Inhaled nitric oxide for preterm infants: a systematic review

Bosentan in the treatment of persistent pulmonary hypertension in newborns: a systematic review and meta-analysis

BACKGROUND

Persistent pulmonary hypertension of the newborn is a life-threatening condition that affects about 1-2 per 1,000 live births worldwide. Bosentan is an oral dual endothelin receptor antagonist that may have a beneficial effect on persistent pulmonary hypertension of the newborn by reducing pulmonary vascular resistance and improving oxygenation. However, its role in persistent pulmonary hypertension of the newborn remains unclear.

OBJECTIVES

To systematically evaluate the efficacy and safety of bosentan as an adjuvant therapy for persistent pulmonary hypertension of the newborn in newborns.

METHODS

We searched six English and two Chinese databases from their inception to 1 January 2023 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included randomised controlled trials and retrospective studies that compared bosentan with placebo or other drugs for persistent pulmonary hypertension of the newborn in newborns. We performed a meta-analysis using random-effects models and assessed the risk of bias and heterogeneity in the included studies.

RESULTS

We included 10 studies with a total of 550 participants. Bosentan significantly reduced the treatment failure rate (relative risk = 0.25, P < 0.001), pulmonary artery pressure (mean difference = -11.79, P < 0.001), and length of hospital stay (mean difference = -1.04, P = 0.003), and increased the partial pressure of oxygen (mean difference = 10.02, P < 0.001) and blood oxygen saturation (SpO2) (mean difference = 8.24, P < 0.001) compared with a placebo or other drugs. The occurrence of adverse reactions was not significantly different between bosentan and a placebo or other drugs.

CONCLUSIONS

Bosentan is effective in the treatment of persistent pulmonary hypertension of the newborn but adverse reactions such as abnormal liver function should be observed when using it.

Morbidity and mortality in neonates with Down Syndrome based on gestational age

BACKGROUND

Greater than 50% of neonates with Down Syndrome (DS) have perinatal complications that require admission to the neonatal intensive care unit (NICU) at birth. Previous studies have shown increased morbidity and mortality rates in neonates without DS delivered prior to 39 weeks of completed gestation.

OBJECTIVE

To determine if an association exists between gestational age at delivery and adverse outcomes in neonates with DS.

STUDY DESIGN

Neonates with DS admitted to a large, tertiary care center NICU from 2010 to 2020 were evaluated. Gestational age (GA) was stratified into 4 groups: <34 (preterm), 34-36 (late-preterm), 37-38 (early-term) and ≥39 (term + post-term) completed weeks. Fisher's exact tests were used to evaluate morbidity and mortality rates between groups.

RESULT

Of the 314 neonates with DS, 10% (N = 31) were <34 weeks, 22% (N = 68) 34-36 weeks, 40% (N = 127) 37-38 weeks, and 28% (N = 88) ≥39 completed weeks at birth. Baseline characteristics were similar between groups. GA at birth <34 weeks was associated with a higher in-hospital mortality rate when compared to those born 37-38 (19% vs. 0%, P < 0.001) and ≥39 (19% vs. 3%, P = 0.01). Neonates with DS born <34 weeks had a higher likelihood of oxygen requirement at time of discharge compared to 34-36, 37-38, and ≥39 groups (P = 0.01; P < 0.001; P < 0.001 respectively). Neonates with DS < 34 weeks were more likely to develop necrotizing enterocolitis (P = 0.02) and require nitric oxide (P = 0.014) compared to neonates with DS ≥ 39. We observed no differences in the need for surgical interventions between groups aside from the rate of gastrostomy/jejunostomy tube placement between 34-36 weeks and 37-38 weeks GA.

CONCLUSION

Neonates with DS born preterm (<34 weeks) represent a highly vulnerable subgroup. Multidisciplinary strategies are needed to address their higher rates of morbidity and mortality.

Use of Inhaled Nitric Oxide in Preterm Infants: Is There Sufficient Evidence?

Nitric oxide (NO) is a potent vasodilator. The inhaled form (iNO) improves outcomes in term infants with persistent pulmonary hypertension of the newborn (PPHN) or bronchopulmonary dysplasia-associated pulmonary hypertension in preterm infants. However, in preterm infants, the risks and benefits of iNO use are controversial. Substantial evidence reveals no significant impact on survival or other morbidities in preterm infants with iNO treatment, independent of indication, timing, or duration of use. Many scientific organizations do not recommend the use of iNO in preterm infants, except in unique clinical circumstances with echocardiographic findings of PPHN in the setting of presumed pulmonary hypoplasia.

Inhaled Nitric Oxide Treatment for Aneurysmal SAH Patients With Delayed Cerebral Ischemia

Background

We demonstrated experimentally that inhaled nitric oxide (iNO) dilates hypoperfused arterioles, increases tissue perfusion, and improves neurological outcome following subarachnoid hemorrhage (SAH) in mice. We performed a prospective pilot study to evaluate iNO in patients with delayed cerebral ischemia after SAH.

