Measurement of nasal mucociliary clearance.
The saccharin test was carried out in a randomly selected sample of schoolchildren (142 boys and 153 girls, age range 11-14 years) to determine the variability and reproducibility of the test and to assess whether it could be used as a screening test for nasal mucociliary clearance. Nasal mucociliary clearance times were analysed according to clinical history (asthma, rhinitis, asthma with rhinitis, and acute upper respiratory tract infections), laboratory findings (positive skin test responses and bronchial hyper-reactivity assessed by methacholine challenge), and parental smoking. Nasal mucociliary clearance times showed a narrow coefficient of repeatability (six minutes) in 50 subjects and there was substantial agreement between the two tests. Nasal mucociliary clearance times were less than 40 minutes in all the children. Normal children had nasal mucociliary clearance times of less than 24 minutes while significantly impaired nasal mucociliary clearance was detected in those with positive skin reactions and a positive response to methacholine challenge. We were unable to show that passive smoking had any consistent effect on nasal mucociliary clearance. We suggest that a time response between 30-60 minutes should be checked again at least two weeks later, and that children in whom repeated saccharin tests show a nasal mucociliary clearance of greater than 30 minutes should have ciliary beat frequency estimated.