Concomitant dynamic changes in autonomic nervous system function and nasal airflow resistance during allergen provocation.

Allergic rhinitis is a major chronic respiratory disease which more than 500 million people suffer from around the world. It is considered to be an immuno-neuronal disorder, but little is known about the part played by the neural system in nasal allergic reaction. This is due mainly to the lack of objective measurement techniques producing accurate, reliable and continuous measurement data about the dynamic changes in nasal respiratory function. Here, a method to assess the association of nasal airflow resistance and the underlying function of autonomic nervous system (ANS) is presented and used during the birch pollen provocation test. Ten allergic volunteers were challenged with allergen. Continuous nasal airflow resistance and spectral heart rate variability parameters were computed and analyzed for the dynamic changes. The derived signals show in detail the timing and intensity differences in subjects' reactions. After the provocation, the nasal airflow resistance rose gradually, whereas LF power and LF/HF ratio decreased gradually for all subjects. This implies gradually increasing sympathetic withdrawal in allergic patients during the provocation with allergen. The proposed method opens entirely new possibilities to assess accurately the dynamic and short-term changes in non-stationary nasal function and could increase the accuracy and reliability of diagnostics and assessment of the effect of nasal treatments.