Background: Allergic rhinitis is a chronic respiratory disease. Sympathetic hypofunction has been identified in allergic rhinitis patients.
Objective: To investigate the effects of six weeks of repeated sauna treatment on the autonomic nervous system, peak nasal inspiratory flow (PNIF) and lung functions in Thai patients with allergic rhinitis.
Methods: Subjects were diagnosed with allergic rhinitis clinically by an attending physician based on history, physical examination and positive reactions to a skin prick test. Subjects were randomly assigned to two groups. Controlsubjects received education and maintained a normal life. The sauna group received sauna treatment over a six-week period, 3 days per week, with 6 sets of 5 minutes per set per day, totaling 30 minutes. Each 5 minute set alternated with a 5 minute period of rest. Heart rate variability (HRV), peak nasal inspiratory flow and lung function were measured at the beginning and after three and six weeks of sauna treatment. The HRV measurement is composed of three components, including low frequency (indicating sympathetic function in normal units or n.u.), high frequency (indicated parasympathetic function in n.u.), and the ratio of LF/HF (indicating the balance of the autonomic system).
Results: Twenty-six allergic rhinitis patients, 12 males and 14 females participated in this study, 13 in the control group and 13 in the sauna treatment group; there were 6 males in each group. Baseline characteristics for the control and sauna treatment groups were comparable. There were significant changes in the HRV after six weeks of sauna treatment. The high frequency component was significantly lower in sauna treatment group (51.8 vs 35.4), while the low frequency component and LF/HF ratio were significantly higher in sauna treatment group than in the control group (48.1 vs 64.5 and 0.9 vs 2.5, respectively). The PNIF and the forced expiratory volume in one second, or FEV1, were also significantly higher in sauna treatment group (103.0 vs 161.9 and 80.1 vs 95.6, respectively).
Conclusion: The six weeks of repeated sauna treatment can increase sympathetic activity, PNIF, and FEV1 in Thai patients with allergic rhinitis.