomycin, piperacillin-tazobactam, and amphotericin. We aim to illustrate the complexity of decision-making involved for both neonatologists and pediatric nephrologists when managing infants with these conditions and advocate for ongoing multidisciplinary collaboration in the development of better AKI surveillance protocols and AKI mitigation strategies to improve care for these vulnerable patients.

Potential and Limitations of Cochrane Reviews in Pediatric Cardiology: A Systematic Analysis

Evidence-based medicine has contributed substantially to the quality of medical care in pediatric and adult cardiology. However, our impression from the bedside is that a substantial number of Cochrane reviews generate inconclusive data that are of limited clinical benefit. We performed a systematic synopsis of Cochrane reviews published between 2001 and 2015 in the field of pediatric cardiology. Main outcome parameters were the number and percentage of conclusive, partly conclusive, and inconclusive reviews as well as their recommendations and their development over three a priori defined intervals. In total, 69 reviews were analyzed. Most of them examined preterm and term neonates (36.2%), whereas 33.3% included also non-pediatric patients. Leading topics were pharmacological issues (71.0%) followed by interventional (10.1%) and operative procedures (2.9%). The majority of reviews were inconclusive (42.9%), while 36.2% were conclusive and 21.7% partly conclusive. Although the number of published reviews increased during the three a priori defined time intervals, reviews with "no specific recommendations" remained stable while "recommendations in favor of an intervention" clearly increased. Main reasons for missing recommendations were insufficient data (n = 41) as well as an insufficient number of trials (n = 22) or poor study quality (n = 19). There is still need for high-quality research, which will likely yield a greater number of Cochrane reviews with conclusive results.

Patent ductus arteriosus in preterm infants: do we have the right answers?

Patent ductus arteriosus (PDA) is a common clinical condition in preterm infants. Preterm newborns with PDA are at greater risk for several morbidities, including higher rates of bronchopulmonary dysplasia (BPD), decreased perfusion of vital organs, and mortality. Therefore, cyclooxygenase (COX) inhibitors and surgical interventions for ligation of PDA are widely used. However, these interventions were reported to be associated with side effects. In the absence of clear restricted rules for application of these interventions, different strategies are adopted by neonatologists. Three different approaches have been investigated including prophylactic treatment shortly after birth irrespective of the state of PDA, presymptomatic treatment using echocardiography at variable postnatal ages to select infants for treatment prior to the duct becoming clinically significant, and symptomatic treatment once PDA becomes clinically apparent or hemodynamically significant. Future appropriately designed randomized controlled trials (RCTs) to refine selection of patients for medical and surgical treatments should be conducted. Waiting for new evidence, it seems wise to employ available clinical and echocardiographic parameters of a hemodynamically significant (HS) PDA to select patients who are candidates for medical treatment. Surgical ligation of PDA could be used as a back-up tool for those patients who failed medical treatment and continued to have hemodynamic compromise.

Clinical pharmacology of furosemide in neonates: a review

Furosemide is the diuretic most used in newborn infants. It blocks the Na⁺-K⁺-2Cl⁻ symporter in the thick ascending limb of the loop of Henle increasing urinary excretion of Na⁺ and Cl⁻. This article aimed to review the published data on the clinical pharmacology of furosemide in neonates to provide a critical, comprehensive, authoritative and, updated survey on the metabolism, pharmacokinetics, pharmacodynamics and side-effects of furosemide in neonates. The bibliographic search was performed using PubMed and EMBASE databases as search engines; January 2013 was the cutoff point. Furosemide half-life (t_1/2) is 6 to 20-fold longer, clearance (Cl) is 1.2 to 14-fold smaller and volume of distribution (Vd) is 1.3 to 6-fold larger than the adult values. t_1/2 shortens and Cl increases as the neonatal maturation proceeds. Continuous intravenous infusion of furosemide yields more controlled diuresis than the intermittent intravenous infusion. Furosemide may be administered by inhalation to infants with chronic lung disease to improve pulmonary mechanics. Furosemide stimulates prostaglandin E2 synthesis, a potent dilator of the patent ductus arteriosus, and the administration of furosemide to any preterm infants should be carefully weighed against the risk of precipitation of a symptomatic patent ductus arteriosus. Infants with low birthweight treated with chronic furosemide are at risk for the development of intra-renal calcifications.

