Inhaled nitric oxide in premature neonates with severe hypoxaemic respiratory failure: a randomised controlled trial

Inhaled Nitric Oxide in Neonatal Pulmonary Hypertension

Pivotal trials investigating the use of inhaled nitric oxide (iNO) in the 1990s led to approval by the Food and Drug Administration in 1999. Inhaled nitric oxide is the only approved pulmonary vasodilator for persistent pulmonary hypertension of the newborn (PPHN). Selective pulmonary vasodilation with iNO in near-term and term neonates with PPHN is safe, and targeted use of iNO in less mature neonates with pulmonary hypertension (PH) can be beneficial. This review addresses a brief history of iNO, clinical features of neonatal PH, and the clinical application of iNO.

Neurodevelopmental outcomes of preterm neonates receiving rescue inhaled nitric oxide in the first week of age: a cohort study

OBJECTIVE

To assess the neurodevelopmental outcomes of preterm neonates who received inhaled nitric oxide (iNO) in the first week of age for hypoxaemic respiratory failure (HRF).

METHODS

In this retrospective cohort study, we included neonates born at <29 weeks gestational age (GA) between January 2010 and December 2018 who had a neurodevelopmental assessment at 18-24 months corrected age (CA) at one of the Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment (NDI). We performed propensity score-matched analysis to compare the outcomes of those who received and did not receive iNO.

RESULTS

Of the 5612 eligible neonates, 460 (8.2%) received iNO in the first week of age. Maternal age, receipt of antenatal corticosteroids, GA and birth weight were lower in the iNO group compared with the no-iNO group. Neonates in the iNO group had higher illness severity scores and higher rates of preterm prolonged rupture of membranes and were small for GA. Severe brain injury, bronchopulmonary dysplasia and mortality were higher in the iNO group. Of the 4889 survivors, 3754 (77%) neonates had follow-up data at 18-24 months CA. After propensity score matching, surviving infants who received rescue iNO were not associated with higher odds of NDI (adjusted OR 1.34; 95% CI 0.85 to 2.12).

CONCLUSIONS

In preterm neonates <29 weeks GA with HRF, rescue iNO use was not associated with worse neurodevelopmental outcomes among survivors who were assessed at 18-24 months CA.

Efficacy of inhaled nitric oxide in preterm infants ≤ 34 weeks: a systematic review and meta-analysis of randomized controlled trials

Background: The effect of inhaled nitric oxide (iNO) in neonates >34 weeks on improving respiration is well documented. However, the efficacy of iNO in preterm infants ≤34 weeks remains controversial. Objectives: The main purpose of this review is to assess the effectiveness and safety of iNO treatment in preterm infants ≤34 weeks. Search methods: We systematically searched PubMed, Embase and Cochrane Libraries from their inception to 1 June 2023. We also reviewed the reference lists of retrieved studies. Selection criteria: Our study involved randomized controlled trials on preterm infants ≤34 weeks, especially those receiving iNO treatment, and mainly assessed outcomes such as bronchopulmonary dysplasia (BPD) and mortality. Two authors independently reviewed these trials, extracted data, and evaluated study biases. Disagreements were resolved by consensus. We used the GRADE method to assess evidence quality. Results: Our research included a total of 17 studies involving 4,080 neonates and 7 follow-up studies. The synthesis of results showed that in neonates, iNO treatment reduced the incidence of BPD (RR: 0.92; 95% CI: 0.86-0.98). It also decreased the composite outcome of death or BPD (RR: 0.94; 95% CI: 0.90-0.98), without increasing the risk of short-term (such as intraventricular hemorrhage, periventricular leukomalacia) and long-term neurological outcomes (including Bayley mental developmental index <70, cerebral palsy and neurodevelopmental impairment). Furthermore, iNO did not significantly affect other neonatal complications like sepsis, pulmonary hemorrhage, necrotizing enterocolitis, and symptomatic patent ductus arteriosus. Subgroup analysis revealed that iNO significantly reduced BPD incidence in neonates at 36 weeks under specific intervention conditions, including age less than 3 days, birth weight over 1,000 g, iNO dose of 10 ppm or higher, or treatment duration exceeding 7 days (p < 0.05). Conclusion: Inhaled NO reduced the incidence of BPD in neonates at 36 weeks of gestation, and the effect of the treatment depended on neonatal age, birth weight, duration and dose of iNO. Therefore, iNO can be considered a promising treatment for the potential prevention of BPD in premature infants. More data, however, would be needed to support nitric oxide registration in this specific patient population, to minimize its off-label use.

The early use of inhaled nitric oxide in premature infants requiring respiratory support

Background: Earlier studies on the use of inhaled nitric oxide (iNO) for premature infants born at <34 weeks of gestation requiring respiratory support did not provide conclusive evidence of benefit. National guidelines generally discouraged the use in this population. More recent national guidelines endorsed the use of iNO in premature infants with hypoxic respiratory failure (HRF) associated with persistent pulmonary hypertension of the newborn (PPHN).Recent Studies: Two recently published observational studies evaluated the effect of administering iNO on oxygenation in the first week of life. These studies compared premature infants born at the gestational age (GA) of <34 weeks with HRF associated with PPHN to term and late preterm infants born at the GA of ≥34 weeks who received iNO. Both studies showed a similar effect of iNO on oxygenation in the two infant cohorts. The response rate in the premature infant cohort was 59% in the first study and 90% in the second. The mean response time was 9.2 h and 10.3 h, and the mean duration of therapy was 3.5 days and 8.2 days, respectively.Conclusion: The results of these studies support a trial of iNO in premature infants with persistent hypoxia despite optimum respiratory support. Obtaining a timely echocardiogram to exclude cardiac diseases and diagnose PPHN is logistically challenging for many clinicians, thus, a clinical diagnosis of PPHN might have to be made in these situations. Questions remain regarding the optimum dose of iNO and the duration of the initial iNO trial in these patients.KEY MESSAGESIn the most recently published studies, the improvement of oxygenation in iNO-treated infants born at <34 weeks of gestation with HRF and PPHN physiology was as effective as in infants born ≥34 weeks.These studies provide evidence supporting a trial of iNO in the subpopulation of premature infants with HRF associated with PPHN.

Echocardiographic Assessment of Pulmonary Arterial Hypertension Following Inhaled Nitric Oxide in Infants with Severe Bronchopulmonary Dysplasia

OBJECTIVES

Inhaled nitric oxide (iNO) is an effective pulmonary vasodilator. However, the efficacy of iNO in former premature infants with established bronchopulmonary dysplasia (BPD) has not been studied. This study aimed to determine the efficacy of iNO in reducing pulmonary artery pressure in infants with severe BPD as measured by echocardiography.

STUDY DESIGN

Prospective, observational study enrolling infants born at less than 32 weeks gestation and in whom (1) iNO therapy was initiated after admission to our institution, or (2) at the outside institution less than 48 h before transfer and received an echocardiogram prior to iNO initiation, and (3) had severe BPD. Data were collected at three time-points: (1) before iNO; (2) 12-48 h after initiation of iNO; and (3) 48-168 h after initiation of iNO. The primary outcome was the effect of iNO on pulmonary artery pressure measured by echocardiography in patients with severe BPD between 48 and 168 h after initiating iNO therapy.

RESULTS

Of 37 enrolled, 81% had echocardiographic evidence of pulmonary arterial hypertension (PAH) before iNO and 56% after 48 h of iNO (p = 0.04). FiO2 requirements were significantly different between time-points (1) and (3) (p = 0.05). There were no significant differences between Tricuspid Annular Plane Systolic Excursion (TAPSE) Z-Scores, time to peak velocity: right ventricular ejection time (TPV:RVET), and ventilator changes.