Methods

SAH patients with delayed cerebral ischemia and hypoperfusion despite conservative treatment were included. iNO was administered at a maximum dose of 40 ppm. The response to iNO was considered positive if: cerebral artery diameter increased by 10% in digital subtraction angiography (DSA), or tissue oxygen partial pressure (PtiO₂) increased by > 5 mmHg, or transcranial doppler (TCD) values decreased more than 30 cm/sec, or mean transit time (MTT) decreased below 6.5 secs in CT perfusion (CTP). Patient outcome was assessed at 6 months with the modified Rankin Scale (mRS).

Results

Seven patients were enrolled between February 2013 and September 2016. Median duration of iNO administration was 23 h. The primary endpoint was reached in all patients (five out of 17 DSA examinations, 19 out of 29 PtiO₂ time points, nine out of 26 TCD examinations, three out of five CTP examinations). No adverse events necessitating the cessation of iNO were observed. At 6 months, three patients presented with a mRS score of 0, one patient each with an mRS score of 2 and 3, and two patients had died.

Conclusion

Administration of iNO in SAH patients is safe. These results call for a larger prospective evaluation.

Prenatal duct closure leading to severe pulmonary hypertension in a preterm neonate-a case report

Prenatal closure of the ductus arteriosus (DA) can lead to cardiovascular dysfunction resulting in pulmonary hypertension (PH), progressive right heart failure, fetal hydrops, and fetal or neonatal demise. Supportive therapies-including mechanical ventilation, oxygen, and nitric oxide (NO)-have been employed with variable success among infants born full term, but there is no widely accepted management of prenatal closure of the DA, particularly for preterm infants. We present the case of an infant born at 31 weeks' gestation with right ventricular (RV) dysfunction and PH due to prenatal ductal closure, who was successfully treated with milrinone, resulting in full recovery of cardiac function. Prenatal ductal closure is rare, particularly under 32 weeks gestation, but should be suspected in cases of postnatal hypoxemia in the absence of significant lung disease or structural heart disease. Milrinone may be considered as a therapeutic agent to treat both PH and RV dysfunction in preterm infants status post in utero closure of the DA.

The effects of gasotransmitters on bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD), which remains a major clinical problem for preterm infants, is caused mainly by hyperoxia, mechanical ventilation and inflammation. Many approaches have been developed with the aim of decreasing the incidence of or alleviating BPD, but effective methods are still lacking. Gasotransmitters, a type of small gas molecule that can be generated endogenously, exert a protective effect against BPD-associated lung injury; nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H₂S) are three such gasotransmitters. The protective effects of NO have been extensively studied in animal models of BPD, but the results of these studies are inconsistent with those of clinical trials. NO inhalation seems to have no effect on BPD, although side effects have been reported. NO inhalation is not recommended for BPD treatment in preterm infants, except those with severe pulmonary hypertension. Both CO and H₂S decreased lung injury in BPD rodent models in preclinical studies. Another small gas molecule, hydrogen, exerts a protective effect against BPD. The nuclear factor erythroid-derived 2 (Nrf2)/heme oxygenase-1 (HO-1) axis seems to play a central role in the protective effect of these gasotransmitters on BPD. Gasotransmitters play important roles in mammals, but further clinical trials are needed to explore their effects on BPD.

Changes in the nitric oxide pathway of the pulmonary vasculature after exposure to hypoxia in swine model of neonatal pulmonary vascular disease

Neonatal pulmonary vascular disease (PVD) is increasingly recognized as a disease that complicates the cardiopulmonary adaptations after birth and predisposes to long-term cardiopulmonary disease. There is growing evidence that PVD is associated with disruptions in the nitric oxide (NO)-cGMP-phosphodiesterase 5 (PDE5) pathway. Examination of the functionality of different parts of this pathway is required for better understanding of the pathogenesis of neonatal PVD. For this purpose, the role of the NO-cGMP-PDE5 pathway in regulation of pulmonary vascular function was investigated in vivo, both at rest and during exercise, and in isolated pulmonary small arteries in vitro, in a neonatal swine model with hypoxia-induced PVD. Endothelium-dependent vasodilatation was impaired in piglets with hypoxia-induced PVD both in vivo at rest and in vitro. Moreover, the responsiveness to the NO-donor SNP was reduced in hypoxia-exposed piglets in vivo, while the relaxation to SNP and 8-bromo-cyclicGMP in vitro were unaltered. Finally, PDE5 inhibition-induced pulmonary vasodilatation was impaired in hypoxia-exposed piglets both in vitro and in vivo at rest. During exercise, however, the pulmonary vasodilator effect of PDE5 inhibition was significantly larger in hypoxia-exposed as compared to normoxia-exposed piglets. In conclusion, the impaired endothelium-dependent vasodilatation in piglets with hypoxia-induced PVD was accompanied by reduced responsiveness to NO, potentially caused by altered sensitivity and/or activity of soluble guanylyl cyclase (sGC), resulting in an impaired cGMP production. Our findings in a newborn animal model for neonatal PVD suggests that sGC stimulators/activators may be a novel treatment strategy to alleviate neonatal PVD.

