[A standard maneuver to measure the concentration of exhaled nitric oxide]

We measured the concentration of nitric oxide (NO) exhaled during a standard maneuver in 55 healthy subjects (nonsmokers: 23 men and 32 women). After two deep breaths, each subject exhaled from total lung capacity through the mouth at 2 L/min into a Teflon tube connected to a chemiluminescence analyzer. The concentration of exhaled NO was defined as the plateau value measured during the latter part of expiration. In nonsmokers, the concentration was 28.7 +/- 12.2 ppb (mean +/- S.D.), which did not differ from that in smokers. The logarithm of the NO concentration (logNO) was normally distributed; it was significantly related to expiratory flow rate, but not to age, height, weight, sex, or the number of cigarettes smoked per day. The 95% confidence interval for the concentration of exhaled NO in healthy nonsmokers was 10.2 to 64.6 ppb.