The Role of the Autonomic Nervous System in the Pathogenesis of Asthma Exacerbation

Summary. The autonomic nervous system (ANS) plays a crucial role in regulating bronchomotor tone and airway reactivity, yet its contribution to the pathogenesis of asthma exacerbations remains insufficiently defined, particularly across eosinophilic (EA) and noneosinophilic (NEA) phenotypes. The aim – to assess ANS activity in patients with EA and NEA during asthma exacerbation and remission using short-term heart rate variability (HRV) analysis. Material and Methods. A total of 60 adults with asthma (30 EA, 30 NEA; aged 35–65 years) and 30 healthy controls participated in this study at Dnipro State Medical University, Ukraine. Phenotypes were classified by blood eosinophil count (EA ≥150 cells/μL; NEA <150 cells/μL). HRV parameters were derived from 5-minute ECG recordings obtained with the Polar H10 chest sensor and analyzed in Kubios HRV software. Measurements were performed during uncontrolled (UA) and controlled asthma (CA). Pulmonary function (FEV₁) and asthma control (ACQ-7) were assessed. Results. During exacerbation, both EA and NEA groups exhibited parasympathetic predominance, reflected by high RMSSD, pNN50, and HF power, and low LF/HF ratio (EA: 0.61±0.32; NEA: 0.58±0.31). In remission, a shift toward sympathetic predominance occurred (EA: LF/HF =2.28±1.12; NEA: 2.14±1.35; p<0.001). No significant differences in HRV parameters were found between EA and NEA. A strong positive correlation existed between parasympathetic markers and ACQ-7 score (ρ=0.875), indicating that higher vagal activity was associated with poorer asthma control. Conclusions. Asthma exacerbation in both EA and NEA phenotypes is characterized by parasympathetic dominance, which normalizes toward sympathetic activity with clinical control. Short-term HRV monitoring offers a practical, non-invasive tool for evaluating autonomic balance and disease control in asthma.