A Pathogenic Relationship of Bronchopulmonary Dysplasia and Retinopathy of Prematurity? A Review of Angiogenic Mediators in Both Diseases

Bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) are common and significant morbidities of prematurely born infants. These diseases have in common altered and pathologic vascular formation in the face of incomplete organ development. Therefore, it is reasonable to question whether factors affecting angiogenesis could have a joint pathogenic role for both diseases. Inhibition or induced expression of a single angiogenic factor is unlikely to be 100% causative or protective of either of BPD or ROP. It is more likely that interactions of multiple factors leading to disordered angiogenesis are present, increasing the likelihood of common pathways in both diseases. This review explores this possibility by assessing the evidence showing involvement of specific angiogenic factors in the vascular development and maldevelopment in each disease. Theoretical interactions of specific factors mutually contributing to BPD and ROP are proposed and, where possible, a timeline of the proposed relationships between BPD and ROP is developed. It is hoped that future research will be inspired by the theories put forth in this review to enhance the understanding of the pathogenesis in both diseases.

Short-term and long-term outcomes of preterm neonates with acute severe pulmonary hypertension following rescue treatment with inhaled nitric oxide

OBJECTIVE

To describe short-term and long-term outcomes of preterm neonates with severe acute pulmonary hypertension (aPHT) in relation to response to rescue inhaled nitric oxide (iNO) therapy.

DESIGN

Retrospective cohort studyover a 6 year period.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

89 neonates <35 weeks gestational age (GA) who received rescue iNO for aPHT, including 62 treated at ≤3 days of age (early aPHT).

INTERVENTIONS

iNO ≥ 1 hour.

MAIN OUTCOME MEASURES

Positive responders (reduction in fraction of inspired oxygen (FiO₂) ≥0.20 within 1 hour of iNO) were compared with non-responders. Primary outcome was survival without moderate-to-severe disability at 18 months of age.

RESULTS

Mean (SD) GA and birth weight was 27.7 (3.0) weeks and 1077 (473) gm, respectively. Median (IQR) pre-iNO FiO₂ was 1.0 (1.0, 1.0). Positive response rate to iNO was 46%. Responders showed improved survival without disability (51% vs 15%; p<0.01), lower mortality (34% vs 71%; p<0.01) and disability among survivors (17% vs 50%; p=0.06). Higher GA (adjusted OR: 1.44 (95% CI 1.10 to 1.89)), aPHT in context of preterm prolonged rupture of membranes (6.26 (95% CI 1.44 to 27.20)) and positive response to rescue iNO (5.81 (95% CI 1.29 to, 26.18)) were independently associated with the primary outcome. Compared with late cases (>3 days of age), early aPHT had a higher response rate to iNO (61% vs 11%; p<0.01) and lower mortality (43% vs 78%; p<0.01).

CONCLUSION

A positive response to rescue iNO in preterm infants with aPHT is associated with survival benefit, which is not offset by long-term disability.

Diuretic exposure in premature infants from 1997 to 2011

OBJECTIVE

Diuretics are often prescribed off-label to premature infants, particularly to prevent or treat bronchopulmonary dysplasia. We examined their use and safety in this group.

STUDY DESIGN

Retrospective cohort study of infants < 32 weeks gestation and < 1,500 g birth weight exposed to diuretics in 333 neonatal intensive care units from 1997 to 2011. We examined use of acetazolamide, amiloride, bumetanide, chlorothiazide, diazoxide, ethacrynic acid, furosemide, hydrochlorothiazide, mannitol, metolazone, or spironolactone combination. Respiratory support and fraction of inspired oxygen on the first day of each course of diuretic use were identified.

RESULTS

About 37% (39,357/107,542) infants were exposed to at least one diuretic; furosemide was the most commonly used (93% with ≥ 1 recorded dose), followed by spironolactone, chlorothiazide, hydrochlorothiazide, bumetanide, and acetazolamide. About 74% patients were exposed to one diuretic at a time, 19% to two diuretics simultaneously, and 6% to three diuretics simultaneously. The most common combination was furosemide/spironolactone, followed by furosemide/chlorothiazide and chlorothiazide/spironolactone. Many infants were not receiving mechanical ventilation on the first day of each new course of furosemide (47%), spironolactone (69%), chlorothiazide (61%), and hydrochlorothiazide (68%). Any adverse event occurred on 42 per 1,000 infant-days for any diuretic and 35 per 1,000 infant-days for furosemide. Any serious adverse event occurred in 3.8 for any diuretic and 3.2 per 1,000 infant-days for furosemide. The most common laboratory abnormality associated with diuretic exposure was thrombocytopenia.

