Position statement
Posted: Feb 1, 2022
Souvik Mitra, Dany Weisz, Amish Jain, Geert ‘t Jong; Canadian Paediatric Society, Fetus and Newborn Committee, Drug Therapy Committee
Paediatr Child Health 2022 27(1): 63 (Abstract)
Management of the patent ductus arteriosus (PDA) is one of the most contentious topics in the care of preterm infants. PDA management can be broadly divided into prophylactic and symptomatic therapy. Prophylaxis with intravenous indomethacin in extremely low birth weight infants may reduce severe intraventricular hemorrhage. Echocardiography should be routinely used to confirm the presence of a PDA before considering symptomatic therapy. A symptomatic PDA can be managed conservatively, using pharmacotherapy or with procedural closure. Ibuprofen should be considered as the pharmacotherapy of choice for a symptomatic PDA. High-dose ibuprofen may be preferable, especially for preterm infants beyond the first 3 to 5 days of age. If pharmacotherapy fails (after two courses) or is contraindicated, procedural closure may be considered for infants with a persistent PDA with significant clinical symptoms in addition to echocardiographic signs of a large PDA shunt volume and pulmonary over-circulation.
Keywords: Cyclo-oxygenase inhibitors (COX-I); Hemodynamically significant (hs)-PDA; Patent ductus arteriosus (PDA); Preterm infants; Procedural PDA closure
Management of the patent ductus arteriosus (PDA) in preterm infants is one of the most contentious topics in neonatal intensive care. PDAs have been associated without proof of causation with numerous adverse outcomes, including prolongation of assisted ventilation, pulmonary hemorrhage, chronic lung disease (CLD), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and death [1][2].
The clinical decision to provide prophylactic PDA treatment using cyclooxygenase-inhibitor (COX-I) drugs has primarily been driven by the perceived benefits versus potential risks as determined by the treating physician. Randomized controlled trials (RCTs) have not shown a clear benefit of symptomatic PDA treatment, partially due to major methodological challenges such as high rates of open-label backup treatment in the experimental and control arms, and a lack of high quality data on clinically important outcomes, such as NEC, CLD, IVH, and mortality. Controversy remains whether a PDA should be treated, and if so, in whom, when, and which pharmacotherapeutic agent to use as well as when to consider procedural closure of the PDA.
Data from the Canadian Neonatal Network suggest an increase in conservative, non-pharmacological management of PDAs in preterm infants in recent years [3]. However, there is no consensus on what conservative management entails and which infants are appropriate candidates. Furthermore, with an increase in conservative PDA management, more infants who are repatriated back to non-tertiary neonatal care units tend to have a persistent PDA. Persistent PDA often poses a management dilemma among physicians caring for these infants, who are otherwise well but may have ongoing respiratory symptoms due to CLD.
This position statement systematically addresses the most important questions that may be a source of variation in clinical practice related to PDA management.
A comprehensive search was conducted including the Cochrane Central Register of Controlled Trials (CENTRAL 2020, issue 12) in the Cochrane Library; MEDLINE (1996 to December 14, 2020); Embase (1980 to December 14, 2020); and CINAHL (1982 to December 14, 2020), using the following search terms: preterm/premature, patent ductus arteriosus, PDA, indomethacin, ibuprofen, paracetamol, acetaminophen, surgery, transcatheter, ligation, and applicable MeSH terms. RCTs, cohort studies, and systematic reviews were specifically sought. Searches were not restricted by language.
The GRADE (Grading of Recommendations, Assessment, Development and Evaluations) Evidence to Decision (EtD) framework was used to formulate the recommendations [4]. The detailed EtDs for each question are available in the online appendix.