Unexpected extra-renal effects of loop diuretics in the preterm neonate

The loop diuretics furosemide and bumetanide are commonly used in neonatal intensive care units (NICUs). Furosemide, because of its actions on the ubiquitous Na(+) -K(+) -2Cl(-) isoform cotransporter and its promotion of prostanoid production and release, also has non-diuretic effects on vascular smooth muscle, airways, the ductus arteriosus and theoretically the gastrointestinal tract. Loop diuretics also affect the central nervous system through modulation of the GABA-A chloride channel.

CONCLUSION

  The loop diuretics have a variety of biological effects that are potentially harmful as well as beneficial. Care should be taken with the use of these agents because the range of their effects may be broader than the single action sought by the prescribing physician.

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.

Neonatal diuretic therapy: furosemide, thiazides, and spironolactone

Diuretics are commonly used to treat infants with oxygen-dependent chronic lung disease. However, there are limited data suggesting a beneficial effect of long-term diuretic therapy on pulmonary function or clinical outcome in this population. Furthermore, data available for review were primarily obtained before the widespread use of antenatal steroids or surfactant replacement therapy, before recognition of the new bronchopulmonary dysplasia. If used in this population, limitations of diuretic therapy as well as significant side effects need to be understood and a rationale approach to clinical use developed on a patient-centered basis.

Diuretics acting on the distal renal tubule for preterm infants with (or developing) chronic lung disease

BACKGROUND

Lung disease in preterm infants is often complicated with lung edema.

OBJECTIVES

To assess the risks and benefits of diuretics acting on distal segments of the renal tubule (distal diuretics) in preterm infants with or developing chronic lung disease (CLD).

SEARCH STRATEGY

The standard method of the Cochrane Neonatal Review Group were used. Initially, MEDLINE (1966 to November 2001), EMBASE (1974 to November 2001) and the Cochrane Controlled Trials Register (CENTRAL,The Cochrane Library, Issue 4, 2001) were searched. In addition, several abstract books of national and international American and European Societies were hand searched. Updated searches in April 2003, April 2007, and December 2010 did not yield any additional trials.

SELECTION CRITERIA

Included in this analysis are trials in which preterm infants with or developing CLD and at least five days of age were randomly allocated to receive a diuretic acting on the distal renal tubule. Eligible studies needed to assess at least one of the outcome variables defined a priori for this systematic review.

DATA COLLECTION AND ANALYSIS

The standard method for the Cochrane Collaboration described in the Cochrane Collaboration Handbook were used. Two investigators extracted, assessed and coded separately all data for each study. Any disagreement was resolved by discussion. Parallel and cross-over trials were combined. Whenever possible, baseline and final outcome data measured on a continuous scale was transformed into change scores using Follmann's formula.

MAIN RESULTS

Of the six studies fulfilling entry criteria, most focused on pathophysiological parameters and did not assess effects on important clinical outcomes defined in this review, or the potential complications of diuretic therapy.In preterm infants > 3 weeks of age with CLD, a four week treatment with thiazide and spironolactone improved lung compliance and reduced the need for furosemide. A single study showed thiazide and spironolactone decreased the risk of death and tended to decrease the risk for remaining intubated after eight weeks in infants who did not have access to corticosteroids, bronchodilators or aminophylline.

AUTHORS' CONCLUSIONS

In preterm infants > 3 weeks of age with CLD, acute and chronic administration of distal diuretics improve pulmonary mechanics. However, positive effects should be interpreted with caution as the numbers of patients studied are small in surprisingly few randomized controlled trials.

Intravenous or enteral loop diuretics for preterm infants with (or developing) chronic lung disease

BACKGROUND

Lung disease in preterm infants is often complicated with lung edema.

OBJECTIVES

To assess the risks and benefits of administration of a diuretic acting on the loop of Henle (loop diuretic) in preterm infants with or developing chronic lung disease (CLD).

