Inhaled nitric oxide for preterm infants: a therapy in search of an indication? The search continues

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.

Inhaled nitric oxide therapy in premature newborns

PURPOSE OF REVIEW

Inhaled nitric oxide therapy reduces the need for extracorporeal membrane oxygenation in near-term and term newborns with hypoxemic respiratory failure and persistent pulmonary hypertension, and is now a standard of care for this population. There is also considerable interest, however, in the potential role of inhaled nitric oxide in premature newborns with hypoxemic respiratory failure. The purpose of this review is to summarize the results of clinical trials of inhaled nitric oxide in premature newborns, with particular emphasis on studies published in the last 12 months.

RECENT FINDINGS

Several trials of inhaled nitric oxide in premature newborns with respiratory failure have been published in the last year. Interpretation of the findings is complicated by differences in the severity of illness of the study populations, the trial designs, and relevant outcome measures recorded.

SUMMARY

Trials of inhaled nitric oxide in premature newborns have yielded conflicting results to date, and the role of inhaled nitric oxide therapy in this population remains controversial. The largest trials of inhaled nitric oxide therapy in premature newborns have completed enrollment but have yet to be published. The results of these ongoing trials will help clarify the potential risks and benefits of inhaled nitric oxide therapy in the premature newborn.

Pre-emptive and continuous inhaled NO counteracts the cardiopulmonary consequences of extracorporeal circulation in a pig model

Cardiopulmonary bypass (CPB) activates a systemic inflammatory response characterized clinically by alterations in cardiovascular and pulmonary function. The aim of this study was to measure the cardiopulmonary consequences in sham-operated pigs, and in animals subjected to CPB in the presence or absence of lipopolysaccharide (LPS). We also investigated, if the perioperative administration of inhaled NO exerts significant cardiopulmonary effects in an anaesthetized and mechanically ventilated pig model of extracorporeal circulation. Thirty pigs were randomized into six equal groups (sham; sham+INO; CPB; CPB+INO; CPB+LPS; CPB+LPS+INO) and subjected to anaesthesia with mechanical ventilation for up to 24h. We found that CPB+LPS group has the highest degree of lung injury. We also demonstrated that there was a significant difference on the cardiovascular parameters (heart rate, central venous pressure, stroke volume index, and mean systemic arterial blood pressure) between the CPB groups and the sham groups. The deteriorated lung mechanics was associated with a decrease in active subfraction of surfactant (LA) with time during the procedure (P=0.0003), on which inhaled NO had only an initial beneficial effect. In our model, inhaled NO had no long-term beneficial effect on lung mechanics and surfactant homeostasis despite improving lung haemodynamics, inflammation, and oxygenation. We conclude from this study that the use of pre-emptive and continuous inhaled NO therapy has protective and safe effects against lung ischemia/reperfusion associated with CPB.

[Recommendations for inhaled nitric oxide treatment in the newborn]

The recommendations in this document describe the current indications for inhaled nitric oxide (iNO) treatment in the newborn and clearly distinguish between those supported by scientific evidence and those for which evidence is still lacking, such as its use in preterm infants. The methodology for iNO administration, its dosage and the main secondary effects are discussed, and the reasons for lack of response to this treatment are analyzed.