CONCLUSIONS

Although we found a statistically significant reduction of PAH between time-point (1) and (3), future trials are needed to further guide clinical care.

Association between short-term air pollution exposure and traumatic intracranial hemorrhage: pilot evidence from Taiwan

Introduction

The detrimental effects of air pollution on the brain are well established. However, few studies have examined the effect of air pollution on traumatic brain injury (TBI). This pilot study evaluated the association between short-term air pollution exposure and traumatic intracranial hemorrhage (TIH).

Methods

Hospital data of patients with TBI following road traffic accidents were retrospectively collected from the electronic medical records at five trauma centers in Taiwan between 1 January and 31 December 2017. TIH was employed as an outcome measure. All road accident locations were geocoded, and air quality data were collected from the nearest monitoring stations. Air pollutants were entered into five multivariable models. A sensitivity analysis was performed on patients who are vulnerable to suffering TBI after road accidents, including motorcyclists, bicyclists, and pedestrians.

Results

Among 730 patients with TBI, 327 had TIH. The ages of ≥65 [odds ratio (OR), 3.24; 95% confidence interval (CI), 1.85-5.70], 45-64 (OR, 2.61; 95% CI, 1.64-4.15), and 25-44 (OR, 1.79; 95% CI, 1.13-2.84) years were identified as significant risk factors in the multivariable analysis. In the best-fit multivariable model, exposure to higher concentrations of particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) was associated with an elevated TIH risk (OR, 1.50; 95% CI, 1.17-1.94). The concentration of nitrogen oxides (NO_X) did not increase the risk of TIH (OR, 0.45; 95% CI, 0.32-0.61). After categorizing the air pollution concentration according to quartile, the trend tests in the multivariate model showed that the concentrations of PM_2.5 and NO_X were significant (p = 0.017 and p < 0.001, respectively). There was a negative borderline significant association between temperature and TIH risk (OR, 0.75; 95% CI, 0.56-1.00, p = 0.05). Notably, the single-vehicle crash was a significant risk factor (OR, 2.11; 95% CI, 1.30-3.42) for TIH.

Discussion

High PM_2.5 concentrations and low temperatures are risk factors for TIH in patients with TBI. High NO_X concentrations are associated with a lower TIH risk.

Effects of Inhaled Iloprost for the Management of Persistent Pulmonary Hypertension of the Newborn

OBJECTIVE

The study aimed to evaluate the effects of inhaled iloprost on oxygenation indices in neonates with persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

We conducted a retrospective chart review of 30 patients with PPHN from January 2014 to November 2018, who did not respond to inhaled nitric oxide (iNO) alone and received inhaled iloprost. Twenty-two patients met the inclusion criteria and eight patients were excluded from the study (complex cardiac disease and extreme prematurity). Patients were categorized as responders or nonresponders (patients who required extracorporeal membrane oxygenation or died). Oxygenation index, mean airway pressure (MAP), and arterial partial pressure of oxygen (PaO₂) were recorded.

RESULTS

Among a total of 22 patients who were included in the study, 10 were classified as nonresponders as they required either extracorporeal membrane oxygenation or died. Gestational age and gender did not differ between responders and nonresponders. The median PaO₂ was lower (37 vs. 42 mm Hg; p < 0.05) and median MAP was higher (20 vs. 17 cm H₂O; p < 0.02) in nonresponders compared with responders just prior to initiating iloprost. Iloprost responders had a significant increase in median PaO₂ and decrease in median oxygenation index in the 24 hours after initiating treatment (p < 0.05), with no significant change in required mean airway pressure over that same period. There was no change in vasopressor use or clinically significant worsening of platelets count, liver, and kidney functions after initiating iloprost.

CONCLUSION

Inhaled iloprost is well tolerated and seems to have beneficial effects in improving oxygenation indices in neonates with PPHN who do not respond to iNO. There is a need of well-designed prospective trials to further ascertain the benefits of using inhaled iloprost as an adjunct treatment in neonates with PPHN who do not respond to iNO alone.

KEY POINTS

· Inhaled iloprost seems to have beneficial effects in improving oxygenation indices in PPHN.. · Inhaled iloprost is generally well tolerated in newborns with PPHN.. · There is a need for prospective randomized controlled trials to further ascertain the benefits of using inhaled iloprost..

Pulmonary vasodilator strategies in neonates with acute hypoxemic respiratory failure and pulmonary hypertension

The management of acute hypoxemic respiratory failure (AHRF) in newborns continues to be a clinical challenge with elevated risk for significant morbidities and mortality, especially when accompanied with persistent pulmonary hypertension of the newborn (PPHN). PPHN is a syndrome characterized by marked hypoxemia secondary to extrapulmonary right-to-left shunting across the ductus arteriosus and/or foramen ovale with high pulmonary artery pressure and increased pulmonary vascular resistance (PVR). After optimizing respiratory support, cardiac performance and systemic hemodynamics, targeting persistent elevations in PVR with inhaled nitric oxide (iNO) therapy has improved outcomes of neonates with PPHN physiology. Despite aggressive cardiopulmonary management, a significant proportion of patients have an inadequate response to iNO therapy, prompting consideration for additional pulmonary vasodilator therapy. This article reviews the pathophysiology and management of PPHN in term newborns with AHRF while highlighting both animal and human data to inform a physiologic approach to the use of PH-targeted therapies.

Therapeutic Gases and Inhaled Anesthetics as Adjunctive Therapies in Critically Ill Patients

The administration of exogenous oxygen to support adequate gas exchange is the cornerstone of respiratory care. In the past few years, other gaseous molecules have been introduced in clinical practice to treat the wide variety of physiological derangement seen in critical care patients.Inhaled nitric oxide (NO) is used for its unique selective pulmonary vasodilator effect. Recent studies showed that NO plays a pivotal role in regulating ischemia-reperfusion injury and it has antibacterial and antiviral activity.Helium, due to its low density, is used in patients with upper airway obstruction and lower airway obstruction to facilitate gas flow and to reduce work of breathing.Carbon monoxide (CO) is a poisonous gas that acts as a signaling molecule involved in many biologic pathways. CO's anti-inflammatory and antiproliferative effects are under investigation in the setting of acute respiratory distress and idiopathic pulmonary fibrosis.Inhaled anesthetics are widely used in the operative room setting and, with the development of anesthetic reflectors, are now a valid option for sedation management in the intensive care unit.Many other gases such as xenon, argon, and hydrogen sulfide are under investigation for their neuroprotective and cardioprotective effects in post-cardiac arrest syndrome.With all these therapeutic options available, the clinician must have a clear understanding of the physiologic basis, therapeutic potential, and possible adverse events of these therapeutic gases. In this review, we will present the therapeutic gases other than oxygen used in clinical practice and we will describe other promising therapeutic gases that are in the early phases of investigation.

Nitric oxide: Clinical applications in critically ill patients

Inhaled nitric oxide (iNO) acts as a selective pulmonary vasodilator and it is currently approved by the FDA for the treatment of persistent pulmonary hypertension of the newborn. iNO has been demonstrated to effectively decrease pulmonary artery pressure and improve oxygenation, while decreasing extracorporeal life support use in hypoxic newborns affected by persistent pulmonary hypertension. Also, iNO seems a safe treatment with limited side effects. Despite the promising beneficial effects of NO in the preclinical literature, there is still a lack of high quality evidence for the use of iNO in clinical settings. A variety of clinical applications have been suggested in and out of the critical care environment, aiming to use iNO in respiratory failure and pulmonary hypertension of adults or as a preventative measure of hemolysis-induced vasoconstriction, ischemia/reperfusion injury and as a potential treatment of renal failure associated with cardiopulmonary bypass. In this narrative review we aim to present a comprehensive summary of the potential use of iNO in several clinical conditions with its suggested benefits, including its recent application in the scenario of the COVID-19 pandemic. Randomized controlled trials, meta-analyses, guidelines, observational studies and case-series were reported and the main findings summarized. Furthermore, we will describe the toxicity profile of NO and discuss an innovative proposed strategy to produce iNO. Overall, iNO exhibits a wide range of potential clinical benefits, that certainly warrants further efforts with randomized clinical trials to determine specific therapeutic roles of iNO.

