IMPROVED METHOD OF MEASRUING EXHALED NITRIC OXIDE (NO)

To measure the concentration on of exhaled NO in children, we improved the system of analyzing NOx and estimated the results. The system we used is a chemiluminescence analyzer CLM-500 (SHI-MADZU, JAPAN) sensitive to NO from 0.1 to 5000 parts per billion (ppb, by volume), adapted for an online recorder U-224 (NDKCL Co., Japan). On the hypothesis that expiration velocity influences NO concentrations in expired air, a flow volume regulator of a control capacity from 0 to 3000ml/min was assembled between a mounthpiece and CLM-500, hence NO concentration is measured under a constant expiration flow rate. In our method, the NO concentration on curves show up-hills first, then plateaus and down-hills finally. If the flow rate increased, the curve reached the plateau sooner and the plateau-value in a serial measurement in one patient were statistically constant. On our speculation, the plateau values are the good parameters of NO production in their bronchi.