CONCLUSION

Despite no Food and Drug Administration (FDA) indication and little safety data, over one-third of premature infants in our population were exposed to a diuretic, many with minimal respiratory support.

Looking beyond PPHN: the unmet challenge of chronic progressive pulmonary hypertension in the newborn

Abstract Infants with forms of pulmonary hypertension (PH) that persist or develop beyond the first week of life are an understudied group of patients with up to 40%-60% mortality. The clinical management of the progressive PH that develops in these infants is challenging because of the nonspecific signs and symptoms of clinical presentation, the limited diagnostic sensitivity of standard echocardiographic techniques, and the lack of proven therapies. The signaling mechanisms that underlie the structural and functional abnormalities in the pulmonary circulation of these infants are not yet clear. The ability to improve outcomes for these patients awaits technological advances to improve diagnostic capabilities and therapeutic discoveries made in basic science laboratories that can be tested in randomized clinical trials.

Nebulized iloprost and noninvasive respiratory support for impending hypoxaemic respiratory failure in formerly preterm infants: a case series

OBJECTIVE

To describe a series of ex-preterm infants admitted to pediatric intensive care unit due to impending hypoxaemic respiratory failure complicated by pulmonary hypertension (PH) who were treated electively combining noninvasive ventilation (NIV) and nebulized iloprost (nebILO).

DESIGN

Open uncontrolled observational study.

SETTING

Pediatric Intensive Care Unit, University Hospital.

PATIENTS

Ten formerly preterm infants with impending hypoxaemic respiratory failure and PH, of whom eight had moderate to severe bronchopulmonary dysplasia.

MEASUREMENTS AND MAIN RESULTS

Median age and body weight were 6.0 (2.75-9.50) months and 4.85 (3.32-7.07) kg, respectively. We observed a significant early oxygenation improvement in terms of PaO(2) /FiO(2) increase (P = 0.001) and respiratory rate reduction (P = 0.01). Hemodynamic also improved, as shown by heart rate (P = 0.002) and pulmonary arterial pressure systolic/systolic systemic pressure (PAPs/SSP) ratio reduction (P = 0.0137). NebILO was successfully weaned in positive response cases: 4 infants were discharged on oral sildenafil. Three patients failed noninvasive modality and needed invasive mechanical ventilation; hypoxic-hypercarbic patients were most likely to fail noninvasive approach. Only one patient requiring invasive ventilation died and surviving babies had a satisfactory 1-month post-discharge follow-up. CONCLUSIONS.: The noninvasive approach combining NIV and nebILO for ex-preterm babies with impending respiratory failure and PH resulted to be feasible and quickly achieved significant oxygenation and hemodynamic improvements.

A comprehensive approach to the prevention of bronchopulmonary dysplasia

The current bronchopulmonary dysplasia (BPD) is seen in infants born extremely premature, with less severe respiratory distress syndrome (RDS) and who received prenatal steroids-"new BPD". The pathophysiology of BPD is based on an impairment of lung maturation with prenatal and postnatal multi-hit insults and genetic susceptibility. This multifactorial pathophysiology of BPD suggests that no single "magic bullet" will prevent it. Thus, to avoid BPD we need to implement a complex and comprehensive strategy. This strategy is based on ventilatory and non-ventilatory measures. The ventilatory route allows an individualized endotracheal intubation approach. Early lung recruitment with nasal respiratory support (nasal continuous positive airway pressure [NCPAP] or nasal intermittent positive pressure ventilation [NIPPV] / synchronized NIPPV [SNIPPV]) and the INSURE (intubation, surfactant and early extubation) approach are discussed. Initial treatment with NCPAP did not reduce the rate of BPD compared to endotracheal ventilation and surfactant administration. While NIPPV/SNIPPV may have short-term advantages over NCPAP, the effect on BPD needs to be further studied. During hospitalization the respiratory goals should aim for adequate oxygenation, permissive hypercapnia, and gentle ventilation. However, these goals were found to have short-term benefits but did not reduce significantly the rate of BPD. Selective use of a short course of low dose corticosteroids can be considered after the first or second week of life in infants who are unable to be weaned from the ventilator and are at high risk for BPD. Non-ventilatory measures include early nutritional support with fluid restriction, caffeine and consideration of vitamin A. Hemodynamic significant patent ductus arteriosus (PDA) may be associated with BPD, but medical or surgical treatment of PDA were not shown to decrease BPD. Each component and the strategy as a whole needs to be further studied in large randomized prospective studies or by meta-analyses, especially in the target population of extremely premature infants who are the most prone to BPD.

The changing pattern of inhaled nitric oxide use in the neonatal intensive care unit

OBJECTIVE

The purpose of this study was to evaluate the demographic characteristics and outcomes of neonates who were admitted to a neonatal intensive care unit and treated with inhaled nitric oxide (iNO) during the years 2000-08. The goal of studying this group of neonates was to evaluate how iNO use has evolved in infants and to estimate the frequency of off-label use of this drug in this population.

