Nasal nitric oxide levels in healthy pre-school children

The evaluation of nasal nitric oxide (nNO) has been proposed as a screening tool in children with clinically suspectable primary ciliary dyskinesia. Nevertheless, normal values have been reported for school-aged children. This study was designed to identify normal nNO levels in pre-school children. nNO was assessed in 300 healthy children aged between 1.5 and 7.2. Two hundred and fifty of them were unable to fulfill the guideline requirements for nNO measurement and were assessed by sampling the nasal air continuously with a constant trans-nasal aspiration flow for 30 s during tidal breathing. For those children who were able to cooperate, the average nNO concentration was calculated according to guidelines. A statistically significant relationship between nNO level and age was demonstrated in this study group of pre-school children (p < 0.001). An increase in nNO of about 100 ppb was observed in children older than 6 yr vs. those aged