We investigated the variability of exhaled nitric oxide over both short (one hour) and extended (four-week) periods of time using the single-breath technique with positive expiratory pressure (SBT-PEP) in a population of 16 healthy (n = 4) and wheezy (n = 12) infants. In addition, wheezy infants with high levels of exhaled nitric oxide and a positive parental history of asthma were randomised to untreated (n = 6) or treated (n = 6) groups. The treated group received nebulised budesonide twice daily for four weeks. Lung function was also assessed by the raised volume rapid thoracic compression technique (RVRTC). Levels of exhaled nitric oxide were obtained by the SBT-PEP technique. The infants' lungs are raised to a transrespiratory pressure of 20 cm H 2O three times, after the third inflation a jacket surrounding the chest and abdomen of the infant is manually inflated and forced expiration is initiated against an expiratory resistance, resulting in constant flow and airway opening pressure. Exhaled nitric oxide was measured using a rapid response chemiluminiscence analyser and plateau values were reported. Mean values of exhaled nitric oxide were lower in healthy than in wheezy infants (10.3 ± 3.2 ppb and 38.2 ± 6.9 ppb, p < 0.001 respectively). Values of exhaled nitric oxide determined one hour (n = 16) and four weeks (n = 10) apart showed good agreement (coefficient of repeatability 5.1 ppb and 7.3 ppb respectively). Wheezy infants treated with inhaled steroids for a period of four weeks had significantly reduced levels of exhaled nitric oxide and increased values of FEV 0.5 (39.4 ± 8.0 ppb and 15.2 ± 1.2 ppb, p < 0.001; 161 ± 31.5 and 210 ± 28.8 ml, p < 0.02), while the untreated group did not. We conclude that measurements of exhaled nitric oxide are highly reproducible over both short and extended periods of time in infants. Inhaled steroids in infants with recurrent wheeze, high levels of exhaled nitric oxide and a positive parental history of asthma reduced exhaled nitric oxide to levels similar to that seen in healthy infants, suggesting that young infants with a history of recurrent wheeze may have underlying chronic airway inflammation.
|Number of pages||6|
|Journal||Schweizerische Medizinische Wochenschrift|
|Publication status||Published - 15 Apr 2000|