Randomized trial of prolonged low-dose versus conventional-dose indomethacin for treating patent ductus arteriosus in very low birth weight infants

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.

High Dose Indomethacin for Patent Ductus Arteriosus Closure Increases Neonatal Morbidity

OBJECTIVE

Symptomatic patent ductus arteriosus (sPDA) is the most common heart abnormality in preterm infants. Optimal duration and dose of medical treatment is still unclear. We assessed undesired effects and closure rate of high-dose indomethacin (HDI) for pharmacological closure of sPDA.

STUDY DESIGN

Retrospective single center analysis of 248 preterm infants born between January 2006 and December 2015 with a birth weight <2,000 g and sPDA which was treated with indomethacin. Patients were treated with either standard dose indomethacin (SDI; n = 196) or HDI (n = 52). Undesired effects and PDA closure were compared between patients treated with SDI and HDI.

RESULTS

In univariate analysis, patients receiving HDI had a significant increase in gastrointestinal hemorrhage (32.7 vs.11.7%, p = 0.001), bronchopulmonary dysplasia (BPD) (77.8 vs. 55.1%, p = 0.003), and retinopathy of prematurity (13.5 vs. 2.6%, p = 0.004). Moreover, HDI patients needed longer mechanical ventilation (2.5 vs. 1.0 days, p = 0.01). Multivariate analyses indicated that necrotizing enterocolitis (17 vs. 7%, p = 0.01) and BPD (79 vs. 55%, p = 0.02) were more frequent in HDI patients. PDA closure rate was 79.0% with HDI versus 65.3% with SDI.

CONCLUSION

HDI used for PDA closure is associated with an increase in necrotizing enterocolitis and BPD. Risks of HDI should be balanced against other treatment options.

Role of dopamine and selective dopamine receptor agonists on mouse ductus arteriosus tone and responsiveness

BACKGROUND

Indomethacin treatment for patent ductus arteriosus (PDA) is associated with acute kidney injury (AKI). Fenoldopam, a dopamine (DA) DA₁-like receptor agonist dilates the renal vasculature and may preserve renal function during indomethacin treatment. However, limited information exists on DA receptor-mediated signaling in the ductus and fenoldopam may prevent ductus closure given its vasodilatory nature.

METHODS

DA receptor expression in CD-1 mouse vessels was analyzed by qPCR and immunohistochemistry. Concentration-response curves were established using pressure myography. Pretreatment with SCH23390 (DA₁-like receptor antagonist), phentolamine (α -adrenergic receptor antagonist) or indomethacin addressed mechanisms for DA-induced changes. Fenoldopam's effects on postnatal ductus closure were evaluated in vivo.

RESULTS

DA₁ receptors were expressed equally in ductus and aorta. High-dose DA induced modest vasoconstriction under newborn O₂ conditions. Phentolamine inhibited DA-induced constriction, while SCH23390 augmented constriction, consistent with a vasodilatory role for DA₁ receptors. Despite this, fenoldopam had little effect on ductus tone nor indomethacin- or O₂-induced constriction and did not impair postnatal closure in vivo.

CONCLUSION(S)

DA receptors are present in the ductus but have limited physiologic effects. DA-induced ductus vasoconstriction is mediated via α-adrenergic pathways. The absence of DA₁-mediated impairment of ductus closure supports the study of potential role for fenoldopam during PDA treatment.

Efficacy and safety of pharmacological treatments for patent ductus arteriosus closure: A systematic review and network meta-analysis of clinical trials and observational studies