SEARCH STRATEGY

Standard search method of the Cochrane Neonatal Review Group was used. Initial search included the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2003), MEDLINE (1966 to April 2003), EMBASE (1974 to 1998). In addition, several abstract books of national and international American and European Societies were hand searched. The MEDLINE and the Cochrane Central searches were updated in March 2007 and December 2010.  The EMBASE search was completed in April 2007 and December 2010. Additional searches in CINAHL, clinicaltrials.gov and controlled-trials.com was completed in December 2010.

SELECTION CRITERIA

Trials in which preterm infants with or developing chronic lung disease and at least five days of age were all randomly allocated to receive a loop diuretic either enterally or intravenously were included in this analysis.

DATA COLLECTION AND ANALYSIS

The standard method for the Cochrane Collaboration described in the Cochrane Collaboration Handbook were used. Two investigators extracted, assessed and coded separately all data for each study. Parallel and cross-over trials were combined and, whenever possible, transformed baseline and final outcome data measured on a continuous scale into change scores using Follmann's formula.

MAIN RESULTS

The only loop diuretic used in the six studies that met the selection criteria was furosemide. Most studies focused on pathophysiological parameters and did not assess effects on important clinical outcomes defined in this review, or the potential complications of diuretic therapy. In preterm infants < 3 weeks of age developing CLD, furosemide administration has either inconsistent effects or no detectable effect. In infants > 3 weeks of age with CLD, a single intravenous dose of 1 mg/kg of furosemide improves lung compliance and airway resistance for one hour. Chronic administration of furosemide improves both oxygenation and lung compliance.

AUTHORS' CONCLUSIONS

In view of the lack of data from randomized trials concerning effects on important clinical outcomes, routine or sustained use of systemic loop diuretics in infants with (or developing) CLD cannot be recommended based on current evidence. Randomized trials are needed to assess the effects of furosemide administration on survival, duration of ventilatory support and oxygen administration, length of hospital stay, potential complications and long-term 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.

Patent ductus arteriosus: an overview

Patent ductus arteriosus (PDA) is one of the most common congenital heart defects, accounting for 5%-10% of all congenital heart disease in term infants. The occurrence of PDA is inversely related to gestational age and weight, with an even greater incidence in preterm infants. The maintenance of ductal patency is essential for the normal development of the fetus. In the neonate, however, persistent patency of the ductus arteriosus (DA) is associated with significant morbidity and mortality. Normally, at birth, the DA constricts, resulting in intraluminal ischemic hypoxia, which eventually leads to closure and remodeling of the ductus. PDA in term infants is usually associated with a functional defect, whereas in preterm infants it is associated with immaturity. Normal physiologic mechanisms contributing to closure - oxygen tension and decreased prostaglandins-are altered in prematurity. Clinical signs of ductal patency include murmur, tachycardia, bounding peripheral pulses, and congestive heart failure and associated symptoms. Symptoms are not always present; therefore, diagnostic imaging is critical if a PDA is suspected on clinical grounds. Three management strategies are currently available for PDA: fluid restriction and diuretics (as clinically appropriate), medical intervention, and surgical ligation. Pharmacologic closure can be achieved via administration of intravenous indomethacin or ibuprofen lysine. While both agents have shown similar efficacy, ibuprofen lysine has demonstrated an improved safety profile, particularly in terms of renal effects, compared to indomethacin.

Patent ductus arteriosus: an overview

Patent ductus arteriosus (PDA) is one of the most common congenital heart defects, accounting for 5%-10% of all congenital heart disease in term infants. The occurrence of PDA is inversely related to gestational age and weight, with an even greater incidence in preterm infants. The maintenance of ductal patency is essential for the normal development of the fetus. In the neonate, however, persistent patency of the ductus arteriosus (DA) is associated with significant morbidity and mortality. Normally, at birth, the DA constricts, resulting in intraluminal ischemic hypoxia, which eventually leads to closure and remodeling of the ductus. PDA in term infants is usually associated with a functional defect, whereas in preterm infants it is associated with immaturity. Normal physiologic mechanisms contributing to closure - oxygen tension and decreased prostaglandins-are altered in prematurity. Clinical signs of ductal patency include murmur, tachycardia, bounding peripheral pulses, and congestive heart failure and associated symptoms. Symptoms are not always present; therefore, diagnostic imaging is critical if a PDA is suspected on clinical grounds. Three management strategies are currently available for PDA: fluid restriction and diuretics (as clinically appropriate), medical intervention, and surgical ligation. Pharmacologic closure can be achieved via administration of intravenous indomethacin or ibuprofen lysine. While both agents have shown similar efficacy, ibuprofen lysine has demonstrated an improved safety profile, particularly in terms of renal effects, compared to indomethacin.

