Study on Safety of Delivery and Scavenger System of Inhaled Nitric Oxide

Abstract

A system for delivering and scavenging inhaled nitric oxide (NO) was organized, and was evaluated, focusing on its safety. NO (5〜50ppm) was provided with a blender by diluting 800 ppm NO (balanced with nitrogen gas) using nitrogen or compressed air, and was delivered to the inlet for compressed air of a ventilator. The exhaled gas from the ventilator was diluted with room air, and was removed via a vacuum system. NO and NOx concentrations in inspired and expired gas were measured continuously with a chemiluminescence analyzer. Nitrate and nitrite concentrations in the humidifier water of the ventilator were measured with an enzyme method and the Griess-Romijin method, respectively. The effect of this scavenging system on the ventilator function was investigated by drawing pressure-volume curves. NO_2 concentration was less than 0.1 ppm when the inhaled NO was adjusted to be less than 10 ppm by being diluted with nitrogen. The concentrations of nitrate and nitrite in the humidifier water after 40 ppm NO inhalation for 6 hours were 1.17 mg/l and 2.30 mg/l, respectively, even when 800 ppm NO was diluted with compressed air. These values were less than the quality standard values for water. No remarkable changes in pressure-volume curves were noted after installing the scavenging system. IN conclusion, This delivering and scavenging system will be safely used in clinical practices.