Use of inhaled nitric oxide in preterm vs term/near-term neonates with pulmonary hypertension: results of the PaTTerN registry study

OBJECTIVE

To evaluate inhaled nitric oxide (iNO) in preterm (PT) vs term/near-term (TNT) neonates with hypoxic respiratory failure (HRF) and pulmonary hypertension (PH) in an observational registry (PaTTerN).

STUDY DESIGN

Non-inferiority study comparing PT neonates of GA ≥ 27 to <34 weeks vs TNT neonates of GA ≥ 34 to ≤40 weeks with HRF associated with PH, who received iNO for 24-96 h during the first 0-7 days after birth. Primary endpoint: Achieving ≥25% decrease in oxygenation index/surrogate oxygenation index during iNO treatment.

RESULTS

Of 140 neonates (PT, n = 55; TNT, n = 85), the primary endpoint was achieved in 50 (90.9%) PT vs 75 (88.2%) TNT neonates (difference [95% CI]: 0.027 [-0.033, 0.087]); PT neonates achieved non-inferiority interval, and the study was stopped early based on prespecified criteria.

CONCLUSIONS

Use of iNO for improving oxygenation in PT neonates with HRF associated with PH is at least as effective as in TNT neonates.

CLINICAL TRIAL REGISTRATION

#NCT03132428, registered April 27, 2017.

Pediatric Pulmonary Hypertension: Definitions, Mechanisms, Diagnosis, and Treatment

Pediatric pulmonary hypertension (PPH) is a multifactorial disease with diverse etiologies and presenting features. Pulmonary hypertension (PH), defined as elevated pulmonary artery pressure, is the presenting feature for several pulmonary vascular diseases. It is often a hidden component of other lung diseases, such as cystic fibrosis and bronchopulmonary dysplasia. Alterations in lung development and genetic conditions are an important contributor to pediatric pulmonary hypertensive disease, which is a distinct entity from adult PH. Many of the causes of pediatric PH have prenatal onset with altered lung development due to maternal and fetal conditions. Since lung growth is altered in several conditions that lead to PPH, therapy for PPH includes both pulmonary vasodilators and strategies to restore lung growth. These strategies include optimal alveolar recruitment, maintaining physiologic blood gas tension, nutritional support, and addressing contributing factors, such as airway disease and gastroesophageal reflux. The outcome for infants and children with PH is highly variable and largely dependent on the underlying cause. The best outcomes are for neonates with persistent pulmonary hypertension (PPHN) and reversible lung diseases, while some genetic conditions such as alveolar capillary dysplasia are lethal. © 2021 American Physiological Society. Compr Physiol 11:2135-2190, 2021.

Inhaled pulmonary vasodilators: a narrative review

Pulmonary hypertension (PH) is a severe disease that affects people of all ages. It can occur as an idiopathic disorder at birth or as part of a variety of cardiovascular and pulmonary disorders. Inhaled pulmonary vasodilators (IPV) can reduce pulmonary vascular resistance (PVR) and improve RV function with minimal systemic effects. IPV includes inhaled nitric oxide (iNO), inhaled aerosolized prostacyclin, or analogs, including epoprostenol, iloprost, treprostinil, and other vasodilators. In addition to pulmonary vasodilating effects, IPV can also be used to improve oxygenation, reduce inflammation, and protect cell. Off-label use of IPV is common in daily clinical practice. However, evidence supporting the inhalational administration of these medications is limited, inconclusive, and controversial regarding their safety and efficacy. We conducted a search for relevant papers published up to May 2020 in four databases: PubMed, Google Scholar, EMBASE and Web of Science. This review demonstrates that the clinical using and updated evidence of IPV. iNO is widely used in neonates, pediatrics, and adults with different cardiopulmonary diseases. The limitations of iNO include high cost, flat dose-response, risk of significant rebound PH after withdrawal, and the requirement of complex technology for monitoring. The literature suggests that inhaled aerosolized epoprostenol, iloprost, treprostinil and others such as milrinone and levosimendan may be similar to iNO. More research of IPV is needed to determine acceptable inclusion criteria, long-term outcomes, and management strategies including time, dose, and duration.

Inhaled nitric oxide and acute kidney injury risk: a meta-analysis of randomized controlled trials

Purpose

There are conflicting results as to the effect of inhaled nitric oxide (iNO) therapy on the risk of acute kidney injury (AKI). The aim of this study was to perform a meta-analysis to assess the updated data.

Methods

We systematically searched Web of Science, the Cochrane Library, Wanfang, and PubMed for relevant randomized control trials between database inception and 9/07/2020. Relative risks (RRs) with 95% confidence intervals (CIs) predicting the risk of AKI were extracted to obtain summary estimates using fixed-effects models. The Trim and Fill method was used to evaluate the sensitivity of the results and adjust for publication bias in meta-analysis.

Results

15 randomized controlled studies from 14 articles involving 1853 patients were included in the study. Analyzing the eligible studies we found: (1) iNO therapy significantly increased the risk of AKI in acute respiratory distress syndrome patients (RR 1.55, 95% CI 1.15–2.10, p = 0.004; I² for heterogeneity 0%; P_het = 0.649). (2) The use of iNO was associated with reduced AKI risk in patients undergoing cardiac surgery (RR 0.80, 95% CI 0.64–0.99, p = 0.037; I² for heterogeneity 0%; P_het = 0.528). (3) For organ transplantation recipients, there was no effect of iNO administration on the risk of AKI (RR 0.50, 95% CI 0.16–1.56, p = 0.233; I² for heterogeneity 0%; P_het = 0.842). The Trim and Fill analysis showed that the overall effect of this meta-analysis was stable.

Conclusions

The effect of iNO on AKI risk might be disease-specific. Future RCTs with larger patient populations should aim to validate our findings.

The Controversy Persists: Is There a Qualification Criterion to Utilize Inhaled Nitric Oxide in Pre-term Newborns?

Inhaled nitric oxide (iNO) use in premature newborns remains controversial among clinicians. In 2014, the American Academy of Pediatrics, Committee on Fetus and Newborn released a statement that the available data do not support routine iNO use in pre-term newborns. Despite the absence of significant benefits, 2016 California data showed that clinicians continue to utilize iNO in pre-term infants. With studies as recent as January 2017, the Cochrane review confirmed no major advantages of iNO in pre-term newborns. Still, it recognized that a subset of pre-term infants with pulmonary hypertension (PHTN) had not been separately investigated. Furthermore, recent non-randomized controlled trials have suggested that iNO may benefit specific subgroups of pre-term newborns, especially those with PHTN, prolonged rupture of membranes, and antenatal steroid exposure. Those pre-term infants who showed a clinical response to iNO had increased survival without disability. These findings underscore the need for future studies in pre-term newborns with hypoxemic respiratory failure and PHTN. This review will discuss the rationale for using iNO, controversies regarding the diagnosis of PHTN, and additional novel approaches of iNO treatment in perinatal asphyxia and neonatal resuscitation in the pre-term population < 34 weeks gestation.

Variation in the definition of pulmonary hypertension and clinical indications for the use of nitric oxide in neonatal clinical trials

AIM

Pulmonary hypertension (PH) frequently complicates neonatal hypoxaemic respiratory failure, but is inconsistently defined. We aimed to describe the variation among randomised controlled trials (RCTs) of inhaled nitric oxide (iNO), in relation to the definition of PH and/or hypoxaemic respiratory failure used to select patients for trial inclusion.