Efficacy and safety profiles of different pharmacological interventions used to treat patent ductus arteriosus (PDA) are relatively unexplored. Integrating the findings of randomized clinical trials (RCTs) with those from observational studies may provide key evidence on this important issue. We aimed at estimating the relative likelihood of failure to close the PDA, need for surgical closure, and occurrence of adverse events among preterm and full-term infants treated with indomethacin, ibuprofen, or acetaminophen, placebo, or no treatment including both RCTs and observational studies. We searched PubMed, Embase, and the Register of Controlled Trials from inception to October 30, 2018. We first estimated proportions of subjects with failure to close the PDA, subjects in whom surgical closure was performed after pharmacological treatment, death, and subjects with selected adverse events (AEs). These estimates were obtained using frequentist random-effect meta-analysis of arm-specific proportions. We then compared active drugs with each other and with control (either placebo or no treatment) by summarizing results at the end of treatment reported in the papers, regardless of number of administration(s), dose, route and type of administration, and study design and quality. We also summarized primary outcome results separately at first, second and third cycles of treatment. These estimates were obtained using Bayesian random-effects network meta-analysis for mixed comparisons, and frequentist random-effect pairwise meta-analysis for direct comparisons. We included 64 RCTs and 24 observational studies including 14,568 subjects (5339 in RCTs and 9229 in observational studies, 8292 subjects received indomethacin, 4761 ibuprofen, 574 acetaminophen, and 941 control (including placebo or no intervention).The proportion of subjects with failure to close the PDA was 0.24 (95% Confidence Interval, CI: 0.20, 0.29) for indomethacin, 0.18 (0.14, 0.22) for ibuprofen, 0.19 (0.09, 0.30) for acetaminophen, and 0.59 (0.48, 0.69) for control. At end of treatment, compared to control, we found inverse associations between all active drugs and failure to close PDA (for indomethacin Odds Ratio, OR, was 0.17 [95% Credible Interval, CrI: 0.11-0.24], ibuprofen 0.19 [0.12-0.28], and acetaminophen 0.15 [0.09-0.26]), without differences among active drugs. We showed inverse associations between effective drugs and need for surgical closure, as compared to control (for indomethacin OR was 0.28 [0.15-0.50], ibuprofen 0.30 [0.16-0.54], and acetaminophen 0.19 [0.07-0.46]), without differences among drugs. Indomethacin was directly associated with intraventricular hemorrhage (IVH) (1.27; 1.00, 1.62) compared to ibuprofen, and to oliguria as compared to ibuprofen (3.92; 1.69, 9.82) or acetaminophen (10.8; 1.86, 93.1). In conclusion, active pharmacological treatment, with indomethacin, ibuprofen, or acetaminophen, is inversely associated with failure to close the PDA compared to non-treatment. Ibuprofen should be preferred to indomethacin to avoid occurrence of IVH or oliguria, acetaminophen should be preferred to indomethacin to avoid oliguria.

Tratamiento farmacológico del conducto arterioso permeable en recién nacidos prematuros

Introducción. Por lo general, el manejo farmacológico del conducto arterioso permeable (CAP) comprende inhibidores no selectivos de la enzima ciclooxigenasa, en especial indometacina e ibuprofeno. En años recientes también se ha sugerido al acetaminofén como alternativa terapéutica.Objetivo. Realizar una revisión narrativa de la literatura acerca del manejo farmacológico del CAP.Materiales y métodos. Se realizó una búsqueda estructurada de la literatura en las bases de datos ProQuest, EBSCO, ScienceDirect, PubMed, LILACS, Embase, Trip Database, SciELO y Cochrane Library con los términos “Ductus Arteriosus, patent AND therapeutics”; “Ductus Arteriosus, patent AND indometacin”; “Ductus Arteriosus, Patent AND ibuprofen”, y “Ductus Arteriosus, patent AND acetaminophen”. La búsqueda se hizo en inglés con sus equivalentes en español.Resultados. Se encontraron 69 artículos con información relevante para llevar a cabo la presente revisión.Conclusiones. En neonatos prematuros, la base del tratamiento farmacológico del CAP continúa siendo los inhibidores no selectivos de la ciclooxigenasa, indometacina e ibuprofeno, ambos con perfiles similares de seguridad y eficacia. La evidencia disponible sugiere que el acetaminofén podría constituir una alternativa útil para el manejo, pero resulta insuficiente para realizar recomendaciones definitivas respecto a la eficacia y seguridad de este medicamento.

