The question how to better predict future asthma exacerbations was recently studied by analysing alveloar NO parameters. In asthma diagnosis and monitoring, the fraction of exhaled nitric oxide (FeNO) at a flow of 50 ml/s is standardized and routinely measured. It is recommended as supportive information for asthma diagnosis and monitoring. As it is known that distal airway disease contributes to the severity of asthma, the question was raised, whether partioning of FeNO into proximal and distal contributions can be used to assess distal airway inflammation and to predics asthma exacerbations.

Paraskakis and colleagues tested 68 asthmatic children by performing spirometry and FeNO measurements with the ANALYZER CLD 88sp. NO concentrations were measured at the flows of 50, 30, 100 and 300 ml/s. According to the Högman–Meriläinen algorithm, JawNO, CawNO, DawNO and CalvNO were calculated. While JawNO correlates highly with FeNO50, CawNO and DawNO represent the proximal airways, and CalvNO the distal airways.

Paraskakis and colleagues found that measurement of the alveolar NO (CalvNO) concentration improves the predication of risk of future asthma attacks in the following four months. An alveolar NO concentration >7 ppb was highly specific for a future exacerbation, while a value of <4 ppb excluded the risk of a future exacerbation. A further advantage is that the measurement of FeNO across various flow rates is a noninvasive method. They conclude that the alveolar NO concentration can give valuable insights into small airway disease relevant to asthma exacerbation.

Original publication:
Paraskakis et al. 2022: “Improved prediction of asthma exacerbations by measuring distal airway inflammation”