STUDY DESIGN

Retrospective review of the Pediatrix Clinical Data Warehouse de-identified data set. Pediatrix Medical Group provides intensive care services in 244 hospitals in 32 states and Puerto Rico. Nine (3.7%) centers provide extracorporeal membrane oxygenation.

RESULT

There were 494 255 neonates in the data set; 4316 (0.9%) were treated with iNO. The use of iNO increased from 154 of 32 967 patients in 2000 to 921 of 75 911 patients in 2008; a 2.6-fold increase (0.47 to 1.23%). There were 155 872 infants <34 weeks estimated gestational age discharged between 1 January 2000 and 31 December 2008; 1656 (1.1%) were treated with iNO. Since approval in 2000, the reported use of iNO in neonates <34 weeks increased from 0.3 to 1.8% in 2008; a sixfold increase in the reported use of iNO. The biggest increase occurred in infants between 23 and 26 weeks' gestational age (0.8 to 6.6%). In contrast, the increase in iNO use among neonates born ≥34 weeks has only increased from 0.5 to 1%.

CONCLUSION

The use of iNO has increased and the greatest increase has been the off-label use among preterm neonates.

NO inhibits hyperoxia-induced NF-κB activation in neonatal pulmonary microvascular endothelial cells

Inhaled NO (iNO) may be protective against hyperoxic injury in the premature lung, but the mechanism is unknown. We hypothesized that NO would prevent hyperoxia-induced nuclear factor kappa B (NF-κB) activation in neonatal pulmonary microvascular endothelial cells [human pulmonary microvascular endothelial cell (HPMEC)] and prevent the up-regulation of target genes. After hyperoxic exposure (O2 >95%), nuclear NF-κB consensus sequence binding increased and was associated with IκBα degradation. Both of these findings were prevented by exposure to NO. Furthermore, intracellular adhesion molecule (ICAM)-1 mRNA and protein levels increased in cells exposed to hyperoxia, an effect abrogated by NO. To evaluate the potentially toxic effect of NO plus hyperoxia, cell viability and proliferation were assessed. Cells exposed to NO plus hyperoxia demonstrated improved survival as measured by trypan blue exclusion when compared with cells exposed to hyperoxia alone. These differences in cell death could not be attributed to apoptosis measured by caspase-3 activity. Finally, cellular proliferation inhibited by hyperoxia was rescued by concurrent exposure to NO. These data demonstrate that NO prevents hyperoxia-induced NF-κB activation in HPMEC and results in decreased expression of adhesion molecules and decreased cellular toxicity. This may help to explain the protective effects of NO on hyperoxic injury in the developing lung vasculature.

Regulation of the Pulmonary Circulation in the Fetus and Newborn

During the development of the pulmonary vasculature in the fetus, many structural and functional changes occur to prepare the lung for the transition to air breathing. The development of the pulmonary circulation is genetically controlled by an array of mitogenic factors in a temporo-spatial order. With advancing gestation, pulmonary vessels acquire increased vasoreactivity. The fetal pulmonary vasculature is exposed to a low oxygen tension environment that promotes high intrinsic myogenic tone and high vasocontractility. At birth, a dramatic reduction in pulmonary arterial pressure and resistance occurs with an increase in oxygen tension and blood flow. The striking hemodynamic differences in the pulmonary circulation of the fetus and newborn are regulated by various factors and vasoactive agents. Among them, nitric oxide, endothelin-1, and prostaglandin I2 are mainly derived from endothelial cells and exert their effects via cGMP, cAMP, and Rho kinase signaling pathways. Alterations in these signaling pathways may lead to vascular remodeling, high vasocontractility, and persistent pulmonary hypertension of the newborn.

The management of evolving bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is associated with increased mortality and significant long-term cardiorespiratory and neurodevelopmental sequelae. Treatment of evolving BPD in the neonatal intensive care unit (NICU) is challenging due to the complex interplay of contributing risk factors which include preterm birth per se, supplemental oxygen, positive pressure ventilation, patent ductus arterious, and pre- and postnatal infection. Management of evolving BPD requires a multimodal approach including adequate nutrition, careful fluid management, effective and safe pharmacotherapy, and respiratory support aiming at minimal lung injury. Among pharmacological interventions, caffeine has the best risk-benefit profile. Systemic postnatal corticosteroids should be reserved to ventilated infants at highest risk of BPD who cannot be weaned from the ventilator. Several ongoing randomised trials are evaluating optimal oxygen saturation targets in preterm infants. The most beneficial respiratory support strategy to minimise lung injury remains unclear and requires further investigation.

Inhaled nitric oxide for prevention of bronchopulmonary dysplasia in premature babies (EUNO): a randomised controlled trial

BACKGROUND

In animal models, inhaled nitric oxide improved gas exchange and lung structural development, but its use in premature infants at risk of developing bronchopulmonary dysplasia remains controversial. We therefore tested the hypothesis that inhaled nitric oxide at a low concentration, started early and maintained for an extended period in babies with mild respiratory failure, might reduce the incidence of bronchopulmonary dysplasia.