Indomethacin use for the management of patent ductus arteriosus in preterms: a web-based survey of practice attitudes among neonatal fellowship program directors in the United States

The objective of this study was to determine whether neonatal-perinatal fellowship programs (NFTPs) in the United States vary in indomethacin use for the management of patent ductus arteriosus (PDA) in < or =28 week gestational age infants at birth. A 53-item web-based survey was sent to 84 NFTP directors who received prenotification, followed 2 weeks later by a reminder letter. A total of 56 NFTP directors responded (67% maximum response rate). Wide variation exists in the maximum number of indomethacin courses used to close ductus, use of indomethacin for reopened PDA beyond 14 days, ductal closure definition, contraindications before consideration of indomethacin, interventions for contraindications, and reported ductal closer rate after each indomethacin course. Indomethacin therapy for symptomatic PDA and short course of indomethacin are common practices. Indomethacin use for the management of PDA in premature infants varies among NFTP directors. Practice attitudes may explain variations in ductal closure and ligation rates. Because practice variations may have implications for long-term outcome of vulnerable premature infants, studies relevant to the management of PDA in premature infants are needed.

Indomethacin decreases furosemide-induced natriuresis and diuresis on the neonatal kidney

Indomethacin is used to pharmacologically occlude patent ductus arteriosus in preterm infants. It induces renal untoward effects and furosemide is administered simultaneously to counteract them. The effect of furosemide is blunted by indomethacin. We analyzed comparatively the interactions of furosemide and indomethacin at the organic anion transport system in adult and newborn individuals. Adult and 5-day-old Wistar rats were allocated into three groups: (1) indomethacin (10 mg/kg, ip); (2) furosemide (2 mg/kg, ip); and (3) indomethacin/furosemide, at the same doses. Urinary flow, glomerular filtration rate (GFR), sodium and potassium fractional excretions, and free-water and osmolal clearances were estimated. Para-aminohippuric acid (PAH) uptake was measured in renal cortical slices to study the organic anion's secretory pathway. In adult and newborn rats, furosemide-induced increments in urinary fluxes and excretions of sodium and potassium were blunted by indomethacin administered simultaneously. PAH uptake was decreased to a further extent by indomethacin than by furosemide, suggesting that inhibition of the diuretic effect might be related to competition in the secretion of furosemide. Inhibitory interaction between indomethacin and furosemide was achieved at approximately 10-fold lower concentrations in the newborn than in the adult rats, suggesting that tubular secretion in the neonate is more sensitive to the action of these drugs than in the adult individual.

Aerosolized diuretics for preterm infants with (or developing) chronic lung disease

BACKGROUND

Lung disease in preterm infants is often complicated with lung edema.

OBJECTIVES

The aim of this review is to assess the risks and benefits of aerosolized diuretic administration in preterm infants with or developing chronic lung disease (CLD). Primary objectives are to assess effects on short term outcome (changes in need for oxygen or ventilatory support) and effects on long-term outcome. Secondary objectives are to assess changes in pulmonary mechanics and potential complications of therapy.

SEARCH STRATEGY

We used the standard search method of the Cochrane Neonatal Review Group. We used the following keywords: {<bronchopulmonary dysplasia> or <chronic lung disease>} and <explode diuretics>, limited to <human> and limited to <infant, newborn> or <infant>. We searched MEDLINE (1966 - 1998), EMBASE (1974 - 1998) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006). In addition, we hand searched several abstract books of national and international American and European Societies. The search of MEDLINE and of CENTRAL was last updated in March 2006.

