THE SAFETY OF A NITRIC-OXIDE INHALATION SYSTEM WITH HIGH-FREQUENCY OSCILLATORY VENTILATION

Nitric oxide (NO) inhalation and high frequency oscillatory ventilatio n (HFOV) has been indicated in infants with severe respiratory failure . The purpose of the present study was to evaluate the safety of an NO inhalation system with HFOV in terms of nitrogen dioxide (NO2) produc tion, The NO inhalation system consisted of a high frequency oscillato ry ventilator, a neonatal circuit and a test lung, The NO concentratio n was changed from 0 to 19 p.p.m. At each level of NO, the oxygen (O-2 ) concentration was changed from 21 to 100%, The NO and NO2 concentrat ions were measured with a chemiluminescence analyzer using a molybdenu m converter. The NO2 concentration was increased when either the O-2 o r the NO concentration was increased. The interposition of the endotra cheal tubes increased NO2 concentrations at 4 p.p.m. NO, The high stro ke volume and high mean airway pressure produced a significant increas e in NO2 production at 4 p.p.m. NO. Tile increase in NO2 production wa s prevented by placing a one-way valve at the joint of the NO gas line to the inspired limb, It was concluded that the NO inhalation system with HFOV can be safely used when a one-way valve is placed at the joi nt of the NO gas line to the inspired limb and when inhaled NO is at a relatively low concentration.