METHODS

800 preterm infants with a gestational age at birth of between 24 weeks and 28 weeks plus 6 days (inclusive), weighing at least 500 g, requiring surfactant or continuous positive airway pressure for respiratory distress syndrome within 24 h of birth were randomly assigned in a one-to-one ratio to inhaled nitric oxide (5 parts per million) or placebo gas (nitrogen gas) for a minimum of 7 days and a maximum of 21 days in a double-blind study done at 36 centres in nine countries in the European Union. Care providers and investigators were masked to the computer-generated treatment assignment. The primary outcome was survival without development of bronchopulmonary dysplasia at postmenstrual age 36 weeks. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00551642.

FINDINGS

399 infants were assigned to inhaled nitric oxide, and 401 to placebo. 395 and 400, respectively, were analysed. Treatment with inhaled nitric oxide and placebo did not result in significant differences in survival of infants without development of bronchopulmonary dysplasia (258 [65%] of 395 vs 262 [66%] of 400, respectively; relative risk 1.05, 95% CI 0.78-1.43); in survival at 36 weeks' postmenstrual age (343 [86%) of 399 vs 359 [90%] of 401, respectively; 0.74, 0.48-1.15); and in development of bronchopulmonary dysplasia (81 [24%] of 339 vs 96 [27%] of 358, respectively; 0.83, 0.58-1.17).

INTERPRETATION

Early use of low-dose inhaled nitric oxide in very premature babies did not improve survival without bronchopulmonary dysplasia or brain injury, suggesting that such a preventive treatment strategy is unsuccessful.

FUNDING

INO Therapeutics.

Maternal preeclampsia predicts the development of bronchopulmonary dysplasia

OBJECTIVE

To test the hypothesis that exposure to preeclampsia is associated with an increased risk of bronchopulmonary dysplasia (BPD).

STUDY DESIGN

A prospective cohort study of 107 babies born between 23 and 32 weeks gestation, collecting maternal, neonatal, and placental data.

RESULTS

Of the 107 infants studied, 27 (25%) developed BPD. The bivariate odds ratio (OR) for the relationship between pre-eclampsia and BPD was 2.96 (95% confidence interval [CI] = 1.17 to 7.51; P = .01). When controlling for gestational age, birth weight z-score, chorioamnionitis, and other clinical confounders, the OR of developing BPD was 18.7 (95% CI = 2.44 to 144.76). Including the occurrence of preeclampsia, clinical chorioamnionitis, male sex, and maternal tobacco use in addition to gestational age and birth weight z-score accounted for 54% of the variability of the odds of developing BPD.

CONCLUSIONS

BPD is increased for infants exposed to preeclampsia. This has possible implications for the prevention of BPD with proangiogenic agents, such as vascular endothelial growth factor.

Inhaled nitric oxide decreases leukocyte trafficking in the neonatal mouse lung during exposure to >95% oxygen

Chronic lung injury in the neonate is termed bronchopulmonary dysplasia (BPD). These patients generally require supplemental oxygen therapy, and hyperoxia has been implicated in the pathogenesis of BPD. The concomitant use of oxygen and inhaled NO (iNO) may result in the generation of reactive nitrogen species or may have an anti-inflammatory effect in the neonatal lung. We tested the hypothesis that exposure to >95% O2 in neonatal mice would increase trafficking of leukocytes into the lung and that the addition of iNO to >95% O2 would decrease this leukocyte trafficking. Hyperoxia resulted in fewer alveoli, increased presence of neutrophils and macrophages, and decreased number of mast cells within the lung parenchyma. Adding iNO to hyperoxia prevented the hyperoxia-induced changes and resulted in the numbers of alveoli, neutrophils, macrophages, and mast cells approximating those found in controls (room air exposure). Intercellular adhesion molecule (ICAM) and monocyte chemotactic protein-1 (MCP-1), two factors responsible for leukocyte recruitment, were up-regulated by hyperoxic exposure, but the addition of iNO to the hyperoxic exposure prevented the hyperoxia-induced up-regulation of ICAM and MCP-1. These data demonstrate that iNO alters the hyperoxia-induced recruitment of leukocytes into the lung.

School-age outcomes of newborns treated for persistent pulmonary hypertension

OBJECTIVE

The aim of this study was to describe the school-age outcome of a cohort of children treated with intensive care support for persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

From 187 term newborns treated for PPHN as neonates, 109 were seen at school age (73% of 150 survivors and 58.2% of the original cohort). Of these 109 term newborns, 77 were treated with inhaled nitric oxide (iNO); of which 12 received extracorporeal membrane oxygenation (ECMO). The remaining 32 received conventional management with no exposure to iNO. Patients were seen at school age (mean 7.1 years). A medical history and physical exam were completed, growth was measured, and chest X-ray and echocardiogram were performed. Psychometric assessments included the Wechsler Scales (Preschool or Child), Vineland Adaptive Behavior Scales, Kaufman Test of Educational Achievement, Children's Category Test, Wisconsin Card Sorting Test and Achenbach Child Behavior Checklist.