Nineteen RCTs (2872 infants) have evaluated use of prophylactic indomethacin. The largest single 2001 trial restricted participation to extremely low birth weight (ELBW; <1000 g) infants [5]. Prophylactic indomethacin significantly reduced rates of severe IVH, PDA ligation, and symptomatic PDA. However, this strategy did not appeare to improve rates of CLD, severe neurodevelopmental impairment, and cerebral palsy among survivors [6] (Table 1). Furthermore, there are concerns regarding the association of prophylactic indomethacin and gastrointestinal (GI) perforation in extremely preterm infants, especially when prophylactic hydrocortisone is used concomitantly [7][8]. Therefore, prophylactic use of indomethacin may only be considered in infants with risk factors predictive of severe IVH, such as extremely low gestational age (GA), lack of antenatal corticosteroids, and being born outside a tertiary care centre [9][10].
Prophylactic ibuprofen (seven RCTs; 931 infants) may marginally reduce severe IVH and PDA ligation [11]. However, use of ibuprofen prophylaxis in preterm infants is not recommended due to its minimal benefits, possible harm related to increased GI hemorrhage, and reports of associated acute severe pulmonary hypertension [11][12]. Prophylactic acetaminophen has not been shown to appreciably improve any patient-important clinical outcomes (two RCTs; 80 infants) [13].
Summary: Selective prophylaxis with intravenous (IV) indomethacin may be considered in ELBW infants at high risk for severe IVH (conditional recommendation). There is insufficient evidence to recommend prophylactic ibuprofen or acetaminophen in extremely preterm or ELBW infants.
RCT evidence on prophylactic COX-I use is summarized in Table 1.
Table 1. Summary of RCT evidence on PDA pharmacoprophylaxis in preterm infants | |||
Author, year | Type of study | Interventions |
Main results (with GRADE certainty of evidence, when available) |
Fowlie 2010 [6] | Systematic review (19 RCTs;2872 infants) | Indomethacin |
|
Ohlsson 2019 [11] | Systematic review (7 RCTs;931 infants) | Ibuprofen |
|
Ohlsson 2020 [13] | Systematic review (2 RCTs;80 infants) | Acetaminophen |
|
CLD chronic lung disease, IVH intraventricular hemorrhage, NEC necrotizing enterocolitis, PDA patent ductus arteriosus, RCT randomized controlled trial |
There is limited consensus on the definition of an hs-PDA [2][14][15]. Clinical signs of a symptomatic PDA, which include precordial murmur in addition to one or more of hyperdynamic precordial impulse, tachycardia, bounding pulses, widened pulse pressure, or worsening respiratory status, are generally unreliable in determining the PDA shunt volume and thereby the need for treatment [16][17]. Treatment of a symptomatic PDA, therefore, should never be initiated based on clinical examination alone [16][18]. Several echocardiographic parameters are used to quantify the PDA shunt volume. A PDA size of >1.5 mm and a left atrium to aortic root ratio >1.4 are the two echocardiographic measures most commonly used in RCTs to define hemodynamic significance [2]. Of these common echocardiographic parameters, a PDA diameter of <1.5 mm can fairly reliably rule out a large volume PDA shunt in most infants [17]. Studies have attempted to define the degree of shunt volume based on clinical and echocardiography-based classification or scoring systems [19][20]. However, the utility of such PDA-severity scores have not been validated through large RCTs.
Summary: Echocardiography should be used to confirm the presence of a left-to-right PDA shunt before considering treatment (strong recommendation). There is insufficient evidence to suggest a set of echocardiographic criteria to define hemodynamic significance of the PDA. A PDA with a diameter of <1.5 mm is unlikely to result in a hemodynamically significant shunt, and therefore may be conservatively managed without pharmacotherapy (conditional recommendation).
Seven RCTs (n=526) have compared early treatment (initiated within 7 days) and seven RCTs (n=384) have compared very early treatment (initiated within 3 days) to early conservative (i.e., non-pharamocological) management of a PDA [21][22]. (Conservative management is reviewed below, following the Summary). Early (or very early) PDA treatment appears to increase overall COX-I exposure in preterm infants without reducing death, severe IVH, CLD, surgical PDA ligation, or neurodevelopmental impairment [21][22]. Two further RCTs that compared treatment initiation between 6 to 14 days of age with conservative management also failed to demonstrate any significant differences in clinical outcomes [23][24]. However, only six trials to date have exclusively enrolled extremely preterm infants [22][23][25]-[28].