Prediction of Therapeutic Response to Cyclooxygenase Inhibitors in Preterm Infants with Patent Ductus Arteriosus

Patent ductus arteriosus (PDA) is a morbid condition commonly seen in premature infants. Cyclooxygenase (COX) inhibitors, such as indomethacin and ibuprofen, are often used for the treatment of PDA in preterm infants, and they work by reducing the production of prostaglandin. However, as observed in clinical practice, not all PDAs in preterm infants can be closed using COX inhibitors. Some studies have demonstrated that gestational age, birth weight, B-type natriuretic peptide (BNP), and ductal diameter can predict the therapeutic responsiveness to COX inhibitors. This paper reviews the factors that can predict successful closure of the PDA in preterm infants using indomethacin or ibuprofen and presents new opinions and recent findings on this topic, including the predictive roles of intrauterine growth restriction, timing of the treatment, and the importance of platelet count and arterial pH. We also discuss the prospects for future studies to improve the individualized therapy of PDA in premature neonates.

[Treatment and prognosis of pulmonary hemorrhage in preterm infants during 2007-2016]

OBJECTIVE

To study the treatment and prognosis of pulmonary hemorrhage in preterm infants.

METHODS

A total of 106 preterm infants diagnosed with pulmonary hemorrhage, who were hospitalized in the neonatal ward of Peking University Third Hospital between 2007 and 2016, were enrolled. These patients were divided into 2007-2011 group (34 cases) and 2012-2016 group (72 cases) according to the time of hospitalization, divided into conventional-frequency ventilation group (43 cases) and high-frequency oscillatory ventilation (HFOV) group (63 cases) according to the respiratory support method used after the development of pulmonary hemorrhage, and divided into non-operation group (34 cases) and operation group (14 cases) according to whether PDA ligation was performed for the unclosed PDA before pulmonary hemorrhage. The general data, treatment, and prognosis were compared between different groups.

RESULTS

Compared with the 2007-2011 group, the 2012-2016 group had higher rates of HFOV and PDA ligation (P&lt;0.05), a lower mortality rate during hospitalization (P&lt;0.05), a longer length of hospital stay (P&lt;0.05), and higher incidence rates of intracranial hemorrhage and bronchopulmonary dysplasia (P&lt;0.05). Compared with the conventional-frequency ventilation group, the HFOV group had a lower mortality rate during hospitalization (P&lt;0.05), a longer length of hospital stay (P&lt;0.05), and higher incidence rates of intracranial hemorrhage and bronchopulmonary dysplasia (P&lt;0.05). Compared with the non-operation group, the operation group had a lower mortality rate during hospitalization (P&lt;0.05), a longer length of hospital stay (P&lt;0.05), and higher incidence rates of intracranial hemorrhage and bronchopulmonary dysplasia (P&lt;0.05).

CONCLUSIONS

The application of HFOV and PDA ligation can improve the survival rate of preterm infants with pulmonary hemorrhage, but the incidence of intracranial hemorrhage and bronchopulmonary dysplasia is also increased.

Association of Placebo, Indomethacin, Ibuprofen, and Acetaminophen With Closure of Hemodynamically Significant Patent Ductus Arteriosus in Preterm Infants: A Systematic Review and Meta-analysis

IMPORTANCE

Despite increasing emphasis on conservative management of patent ductus arteriosus (PDA) in preterm infants, different pharmacotherapeutic interventions are used to treat those developing a hemodynamically significant PDA.

OBJECTIVES

To estimate the relative likelihood of hemodynamically significant PDA closure with common pharmacotherapeutic interventions and to compare adverse event rates.

DATA SOURCES AND STUDY SELECTION

The databases of MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched from inception until August 15, 2015, and updated on December 31, 2017, along with conference proceedings up to December 2017. Randomized clinical trials that enrolled preterm infants with a gestational age younger than 37 weeks treated with intravenous or oral indomethacin, ibuprofen, or acetaminophen vs each other, placebo, or no treatment for a clinically or echocardiographically diagnosed hemodynamically significant PDA.

DATA EXTRACTION AND SYNTHESIS

Data were independently extracted in pairs by 6 reviewers and synthesized with Bayesian random-effects network meta-analyses.

MAIN OUTCOMES AND MEASURES

Primary outcome: hemodynamically significant PDA closure; secondary: included surgical closure, mortality, necrotizing enterocolitis, and intraventricular hemorrhage.

