A pilot study of inhaled nitric oxide in preterm infants treated with nasal continuous positive airway pressure for respiratory distress syndrome

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.

Inhaled nitric oxide (iNO) for preventing prematurity-related bronchopulmonary dysplasia (BPD): 7-year follow-up of the European Union Nitric Oxide (EUNO) trial

OBJECTIVES

Most studies of inhaled nitric oxide (iNO) for prevention of bronchopulmonary dysplasia (BPD) in premature infants have focused on short-term mortality and morbidity. Our aim was to determine the long-term effects of iNO.

METHODS

A 7-year follow-up was undertaken of infants entered into a multicenter, double-blind, randomized, placebo-controlled trial of iNO for prevention of BPD in premature infants born between 24 and 28 weeks plus six days of gestation. At 7 years, survival and hospital admissions since the 2-year follow-up, home oxygen therapy in the past year, therapies used in the previous month and growth assessments were determined. Questionnaires were used to compare general health, well-being, and quality of life.

RESULTS

A total of 305 children were assessed. No deaths were reported. Rates of hospitalization for respiratory problems (6.6 vs. 10.5%, iNO and placebo group, respectively) and use of respiratory medications (6.6 vs. 9.2%) were similar. Two patients who received iNO and one who received placebo had received home oxygen therapy. There were no significant differences in any questionnaire-documented health outcomes.

CONCLUSIONS

iNO for prevention of BPD in very premature infants with respiratory distress did not result in long-term benefits or adverse long-term sequelae. In the light of current evidence, routine use of iNO cannot be recommended for prevention of BPD in preterm infants.

Post-Extubation Inhaled Nitric Oxide Therapy via High-Flow Nasal Cannula After Fontan Procedure

In 2014, our hospital introduced inhaled nitric oxide (iNO) therapy combined with high-flow nasal cannula (HFNC) oxygen therapy after extubation following the Fontan procedure in patients with unstable hemodynamics. We report the benefits of HFNC-iNO therapy in these patients. This was a single-center, retrospective review of 38 patients who underwent the Fontan procedure between January 2010 and June 2016, and required iNO therapy before extubation. The patients were divided into two groups: patients in Epoch 1 (n = 24) were treated between January 2010 and December 2013, receiving only iNO therapy; patients in Epoch 2 (n = 14) were treated between January 2014 and June 2016, receiving iNO therapy and additional HFNC-iNO therapy after extubation. There were no significant differences between Epoch 1 and 2 regarding preoperative cardiac function, age at surgery, body weight, initial diagnosis (hypoplastic left heart syndrome, 4 vs. 2; total anomalous pulmonary venous return, 5 vs. 4; heterotaxy, 7 vs. 8), intraoperative fluid balance, or central venous pressure upon admission to the intensive care unit. Epoch 2 had a significantly shorter duration of postoperative intubation [7.2 (3.7-49) vs. 3.5 (3.0-4.6) hours, p = 0.033], pleural drainage [23 (13-34) vs. 9.5 (8.3-18) days, p = 0.007], and postoperative hospitalization [36 (29-49) vs. 27 (22-36) days, p = 0.017]. Two patients in Epoch 1 (8.3%), but none in Epoch 2, required re-intubation. Our results suggest that HFNC-iNO therapy reduces the duration of postoperative intubation, pleural drainage, and hospitalization.

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.

Non-invasive inhaled nitric oxide in the treatment of hypoxemic respiratory failure in term and preterm infants

OBJECTIVES

Inhaled nitric oxide (iNO) is effective in conjunction with tracheal intubation (TI) and mechanical ventilation (MV) for treating arterial pulmonary hypertension and hypoxemic respiratory failure (HRF) in near-term and term newborns. Non-invasive respiratory support with nasal continuous positive airway pressure (CPAP) is increasingly used to avoid morbidity associated with TI and MV, yet the effectiveness of iNO delivery via nasal CPAP remains unknown. To evaluate the effectiveness of iNO delivered via the bubble nasal CPAP system in term and preterm newborns with HRF.