METHODS

PubMed, Cochrane Library and ClinicalTrials.gov were systematically searched for RCTs of iNO in neonates. Included studies were assessed for clinical and/or echocardiography criteria used to define PH/hypoxaemic respiratory failure.

RESULTS

Thirty-two trials were included in this review, of which 23 enrolled infants ≥34 weeks' gestation. Echocardiographic diagnosis was used in 21 studies, but there was considerable variation in the echocardiographic parameters used to diagnose PH. The most commonly used indices included markers of tricuspid regurgitation and extrapulmonary shunt.

CONCLUSION

There is wide variation in the definition of PH used to select infants for inclusion into RCTs of iNO therapy in neonates. We recommend that an international consensus be reached on which parameters should be used and the thresholds defining severity of disease.

Inhaled Nitric Oxide in Emergency Medical Transport of the Newborn

Randomized controlled trials in the 1990s confirmed the safety and efficacy of inhaled nitric oxide (iNO) in near-term and term newborns with hypoxemic respiratory failure and pulmonary hypertension, demonstrating improved oxygenation and reduced need for extracorporeal membrane oxygenation (ECMO) therapy. However, in about 30% to 40% of sick newborns, these improvements in oxygenation and hemodynamics are not sustained and affected infants often require rapid transfer to an ECMO center despite the initiation of iNO. Abrupt discontinuation of iNO therapy before transport in patients who have had little apparent clinical benefit can be harmful because of acute deterioration with severe hypoxemia. Thus, continued use of iNO therapy during hospital transfer of infants with pulmonary hypertension is important. In this review, we describe: 1) the history of iNO use during transport; 2) a practical approach to iNO during transport; and 3) guidelines for the initiation of iNO before or during transport.

Impact of inhaled nitric oxide stewardship programme in a neonatal intensive care unit

AIM

Inhaled nitric oxide (iNO) is the most common, although expensive, therapy for persistent pulmonary hypertension of the newborn and hypoxaemic respiratory failure. With significant variation in iNO delivery practices amongst clinicians, this study aimed to assess the effectiveness of a stewardship programme in increasing clinician compliance with revised, standardised protocols and to measure the impact of compliance on iNO therapy use.

METHODS

Initiation and weaning protocols for iNO were introduced to the neonatal intensive care unit at The Centenary Hospital on 01 March 2016. A 2-year stewardship programme was utilised to assess protocol compliance and the resulting iNO usage impacts were measured. A combined retrospective and prospective study from 1 March 2014 to 28 February 2018 was conducted to compare the patterns of iNO utilisation between the pre- and post-stewardship cohorts.

RESULTS

The pre-stewardship cohort incorporated 18 neonates, receiving 19 iNO treatment episodes, and 18 neonates, receiving 21 iNO treatment episodes, in the post-stewardship cohort. No significant difference in patient demographics was determined. Compliance with the protocols improved from 61% in year 1 to 88% in year 2 of the stewardship programme. Significant reductions were observed in median total hours of iNO therapy per patient (P = 0.0014) and in median time from therapy initiation to initial wean (P < 0.0001). The cost of iNO therapy reduced 52% during the stewardship programme with no increase in adverse patient outcomes.

CONCLUSION

An iNO stewardship programme could be safely implemented in any NICU leading to increased protocol compliance with a beneficial reduction in iNO usage and cost.

Inhaled nitric oxide use in neonates: Balancing what is evidence-based and what is physiologically sound

Inhaled nitric oxide is a powerful therapeutic used in neonatology. Its use is evidenced-based for term and near-term infants with persistent pulmonary hypertension; however, it is frequently used off-label both in term and preterm babies. This article reviews the off-label uses of iNO in infants. Rationale is discussed for a selective application of iNO based on physiologically guided principles, and new research avenues are considered.

Outcomes of early inhaled nitric oxide use in premature African American neonates

OBJECTIVE

Meta-analysis of individual-patient clinical trial data suggests that inhaled nitric oxide (iNO) improves respiratory outcomes in premature African American neonates. We hypothesized that early iNO therapy would be associated with lower mortality and less chronic lung disease (CLD) in extremely premature African American neonates.

STUDY DESIGN

We conducted a retrospective cohort study of propensity score- and race-matched neonates 22-29 weeks gestation who were mechanically ventilated for treatment of respiratory distress and associated pulmonary hypertension (RDS + PPHN). We evaluated the association of iNO within 7 days of life with in-hospital mortality and CLD, using Cox proportional hazards regression and logistic regression, respectively.

RESULT

Among 178 matched pairs of African American patients, iNO was not associated with lower mortality (HR = 0.94, 95% CI 0.69-1.30) or less CLD (OR = 0.94, 95% CI 0.47-1.87).

CONCLUSIONS

Early, off-label iNO use is not associated with improved outcomes in premature African American neonates with RDS + PPHN.

Efficacy of inhaled nitric oxide in neonates with hypoxic respiratory failure and pulmonary hypertension: the Japanese experience

OBJECTIVE

To analyze data from a registry of Japanese neonates with hypoxic respiratory failure associated with pulmonary hypertension (PH) to compare the effectiveness of inhaled nitric oxide (iNO) in neonates born <34 weeks vs. ≥34 weeks gestational age (GA).

MATERIALS AND METHODS

iNO was administered according to approved Japanese product labeling. Study data were collected before iNO administration and at predefined intervals until discontinuation.

RESULTS

A total of 1,114 neonates were included (n=431, <34 weeks GA; n=675, ≥34 weeks GA; n=8, missing age data). Mean decrease from baseline oxygenation index (OI) was similar in both age groups. OI reduction was more pronounced in the <34 weeks subgroups with baseline OI ≥25. Survival rates were similar in the <34 weeks GA and ≥34 weeks GA groups stratified by baseline OI (OI<15, 89% vs. 93%; 15≤OI<25, 85% vs. 91%; 25≤OI≤40, 73% vs. 79%; OI>40, 64% vs. 66%).

CONCLUSION

iNO improved oxygenation in preterm neonates as effectively as in late preterm and term neonates, without negative impact on survival. If clinically significant PH is present, as measured by pulse oximetry or echocardiography, a therapeutic trial of iNO might be indicated for preterm neonates.

Association of Early Inhaled Nitric Oxide With the Survival of Preterm Neonates With Pulmonary Hypoplasia

IMPORTANCE

Pulmonary hypoplasia affects a very small percentage of preterm neonates, but its presence is associated with high rates of mortality.

OBJECTIVE

To determine whether treatment with inhaled nitric oxide during the first week of life was associated with improved in-hospital survival in a cohort of extremely preterm neonates with pulmonary hypoplasia.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used data from the Pediatrix Medical Group's Clinical Data Warehouse, a data set containing information from more than 350 neonatal intensive care units in 35 US states and Puerto Rico. Since inhaled nitric oxide was not randomly prescribed, we used 1-to-1 propensity score matching to reduce the imbalance of measured covariates between the 2 treatment groups. The initial, unmatched cohort included singleton neonates who were born between 22 and 29 weeks' gestation, had a birth weight of 400 g or more, were diagnosed with pulmonary hypoplasia as a cause of their respiratory distress, remained free of major anomalies, and were discharged between January 1, 2000, and December 31, 2014. We defined exposure as the initiation of inhaled nitric oxide on day t in days 0 to 7 of the life of a neonate. Each exposed neonate was matched 1-to-1 to a neonate who had not initiated inhaled nitric oxide on a given day.

MAIN OUTCOMES AND MEASURES

The primary outcome was mortality defined as death prior to transfer or discharge home. Secondary outcomes were any-stage necrotizing enterocolitis, retinopathy of prematurity requiring treatment, chronic lung disease, and periventricular leukomalacia.