Interestingly, a follow-up analysis of eligible infants who were not enrolled in one of the recent (PDA-TOLERATE) trials due to lack of physician equipoise showed that the group treated before 6 days postnatal age had a significantly lower incidence of CLD and/or death, despite having a significantly lower GA and substantially higher initial respiratory morbidity [29]. Furthermore, other observational studies have shown that a persistent, symptomatic PDA in extremely preterm infants is associated with increased risk for mortality, while routine early screening echocardiography before day 3 of age is associated with lower in-hospital mortality and a lower likelihood of pulmonary hemorrhage [30]-[32].
Summary: Clinicians may choose to conservatively manage a symptomatic PDA within the first 1 to 2 weeks after birth (conditional recommendation). However, they should exercise caution with conservative management in clinically unstable extremely preterm infants (<26 weeks GA), for whom earlier pharmacotherapy may be considered.
Conservative management of the PDA: There is little consensus on what conservative PDA management entails. Prophylactic restriction of IV fluids may reduce incidence of symptomatic PDA in older infants, but the benefits of this practice remain unclear for very low birth weight (VLBW) infants [33][34]. There is no evidence to support restricting fluids to treat a symptomatic PDA. Moreover, there are concerns that aggressive fluid restriction (restricting fluids to <120 mL/kg/day) may significantly worsen regional blood flow, and this practice therefore cannot be recommended [35]. Loop diuretics such as furosemide are often used to reduce pulmonary edema and improve lung function [36]. Earlier concerns that renal upregulation of prostaglandin E2 (PGE2) induced by furosemide would inhibit ductal closure have not been substantiated by recent studies [37][38]. One recent large observational study (n=43,576) demonstrated that exposure to furosemide decreased the odds of PDA treatment (adjusted odds ratio (OR)=0.72, 95% CI, 0.65 to 0.79), lending further credence to furosemide use as part of conservative management strategy [39]. Other physiological manoeuvres, such as increasing the positive end-expiratory pressure (PEEP), have also been shown to reduce left-to-right shunting without significantly affecting cerebral perfusion or oxygenation [40].
Summary: Use of diuretics and PEEP modulation may be considered for conservative PDA management in preterm infants (conditional recommendation). Given the unclear benefits and potential harms of restricting fluids in VLBW infants, aggressive fluid restriction as a management strategy for symptomatic PDA is not suggested (conditional recommendation).
At least eighty RCTs have been conducted comparing different COX-I medications, doses, and routes to treat symptomatic PDA. Standard-dose ibuprofen (10 mg/kg followed by two doses of 5 mg/kg at 24 h-intervals) is the most common regimen and has a significantly better safety profile than indomethacin (the previous gold standard) [41]. Acetaminophen has also emerged as a potential treatment option for PDA closure, with its enteral formulation being as effective as standard-dose ibuprofen or indomethacin, and a significantly better GI/renal safety profile [13]. However, recent RCTs have suggested that PDA closure with IV acetaminophen is significantly lower than with either indomethacin or ibuprofen [42]-[44].
One recent network meta-analysis of sixty-eight RCTs (4802 infants) showed that higher doses of ibuprofen (15 mg/kg to 20 mg/kg followed by two doses of 7.5 mg/kg to 10 mg/kg at 24 h-intervals), especially when given enterally, may achieve better PDA closure without increasing risk for adverse outcomes (such as NEC) compared with standard-dose ibuprofen, indomethacin, or acetaminophen (low certainty) [15]. These data are consistent with recent studies suggesting that higher doses of ibuprofen may be required beyond the first 3 to 5 days post-birth to achieve therapeutic serum levels [24][45][46]. However, the effect estimates for high-dose ibuprofen were derived from four small RCTs (n=319), three of which enrolled infants with a mean GA ≥30 weeks. Therefore, the effectiveness and safety of high-dose ibuprofen use in extremely preterm infants remains unknown, which has resulted in widely variable clinical practice among Canadian NICUs. RCT evidence on pharmacotherapy for symptomatic PDA is summarized in Table 2.