STUDY DESIGN

Electronic medical records from all infants admitted to the neonatal intensive care unit (NICU) during 2005 to 2014 (n=10, 895) were screened for treatment with iNO therapy for HRF. Detailed data on population characteristics and cardiorespiratory, iNO and respiratory support indices were abstracted for all infants, who were administered iNO non-invasively using bubble nasal CPAP. Change in relevant indices at baseline (before initiating non-invasive iNO) and at 3, 6, 12 and 24 h after non-invasive iNO therapy were analyzed using repeated measures analysis of variance.

RESULTS

Of 795 infants treated with iNO (7.3% of total NICU admissions) over a 10-year period, 107 infants (13.4% of iNO treated) with birth weight 2448±1112 g and gestational age 35.3±5.8 weeks received iNO non-invasively. 25 infants received iNO exclusively non-invasively, whereas in remaining 82 infants non-invasive route followed invasive delivery via TI and MV. Indications for using non-invasive iNO included idiopathic pulmonary hypertension (39%), congenital heart disease (37%), bronchopulmonary dysplasia (10%), meconium aspiration syndrome (9%) and congenital diaphragmatic hernia (5%). Over the 24 h following initiation of non-invasive iNO, fractional oxygen requirements decreased (0.38 to 0.32; P<0.0005) and SpO₂ increased (90.7 to 91.6%; P<0.01) with no significant changes in heart rate, respiratory rate, blood pressure, pH and PaCO₂. On average non-invasive iNO was initiated on day of life 9 with a maximal dose was 20 p.p.m. The average duration of iNO therapy and the duration over which it was weaned off were 134 and 51 h, respectively. Analysis of environmental gases during non-invasive iNO therapy revealed median ambient nitrogen dioxide and nitric oxide levels of 0.30 and 0.01 p.p.m., respectively.

CONCLUSIONS

Initiation of iNO in infants on bubble nasal CPAP or continuation of iNO in infants transitioning from MV to bubble nasal CPAP is associated with improved oxygenation during HRF in term and preterm infants. Non-invasive iNO may have a synergistic effect with airway recruitment strategies such as nasal CPAP.

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).

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

CPAP combined with inhaled nitric oxide for treatment of lung hypoplasia and persistent foetal circulation due to prolonged PPROM

BACKGROUND

Second trimester preterm premature rupture of the membranes (PPROM) before 24 weeks of gestation is associated with a high morbidity and mortality rate.

AIM

To demonstrate the efficacy of early continuous positive airway pressure (CPAP) combined with inhaled nitric oxide (iNO) for treatment of preterm infants with lung hypoplasia and persistent foetal circulation (PFC) due to very early PPROM and prolonged severe oligohydramnios.

METHODS

Seven infants with prolonged PPROM, lung hypoplasia, respiratory distress and persistent foetal circulation were intubated in the delivery room for subsequent surfactant and iNO application. As our new treatment strategy was to keep the period of mechanical ventilation as short as possible, all infants were switched on nasal CPAP combined with iNO within the first 24 hours.

RESULTS

Mean gestational age at PPROM was 19+6 weeks (range 14+2 to 23+6 weeks) and the average latency period between rupture of membranes and delivery was 10+3 weeks (7+3 to 16+4 weeks). Infants were born at 30+3 weeks of gestation (28+3 to 33+1 weeks) with an average birth weight of 1468g (884 to 2200g). In all neonates CPAP combined with iNO reversed PFC and 6 patients stabilised without the need for reintubation and mechanical ventilation. One infant had to be reintubated following 12 hours of CPAP combined with iNO due to respiratory insufficiency. All seven infants survived to discharge.

CONCLUSION

CPAP combined with iNO might be a promising approach for therapy of preterm infants with lung hypoplasia and persistent foetal circulation due to very early PPROM.

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 study in this population.

OBJECTIVES

To determine the effect of treatment with iNO on death, bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and neurodevelopmental disability in preterm newborn infants with respiratory disease.

SEARCH STRATEGY

Standard methods of the Cochrane Neonatal Review Group were used. MEDLINE, EMBASE, Healthstar and the Cochrane Central Register of Controlled Trials (The Cochrane Library) were searched covering the years from 1985 to 2010. In addition, the abstracts of the Pediatric Academic Societies were also searched.