RESULTS

Among 92 635 neonates in our study sample, we identified 767 (0.8%) with pulmonary hypoplasia who met all study inclusion criteria, of whom 185 (0.2%) were exposed to inhaled nitric oxide. Among 151 matched pairs of exposed and unexposed neonates, we did not identify a significant association between inhaled nitric oxide use and mortality (hazard ratio [HR], 0.79; 95% CI, 0.57-1.11). Subgroup analyses of neonates with and without persistent pulmonary hypertension (PPHN) likewise revealed no significant association between inhaled nitric oxide use and mortality (pulmonary hypoplasia with PPHN: HR, 0.67; 95% CI, 0.45-1.01; pulmonary hypoplasia without PPHN: HR, 1.11; 95% CI, 0.61-2.02), but these findings may have been influenced by ascertainment bias.

CONCLUSIONS AND RELEVANCE

Early treatment with inhaled nitric oxide is not associated with improved survival among extremely preterm neonates with pulmonary hypoplasia. Clinical trials are warranted to clarify the matter.

Inhaled Nitric Oxide in Extremely Premature Neonates With Respiratory Distress Syndrome

BACKGROUND

Inhaled nitric oxide (iNO) is increasingly prescribed to extremely premature neonates with respiratory distress syndrome (RDS). Most of this off-label use occurs during the first week of life. We studied this practice, hypothesizing that it would not be associated with improved survival.

METHODS

We queried the Pediatrix Medical Group Clinical Data Warehouse to identify all neonates born at 22 to 29 weeks' gestation from 2004 to 2014. In our study sample, we included singletons who required mechanical ventilation for treatment of RDS and excluded those with anomalies. The primary outcome was death before discharge. Through a sequential risk set approach, each patient who received iNO during the first 7 days of life ("case patient") was matched by using propensity scores to a patient who had not received iNO at a chronological age before the case patient's iNO initiation age (defined as the index age for the matched pair). The association between iNO status and in-hospital mortality was evaluated in a Cox proportional hazards regression model by using age as the time scale with patients entering the risk set at their respective index age.

RESULTS

Among 37 909 neonates in our study sample, we identified 993 (2.6%) who received iNO. The 2 matched cohorts each contained 971 patients. We did not observe a significant association between iNO exposure and mortality (hazard ratio, 1.08; 95% confidence interval, 0.94-1.25; P = .29).

CONCLUSIONS

Off-label prescription of iNO is not associated with reduced in-hospital mortality among extremely premature neonates with RDS.

Controversies in the identification and management of acute pulmonary hypertension in preterm neonates

It is increasingly recognized that the abnormal physiologic consequences of pulmonary hypertension (PH) may contribute to poor cardiopulmonary health in premature babies. Conflicting literature has led to clinical uncertainty, pathological misinterpretation, and variability in treatment approaches among practitioners. There are several disorders with overlapping and interrelated presentations, and other disorders with a similar clinical phenotype but diverse pathophysiological contributors. In this review, we provide a diagnostic approach for acute hypoxemic respiratory failure in the preterm neonate, outline the pathophysiological conditions that may present as acute PH, and discuss the implications of high pulmonary vascular resistance (PVR) on the cardiovascular system. Although PVR and respiratory management are highly interrelated, there may be a population of preterm neonates in whom inhaled nitric oxide may improve illness severity and may relate to outcomes. A management approach based on physiology that considers common clinical conundrums is provided. A more comprehensive understanding of the physiology may help in informed decision-making in clinical situations where conclusive scientific evidence is lacking. Regardless, high-quality research is required, and appropriate definition of the target population is paramount. A thoughtful approach to cardiovascular therapy may also provide an avenue to improve neurodevelopmental outcomes while awaiting more clear answers.

Early Use of Inhaled Nitric Oxide in Preterm Infants: Is there a Rationale for Selective Approach?

Background Inhaled nitric oxide (iNO) is being increasingly used in preterm infants < 34 weeks with hypoxemic respiratory failure (HRF) and/or pulmonary hypertension (PH). Objective To evaluate the risk factors, survival characteristics, and lung histopathology in preterm infants with PH/HRF. Methods Retrospective chart review was conducted to determine characteristics of 93 preterm infants treated with iNO in the first 28 days and compared with 930 matched controls. Factors associated with survival with preterm HRF and smooth muscle actin from nine autopsies were evaluated. Results Preterm neonates treated with iNO had a higher incidence of preterm prolonged rupture of membrane (pPROM ≥ 18 hours), oligohydramnios and delivered by C-section. In infants treated with iNO, antenatal steroids (odds ratio [OR],3.7; confidence interval [CI], 1.2-11.3; p = 0.02), pPROM (OR, 1.001; CI, 1.0-1.004; p = 0.3), and oxygenation response to iNO (OR, 3.7; CI, 1.08-13.1; p = 0.037) were associated with survival. Thirteen infants with all three characteristics had 100% (13/13) survival without severe intraventricular hemorrhage (IVH)/periventricular leukomalacia (PVL) compared with 48% survival (12/25, p = 0.004) and 16% severe IVH/PVL without any of these factors. Severity of HRF correlated with increased smooth muscle in pulmonary vasculature. Conclusion Preterm infants with HRF exposed to antenatal steroids and pPROM had improved oxygenation with iNO and survival without severe IVH/PVL. Precisely targeting this subset may be beneficial in future trials of iNO.

Inhaled nitric oxide for respiratory failure in preterm infants

BACKGROUND

Inhaled nitric oxide (iNO) is effective in term infants with hypoxic respiratory failure. The pathophysiology of respiratory failure and the potential risks of iNO differ substantially in preterm infants, necessitating specific study in this population.

OBJECTIVES

To determine effects of treatment with inhaled nitric oxide (iNO) on death, bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH) or other serious brain injury and on adverse long-term neurodevelopmental outcomes in preterm newborn infants with hypoxic respiratory failure.Owing to substantial variation in study eligibility criteria, which decreases the utility of an overall analysis, we divided participants post hoc into three groups: (1) infants treated over the first three days of life because of defects in oxygenation, (2) preterm infants with evidence of pulmonary disease treated routinely with iNO and (3) infants treated later (after three days of age) because of elevated risk of BPD.

SEARCH METHODS

We used standard methods of the Cochrane Neonatal Review Group. We searched MEDLINE, Embase, Healthstar and the Cochrane Central Register of Controlled Trials in the Cochrane Library through January 2016. We also searched the abstracts of the Pediatric Academic Societies.

SELECTION CRITERIA

Eligible for inclusion were randomised and quasi-randomised studies in preterm infants with respiratory disease that compared effects of iNO gas versus control, with or without placebo.

DATA COLLECTION AND ANALYSIS

We used standard methods of the Cochrane Neonatal Review Group and applied the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

We found 17 randomised controlled trials of iNO therapy in preterm infants. We grouped these trials post hoc into three categories on the basis of entry criteria: treatment during the first three days of life for impaired oxygenation, routine use in preterm babies along with respiratory support and later treatment for infants at increased risk for bronchopulmonary dysplasia (BPD). We performed no overall analyses.Eight trials providing early rescue treatment for infants on the basis of oxygenation criteria demonstrated no significant effect of iNO on mortality or BPD (typical risk ratio (RR) 0.94, 95% confidence interval (CI) 0.87 to 1.01; 958 infants). Four studies examining routine use of iNO in infants with pulmonary disease reported no significant reduction in death or BPD (typical RR 0.94, 95% CI 0.87 to 1.02; 1924 infants), although this small effect approached significance. Later treatment with iNO based on risk of BPD (three trials) revealed no significant benefit for this outcome in analyses of summary data (typical RR 0.92, 95% CI 0.85 to 1.01; 1075 infants).Investigators found no clear effect of iNO on the frequency of all grades of IVH nor severe IVH. Early rescue treatment was associated with a non-significant 20% increase in severe IVH.We found no effect on the incidence of neurodevelopmental impairment.