Summary: Ibuprofen should be considered the pharmacotherapy of choice for a symptomatic PDA (strong recommendation). High-dose ibuprofen may be considered as the preferred dosage, especially for preterm infants beyond the first 3 to 5 days of age (conditional recommendation). Exercise caution when treating extremely preterm infants (<26 weeks GA) with high-dose ibuprofen due to limited safety and efficacy data.
Table 2. Summary of RCT evidence on pharmacotherapy for symptomatic PDA in preterm infants | |||
Author, year | Type of study | Interventions |
Main results (with GRADE certainty of evidence, when available) |
Mitra 2018 [15] | Systematic review and network meta-analysis (68 RCTs;4802 infants) | Compared indomethacin, ibuprofen, or acetaminophen with another medication, placebo, or no treatment |
|
Ohlsson 2020 [41] | Systematic review (39 RCTs;2843 infants) | Compared ibuprofen in different doses and by different routes of administration, and against indomethacin or placebo |
Ibuprofen versus indomethacin
High-dose versus standard-dose ibuprofen
Oral versus IV standard-dose ibuprofen
|
Ohlsson 2020 [13] | Systematic review (8 RCTs;916 infants) | Acetaminophen compared against ibuprofen or indomethacin |
Acetaminophen versus ibuprofen
Acetaminophen versus indomethacin
|
CLD chronic lung disease, IVH intraventricular hemorrhage, NEC necrotizing enterocolitis, PDA patent ductus arteriosus, RCT randomized controlled trial |
There is insufficient evidence regarding the efficacy and safety of repeat courses of pharmacotherapy for a persistent PDA. Observational studies have demonstrated that a second course of ibuprofen may significantly improve overall PDA closure rates as compared with the initial course, without increasing adverse effects, while benefits of a third course have not been consistently demonstrated [47]-[50]. Similarly, repeat courses of indomethacin have also shown improving, cumulative PDA closure rates. However, increased rates of periventricular leukomalacia have been reported in infants receiving more than two courses of indomethacin [51].
Given the better safety profile of acetaminophen, some centres may choose to use a third course of pharmacotherapy using acetaminophen while contemplating procedural PDA closure. A recent retrospective observational study showed that extremely preterm infants with a persistent symptomatic PDA who were treated with a 3 to 7-day course of oral acetaminophen following two failed courses with indomethacin or ibuprofen had significantly reduced surgical ligation but increased rates of CLD [52].
Summary: A second course of COX-I therapy should be considered over invasive management for a persistent, symptomatic PDA when there are no contraindications (strong recommendation). The benefit of a third course of pharmacotherapy with enteral acetaminophen is unclear but may be considered after discussion with the infant’s parents or guardians, especially while awaiting invasive PDA closure (conditional recommendation).
Procedural closure of the PDA: There is considerable debate regarding the usefulness and timing of invasive PDA closure in preterm infants. It has been shown that persistence of a symptomatic PDA is associated with increased risk for death or CLD [53][54]. However, outcomes following surgical PDA ligation are controversial because most evidence for and against the procedure is obtained from studies that failed to address confounding by indication. One recent Canadian observational study (n=166) showed that a pre-ligation PDA diameter >2.5 mm and left ventricular dilatation (z score ≥2) predicted earlier extubation following surgical ligation in ventilator-dependent preterm infants. This finding suggests possible short-term respiratory benefit of procedural PDA closure in the subgroup of preterm infants with echocardiographic markers of large shunt volume and pulmonary overcirculation [55].
Summary: Procedural closure may be considered for infants with persistent PDA, even after two courses of pharmacotherapy or with contraindications to pharmacotherapy, when clinical symptoms are significant and echocardiography shows signs of large shunt volume and pulmonary overcirculation (conditional recommendation).
PDA ligation has been associated with complications such as post-PDA ligation syndrome, vocal cord paresis, phrenic nerve palsy, thoracic scoliosis, and inadvertent ligation of the left pulmonary artery (LPA) and aorta, with substantial variation in reported rates among centres [56][57]. One systematic review estimated the incidence of left vocal cord paralysis after PDA ligation in extremely preterm infants at 9% (95% CI, 5 to 15) with a wide variability among studies [58].