SELECTION CRITERIA

Randomized and quasi-randomized studies in preterm infants with respiratory disease that compared the effects of iNO gas to control, with or without placebo were eligible.

DATA COLLECTION AND ANALYSIS

Standard methods of the Cochrane Neonatal Review Group were used.

MAIN RESULTS

Fourteen randomized controlled trials of inhaled nitric oxide therapy in preterm infants were found. The trials have been grouped post hoc into three categories depending on entry criteria; entry in the first three days of life based on oxygenation criteria, routine use in preterm babies with pulmonary disease, and later enrolment based on an increased risk of BPD. No overall analyses were performed.Nine trials of early rescue treatment of infants based on oxygenation criteria demonstrated no significant effect of iNO on mortality or BPD. Three studies with routine use of iNO in infants with pulmonary disease also demonstrated no significant reduction in death or BPD [typical RR 0.93 (95% CI 0.86 to 1.01)] although this small effect approached significance. Later treatment with iNO based on the risk of BPD (two trials) demonstrated no significant benefit for this outcome in analyses which are possible using summary data.There is no clear effect of iNO on the frequency of all grades of IVH or of severe IVH. Early rescue treatment was associated with a non-significant 20% increase in severe IVH.No effect on the incidence of neurodevelopmental impairment was found.

AUTHORS' CONCLUSIONS

iNO as rescue therapy for the very ill preterm infant does not appear to be effective. Early routine use of iNO in preterm infants with respiratory disease does not affect serious brain injury or improve survival without BPD. Later use of iNO to prevent BPD might be effective, but requires further study.

Continuous positive airway pressure: scientific and clinical rationale

PURPOSE OF REVIEW

To present recent data on the role of noninvasive ventilation in the respiratory management of newborn infants.

RECENT FINDINGS

Noninvasive ventilation is growing in popularity but is applied using widely varying devices and settings. Although short-term physiological advantages were reported for bubble and variable-flow continuous positive airways pressure, neither has convincingly shown superior clinically important outcomes. Continuous positive airways pressure may be used as the initial mode of support for very preterm infants but increased rates of pneumothorax in infants not receiving surfactant are a concern. Methods of administering surfactant without endotracheal intubation deserve further study. Nasal intermittent positive-pressure ventilation shows promise as a primary treatment for respiratory distress syndrome. Optimal pressure settings for continuous positive airways pressure and nasal intermittent positive-pressure ventilation remain uncertain.

SUMMARY

Noninvasive ventilation has partially fulfilled its promise as a gentler alternative to ventilation via an endotracheal tube. Appropriately designed randomized clinical trials are required to determine the best nasal interfaces and pressure generators.

Feasibility of nitric oxide administration by neonatal helmet-CPAP: a bench study

BACKGROUND

Inhaled nitric oxide (NO) may have a role in the treatment of preterm infants with respiratory failure. We evaluated the feasibility of administering NO therapy by a new continuous positive airway pressure (CPAP) system (neonatal helmet-CPAP).

METHODS

While maintaining a constant total flow of 8, 10, and 12 l.min(-1), NO concentrations were progressively increased to 5, 10, 20, and 40 p.p.m. in the neonatal helmet-CPAP pressure chamber (5 cmH2O). NO, NO2, and O2 concentrations were measured in the pressure chamber and the immediate external environment.

RESULTS

In the chamber, NO2 levels remained low (<or=0.8 p.p.m.) at inhaled therapeutic NO concentrations (5, 10, 20, and 40 p.p.m.). The lower O2 concentrations were 95% at 40 p.p.m. NO levels. Leakage of NO and NO2 to the surrounding environment was negligible.

CONCLUSIONS

NO administration is safe and feasible using the neonatal helmet-CPAP system. This method allows the delivery of accurate NO levels and high O2 concentrations avoiding NO2 accumulation. Further experimental and clinical studies are needed.