RESULT

Medical, neurodevelopmental and social/emotional/behavioral outcome did not differ between children treated with iNO, with or without ECMO, and those managed with no exposure to iNO. Overall, 24% had respiratory problems, 60% had abnormal chest X-rays and 6.4% had some sensorineural hearing loss. The cohort performed at the average level for full scale IQ, adaptive function, academic achievement, higher-order cognition and executive functioning, and social/behavioral/emotional functioning. Overall, 9.2% of the cohort had a full scale IQ less than 70 and 7.4% had an IQ from 70 to 84.

CONCLUSION

The outcome for this cohort of children treated as newborns for PPHN, which included a large group of infants exposed to iNO, was comparable to previous reports of children treated with ECMO or conventionally.

Pitfalls, problems, and progress in bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a chronic lung disease associated with premature birth and characterized by early lung injury. In this review we discuss some pitfalls, problems, and progress in this condition over the last decade, focusing mainly on the last 5 years, limited to studies in human neonates. Changes in the definition, pathogenesis, genetic susceptibility, and recent biomarkers associated with bronchopulmonary dysplasia will be discussed. Progress in current management strategies, along with novel approaches/therapies, will be critically appraised. Finally, recent data on long-term pulmonary and neurodevelopmental outcomes of infants with bronchopulmonary dysplasia will be summarized.

Sildenafil attenuates pulmonary inflammation and fibrin deposition, mortality and right ventricular hypertrophy in neonatal hyperoxic lung injury

Background

Phosphodiesterase-5 inhibition with sildenafil has been used to treat severe pulmonary hypertension and bronchopulmonary dysplasia (BPD), a chronic lung disease in very preterm infants who were mechanically ventilated for respiratory distress syndrome.

Methods

Sildenafil treatment was investigated in 2 models of experimental BPD: a lethal neonatal model, in which rat pups were continuously exposed to hyperoxia and treated daily with sildenafil (50–150 mg/kg body weight/day; injected subcutaneously) and a neonatal lung injury-recovery model in which rat pups were exposed to hyperoxia for 9 days, followed by 9 days of recovery in room air and started sildenafil treatment on day 6 of hyperoxia exposure. Parameters investigated include survival, histopathology, fibrin deposition, alveolar vascular leakage, right ventricular hypertrophy, and differential mRNA expression in lung and heart tissue.

Results

Prophylactic treatment with an optimal dose of sildenafil (2 × 50 mg/kg/day) significantly increased lung cGMP levels, prolonged median survival, reduced fibrin deposition, total protein content in bronchoalveolar lavage fluid, inflammation and septum thickness. Treatment with sildenafil partially corrected the differential mRNA expression of amphiregulin, plasminogen activator inhibitor-1, fibroblast growth factor receptor-4 and vascular endothelial growth factor receptor-2 in the lung and of brain and c-type natriuretic peptides and the natriuretic peptide receptors NPR-A, -B, and -C in the right ventricle. In the lethal and injury-recovery model we demonstrated improved alveolarization and angiogenesis by attenuating mean linear intercept and arteriolar wall thickness and increasing pulmonary blood vessel density, and right ventricular hypertrophy (RVH).

Conclusion

Sildenafil treatment, started simultaneously with exposure to hyperoxia after birth, prolongs survival, increases pulmonary cGMP levels, reduces the pulmonary inflammatory response, fibrin deposition and RVH, and stimulates alveolarization. Initiation of sildenafil treatment after hyperoxic lung injury and continued during room air recovery improves alveolarization and restores pulmonary angiogenesis and RVH in experimental BPD.

Inhaled nitric oxide for preterm premature rupture of membranes, oligohydramnios, and pulmonary hypoplasia

We sought to determine if inhaled nitric oxide (iNO) administered to preterm infants with premature rupture of membranes (PPROM), oligohydramnios, and pulmonary hypoplasia improved oxygenation, survival, or other clinical outcomes. Data were analyzed from infants with suspected pulmonary hypoplasia, oligohydramnios, and PPROM enrolled in the National Institute of Child Health and Development Neonatal Research Network Preemie Inhaled Nitric Oxide (PiNO) trial, where patients were randomized to receive placebo (oxygen) or iNO at 5 to 10 ppm. Outcome variables assessed were PaO (2) response, mortality, bronchopulmonary dysplasia (BPD), and severe intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL). Twelve of 449 infants in the PiNO trial met criteria. Six infants received iNO and six received placebo. The iNO group had a mean increase in PaO (2) of 39 +/- 50 mm Hg versus a mean decrease of 11 +/- 15 mm Hg in the control group. Mortality was 33% versus 67%, BPD (2/5) 40% versus (2/2) 100%, and severe IVH or PVL (1/5) 20% versus (1/2) 50% in the iNO and control groups, respectively. None of these changes were statistically significant. Review of a limited number of cases from a large multicenter trial suggests that iNO use in the setting of PPROM, oligohydramnios, and suspected pulmonary hypoplasia improves oxygenation and may decrease the rate of BPD and death without increasing severe IVH or PVL. However, the small sample size precludes definitive conclusions. Further studies are required to determine if iNO is of benefit in this specific patient population.