RESULTS

In 68 randomized clinical trials of 4802 infants, 14 different variations of indomethacin, ibuprofen, or acetaminophen were used as treatment modalities. The overall PDA closure rate was 67.4% (2867 of 4256 infants). A high dose of oral ibuprofen was associated with a significantly higher odds of PDA closure vs a standard dose of intravenous ibuprofen (odds ratio [OR], 3.59; 95% credible interval [CrI], 1.64-8.17; absolute risk difference, 199 [95% CrI, 95-258] more per 1000 infants) and a standard dose of intravenous indomethacin (OR, 2.35 [95% CrI, 1.08-5.31]; absolute risk difference, 124 [95% CrI, 14-188] more per 1000 infants). Based on the ranking statistics, a high dose of oral ibuprofen ranked as the best pharmacotherapeutic option for PDA closure (mean surface under the cumulative ranking [SUCRA] curve, 0.89 [SD, 0.12]) and to prevent surgical PDA ligation (mean SUCRA, 0.98 [SD, 0.08]). There was no significant difference in the odds of mortality, necrotizing enterocolitis, or intraventricular hemorrhage with use of placebo or no treatment compared with any of the other treatment modalities.

CONCLUSIONS AND RELEVANCE

A high dose of oral ibuprofen was associated with a higher likelihood of hemodynamically significant PDA closure vs standard doses of intravenous ibuprofen or intravenous indomethacin; placebo or no treatment did not significantly change the likelihood of mortality, necrotizing enterocolitis, or intraventricular hemorrhage.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42015015797.

Pharmacological Closure of Patent Ductus Arteriosus: Selecting the Agent and Route of Administration

Opinions are divided regarding the management of a persistently patent ductus arteriosus (PDA). Some of the adverse effects associated with a large hemodynamically significant duct, including prolonged ventilation, pulmonary hemorrhage, bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and mortality, indicate that active management of infants with large ductal shunts may sometimes be necessary. Indomethacin and ibuprofen are the two US FDA-approved cyclooxygenase (COX) inhibitors used for the closure of a ductus in preterm babies. Both these drugs are effective in 70-80% of extremely low birthweight infants. Treatment with COX inhibitors may be associated with renal impairment, gastrointestinal hemorrhage, NEC, and spontaneous intestinal perforation when given concurrently with steroids, as well as changes in cerebrovascular auto-regulation. Ibuprofen appears to be a better choice for PDA closure, with a better side effect profile and efficacy that equals that of indomethacin. However, long-term outcome studies of ibuprofen are lacking, and prophylactic ibuprofen is ineffective in decreasing severe IVH. The choice of one drug over the other also depends on local availability of both drugs and the intravenous or enteral preparation. The oral preparation of ibuprofen appears as effective as the intravenous preparation. The use of paracetamol to close a hemodynamically significant PDA has increased in recent years. Paracetamol also decreases prostacyclin synthesis; however, unlike COX inhibitors, it does not have a peripheral vaso-constrictive effect and can be given to infants with contraindications to non-steroidal anti-inflammatory drugs. It appears to have similar efficacy based on limited data available from randomized trials. Until more data are available on efficacy, safety, and long-term outcomes, it cannot be recommended as the first choice.

Clinical pharmacology of indomethacin in preterm infants: implications in patent ductus arteriosus closure

