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.