Validation study of fractional exhaled nitric oxide measurements using a handheld monitoring device

We tested reproducibility of exhaled nitric oxide (FENO) and inter-operator handling when measured with a handheld device, NIOX MINO(R). We enrolled 20 volunteers using a priori goals of acceptable reproducibility to be mean within-subject standard deviation less than 3 parts per billion (ppb) for FENO measurements less than 30 ppb, and mean coefficient of variation less than 10% for FENO measurements more than 30 ppb. Seventeen subjects with measurements less than 30 ppb displayed a mean standard deviation of 1.15, and 3 subjects with FENO more than 30 ppb had a mean coefficient of variation of 2.4%. We conclude that NIOX MINO demonstrates excellent reproducibility for all ranges of FENO.