Indomethacin is a non-steroidal anti-inflammatory drug that is a potent inhibitor of prostaglandin E(2) synthesis. After birth, the ductus arteriosus closes spontaneously within 2-4 days in term infants. The major factor closing the ductus arteriosus is the tension of oxygen, which increases significantly after birth. Prostaglandin E(2) has the opposite effect to that of oxygen; it relaxes smooth muscle and tends to inhibit the closure of the ductus arteriosus. In preterm infants with respiratory distress syndrome, the ductus arteriosus fails to close (patent ductus arteriosus [PDA]) because the concentration of prostaglandin E2 is relatively high. PDA occurs in more than 70 % of neonates weighing less than 1,500 g at birth. The aim of this article was to review the published data on the clinical pharmacology of indomethacin in preterm infants in order to provide a critical analysis of the literature and a useful tool for physicians. The bibliographic search was performed electronically using the PubMed and EMBASE databases as search engines and February 2012 was the cutoff point. A remarkable interindividual variability was observed for the half-life (t(½)), clearance (CL), and volume of distribution (V(d)) of indomethacin. Prophylactic indomethacin consists of a continuous infusion of low levels of indomethacin and may be useful in preterm infants. Extremely preterm infants are less likely to respond to indomethacin. Infants with a postnatal age of 2 months do not respond to treatment with indomethacin. Indomethacin has several adverse effects, the most common of which is renal failure. An increase in serum creatinine of ≥0.5 % mg/dL after indomethacin was observed in about 10-15 % of the patients and creatinine returns to a normal level about 1 week after cessation of therapy. Indomethacin should be administered intravenously by syringe pump for at least 30 min to minimize adverse effects on cerebral, gastrointestinal, and renal blood flow velocities. A prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in patients with PDA. In conclusion, indomethacin is a useful drug to treat PDA.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Spontaneous intestinal perforation in extremely low birth weight infants: association with indometacin therapy and effects on neurodevelopmental outcomes at 18-22 months corrected age

BACKGROUND

Spontaneous intestinal perforation (SIP) is associated with the use of postnatal glucocorticoids and indometacin in extremely low birth weight (ELBW) infants. The authors hypothesised: 1) an association of SIP with the use of antenatal steroids (ANS) and indometacin either as prophylaxis for intraventricular hemorrhage (IVH) (P Indo) or for treatment of PDA (Indo/PDA) and 2) an increased risk of death or abnormal neurodevelopmental outcomes in infants with SIP at 18-22 months corrected age.

DESIGN/METHODS

The authors retrospectively identified ELBW infants with SIP in the Neonatal Research Network's generic database. Unadjusted analysis identified the differences in maternal, neonatal and clinical variables between infants with and without SIP. Logistic regression analysis identified the adjusted OR for SIP with reference to ANS, P Indo and Indo/PDA. Neurodevelopmental outcomes were assessed among survivors at 18-22 months corrected age.

RESULTS

Indo/PDA was associated with an increased risk of SIP (adjusted OR 1.61; 95% CI 1.25 to 2.08), while P Indo and ANS were not. SIP was independently associated with an increased risk of death or neurodevelopmental impairment (NDI) (adjusted OR 1.85; 95% CI 1.32 to 2.60) and NDI among survivors (adjusted OR 1.75, 95% CI 1.20 to 2.55).

CONCLUSION

Indometacin used for IVH prophylaxis and ANS were not associated with the occurrence of SIP in ELBW infants. Indometacin used for treatment of symptomatic PDA was however associated with an increased risk of SIP. ELBW infants with SIP have an increased risk of poor neurodevelopmental outcomes.

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.

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.

Factors affecting successful closure of hemodynamically significant patent ductus arteriosus with indomethacin in extremely low birth weight infants

BACKGROUND

The incidence of patent ductus arteriosus (PDA) is high in extremely low birth weight (ELBW) infants. Indomethacin has been widely used in the prophylaxis and treatment of hemodynamically significant PDA. This retrospective study was undertaken to identify factors such as birth weight, gestational age, gender, fetal growth retardation, ductal size, timing of the first dose of indomethacin and side effects of indomethacin, which may affect the successful closure of the PDA with indomethacin in ELBW infants.

METHODS

A cohort of 139 ELBW infants who had received indomethacin treatment for PDA during a consecutive period of more than three years (September 2000 to December 2003) was retrospectively analyzed. Administration

RESULTS

of indomethacin was associated with closure of PDA in 108 (77.7%) of 139 ELBW infants, and only 19.4% of infants required surgical ligation of the ductus eventually. There was no significant relationship between closure of PDA with gestational age, gender, fetal growth retardation, and ductal size. A higher birth weight and early use of indomethacin after birth could significantly increase the closure rate of PDA (P<0.05). Side effects of indomethacin such as transient oliguria and hyponatremia during indomethacin therapy did not affect PDA closure.

CONCLUSIONS

Indomethacin is effective for the treatment of PDA in ELBW infants. A higher rate of ductal closure is related to the increase of birth weight. PDA closure with indomethacin is age-related, and early administration of indomethacin could increase PDA closure and reduce the incidence of hyponatremia. There is no significant difference in major morbidities such as bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), and retinopathy of prematurity (ROP) after early treatment. Early screening for hemodynamically significant PDA in ELBW infants and early treatment with indomethacin are recommended.

