Ibuprofen lysine administration to neonates with a patent ductus arteriosus: effect on platelet plug formation assessed by in vivo and in vitro measurements

Platelets and ductus arteriosus closure in neonates

Platelet plug formation is critically involved in murine ductus arteriosus closure and thrombocytopenia in preterm infants seems to negatively affect spontaneous and pharmacologically induced ductal closure. Furthermore, platelet dysfunction may contribute to ductal patency, especially in extremely immature infants. Neonatal platelets likely have multifaceted roles during ductal closure, such as secretion of several signaling molecules and facilitation of specific cell-cell interactions. The only available randomized-controlled trial on platelet transfusions in preterm infants with patent ductus arteriosus demonstrated that a liberal transfusion regimen did not promote ductal closure, but was associated with an increased rate of intraventricular hemorrhage. Herein, we discuss the available mechanistic evidence on the role of platelets in ductus arteriosus closure and their potential clinical implications in preterm infants. We further briefly outline future research directions aimed at a better understanding of platelet-endothelial interactions in neonatal health and disease.

Oral ibuprofen promoted cholestatic liver disease in very low birth weight infants with patent ductus arteriosus

OBJECTIVES

Hemodynamically significant patent ductus arteriosus (hsPDA) in very low birth weight (VLBW) infants is routinely treated in many countries with oral ibuprofen. This study retrospectively assessed whether the risk of cholestatic liver disease (CLD) increased due to oral ibuprofen administration in VLBW infants.

METHODS

A total of 122 VLBW preterm infants (26∼32 weeks, birth weight<1500g) diagnosed with patent ductus arteriosus (PDA) admitted to our neonatal intensive care unit (NICU) between September 2016 to August 2018 were included. Sixty-four infants were diagnosed with hs-PDA and received ibuprofen treatment. VLBW infants with PDA untreated with ibuprofen served as controls. Soybean oil and fat emulsions were routinely added to parenteral nutrition (PN). Once CLD was diagnosed, the fat emulsions were immediately replaced with multi-oil fat emulsion injections. To assess the independent association of treatment and duration of ibuprofen with CLD and duration of fasting and PN, binary logistic regression or multivariate linear regression analyses were conducted, adjusting for major confounders (birth weight, gestational age, Clinical Risk Index for Babies, and cholestasis-associated risk factors).

RESULTS

The duration of PN increased due to ibuprofen treatment for 6.559 days (95% CI: 1.769, 11.349; P=0.008), and the risk of prolonged fasting (cutoff>5 days) might have increased due to ibuprofen treatment (OR: 3.043, 95% CI: 0.965, 9.594; P=0.057). Furthermore, CLD was influenced by ibuprofen treatment (OR: 6.730; 95% CI: 1.279, 35.41; P=0.024), early thrombocytopenia 7 days postnatal (OR: 6.996; 95% CI: 1.769, 27.658; P=0.004), and late onset sepsis (OR: 6.976; 95% CI: 1.561, 31.169; P=0.011). Further analysis adjusting for cholestasis-associated risk factors revealed that CLD was influenced by the duration of ibuprofen treatment (OR: 2.864; 95% CI: 1.104, 7.422; P=0.030), Platlets counts 7 days postnatal (OR: 0.971; 95% CI: 0.950, 0.994; P=0.013), and duration of antibiotics (OR: 1.134; 95% CI: 1.002, 1.282; P=0.046).

CONCLUSIONS

This retrospective study indicated oral ibuprofen duration-dependently increased the risk of CLD in VLBW infants with PDA, and early thrombocytopenia served as the critical risk factor.

Current Controversy on Platelets and Patent Ductus Arteriosus Closure in Preterm Infants

Platelets are critically involved in murine patent ductus arteriosus (PDA) closure. To date, the clinical significance of these findings in human preterm infants with PDA is still controversial. We discuss the available study data on the role of platelets for PDA closure in preterm infants: Several mostly retrospective studies have yielded conflicting results on whether thrombocytopenia contributes to failed spontaneous ductal closure. The same applies to investigations on the role of thrombocytopenia as a risk factor for unsuccessful ductus arteriosus closure by pharmacological treatment with cyclooxygenase inhibitors. Nonetheless, recent meta-analyses have concluded that thrombocytopenia constitutes an independent risk factor for both failed spontaneous and pharmacological PDA closure in preterm infants. However, the available investigations differ in regard to patient characteristics, diagnostic strategies, and treatment protocols. Several studies suggest that impaired platelet function rather than platelet number is critically involved in failure of ductus arteriosus closure in the preterm infant. A recent randomized-controlled trial on platelet transfusions in preterm infants with PDA failed to show any benefit for liberal vs. restrictive transfusion thresholds on PDA closure rates. Importantly, liberal transfusions were associated with an increased rate of intraventricular hemorrhage, and thus should be avoided. In conclusion, the available evidence suggests that thrombocytopenia and platelet dysfunction contribute to failure of spontaneous and pharmacological PDA closure in preterm infants. However, these platelet effects on PDA seem to be of only moderate clinical significance. Furthermore, platelet transfusions in thrombocytopenic preterm infants in order to facilitate PDA closure appear to cause more harm than good.