Inhaled nitric oxide for preterm neonates

The evidence for the benefits of inhaled nitric oxide (iNO) on gas exchange, cytokine-induced lung inflammation, and vascular dysfunction has been demonstrated by several animal and human studies. The use of iNO in extremely low birth weight neonates for the prevention of adverse outcomes like chronic lung disease and neurologic injury has been investigated, but the findings remain inconclusive. This review briefly outlines the biologic rationale for the use of iNO in preterm neonates and the results on the outcome measures of bronchopulmonary dysplasia and brain injury from the recent clinical trials. This article focuses on the potential toxicities, persistent controversies, and unanswered questions regarding the use of this treatment modality in this patient population at high risk for adverse outcomes.

[Is it possible to protect the preterm infant brain and to decrease later neurodevelopmental disabilities?]

With improving neonatal survival for very premature babies, the challenge for neonatalogists is to ameliorate outcome of surviving babies. Several pharmacological molecules have been shown to have protective effects in different types of in vitro or in vivo animal models of acquired cerebral brain damages. However translational research and conduction of therapeutic trials in human remain difficult due to failure to recognize start of deleterious cascade leading to cerebral damage and additional toxic effect of potential protective molecules. This review concentrates on best evidence emerging in recent years on prevention on brain damage by early drug administration. It has been shown in two randomised trials that prenatal low-dose of magnesium sulphate does not increase paediatric mortality in very-preterm infants and has non significant neuroprotective effects on occurrence of motor dysfunction (with a 0.62 odds ratio in the French trial Premag and 0.71 relative risk in the Australian trial ACTOMgSO4), justifying that magnesium sulphate should be discussed as a stand-alone treatment or as part of a combination treatment, at least in the context of clinical trials. Antenatal corticosteroid therapy increases the survival of very-preterm infants, including the most immature. Moreover in an observational recent study of the Epipage cohort, it has been observed a significant decrease in white matter injury in the 28-32 weeks' gestation group but no effect on long term outcome and behaviour. Conversely in the most immature of the 24-27 weeks' gestation group, no effect has been detected either in white matter injury incidence or in long term outcome rates. Caffeine has a protective effect since a decrease in cerebral palsy has been noted in the caffeine group in a randomised trial studying caffeine versus placebo. For what concern other widely used potential protective molecules during the perinatal period, there is no evidence of cerebral protection with indometacine, nitric oxide, eythropoietin, phenobarbital, and etamsylate. Due to their specific properties, a careful evaluation of aspirin, anaesthetic drugs and tocolytics should be done in the next months.

Emerging drugs for the prevention of bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common adverse outcome of very premature birth and is associated with chronic respiratory morbidity.

OBJECTIVE

To determine if there were preventative therapies proven safe and efficacious in appropriately powered randomised trials.

METHODS

A literature review was undertaken.

RESULTS

Systemically administered corticosteroids, if given in the first 2 weeks, do significantly reduce BPD but have serious side effects. Vitamin A also reduces BPD, but has side effects, and further investigation is needed to identify the safest dosage regimen. There are, however, promising therapies that include antioxidants, low-dose nitric oxide and methylxanthines.

CONCLUSION

Further work is necessary to identify safe and effective preventative drugs for BPD.

Neurodevelopmental outcomes of preterm infants

PURPOSE OF REVIEW

Preterm birth is emerging as a major public health problem in the USA. Improvements in preterm birth and survival rates translate to increasing numbers of preterm survivors, and many develop motor, cognitive and sensory impairments.

RECENT FINDINGS

The review discusses the recently reported prevalence of neurodevelopmental disabilities in preterm survivors, in addition to studies of factors associated with neurodevelopmental outcome.

SUMMARY

A 2007 report from the Institute of Medicine emphasizes preterm birth as an increasingly common complex condition with multiple risk factors resulting from multiple gene-environmental interactions, leading to birth before 37 weeks gestation, neonatal complications and a disproportionately high contribution to neurodevelopmental disability rates. The increased risk of cerebral palsy with decreasing gestational age categories is well documented, but recent studies highlight the range and severity of cognitive, sensory, language, visual-perceptual, attention and learning deficits in very preterm children. Combined with increasingly sophisticated neuroimaging studies to identify perinatal risk factors, neurodevelopmental follow-up of neonatal intensive care unit trials offers the potential to really improve our understanding of how the preterm brain develops, is injured and recovers from injuries. Knowledge of what influences neurodevelopmental outcomes is key to developing better treatment strategies.