Abstract

Background: Mylar balloons are used to collect exhaled air for analysis of fractional nitric oxide concentration (FENO).Aim: We studied the effect of storage conditions on the stability of nitric oxide (NO) in mylar balloons.Methods: Exhaled air samples and calibration gases were stored in mylar balloons at 4, 21 and 37°C, with or without silica gel. NO was measured after 0, 6, 9, 24 and 48 h. Scheffe F-tests were used to compare NO values. Results NO remained stable in balloons for 9 h at all temperatures, without silica gel. NO increased between 9 and 48 h, but only with low initial FENO. Silica gel increased variability.Conclusions: FENO in mylar balloons is stable for at least 9 h. The storage temperature is not critical, but silica gel increases variability.