Inhaled nitric oxide for respiratory failure in preterm infants

BACKGROUND

Inhaled nitric oxide (iNO) has been proven to be effective in term infants with hypoxic respiratory failure. The pathophysiology of respiratory failure, and the potential risks, differ substantially in preterm infants. Therefore, analysis of the efficacy and toxicities of iNO in infants born before 35 weeks is necessary.

OBJECTIVES

To determine the effect of treatment with iNO on the rates of death, bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH), or neurodevelopmental disability in preterm newborn infants (< 35 weeks gestation) with respiratory disease.

SEARCH STRATEGY

Standard methods of the Cochrane Neonatal Review Group were used. MEDLINE, EMBASE, Healthstar and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) were searched, using the following keywords: nitric oxide, clinical trial, and newborn covering the years from 1985 to 2006. In addition, the abstracts of the Pediatric Academic Societies were also searched.

SELECTION CRITERIA

Randomised and quasi-randomised studies in preterm infants with respiratory disease that compared the effects of administration of iNO gas compared to control, with or without placebo are included in this review.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes including death, BPD (defined as oxygen dependence at 36 weeks postmenstrual age), IVH, periventricular leukomalacia (PVL), long term neurodevelopmental outcome and short term effects on oxygenation were excerpted from the trial reports by the investigators. Standard methods of the Cochrane Neonatal Review Group were used. Two investigators extracted, assessed and coded separately all data for each study. Any disagreement was resolved by discussion.

MAIN RESULTS

Eleven randomised controlled trials of inhaled nitric oxide therapy in preterm infants were found. The trials have been grouped post hoc into three categories depending on the entry criteria; entry in the first three days of life based on oxygenation criteria (Kinsella 1999; Hascoet 2004; INNOVO 2005; Van Meurs 2004; Mercier 1999; Dani 2006), routine use in intubated preterm babies (Schreiber 2003; Kinsella 2006) and later enrolment based on an increased risk of BPD (Subhedar 1997; Ballard 2006). The usefulness of the overall analyses was considered limited by the differing characteristics of the studies, and only subgroup analyses were performed. Trials of early rescue treatment of infants based on oxygenation criteria demonstrated no significant effect of iNO on mortality or BPD. The subgroup of studies with routine use of iNO in intubated preterm infants demonstrated a marginally significant reduction in the combined outcome of death or BPD [typical RR 0.91 (95% CI 0.84, 0.99); typical RD -0.06 (95% CI -0.12, -0.01)]. Later treatment with iNO based on the risk of BPD demonstrated no significant benefit for this outcome in our analysis. Studies of early rescue treatment with iNO demonstrated a trend toward increased risk of severe IVH, whereas the subgroup of studies with routine use in intubated preterm infants seems to show a reduction in the risk of having either a severe IVH or PVL [typical RR 0.70 (95% CI 0.53, 0.91); typical RD -0.07 (95% CI -0.12, -0.02)]. Later iNO treatment of infants at risk of BPD is given after the major risk period for IVH, and does not appear to lead to progression of old lesions. Two studies (Schreiber 2003; INNOVO 2005) presented data on long term neurodevelopmental outcome. The early routine treatment study (Schreiber 2003) showed an improved outcome at two years corrected age, while the rescue treatment study (INNOVO 2005) showed no effect of iNO.

AUTHORS' CONCLUSIONS

iNO as rescue therapy for the very ill ventilated preterm infant does not appear to be effective and may increase the risk of severe IVH. Later use of iNO to prevent BPD also does not appear to be effective. Early routine use of iNO in mildly sick preterm infants may decrease serious brain injury and may improve survival without BPD. Further studies are needed to confirm these findings, to define groups most likely to benefit, and to describe long term outcomes.

Prolonged exposure to inhaled nitric oxide does not affect haemostasis in piglets

OBJECTIVE

To examine possible adverse effects on haemostasis from prolonged exposure to inhaled nitric oxide (iNO).

DESIGN AND SETTING

Blinded, randomised, experimental animal study in a university animal laboratory.