SELECTION CRITERIA

For the purpose of this analysis, we included trials in which preterm infants with or developing chronic lung disease and at least five days of age were all randomly allocated to receive an aerosolized loop diuretic. Eligible studies needed to assess at least one of the outcome variables defined a priori for this systematic review. Primary outcome variables included need for ventilator support, chronic lung disease, mortality and other important clinical outcomes. Secondary outcome variables included pulmonary mechanics and potential complications of therapy.

DATA COLLECTION AND ANALYSIS

We used the standard method for the Cochrane Collaboration which is described in the Cochrane Collaboration Handbook. Two investigators extracted, assessed and coded separately all data for each study, using a form that was designed specifically for this review. Any disagreement was resolved by discussion. We combined parallel and cross-over trials and, whenever possible, transformed baseline and final outcome data measured on a continuous scale into change scores using Follmann's formula.

MAIN RESULTS

We identified eight studies that met selection criteria. Most studies focused on pathophysiological parameters and did not assess effects on important clinical outcomes defined in this review or the potential complications of diuretic therapy. No study assessed the amount of diuretic effectively delivered to the patient. Furosemide was the only diuretic used in the eight studies included in this review. Among preterm infants < 3 weeks of age developing CLD, not enough information is available to assess the effect of aerosolized furosemide on outcome or lung function. Among infants > 3 weeks with CLD, a single aerosolized dose of 1 mg/kg of furosemide may transiently improve pulmonary mechanics. Not enough information is available to assess the effect of chronic administration of aerosolized furosemide on oxygenation and pulmonary mechanics.

AUTHORS' CONCLUSIONS

In preterm infants > 3 weeks with CLD administration of a single dose of aerosolized furosemide improves pulmonary mechanics. In view of the lack of data from randomized trials concerning effects on important clinical outcomes, routine or sustained use of aerosolized loop diuretics in infants with (or developing) CLD cannot be recommended based on current evidence.More double-blinded randomized trials are needed (1) to analyze factors likely to affect the response to aerosolized furosemide, e.g., washout period and delivery of furosemide to distal airways, and (2) to assess the effects of chronic administration of aerosolized furosemide on mortality, O2 dependency, ventilator dependency, length of hospital stay and long-term outcome.

Diurétiques et prématuré

Diuretics are frequently used in preterm infants in various situations such as patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia or neonatal renal insufficiency. However, the beneficial effects reported in the literature are usually transient, without any obvious effect on important parameters such as duration of oxygen dependency, ventilator dependency, length of hospital stay, long-term outcome, or mortality. Moreover, these drugs may induce water-electrolyte disorders especially when used for a long-term period. Thus, we recommend a systematic analysis of the beneficial/risk ratio before any use of these drugs.

Dopamine versus no treatment to prevent renal dysfunction in indomethacin-treated preterm newborn infants

BACKGROUND

Indomethacin therapy for closure of patent ductus arteriosus frequently causes oliguria, and occasionally more serious renal dysfunction. Low dose dopamine has been suggested as a means for preventing this side effect.

PRIMARY OBJECTIVE

To determine whether dopamine therapy may prevent indomethacin-mediated deterioration in renal function in the preterm newborn infant without serious adverse effects.

SECONDARY OBJECTIVE

To assess the effects of dopamine on the above variables in two subgroups: (1) patients given indomethacin as prophylaxis of intraventricular hemorrhage, and (2) patients given indomethacin as treatment of patent ductus arteriosus

SEARCH STRATEGY

Standard methods of the Cochrane Neonatal Review Group (CNRG) were used. We searched MEDLINE (1966-2001) using PubMed as the search engine, EMBASE (1974-2001) and the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library (Issue 3, 2001). In addition we contacted the principal investigators if necessary to ascertain the required information.

SELECTION CRITERIA

Randomized or quasi-randomized studies of the effects of dopamine on urine output, glomerular filtration rate, fluid balance or incidence of renal failure, in preterm newborn infants receiving indomethacin. The comparison group should have received no dopamine.