AUTHORS' CONCLUSIONS

iNO does not appear to be effective as rescue therapy for the very ill preterm infant. Early routine use of iNO in preterm infants with respiratory disease does not prevent serious brain injury or improve survival without BPD. Later use of iNO to prevent BPD could be effective, but current 95% confidence intervals include no effect; the effect size is likely small (RR 0.92) and requires further study.

Outcome of Preterm Neonates with a Birth Weight <1,500 g with Severe Hypoxemic Respiratory Failure Rescued by Inhaled Nitric Oxide Therapy and High-Frequency Oscillatory Ventilation

BACKGROUND

Despite being an experimental therapy in preterm neonates, inhaled nitric oxide (iNO) is used as a rescue therapy when high-frequency oscillatory ventilation (HFOV) and other conventional therapies fail.

OBJECTIVE

We aimed to determine the outcomes of very-low-birth-weight (VLBW) neonates with hypoxemic respiratory failure (HRF) who had received iNO after maximal conventional therapies.

METHODS

We retrospectively reviewed preterm neonates (<33 weeks of gestation with a birth weight <1,500 g) who had all received HFOV and then iNO from March 1, 2009 to April 1, 2014 at the Royal Alexandra Hospital. We collected demographic and clinical parameters, doses, duration and response to iNO, survival to neonatal intensive care unit (NICU) discharge, major complications, and neurodevelopmental outcome at 18-24 months of corrected age.

RESULTS

During the study period, 1,168 eligible preterm neonates were admitted; 155 (13%) had HRF treated with HFOV, of whom 47 (30%) received iNO. The baseline characteristics between the 24 survivors and 23 nonsurvivors were not different. Survivors had a greater decrease in oxygenation index than nonsurvivors (61 vs. 33%) after 6 h of iNO (p = 0.003). The causes of death were refractory hypoxemia (8), multi-organ failure (7), treatment withdrawal (6), and others (2). During the NICU stay, 23 survivors (96%) developed complications. At 18-24 months, 7 (29%) had significant disabilities.

CONCLUSIONS

Of the VLBW neonates with severe HRF rescued by HFOV and iNO, many survived without neurodevelopmental disability at early childhood, despite multiple short-term complications. Further research is necessary to understand the clinical course and risk factors of adverse outcomes and to improve the management care of these critically ill neonates.

Early inhaled nitric oxide in preterm infants <34 weeks with evolving bronchopulmonary dysplasia

OBJECTIVE

To investigate whether early treatment with inhaled nitric oxide (iNO) could prevent bronchopulmonary dysplasia (BPD) in very preterm infants.

STUDY DESIGN

A non-randomized, controlled trial was conducted prospectively in 27 neonatal intensive care units over 12 months. Preterm infants with gestational age <34 weeks and after 7 days of life, who received invasive mechanical ventilation (MV) or nasal continuous positive airway pressure for >2 days, were treated either with low-dose iNO (from 5 as initial dose to 2 parts per million as maintenance dose for ⩾7 days, n=162) or as non-placebo control (n=240). Primary outcome was the incidence of moderate-to-severe BPD at 36 weeks postmenstrual age and/or death before discharge. Secondary outcomes were major complications.

RESULTS

iNO was started on average on day 19 of life (median duration 18 days, range 7 to 55 days). Rate of survival without BPD was significantly lower in the iNO than in the control group, whereas overall rates of BPD, death and major complications were similar between the two groups. Infants who started MV and iNO on postnatal days 15 to 21 had significantly increased survival without BPD (47.6% vs 17.1%, P=0.03, relative risk 2.7, 95% confidence interval 1.1 to 6.5). Additionally, pooled data from both groups showed that rates of perinatal co-morbidities and postnatal complications were higher in BPD infants than in non-BPD infants. The overall incidence of BPD was 55.6% and 75.9% for birth weight <1500 and <1000 g, respectively, or 1.6% for the total population <34 weeks of gestation admitted through the network.

CONCLUSION

Treatment with low-dose iNO did not decrease the overall risk of BPD and death nor showed adverse effects in short-term morbidities among very preterm infants. The benefit of delayed iNO treatment on BPD warrants further studies.

Impact of Stewardship on Inhaled Nitric Oxide Utilization in a Neonatal ICU

OBJECTIVES

Inhaled nitric oxide (iNO) remains the "gold standard" therapy for hypoxemic respiratory failure in newborns. Despite good quality evidence to guide iNO use in this population, we observed considerable practice variation, particularly in timing and rate of weaning. To promote evidence-based practice, we launched an iNO stewardship program in April 2013. Our objective was to determine whether iNO stewardship led to changes in iNO utilization and weaning.

METHODS

We conducted a quality improvement project in an outborn quaternary NICU, targeting improved iNO guideline compliance. We compared patterns of iNO utilization between 2 cohorts: prestewardship (April 2011-March 2013; retrospective data collection) and poststewardship (April 2013-March 2015; prospective data collection).

RESULTS

Eighty-seven neonates received 88 courses of iNO in the 2 years prestewardship, and 64 neonates received 64 courses of iNO in the 2 years poststewardship. There were no significant differences (P > .05) in patient demographics, in the proportion of patients receiving iNO "off-label," in proportion initiated at the referring hospital, or in outcomes (death or extracorporeal membrane oxygenation). There were significant (P < .05) reductions in median total hours on iNO per patient (47 vs 20; P < .001), in iNO hours per patient from maximum dose to initial wean (28 vs 9; P < .01), and in hours from initial wean to discontinuation (14 vs 8; P < .05).

CONCLUSIONS

The introduction of iNO stewardship was associated with improved adherence to evidence-based guidelines and an overall reduction in total and per-patient iNO use.

Lung Injury and Bronchopulmonary Dysplasia in Newborn Infants

Bronchopulmonary dysplasia is the most common morbidity among surviving premature infants. Injury to the developing lung is the result of the interaction between a susceptible host and a number of contributing factors such as mechanical ventilation and infection. The resulting persistent impairment of pulmonary function and need for ongoing therapy are the underlying characteristics of bronchopulmonary dysplasia. Important insights into the pathogenesis of bronchopulmonary dysplasia have led to numerous therapies and preventive approaches. Although significant progress has been made, in order to further affect the incidence and severity of the disease, we need to further study (a) the genetically determined predisposing factors, (b) the relative contribution of the various pathogenetic pathways, and, most important, (c) how to best translate the knowledge gained from these studies into effective clinical approaches.

Inhaled nitric oxide use in preterm infants in California neonatal intensive care units

OBJECTIVE

To describe inhaled nitric oxide (iNO) exposure in preterm infants and variation in neonatal intensive care unit (NICU) use.

STUDY DESIGN

This was a retrospective cohort study of infants, 22 to 33+6/7 weeks of gestational age (GA), during 2005 to 2013. Analyses were stratified by GA and included population characteristics, iNO use over time and hospital variation.

RESULTS

Of the 65 824 infants, 1718 (2.61%) received iNO. Infants, 22 to 24+6/7 weeks of GA, had the highest incidence of iNO exposure (6.54%). Community NICUs (n=77, median hospital use rate 0.7%) used less iNO than regional NICUs (n=23, median hospital use rate 5.8%). In 22 to 24+6/7 weeks of GA infants, the median rate in regional centers was 10.6% (hospital interquartile range 3.8% to 22.6%).

CONCLUSION

iNO exposure varied with GA and hospital level, with the most use in extremely premature infants and regional centers. Variation reflects a lack of consensus regarding the appropriate use of iNO for preterm infants.