INTERVENTIONS

Anaesthetised and intubated piglets received central venous, arterial, and transabdominal urinary catheters. Twelve piglets were studied with triggered pressure support ventilation breathing with an air-oxygen mixture for 30 h with nitric oxide (NO), 40 parts per million (ppm) (n = 6) or without NO gas (n = 6) added. The tests of platelet function were assessed in a separate 1-h experiment in which 12 additional animals were blindly randomised to receive intravenous acetylsalicylic acid (ASA) (n = 7) or placebo (n = 5).

MEASUREMENTS AND RESULTS

All 12 animals were clinically stable during the study period of 30 h. Haemostasis was assessed in terms of bleeding time and platelet function by Adeplat-S, reflecting platelet adhesion. Prothrombin fragment 1 + 2, fibrin D-dimer, tissue plasminogen activator and prothrombin complex were measured to investigate whether inhaled NO (iNO) had any effects on thrombin formation, fibrin formation, fibrinolysis or coagulation. All parameters including bleeding time and Adeplat-S were unaffected by iNO. ASA significantly increased bleeding time, but did not affect Adeplat-S. Nitrate in plasma and NOx (nitrate and nitrite) in urine increased significantly in pigs receiving iNO compared with controls.

CONCLUSIONS

Prolonged exposure to iNO at 40[Symbol: see text]ppm did not affect bleeding time or coagulation parameters in healthy piglets. The findings do not support the hypothesis that iNO increases the risk of bleeding in humans.

Use of inhaled nitric oxide in the preterm infant

PURPOSE OF REVIEW

Inhaled nitric oxide is established therapy for term infants with hypoxemic respiratory failure. Laboratory studies demonstrate that inhaled nitric oxide improves lung function and morphology in animal models of bronchopulmonary dysplasia, creating a rationale for clinical studies in premature infants. Four large multicenter randomized trials have now completed enrollment, and one trial has reported neurodevelopmental outcomes at 18-22 months. The purpose of this review is to summarize the results of the most recent preclinical studies and clinical trials.

RECENT FINDINGS

In 2006, short-term outcomes from two large multicenter randomized trials were published. These studies differed in their target population and study design. Early use of inhaled nitric oxide was associated with a decrease in brain injury, and decreased chronic lung disease in infants over 1000 g. Inhaled nitric oxide use in older infants (7-21 days) was associated with decreased chronic lung disease, particularly if started early.

SUMMARY

Neurodevelopmental outcomes after discharge are still needed from three large multicenter randomized trials. These results will help confirm the long-term implications of the benefits reported in the two most recent trials.

Workplace NO and NO2 during combined treatment of infants with nasal CPAP and NO

OBJECTIVE

To determine the workplace concentrations of NO and NO(2) in and around a paediatric incubator during inhaled NO (iNO) treatment and during an accidental emptying of NO cylinders into room air.

DESIGN

We simulated iNO-nasal CPAP treatment in order to assess the impact on the occupational environment. Furthermore, two full NO cylinders for therapy, 1,000 ppm, 20 litres, 150 bar and 400 ppm, 10 litres, 150 bar, were emptied as rapidly as possible into an intensive care unit (ICU) room.

SETTING

University hospital ICU.

MEASUREMENTS AND RESULTS

To correctly gauge the contribution from iNO-CPAP we constructed a system measuring breathing zone and room ventilation inlet-outlet values during a 10-ppm iNO treatment of a simulated infant. Maximal breathing zone values were 17.9 +/- 7.0 (mean +/- 95% CI) ppb for NO and 25.2 +/- 4.8 ppb for NO(2). If room inlet values were subtracted, the contributions to breathing zone values emanating from iNO-CPAP were 14.8 +/- 4.6 ppb for NO and 14.6 +/- 4.6 ppb for NO(2). At the ventilation outlet the maximal contributions were 4.2 +/- 2.9 ppb NO and 9.6 +/- 4.3 ppb NO(2). During rapid total release of a gas cylinder in the ICU room, simulating an accident, we found transient NO levels comparable to the high therapeutic dosing range, but only low NO(2) levels.

CONCLUSIONS

Neither 8-h time-weighted average (TWA) nor 15 min short-term exposure limits (STEL) were exceeded during normal operation or during a simulated accident. The contribution of nitrogen oxides from treatment to workplace air were minor compared to those from ambient air.