DATA COLLECTION AND ANALYSIS

We used the standard methods of the Cochrane Collaboration and those of the CNRG. The primary outcomes of interest were: mortality before discharge; intraventricular hemorrhage, grade three or four; cystic periventricular leukomalacia; renal failure (either oliguria, defined as a urine output less than 1 ml/kg/hour or an elevation in creatinine by more than 40 micromoles/L); failure to close the ductus arteriosus; need for surgical PDA ligation. For categorical outcomes, we calculated typical estimates for relative risk and risk difference. For continuous outcomes the weighted mean difference (WMD) was calculated. Fixed effect models were assumed for meta-analysis.

MAIN RESULTS

Three studies were found (total number randomized patients, 75) which fulfilled the entry criteria for this review. All were single center trials which enrolled NICU patients receiving indomethacin for symptomatic patent ductus arteriosus. There are no (or only partial) results for effects of dopamine on several of the primary outcomes, including death before discharge, serious intraventricular hemorrhage, cystic periventricular leukomalacia, or renal failure. There has been inadequate investigation of the effects of dopamine on cerebral perfusion or cardiac output, or GI complications, or endocrine toxicity. Dopamine improved urine output [WMD 0.68 ml/kg/hour (95% CI 0.22, 1.44)], but there was no evidence of effect on serum creatinine (WMD 2.04 micromoles/liter, CI -17.90, 21.97) or the incidence of oliguria (urine output < 1 ml/kg/hour) (RR 0.73, CI 0.35, 1.54). There was no evidence of effect of dopamine on the frequency of failure to close the ductus arteriosus (RR 1.11, CI 0.56, 2.19).

REVIEWER'S CONCLUSIONS

There is no evidence from randomized trials to support the use of dopamine to prevent renal dysfunction in indomethacin-treated preterm infants.

Furosemide for symptomatic patent ductus arteriosus in indomethacin-treated infants

BACKGROUND

Inhibition of prostaglandin synthesis mediates closure of the ductus arteriosus and renal side effects after indomethacin administration. Because furosemide increases prostaglandin production, it could potentially help prevent indomethacin-related toxicity but also decrease ductal response to indomethacin.

OBJECTIVES

The primary objectives of this review were to assess (1) whether furosemide affects the incidence of failure of ductal closure after indomethacin and that of indomethacin-related toxicity and (2) the effect of furosemide on mid-term and long-term outcome. The secondary objective was to determine whether the effect of furosemide on renal function and water balance depends on prior extracellular volume (assessed by blood urea nitrogen [BUN]/creatinine ratio).

SEARCH STRATEGY

We searched electronic databases (Medline, Embase and Cochrane) and selected abstract books, without language restriction.

SELECTION CRITERIA

We selected studies with (1) random allocation to either indomethacin alone or indomethacin and furosemide and (2) analysis of either short-term risk-benefit ratio of furosemide, mid- or long-term outcome, or the relationship between extracellular volume at study entry and changes in renal function.

DATA COLLECTION AND ANALYSIS

We assessed studies for possible bias and for quality of assessment of ductal patency. We assessed categorical variables using relative risk and absolute risk reduction. We assessed the effects of furosemide on renal function and fluid balance by comparing changes from baseline in the treatment group with those in controls. Subsets were determined a priori based on BUN/creatinine ratio at study entry.

MAIN RESULTS

All 3 studies fulfilling the entry criteria had limitations, including possible or definite bias. There was substantial heterogeneity among studies. Furosemide administration did not significantly increase the risk of failure of ductal closure; however, sample size was insufficient to rule out even a 31% increase. In the subset with initial BUN/creatinine ratio > 20 mg/mg, 2 of 18 patients receiving furosemide could not complete a 3-dose course of indomethacin because of toxicity. Minimal or no information was available about any of the other main outcome variables. Furosemide increased urine output regardless of the initial BUN/creatinine ratio, leading to a 5% weight loss during a 3-dose course, an undesired effect in patients with initial BUN/creatinine ratio > 20 mg/mg. Furosemide increased creatinine clearance only in patients with initial BUN/creatinine ratio <20 mg/mg.

REVIEWER'S CONCLUSIONS

There is not enough evidence to support the administration of furosemide to premature infants treated with indomethacin for symptomatic patent ductus arteriosus. Furosemide appears to be contraindicated in the presence of dehydration in those infants.