Comparative analysis of parameters of cardiointervalometry, ergoreflex and data of 6 minute walk test in patients with chronic obstructive pulmonary disease

Aim. To study the relationship between parameters of cardiointervalometry and ergoreflex, and 6-minute walk test data in patients with chronic obstructive pulmonary disease (COPD).

Materials and Methods. The study included 103 men, of them 63 patients with COPD, 40 patients of the control group. Functional assessment of external respiration and a 6-minute walk test were performed using Spiropalm 6MWT equipment (Cosmed, Italy). The autonomic status and the influence of the ergoreflex on it were assessed by the method of cardiointervalometry before, during and after the test with external peripheral vascular occlusion using Varicard hardware and software complex (LLC Ramena, Ryazan, Russia).

Results. When performing a 6-minute walk test, significant differences were obtained between the groups of patients with COPD and of the control group in the majority of the studied parameters (p<0.01). In 18 of 63 patients with COPD, the level of SpO₂ in 6-minute walk test decreased by≥ 4% (p<0.01). The obtained result is of considerable importance for assessment of exercise tolerance in patients with COPD. In tests with external peripheral vascular occlusion in patients with COPD and of the control group, the index of activity of regulatory systems (IARS) increased in both groups. However, after completion of the test, the index in patients with COPD decreased below the initial values (p<0.05), and in patients of the control group the changes were even more pronounced (p<0.01). Patients with COPD were divided into groups depending on the distance covered in 6-minute walk test. Analysis of the data revealed a moderate positive correlation between the covered distance and the forced expiratory volume in the 1st second (FEV₁, R=0.45, p<0.01).The maximum level of the total effect of the autonomic regulation of blood circulation was recorded in patients who covered the minimum distance (227.77±48.13 m) in 6-minute walk test. Besides, a moderate negative correlation between IARS and the results of 6-minute test was recorded (R=-0.34, p<0.01).

Conclusions. 1. For assessment of the functional status of patients in 6-minute walk test it is important to take measurement of saturation throughout the whole test. 2. The change in IARS values in the test with external peripheral vascular occlusion can be regarded as a reduction of the influence of reflex from the lower limb ergoreceptors on the functional condition of patients. 3. Patients with COPD showed a marked autonomic imbalance. IARS showed a moderate negative correlation with the distance covered in 6-minute walk test. 4. Maximum value of IARS was obtained in patients with the minimal distance covered in 6-minute walk test.