Percutaneous transcatheter PDA closure is an emerging option for preterm infants. A recent systematic review reported a technical success rate of 96% (95% CI, 93 to 98) in preterm infants ≤1.5 kg. However, this finding is balanced by an overall adverse event rate of 27% (95% CI, 17 to 38), a clinically significant adverse event rate (e.g., cardiac or vascular perforation, device embolization, and LPA stenosis requiring intervention) of 8% (95% CI, 5 to 10), and a procedure-related mortality rate of 2% (95% CI, 1 to 4) [59]. No RCTs have yet compared the efficacy and safety of these two approaches. Data on the cost-effectiveness of catheter-based PDA closure in preterm infants are also limited.
Summary: If institutional expertise is available and patient characteristics are suitable, percutaneous transcatheter PDA closure may be considered as an alternative to surgical PDA ligation (conditional recommendation). Further data on safety and cost-effectiveness are required before a strong recommendation can be made for this procedure to replace surgical PDA ligation as the invasive procedure of choice.
A persistent low-volume PDA shunt in stable and growing preterm infants who are not experiencing cardiorespiratory compromise is unlikely to affect clinical outcomes [60]. Most milder PDA shunts close spontaneously before term-corrected gestation [61][62]. However, there have been reports of preterm infants developing chronic pulmonary hypertension from prolonged exposure to large PDA shunts [63][64].
Summary: Routine referral to a tertiary care centre for echocardiographic evaluation of a persistent PDA in an otherwise clinically stable, growing, preterm infant before term-corrected GA is not recommended (strong recommendation). Paediatric cardiology referral should be sought for ongoing evaluation and follow-up when the PDA is deemed to be present at discharge (strong recommendation).
Note that conditional recommendations are opportunities for shared decision-making with an infant’s parents or guardians, with choices based on thorough discussion of the benefits and risks, prospective health outcomes, and the family’s values and preferences. Conditional recommendations also imply that the strength and the direction of recommendations may change as new evidence emerges.
This statement was reviewed by the Canadian Paediatric Society’s Community Paediatrics Committee as well as by members of the Canadian Targeted Neonatal Echocardiography Consortium (CANTEC).
CANADIAN PAEDIATRIC SOCIETY FETUS AND NEWBORN COMMITTEE (2020-2021)
Members: Gabriel Altit MD, Nicole Anderson MD (Resident Member), Heidi Budden MD (Board Representative), Leonora Hendson MD (past member), Souvik Mitra MD, Michael R. Narvey MD (Chair), Eugene Ng MD, Nicole Radziminski MD, Vibhuti Shah MD (past member)
Liaisons: Radha Chari MD (The Society of Obstetricians and Gynaecologists of Canada), James Cummings MD (Committee on Fetus and Newborn, American Academy of Pediatrics), William Ehman MD (College of Family Physicians of Canada), Danica Hamilton RN (Canadian Association of Neonatal Nurses), Chloë Joynt MD (CPS Neonatal-Perinatal Medicine Section Executive), Chantal Nelson PhD (Public Health Agency of Canada)
CANADIAN PAEDIATRIC SOCIETY DRUG THERAPY AND HAZARDOUS SUBSTANCES COMMITTEE (2020-2021)
Members: Jean-François Turcotte MD (Board Representative), Yaron Finkelstein MD, Shinya Ito, Geert ‘t Jong MD (Chair), Tom McLaughlin MD, Shahrad Rassekh MD, Smita Roychoudhury MD (Resident Member)
Liaison: Michael J. Rieder MD PhD (Canadian Society of Pharmacology and Therapeutics)
Principal authors: Souvik Mitra MD, MSc, Dany Weisz MD, Amish Jain MBBS, MRCPCH, PhD, Geert ‘t Jong MD
Disclaimer: The recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication.
Last updated: Feb 8, 2024