Pharmacologic, pharmacodynamic, and pharmacokinetic considerations with intravenous Ibuprofen lysine

Patent ductus arteriosus (PDA) is a common complication in preterm infants. An intravenous (IV) cyclooxygenase (COX) inhibitor is the pharmacotherapy of choice. Concerns over adverse effects associated with the traditional treatment, IV indomethacin, have led to the investigation of other COX inhibitors to assist closure of PDA. IV ibuprofen lysine is a COX inhibitor that demonstrates similar efficacy to indomethacin with few adverse effects. In addition, IV ibuprofen lysine does not cause reductions in cerebral, renal, and mesenteric blood flow that can be seen with indomethacin, and thus ibuprofen therapy is not associated with reduced renal function. Ibuprofen is primarily metabolized by cytochrome P450 (CYP) 2C9. The immaturity of neonatal biotransformation pathways has a pronounced effect on the pharmacokinetic parameters of ibuprofen, particularly because CYP2C9 enzyme activity is known to be very low at birth and to increase rapidly over the first several days of life. Ibuprofen is highly bound to albumin, raising concern that ibuprofen may displace bilirubin and subsequently increase free bilirubin concentrations. However, the ibuprofen concentrations achieved with approved dosing with IV ibuprofen lysine are lower than those expected to result in displacement of bilirubin and related adverse effects. Factors such as gestational age and CYP2C9 polymorphism may affect ibuprofen metabolism and therefore optimal dosing, but further clinical investigation is needed in these areas. Other areas for future investigation include prolonged dosing regimens, prophylactic administration, and alternate indications. At the approved dose, IV ibuprofen lysine is a safe, effective pharmacologic agent to promote closure of PDAs in preterm infants.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. Prolonging the course of indomethacin has the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine the effect of a prolonged course of indomethacin (compared to a short course) on the rate of treatment failure without unwanted side-effects in preterm infants with PDA.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to December 2006), EMBASE (1974 to December 2006), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2006). No language restrictions were applied.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials including preterm infants with PDA, diagnosed on clinical and/or echocardiographic examination that evaluated indomethacin treatment by any route given as a long course (four or more doses) vs. a short course (three or fewer doses) were included in the review. Trials needed to report on at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three review authors independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. The I squared statistic was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Five trials met inclusion criteria and included 431 infants. Prolonged indomethacin treatment when compared to the short course did not result in a statistically significant difference in PDA closure, re-treatment, re-opening, or ligation rates. The prolonged course was associated with an increased risk of NEC [typical RR 1.87 (95% CI 1.07, 3.27); typical RD 0.08 (95% CI 0.01, 0.15); NNH 13 (7, 100)] and a decreased incidence of renal function impairment, as evidenced by a lower proportion of infants having diminished urine output [typical RR 0.27 (95% CI 0.13, 0.6); typical RD -0.19 (95% CI -0.28, -0.09); NNT 5 (4, 11)] and increased serum creatinine level [typical RR 0.51 (95% CI 0.33, 0.77); typical RD -0.14 (95% CI -0.23, -0.06); NNT 7 (4, 16)].

AUTHORS' CONCLUSIONS

Implications for practiceProlonged indomethacin course does not appear to have a significant effect on improving important outcomes, such as PDA treatment failure, CLD, IVH, or mortality. The reduction of transient renal impairment does not outweigh the increased risk of NEC associated with the prolonged course. Based on these results, a prolonged course of indomethacin cannot be recommended for the routine treatment of PDA in preterm infants. Implications for researchThere is a paucity of data on optimal dosing and duration of indomethacin therapy for the treatment of PDA, in particular for extremely low birth weight infants (ELBW) premature infants. It is likely that a single standard indomethacin regime is not the ideal for every premature infant. Therefore, individual patient response should be considered and evaluated, in particular in ELBW infants. Future randomized clinical trials should include this high risk population and investigate the effect of tailoring dose and duration of therapy to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes, including long-term neurodevelopmental outcomes. In addition, factors that may influence treatment effect, such as birth weight, gestational age, age at the time of randomization, total fluid intake, feeding practice, and severity of PDA, need to be taken into account when designing such studies.

