Cássia da Luz Goulart

Is cardiac autonomic modulation during upper limb isometric contraction and Valsalva maneuver impaired in COPD patients

Purpose To evaluate the heart rate variability (HRV) indices and heart rate (HR) responses during isometric contraction (IC) and Valsalva maneuver (VM) in COPD patients. Methods Twenty-two stable moderate to severe COPD patients were evaluated. R-R intervals were recorded (monitor Polar® S810i) during dominant upper limb IC (2 minutes). Stable signals were analyzed by Kubios HRV® software. Indices of HRV were computed in the time domain (mean HR; square root of the mean squared differences of successive RR intervals [RMSSD] and HRV triangular index [RR tri index]) and in the frequency domain (high frequency [HF]; low frequency [LF] and LF/HF ratio). The HR responses were evaluated at rest, at the peak and at the nadir of the VM (15 seconds). The Valsalva index was also calculated. Results During IC: time domain indices (mean HR increased [P=0.001], RMSSD, and RR tri index decreased [P=0.005 and P=0.005, respectively]); frequency domain indices (LF increased [P=0.033] and HF decreased [P=0.002]); associations were found between forced expiratory volume in 1 second (FEV1) vs RMSSD (P=0.04; r=−0.55), FEV1 vs HR (P=0.04; r=−0.48), forced vital capacity (FVC) vs RMSSD (P=0.05; r=−0.62), maximum inspiratory pressure (MIP) vs HF (P=0.02; r=0.68). FEV1 and FVC justified 30% of mean HR. During VM: HR increased (P=0.01); the nadir showed normal bradycardic response; the Valsalva index was =0.7. Conclusion COPD patients responded properly to the upper limb IC and to the VM; however, HR recovery during VM was impaired in these patients. The severity of the disease and MIP were associated with increased parasympathetic modulation and higher chronotropic response.

Respiratory muscle strength effect on linear and nonlinear heart rate variability parameters in COPD patients

Introduction Chronic obstructive pulmonary disease (COPD) is recognized as a multisystemic inflammatory disease associated with extrapulmonary comorbidities, including respiratory muscle weakness and cardiovascular and cardiac autonomic regulation disorders. We investigated whether alterations in respiratory muscle strength (RMS) would affect cardiac autonomic modulation in COPD patients. Methods This study was a cross-sectional study done in ten COPD patients affected by moderate to very severe disease. The heart rate variability (HRV) signal was recorded using a Polar cardiofrequencimeter at rest in the sitting position (10 minutes) and during a respiratory sinus arrhythmia maneuver (RSA-M; 4 minutes). Linear analysis in the time and frequency domains and nonlinear analysis were performed on the recorded signals. RMS was assessed using a digital manometer, which provided the maximum inspiratory pressure (PImax) and the maximum expiratory pressure (PEmax). Results During the RSA-M, patients presented an HRV power increase in the low-frequency band (LFnu) (46.9±23.7 vs 75.8±27.2; P=0.01) and a decrease in the high-frequency band (HFnu) (52.8±23.5 vs 24.0±27.0; P=0.01) when compared to the resting condition. Significant associations were found between RMS and HRV spectral indices: PImax and LFnu (r=−0.74; P=0.01); PImax and HFnu (r=0.74; P=0.01); PEmax and LFnu (r=−0.66; P=0.01); PEmax and HFnu (r=0.66; P=0.03); between PEmax and sample entropy (r=0.83; P<0.01) and between PEmax and approximate entropy (r=0.74; P=0.01). Using a linear regression model, we found that PImax explained 44% of LFnu behavior during the RSA-M. Conclusion COPD patients with impaired RMS presented altered cardiac autonomic control, characterized by marked sympathetic modulation and a reduced parasympathetic response; reduced HRV complexity was observed during the RSA-M.

Does peripheral arterial occlusive disease influence muscle strength and exercise capacity in COPD patients

Abstract Background The pathophysiology of chronic obstructive pulmonary disease (COPD) is complex and understanding of it has been changing in recent years, with regard to its multisystemic manifestations, especially peripheral dysfunction and its influence on intolerance to exercise. Objectives To evaluate the relationship between peripheral arterial occlusive disease (PAOD) and peripheral muscle strength and exercise capacity in COPD patients. Methods We conducted a cross-sectional study of 35 patients with COPD who were evaluated with the Ankle-Brachial Index, handgrip strength test, 1 repetition maximum (1RM) of knee extensors and flexors, and distance covered in the incremental shuttle walking test (dISWT). Results COPD patients with coexisting PAOD had lower dominant handgrip strength test results (33.00 vs. 26.66 kgf, p = 0.02) and worse performance in the dISWT (297.32 vs. 219.41 m, p = 0.02) when compared to the COPD patients without PAOD. Strong correlations were found between the result of the handgrip strength test and both the dISWT (r = 0.78; p < 0.001) and the 1RM/knee extension (r = 0.71; p = 0.03); and also between the dISWT and both the 1RM/knee extension (r = 0.72; p = 0.02) and the 1RM/knee flexion (r = 0.92; p < 0.001). The linear regression model showed that the dISWT variable alone explains 15.3% of the Ankle-Brachial Index result (p = 0.01). Conclusion COPD patients with PAOD exhibit reduced muscle strength and lower exercise capacity than COPD patients without PAOD.

INFLUÊNCIA DO FLUXO ARTERIAL PERIFÉRICO NA CAPACIDADE FUNCIONAL EM INDIVÍDUOS HIPERTENSOS

A hipertensao arterial sistemica (HAS) se caracteriza pela disfuncao endotelial e o Indice Tornozelo-Braquial (ITB) e um metodo utilizado para avaliar o fluxo sanguineo periferico. O presente estudo objetiva avaliar a influencia do fluxo arterial periferico em membros inferiores sobre a capacidade funcional na HAS. A metodologia consistiu em um estudo transversal que avaliou 16 portadores de HAS (6 homens, idade 60,4 ± 8,7 anos). Foi obtido o ITB antes e apos o Teste do Degrau de 4 minutos (TD4M) pela medida da pressao arterial sistolica braquial e em tornozelos, sendo os individuos classificados em Grupo ITB Normal (GITBN) e Grupo Doenca Arterial Periferica (GDAP). O GDAP apresentou ITB pre-TD4M significativamente menor que o GITBN (p<0,001). Houve reducao significativa do ITB pre para o pos-TD4M apenas no GDAP (p= 0,029). Foi observada correlacao moderada entre o numero de degraus obtidos no TD4M e o ITB pre-TD4M na amostra total (r=0,700, p=0,003), tendo ainda o ITB pre influenciado no desempenho do TD4M (R 2 ajustado =0,221. Considerando ITB menor que 0,9 indicativo de doenca oclusiva. Deve-se destacar, a importância do momento da afericao do ITB, pois apos o exercicio ha uma reducao da pressao do tornozelo. A limitacao da capacidade funcional em pacientes com DAP, esta atribuida a diminuicao do fluxo sanguineo induzido por obstrucao. O TD4M demonstrou ser um teste valido para avaliar individuos com ITB indicativo de DAP, visto que houve associacao entre numero de degraus e o ITB avaliado antes do teste do degrau.