Use of combination therapy with acetaminophen and ibuprofen for closure of the patent ductus arteriosus in preterm neonates

Objective

To compare effectiveness and safety of combination therapy (acetaminophen and ibuprofen) to monotherapy (ibuprofen, indomethacin, or acetaminophen alone) in treatment of the patent ductus arteriosus (PDA) in premature neonates.

Methods

This was a retrospective cohort study of neonates admitted to a tertiary-level neonatal intensive care unit. Included neonates were born at <32 weeks gestation and received pharmacotherapy for PDA closure. Based on the primary therapy received, our cohort was divided into the following four groups: indomethacin alone, ibuprofen alone, acetaminophen alone, and ibuprofen and acetaminophen (in combination). Baseline characteristics, effectiveness, safety, neonatal mortality, and morbidities rates between these groups were compared.

Results

One hundred and forty neonates were analyzed; 17 received combination therapy, and 123 neonates received monotherapy: 22 (17.9%) ibuprofen, 29 (23.6%) acetaminophen, and 72 (58.5%) indomethacin. The PDA closure rates were 41.7% for indomethacin, 41.2% for combination therapy, 37.9% for acetaminophen, and 31.8% for ibuprofen (P=0.100). Rates of adverse effects were comparable between the groups.

Conclusion

The rate of ductal closure was not different between combination therapy and monotherapy. The study did not demonstrate any increased adverse effects in the combination group. Future well-designed prospective clinical trials are needed to guide clinical practice.

Neonatal Platelet Function

Similarly to the development of the plasma coagulation system, which matures during the early weeks and months of life, age-dependent mechanisms and developmental changes influence platelet production and function in neonates. Platelet function testing on cord blood and peripheral blood demonstrates a generalized platelet hyporeactivity, during the first days of life. This reactivity reaches normal adult levels between the fifth and ninth day of life. The persistence of hyporeactivity after the tenth day of life might indeed suggest a platelet disorder.

Patent ductus arteriosus, low platelets, cyclooxygenase inhibitors, and intraventricular hemorrhage in very low birth weight preterm infants

OBJECTIVE

To assess the risk for intraventricular hemorrhage (IVH) in very low birth weight preterm infants with patent ductus arteriosus (PDA) and low platelet count with treatment with cyclooxygenase (COX) inhibitors.

STUDY DESIGN

Diagnosis and treatment of PDA, as well as risk factors for IVH, were assessed using prospectively collected data of all infants born at a gestational age <32 weeks and with a birth weight ≤ 1500 g at Innsbruck University Hospital (January 2003-December 2009). Infants with severe thrombocytopenia (<50 × 10(9)/L) were excluded from analysis.

RESULTS

Sixty-five (20%) of the 325 infants had IVH, and 149 (45.9%) of the 325 were treated with COX inhibitors. Treatment of PDA with COX inhibitors was not an independent risk predictor for IVH in preterm infants with platelets ≥ 100 × 10(9)/L. However, COX inhibitors amplified the risk of bleeding in the presence of moderately decreased platelets (50-99 × 10(9)/L) on days of life 2-7. Multivariable OR for IVH were 0.89 [95% CI 0.43-1.87] for patients with platelets ≥ 100 × 10(9)/L and treatment with COX inhibitors, 3.40 [95% CI 1.13-10.29] for those with moderately decreased platelets without treatment, and 53.3 [95% CI 5.9-484] for patients with both moderately decreased platelets and COX inhibitor treatment compared with those with platelets ≥ 100 × 10(9)/L and no treatment (reference group) (P < .001).

CONCLUSION

In very low birth weight infants with moderate thrombocytopenia treatment with COX inhibitors increased the risk for intracerebral bleeding. Any benefits of this therapy should be carefully balanced against this potential hazard.

Platelets in the neonatal period: developmental differences in platelet production, function, and hemostasis and the potential impact of therapies

Thrombocytopenia is a common problem among sick neonates admitted to the neonatal intensive care unit. Frequently, platelet transfusions are given to thrombocytopenic infants in an attempt to decrease the incidence or severity of hemorrhage, which is often intracranial. Whereas there is very limited evidence to guide platelet transfusion practices in this population, preterm infants in the first week of life (the highest risk period for bleeding) are nearly universally transfused at higher platelet counts than older infants or children. To a large extent, this practice has been influenced by the observation that neonatal platelets are hyporeactive in response to multiple agonists in vitro, although full-term infants exhibit normal to increased primary hemostasis. This apparently paradoxical finding is due to factors in the neonatal blood that enhance the platelet-vessel wall interaction and counteract the platelet hyporeactivity. Relatively few studies have evaluated the platelet function and primary hemostasis of preterm infants, the subset of neonates at highest risk of bleeding and those most frequently transfused. Current understanding of platelet production and function in preterm and full-term neonates, how these factors affect their response to thrombocytopenia and their primary hemostasis, and the implications of these developmental differences to transfusion medicine are reviewed herein.

