2P-S4-5

USE AND MISUSE OF NO IN CHILDHOOD

Ramet J

Academisch Ziekenhuis Vrije Universiteit, Brussels, Belgium

 

During the past years, remarkable progress has been made in understanding the functions of Nitric Oxide (NO) as signalling molecule in endothelial and nerve cells and as selective pulmonary vasodilatator. Despite the fact that the fundamental understanding of inhaled Nitric Oxide (iNO) has grown, discussion about its use, indications, influence on survival in selected diseases, potential risks and safety issues still remains tangible.

iNO is an important endothelium-dependent relaxing factor. When inhaled as a gas, it selectively dilates the pulmonary circulation. Systemic vasodilation does not occur because NO is rapidly inactivated. In injured lungs, iNO produces local vasodilation of well-ventilated lung units and may derive blood flow away from unventilated regions. This reduces intrapulmonary shunting and improves systemic arterial oxygenation. In this aspect iNO is a valuable therapy in children with ARDS with acute lung injury and pulmonary hypertension.

iNO may produce other theoretical benefits through effects on lung leak, oxidant injury, right ventricular function, adhesion molecules or inflammatory mediators. Alternatively, iNO may produce potential harmful effects, such as increasing pulmonary vascular permeability, inactivation of surfactant and damage to alveolar cells. A major safety issue of iNO is to avoid inadvertent withdrawal, leading to pulmonary hypertensive crisis and severe hypoxemia.

Despite the theoretical harms or benefits that might arise from iNO therapy, its potential to improve oxygenation serves as its primary rationale. iNO can be delivered safely to children with acute, hypoxic respiratory failure and can significantly improve indexes of oxygenation and ventilation.