Inhaled nitric oxide in preterm infants: An updated meta-analysis

Background:

In the past several years, randomized controlled trials (RCTs) have indicated that inhaled nitric oxide (iNO) can potentially lower for both the incidence of bronchopulmonary dysplasia (BPD) and mortality in affected infants. Other research has, however, disagreed with these findings.

Materials and Methods:

We performed an updated meta analysis of all relevant RCTs to assess the benefits of iNO in preterm infants by searching PubMed, EMBASE, Cochrane databases, Wanfang, VIP, and CNKI databases for English and Chinese references.

Results:

Ultimately, 22 RCTs were incorporated. (1) Risk of BPD was significantly lower in preterm infants supplemented with iNO (relative risk [RR] = 0.88; P = 0.0007). There are no differences concerning pulmonary hemorrhage (PH) (RR = 0.94; P = 0.72). (2) Incidences of necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), and severe intracranial hemorrhage (ICH) were compared. No significant difference was discovered concerning these risks (RR = 1.21, P = 0.08; RR = 1.01, P = 0.89; and RR = 0.99, P = 0.86). (3) In addition, no significant differences were found between experimental and control groups with respect to morality. (RR = 1.00, P = 0.98).

Conclusion:

Our meta analysis has shown a beneficial effect in BPD and morality. In addition, our meta analysis suggests that iNO therapy does not increase the risk of common complications, such as NEC and ROP, and that it may also have no adverse effect on bleeding tendency diseases (severe ICH and PH).

Pediatric Pulmonary Hypertension: Guidelines From the American Heart Association and American Thoracic Society

Pulmonary hypertension is associated with diverse cardiac, pulmonary, and systemic diseases in neonates, infants, and older children and contributes to significant morbidity and mortality. However, current approaches to caring for pediatric patients with pulmonary hypertension have been limited by the lack of consensus guidelines from experts in the field. In a joint effort from the American Heart Association and American Thoracic Society, a panel of experienced clinicians and clinician-scientists was assembled to review the current literature and to make recommendations on the diagnosis, evaluation, and treatment of pediatric pulmonary hypertension. This publication presents the results of extensive literature reviews, discussions, and formal scoring of recommendations for the care of children with pulmonary hypertension.

Outcomes of inhaled nitric oxide in preterm neonates - a five-year experience in a tertiary neonatal centre

AIM

To review the outcome of preterm neonates treated with iNO.

METHODS

The neonatal electronic database was reviewed between April 1, 2009 and March 31, 2014.

RESULTS

In the five-year period, 142 babies were treated with iNO. Forty-two preterm neonates <34(+0)  weeks were included in this review. During this period, the use of iNO in preterm neonates <26(+0)  weeks rose from 1.4% to 4.8% and the mortality was significantly higher in this group (69%).

CONCLUSION

There is an increasing trend in using iNO as a rescue treatment in preterm neonates. The outcomes were very poor in the preterm neonates <26(+0)  weeks. A cautious approach is warranted in the absence of robust evidence to support the use of iNO, in preterm neonates <26(+0)  weeks.

Inhaled nitric oxide therapy and risk of renal dysfunction: a systematic review and meta-analysis of randomized trials

INTRODUCTION

Inhaled nitric oxide (iNO) is an important therapy for acute respiratory distress syndrome (ARDS), pulmonary hypertension and pediatric hypoxemic respiratory failure. Safety concerns regarding iNO and renal dysfunction have been reported; however, there are currently no systematic reviews on this issue. Our objective was to evaluate published randomized controlled trials (RCTs) to ascertain the risk of renal dysfunction associated with iNO therapy in patients with and without ARDS.

METHODS

A systematic review of databases was performed to identify RCTs which compared iNO with controls up to September 2014. Effect estimates for risk ratio (RR) of acute kidney injury (AKI) were pooled using a random-effects model.

RESULTS

Ten RCTs involving 1363 participants were included. Inhaled nitric oxide significantly increased the risk of AKI compared with controls (RR, 1.4, 95%CI, 1.06 to 1.83, p = 0.02). In the stratified analysis, a high cumulative-dose of iNO significantly increased the risk of AKI (RR, 1.52, 95%CI, 1.14 to 2.02, p = 0.004), whereas medium and low cumulative-doses did not (RR, 0.64, 95%CI, 0.23 to 1.81 and RR, 0.56, 95%CI, 0.11 to 2.86 respectively). In subgroup analysis by study population, an increased risk of AKI was observed in patients with ARDS (RR, 1.55, 95%CI, 1.15 to 2.09, p = 0.005) but not in those without (RR, 0.90, 95%CI, 0.49 to 1.67, p = 0.75).

CONCLUSIONS

The available data show that iNO therapy may increase the risk of renal dysfunction, especially with prolonged use and in patients with ARDS. The risk in pediatric population is unknown owing to limited data. We suggest monitoring renal function during iNO therapy, and that future trials of iNO should evaluate renal safety.

Off-label use of inhaled nitric oxide after release of NIH consensus statement

BACKGROUND

Inhaled nitric oxide (iNO) therapy is an off-label medication in infants <34 weeks' gestational age. In 2011, the National Institutes of Health released a statement discouraging routine iNO use in premature infants. The objective of this study was to describe utilization patterns of iNO in American NICUs in the years surrounding the release of the National Institutes of Health statement. We hypothesized that iNO prescription rates in premature infants have remained unchanged since 2011.

METHODS

The Pediatrix Medical Group Clinical Data Warehouse was queried for the years 2009-2013 to describe first exposure iNO use among all admitted neonates stratified by gestational age.

RESULTS

Between 2009 and 2013, the rate of iNO utilization in 23- to 29-week neonates increased from 5.03% to 6.19%, a relative increase of 23% (confidence interval: 8%-40%; P = .003). Of all neonates who received iNO therapy in 2013, nearly half were <34 weeks' gestation, with these infants accounting for more than half of all first exposure iNO days each year of the study period.

CONCLUSIONS

The rates of off-label iNO use in preterm infants continue to rise despite evidence revealing no clear benefit in this population. This pattern of iNO prescription is not benign and comes with economic consequences.

Noninvasive inhaled nitric oxide does not prevent bronchopulmonary dysplasia in premature newborns

OBJECTIVE

To assess the efficacy and safety of early, noninvasive inhaled nitric oxide (iNO) therapy in premature newborns who do not require mechanical ventilation.

STUDY DESIGN

We performed a multicenter randomized trial including 124 premature newborns who required noninvasive supplemental oxygen within the first 72 hours after birth. Newborns were stratified into 3 different groups by birth weight (500-749, 750-999, 1000-1250 g) prior to randomization to iNO (10 ppm) or placebo gas (controls) until 30 weeks postmenstrual age. The primary outcome was a composite of death or bronchopulmonary dysplasia (BPD) at 36 weeks postmenstrual age. Secondary outcomes included the need for and duration of mechanical ventilation, severity of BPD, and safety outcomes.

RESULTS

There was no difference in the incidence of death or BPD in the iNO and placebo groups (42% vs 40%, P = .86, relative risk = 1.06, 0.7-1.6). BPD severity was not different between the treatment groups. There were no differences between the groups in the need for mechanical ventilation (22% vs 23%; P = .89), duration of mechanical ventilation (9.7 vs 8.4 days; P = .27), or safety outcomes including severe intracranial hemorrhage (3.4% vs 6.2%, P = .68).

CONCLUSIONS

We found that iNO delivered noninvasively to premature infants who have not progressed to early respiratory failure is a safe treatment, but does not decrease the incidence or severity of BPD, reduce the need for mechanical ventilation, or alter the clinical course.

