Introduction: Acute viral bronchiolitis (AB) in infants is a risk factor for recurrent wheezing. Fractional exhaled nitric-oxide (FeNO) is a marker for eosinophilic airway inflammation and has been shown to be high in asthma.
Aim: To evaluate determinants for recurrent wheezing after AB and to investigate FeNO levels during the acute phase and convalescence and investigate whether FeNO levels during AB can predict future wheezing.
Methods: Children (0-2 years) admitted to the Emergency Department with AB were recruited. The following data was collected: family and patient`s history, disease severity and FeNO levels. Real-time PCR for respiratory viruses was performed. The occurrence of wheezing episodes and repeat FeNO levels were assessed 2 and 6 months later.
Results: A total of 115 children with AB were recruited, 52% had isolated RSV infection, 23% had co-infection of RSV and other virus, 19% had a non-RSV virus and in 6% PCR was negative. Recurrent wheezing was reported in 54% of the children. Neither parental factors, nor clinical variables during acute stage were associated with higher occurrence of future wheezing. FeNO levels were low during AB and increased to normal-high levels over 6 months. However, these levels and pattern were common to all viral pathogens. FeNO levels did not predict recurrent wheezing.
Conclusions: FeNO levels during AB are low with subsequent increase. This pattern is not specific for RSV. FeNO levels at any stage had no predictive value for later wheezing. Its predictive value for future asthma should be studied at a later age.