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.

Effectiveness and side effects of an escalating, stepwise approach to indomethacin treatment for symptomatic patent ductus arteriosus in premature infants below 33 weeks of gestation

OBJECTIVE

Symptomatic patent ductus arteriosus (sPDA) is a common problem in premature infants and can be treated effectively with intravenous indomethacin, leading to permanent ductal closure in 70% to 80% of infants. Infants who do not respond to pharmacologic closure of the duct ultimately have to undergo surgical or interventional closure of the PDA. Optimizing the pharmacologic treatment could offer an interesting approach to reduce the number of infants who need surgical closure of the duct.

METHODS

We conducted a retrospective analysis in infants who were <33 weeks' gestation, had sPDA, and were treated with high-dose intravenous indomethacin. From 1993 to 2002, 129 infants with sPDA received indomethacin after diagnosis of sPDA was confirmed by echocardiography. Treatment was started in all infants with intravenous indomethacin (0.2 mg/kg given 5 times at 0 hours, 12 hours, 24 hours, 48 hours, and 72 hours). When the ductus was still open at 36 hours, indomethacin every 12 hours was continued and single doses increased up to 1 mg/kg until ductal closure was achieved.

RESULTS

In 68 (53%) of 129 infants who were treated with indomethacin, ductal closure occurred during intermediate-dose indomethacin therapy (up to 1.5 mg/kg total dose). In the 61 initial nonresponders, the continuation of indomethacin led to ductal closure in 59 infants. When infants who were treated with an intermediate dose were compared with the initial nonresponders, no differences in the incidences of renal or electrolyte abnormalities, gastrointestinal bleeding, intraventricular hemorrhage, or periventricular leukomalacia were found.

CONCLUSIONS

High-dose indomethacin after intermediate-dose therapy resulted in an overall closure rate of 98.5% (127 of 129). Although single indomethacin doses of up to 1 mg/kg were given, high-dose indomethacin was safe.

Basic principles of noninvasive blood pressure measurement in infants

Correct measurement of blood pressure in infants is essential because blood pressure is an important indicator of cardiovascular status. This article provides a review of the fundamental principles of blood pressure measurement. Formulas to estimate mean arterial pressure are discussed along with an overview of pulse pressure. The advantages, challenges, and accuracy of the widely used oscillometric method of noninvasive blood pressure measurement are discussed. A step-by-step guide to noninvasive blood pressure measurement is outlined along with pragmatic strategies to ensure appropriate technique, thereby improving accuracy.

Patent Ductus Arteriosus and Respiratory Outcome in Premature Infants

A persistent ductus arteriosus is a common event in preterm infants. The systemic-to-pulmonary shunting that occurs as the pulmonary vascular resistance decreases after birth can have significant cardiovascular and respiratory consequences. Acute pulmonary effects include pulmonary edema and hemorrhage, worsened lung mechanics and deterioration in gas exchange with hypoxemia and hypercapnia. The increased pulmonary blood flow can also produce damage to the capillary endothelium and trigger an inflammatory cascade. This, plus the need for longer and more aggressive mechanical ventilation, can explain the association between patent ductus arteriosus and an increased risk for bronchopulmonary dysplasia in extremely premature infants.

The pharmacologic closure of the patent ductus arteriosus

The ductus arteriosus is a fetal vessel that allows most of the blood leaving the right ventricle of the heart to bypass the lungs. Fetal patency of the ductus, and its spontaneous closure after birth, is the result of a balanced interaction of locally produced and circulating mediators (of which prostaglandins seem to be the most important), and the unique structure of the vessel wall. Persistent patency of the ductus occurs in almost 60% of very low birthweight infants. A significant left-to-right shunt through the ductus increases morbidity and mortality in premature infants. As prostaglandins play a major role in patency of the ductus, cyclooxygenase inhibitors are conventionally used to induce its closure. This chapter focuses on some of the basic mechanisms underlying ductal patency and the clinical attempts to diminish side effects associated with indomethacin, including the alternative use of ibuprofen.