Guidelines for Rational and Cost-Effective Use of iNO Therapy in Term and Preterm Infants

Inhaled nitric oxide (iNO) is an effective but costly therapy for infants with hypoxemic respiratory failure. The approved and solidly evidence-based indication is for treatment of late preterm and term infants with persistent pulmonary hypertension of the newborn (PPHN); however, off-label use of iNO has become widespread. Although iNO treatment of infants with congenital diaphragmatic hernia constitutes one of the approved indications, available evidence from randomized trials suggests marginal if any efficacy. Rescue therapy in preterm infants with severe respiratory failure has been studied extensively and is not supported by data from a number of controlled trials. Such use is widespread, but should be discouraged. There may be a subgroup of such infants with pulmonary hypoplasia and documented PPHN who may benefit from this treatment, but the data are limited. Several studies have examined the use of iNO for prevention of chronic lung disease with inconsistent results. This promising application requires more study before it can be recommended. There may be a role of iNO in treating infants with pulmonary hypertension complicating severe bronchopulmonary dysplasia, but there are limited data on long term outcomes. Alternate therapies such as sildenafil may be beneficial in this specific population as well as in other causes of pulmonary hypertension. Rational use of this expensive treatment will maximize cost:benefit and avoid potential exposure to unknown adverse effects not balanced by documentable benefits.

Use of inhaled nitric oxide in preterm infants: a regional survey of practices

OBJECTIVES

To conduct a regional survey of neonatal intensive care unit (NICU) Directors in Australia and New Zealand (ANZ) to ascertain current practice.

BACKGROUND

Use of inhaled nitric oxide (iNO) therapy in infants < 34 weeks gestational age is not supported by current evidence.

METHODS

A cross-sectional electronic survey based on structured questionnaire was conducted amongst the Directors of all the tertiary neonatal intensive care units in Australia and New Zealand Neonatal Network (ANZNN). Information was collected on indications, dosage, monitoring response and weaning for iNO therapy.

RESULTS

The survey was sent to 28 units, of which 2 were quaternary units' not routinely admitting preterm infants, hence were excluded from analysis. The response rate was 77% (20/26). Majority of units (16; 80%) did not have preterm specific protocol. In almost all units nitric was used as early rescue for hypoxemic respiratory failure (95%; 19/20). Neonatologist performed functional echocardiography (fECHO) was frequently used for prior assessment (90%) and monitoring (65%). Variations were noted regarding initiating criteria, dosage and weaning strategies.

CONCLUSIONS

Wide variation in practice was noted highlighting the need for the formulation of consensus guidelines.

Effects of early inhaled nitric oxide therapy and vitamin A supplementation on the risk for bronchopulmonary dysplasia in premature newborns with respiratory failure

OBJECTIVE

To assess whether the combination of early inhaled nitric oxide (iNO) therapy and vitamin A supplementation lowers the incidence of bronchopulmonary dysplasia (BPD) in premature newborns with respiratory failure.

STUDY DESIGN

A total of 793 mechanically ventilated infants (birth weight 500-1250 g) were randomized (after stratification by birth weight) to receive placebo or iNO (5 ppm) for 21 days or until extubation (500-749, 750-999, or 1000-1250 g). A total of 398 newborns received iNO, and of these, 118 (30%) received vitamin A according to their enrollment center. We compared patients who received iNO + vitamin A with those who received iNO alone. The primary outcome was a composite of death or BPD at 36 weeks postconceptual age.

RESULTS

BPD was reduced in infants who received iNO + vitamin A for the 750-999 g birth weight group compared with iNO alone (P = .01). This group also showed a reduction in the combined outcome of BPD + death compared with iNO alone (P = .01). The use of vitamin A did not change the risk for BPD in the placebo group. Overall, the use of vitamin A was low (229 of 793 patients, or 29%). Combined therapy improved Bayley Scales of Infant Development II Mental and Psychomotor Developmental Index scores at 1 year compared with infants treated solely with iNO for the 500-749 g birth weight group.

CONCLUSIONS

In this retrospective analysis of the nonrandomized use of vitamin A, combined iNO + vitamin A therapy in preterm infants with birth weight 750-999 g reduced the incidence of BPD and BPD + death and improved neurocognitive outcomes at 1 year in the 500-749 g birth weight group.

Use of inhaled nitric oxide in preterm infants

Nitric oxide, an important signaling molecule with multiple regulatory effects throughout the body, is an important tool for the treatment of full-term and late-preterm infants with persistent pulmonary hypertension of the newborn and hypoxemic respiratory failure. Several randomized controlled trials have evaluated its role in the management of preterm infants ≤ 34 weeks' gestational age with varying results. The purpose of this clinical report is to summarize the existing evidence for the use of inhaled nitric oxide in preterm infants and provide guidance regarding its use in this population.

Gas exchange in the respiratory distress syndromes

This article describes the gas exchange abnormalities occurring in the acute respiratory distress syndrome seen in adults and children and in the respiratory distress syndrome that occurs in neonates. Evidence is presented indicating that the major gas exchange abnormality accounting for the hypoxemia in both conditions is shunt, and that approximately 50% of patients also have lungs regions in which low ventilation-to-perfusion ratios contribute to the venous admixture. The various mechanisms by which hypercarbia may develop and by which positive end-expiratory pressure improves gas exchange are reviewed, as are the effects of vascular tone and airway narrowing. The mechanisms by which surfactant abnormalities occur in the two conditions are described, as are the histological findings that have been associated with shunt and low ventilation-to-perfusion.

Inhaled nitric oxide use in newborns

Inhaled nitric oxide (iNO) is a pulmonary vasodilator that plays a major role in regulating vascular muscle tone. It has emerged as a treatment for hypoxemic respiratory failure in newly born infants that is associated with persistent high pulmonary vascular pressure and resultant right-to-left shunting of blood (persistent pulmonary hypertension of the newborn). Current evidence shows that iNO improves oxygenation and decreases the combined outcome of death or need for extracorporeal membrane oxygenation in infants ≥35 weeks' gestational age at birth. Its role in managing preterm infants <35 weeks' gestational age is not yet established. iNO is safe when administered in tertiary care settings using strict protocols and monitoring. The recommended starting dose is 20 ppm with gradual reduction of the dose following improvement in oxygenation.

Nitric oxide for the treatment of preterm infants with respiratory distress syndrome

INTRODUCTION

Inhaled Nitric oxide (iNO) has been proposed as effective treatment for improving oxygenation in preterm infants with respiratory distress syndrome (RDS), and for preventing the development of bronchopulmonary dysplasia (BPD).

AREAS COVERED

This drug evaluation mainly reviews the results of clinical studies on the effects of iNO in preterm infants with RDS which have provided contradictory results probably due to their different designs. Three recent meta-analyses of these studies have concluded that iNO therapy is not effective in decreasing the risk of death and BPD and cannot be recommended as routine treatment. The same meta-analyses suggest that some strategy of iNO treatment and some subgroups of patients, such as infants with persistent pulmonary hypertension of the newborn (PPHN), should be further studied.

EXPERT OPINION

At present, the available evidence does not support the use of iNO in preterm infants with RDS, and iNO therapy cannot be recommended for the routine treatment of respiratory failure in premature neonates. In the future, further studies in selected populations using adequate doses and investigating the effectiveness of other drugs, such as sildenafil, might affect the use and diffusion of iNO.

Can nitric oxide-based therapy prevent bronchopulmonary dysplasia?

A growing understanding of endogenous nitric oxide (NO) biology is helping to explain how and when exogenous NO may confer benefit or harm; this knowledge is also helping to identify new better-targeted NO-based therapies. In this review, results of the bronchopulmonary dysplasia clinical trials that used inhaled NO in the preterm population are placed in context, the biologic basis for novel NO therapeutics is considered, and possible future directions for NO-focused clinical and basic research in developmental lung disease are identified.