Fig. 1.

Scheme of data acquisition. FeNOstand, slope of NO values generated with the standard method; FeNOmodif: slope of NO values generated with the mathematical modification; cENOi, calculated initial NO chamber concentration. Points 1 and 2: Data from the final 270 s are used to generate 2 points by average determination. Slope 3: a partial regression line is laid through points 1 and 2 resulting in FeNOstand. Point 4: by extrapolation of points 1 and 2 cENOi can be established. Slope 5: finally, a straight line is laid through point 4 and the zero baseline to determine FeNOmodif.