Prolonged versus short course of indomethacin for the treatment of patent ductus arteriosus in preterm infants

BACKGROUND

Indomethacin is a prostaglandin inhibitor used to treat patent ductus arteriosus (PDA) in preterm infants. Although indomethacin produces ductal closure in the majority of cases, it is ineffective in up to 40% of patients. Furthermore, the ductus will re-open in up to 35% of infants who initially respond to the drug. A more prolonged course of indomethacin has been studied regarding the potential to achieve higher rates of ductal closure.

OBJECTIVES

To determine if a prolonged course of indomethacin (compared to a short course) reduces the rate of treatment failure in preterm infants with PDA without unwanted side-effects.

SEARCH STRATEGY

The search included review of personal files, abstracts of conferences, and the following electronic databases: MEDLINE (1966 to April 2003), EMBASE (1974 to April 2003), and Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2003). No language restrictions were applied.

SELECTION CRITERIA

1) DESIGN AND POPULATION: Randomized or quasi-randomized controlled trials including preterm infants with PDA diagnosed on clinical and/or echocardiographic examination.2) INTERVENTION: Indomethacin treatment by any route given as a long course (four or more doses) vs a short course (three or fewer doses). 3) OUTCOMES: Report of at least one of the following outcomes: failure of PDA to close, need for re-treatment, PDA re-opening, PDA ligation, mortality, duration of assisted ventilation, chronic lung disease (CLD), duration of supplemental oxygen dependence, intraventricular hemorrhage (IVH) (all and severe), diminished urine output, increased serum creatinine, necrotizing enterocolitis (NEC), bleeding diathesis, retinopathy of prematurity (ROP), and duration of hospital stay.

DATA COLLECTION AND ANALYSIS

The three reviewers independently abstracted data from each study. Relative risk (RR) and Risk Difference (RD) with 95% confidence intervals (CI) using the fixed effect model for meta-analysis are reported. When a statistically significant RD was found, the number needed to treat (NNT) or number needed to harm (NNH) was also calculated with 95% CIs. A chi-square test was used to test for heterogeneity of results among included trials.

MAIN RESULTS

Prolonged indomethacin treatment when compared to the short course resulted in a borderline statistically significant difference in PDA re-opening rate favoring the prolonged course [RR 0.54 (95% CI 0.3, 0.99); RD -0.12 (95% CI -0.24, -0.01); NNT = 8 (4, 100). There was no statistically significant treatment effect on PDA closure, re-treatment, or ligation rates. The prolonged course was associated with a decreased incidence of severe IVH [RR 0.49 (95% CI 0.25, 0.98); RD -0.12 (95% CI -0.24, -0.01); NNT 8 (4, 100)] and renal function impairment, as evidenced by a lower proportion of infants having an increased creatinine level [RR 0.52 (95% CI 0.34, 0.81); RD -0.20 (95% CI -0.33, -0.08); NNT 5 (3, 13)]. However, there was a trend for the prolonged course to increase the proportion of infants with CLD in the one trial reporting this outcome [RR 2.24 (95% CI 0.98, 5.12); RD 0.24 (95% CI 0.01, 0.47)].

IMPLICATIONS FOR PRACTICE

Prolonged as compared to short course of indomethacin for the treatment of PDA in preterm infants has a borderline effect on reducing the rate of PDA re-opening and it may be associated with an increased risk for CLD. However, prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in this population. Definitive recommendations about the preferred duration of indomethacin therapy, i.e. prolonged versus short course, for the treatment of PDA in premature infants cannot be made based on the current findings of this review.

IMPLICATIONS FOR RESEARCH

There is a paucity of data on optimal duration of indomethacin therapy for the treatment of PDA, in particular for ELBW premature infants. Future randomized clinical trials should include this high risk population and investigate the premature infants. Future randomized clinical trials should include this high risk population and investigate the possibility of tailoring duration of therapy (prolonged versus short) to individual response in terms of echocardiographic findings and/or prostaglandin levels, focusing on clinically significant outcomes and potential complications associated with either strategy. In addition, factors which may influence treatment effect need to be taken into account when designing such studies.