Effect of ampicillin on bleeding time in very low birth-weight neonates during the first week after birth

OBJECTIVE

On the day of birth, the bleeding time of very low birth-weight (VLBW, <1500 g) neonates is generally prolonged, compared with term neonates. However, their bleeding time generally improves (shortens) over the next 7 to 10 days. Ampicillin can prolong the bleeding times of term and late preterm neonates, but its effect on VLBW neonates, who already have a somewhat prolonged bleeding time initially, is not known.

STUDY DESIGN

This was a prospective, single-centered, paired, before vs after test of the effect of ampicillin on template bleeding time and PFA-100 time (platelet function analyzer). Ampicillin was dosed at every 12 h intravenously, but decisions about discontinuation were made by the responsible clinician, independent of this study.

RESULT

A total of 20 VLBW neonates were studied. They ranged from 23- to 30-weeks gestation at birth and weighed 500 t 1410 g. Initial bleeding times averaged 166 s (95% CI, 138 to 194) and initial PFA-100 times averaged 119 s (95% CI, 90 to 148). In all, 10 had ampicillin dosing stopped after a shorter course (4 to 7 doses) and 10 had it continued for a longer course (10 to 15 doses). Blood cultures were sterile in all 20, and no differences in laboratory or clinical features were found between those treated with a shorter vs longer course. After stopping the ampicillin following a short course the bleeding times and PFA-100 times were similar to the initial values. However, after a longer course the bleeding times were prolonged by an average of 2 min, to 284 s (95% CI, 242 to 326; P=0.001 vs initial). The PFA-100 times also trended longer by an average of 44 s (P=0.07). The number of doses of ampicillin received in the first week correlated with the degree of prolongation in bleeding time (r=0.68).

CONCLUSION

Over the first week of life, a period when the bleeding time of VLBW neonates normally shortens, the opposite occurred (the bleeding time lengthened) if ≥ 10 doses of ampicillin were administered.

Learning to live with patency of the ductus arteriosus in preterm infants

Treatment of persistent patency of the ductus arteriosus in preterm infants remains heterogeneous and controversial. Routine early treatment to induce ductal closure is not beneficial, but the potential criteria for, timing of, methods for and benefits of later ductal closure have not been determined. Management strategies for infants awaiting spontaneous closure or meeting criteria for treatment may be based on pathophysiological considerations but require evaluation in clinical trials. Better diagnostic tools allowing the identification of infants who might benefit from ductal closure, supplemented by data from clinical trials confirming realization of that potential, are urgently needed.

Platelet transfusion in the neonatal intensive care unit: benefits, risks, alternatives

Platelet transfusions were introduced into clinical medicine about 60 years ago when they were shown to reduce the mortality rate of patients with leukemia who were bleeding secondary to hyporegenerative thrombocytopenia. In modern neonatology units, platelet transfusions are integral and indeed lifesaving for some neonates. However, the great majority of platelet transfusions currently administered in neonatal intensive care units (NICUs) are not given in the original paradigm to treat thrombocytopenic hemorrhage, but instead are administered prophylactically with the hope that they will reduce the risk of spontaneous bleeding. Weighing the risks and benefits of platelet transfusion, although imprecise, should be attempted each time a platelet transfusion is ordered. Adopting guidelines specific for platelet transfusion will improve consistency of care and will also generally reduce transfusion usage, thereby reducing costs and conserving valuable blood bank resources. Initiating specific programs to improve compliance with transfusion guidelines can further improve NICU transfusion practice.

Effect of ampicillin on the bleeding time of neonatal intensive care unit patients

OBJECTIVE

Studies in adults indicate that ampicillin, in a dose-dependent manner, impairs platelet function and moderately prolongs the bleeding time (generally by 60 to 90 s). Unlike aspirin, the inhibition induced by ampicillin involves both reversible and irreversible mechanisms and is not observed immediately after initial dosing (generally requiring approximately 24 h). Ampicillin is administered commonly to neonatal intensive care unit (NICU) patients, but its effect on bleeding time in this population has not been reported earlier.

STUDY DESIGN

We performed neonatal template bleeding times and platelet function analyzer (PFA)-100 tests on 15 NICU patients before and at various intervals after intravenous ampicillin dosing.

RESULT

Neonates were only studied if no beta-lactam antibiotics were administered to their mother during labor, and if they had ampicillin ordered by the clinician at a dose of 50 to 100 mg kg(-1) every 12 h. Subjects ranged from 33 to 41 weeks gestation and weighed 1760 to 3835 g. Bleeding times before the first ampicillin dose (n=15) averaged 134 s (95% confidence interval (CI), 120 to 148 s) and PFA-100 times averaged 123 s (95% CI, 96 to 149 s). After the first dose of ampicillin (n=5), bleeding times and PFA-100 times did not increase, but after the third (n=5) and fourth doses (n=4) bleeding times lengthened by an average of 60 s (95% CI, 37 to 83 s, P<0.001) and PFA-100 times lengthened by an average of 20 s (95% CI, -20 to 60 s, P=0.15).

CONCLUSION

Ampicillin administered intravenously to NICU patients prolongs the bleeding time, with a magnitude-of-effect and time-to-effect similar to that shown earlier in adults.

Patent ductus arteriosus of the preterm infant

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