| Popis: |
Aim: Evaluate the response of heart rate variability by non-linear analysis at the 6-minute step test (6MST) in Chronic Obstructive Pulmonary Disease (COPD) patients. Methods: Cross-sectional study, included patients with lung disease without cardiac arrhythmia. Heart rate (HR) was recorded with a cardiofrequencimeter (Polar® S810i) during rest (rest=5minutes) and recovery post-test (rec=5minutes). Data was analyzed by Kubios® (version 2.2). To determine vagal resumption, delta of variation between peak HR and recovery was calculated (HRRec= peak HR - HR recovered in the 1st min post-test). For 6MST, a 20cm high step was used, patients were instructed to go down and up in the steps for 6 min. Results were analyzed in SPSS (version 23.0), a p≤0.05 was significant. Results: 11 patients with moderate to very severe COPD stage were evaluated [male (n=9;81.8%); age 67.9±7.3 years]. The number of steps up and down was 80.2±19.6. No differences were found between rest and recovery for α1 (rest=0.9 ±0.2 vs rec=1.0±0.2, p=0.117) and α2 (rest=0.6±0.1 vs rec=0.5±0.1, p=0.199). We found differences between HRrest to HRpeak (78.9±10.5 vs 109.0±13.9 bpm, p Conclusion: In the analysis of the α1 and α2 indices, COPD patients showed normal parameters at rest and in recovery of 6MST. The α1 index was shown to be sensitive to HR variations due to its strong correlation with the number of steps climbed in the 6MST. |
