The study of heart rate variability in elderly patients with chronic obstructive pulmonary disease undergoing inpatient treatment in a mid-mountain environment

Introduction. Chronic obstructive pulmonary disease (COPD) is frequently associated with cardiovascular dysfunction. Heart rate variability (HRV) analysis serves as an additional criterion for evaluating the functional status of COPD patients, reflecting the integrated state of autonomic regulation. Aim. To assess HRV parameters in elderly COPD patients undergoing inpatient treatment under middle-mountain climatotherapy conditions before and after a standardized therapeutic course. Materials and methods. Thirty-three patients (median age 67.5 years; IQR 62.08; 73.98) with COPD exacerbation received 14 days of standard therapy at a climatic health resort located at 1,342 m above sea level. HRV was assessed on admission and after 10 days using the “Varicard 2.51” system during an orthostatic test. Results. On admission, all patients exhibited reduced heart rate variability and diminished total autonomic regulatory effect on circulation. This pattern persisted in the majority (n = 24) after treatment, and postural responses remained blunted. However, in 9 patients (27.3 %), treatment resulted in increased HRV indices (MxDMn, CV), enhanced parasympathetic activity (RMSSD, pNN50), greater total autonomic modulation (SDNN), and reduced regulatory strain (stress index, SI). Their autonomic status shifted from a state of overstrain (PARS [Index of Regulatory System Activity] = 7.0 points) tofunctional tension (PARS = 4.5 points), characteristic of adaptive–compensatory processes. In contrast, 24 patients (72.7 %) developed rigid heart rhythm with further HRV deterioration post-treatment. Conclusion. Positive HRV dynamics following therapy were observed in only 27.3 % of patients; no significant improvement occurred in the remaining 72.7 %. This lack of response is likely due to incomplete acclimatization, influenced by individual functional capacities and specific adaptive reactions. Therefore, extending the duration of inpatient stays in middle-mountain settings appears necessary to achieve full physiological adaptation in COPD patients. Identifying predictors of heightened sensitivity to high-altitude climatotherapy may provide deeper insights into COPD pathophysiology and personalized therapeutic approaches.