Heart Failure Worsens Muscle Strength in COPD

Summary

The combination of heart failure (HF) and chronic obstructive pulmonary disease (COPD) is highly prevalent, but underdiagnosed and poorly recognized. It has been suggested that the decline in functional capacity is associated with musculoskeletal and systemic changes than primary organ (heart and/or lung) failure. In addition, it is recognized that both diseases have several mechanisms that are responsible for musculoskeletal impairment. However, the association of reduced systemic perfusion with low oxygen content observed in the association of HF and COPD may contribute to the worsening of the components of the muscle impairment cascade. Thus, muscle strength and fatigue may not only be even more altered but may also be the main determinants of functional capacity in patients with coexistence of HF and COPD. Although many studies have evaluated the muscle performance of patients with HF or COPD, the literature did not show data on worsening due to the association of the diseases. Particularities identification of the muscle impairment in the coexistence of HF and COPD is fundamental for the development of rehabilitation strategies, mainly through physical exercise. In this line, the present study tested the hypothesis that the coexistence of HF and COPD could present lower values of strength and greater fatigue. Similarly, the muscle dysfunction degree could strongly correlate with the performance markers of the incremental or functional tests in patients with HF associated with COPD.

The study protocol was reviewed and approved by the Institutional Research Board. All subjects gave written informed consent before participating in the study.

Conditions

• COPD
• CHF
• Muscle Weakness

Interventions

DIAGNOSTIC_TEST

isokinetic dynamometer

Knee flexors and extensors muscles were analysed by an isokinetic dynamometer. Positioning of the subjects (sitting with hips flexed to 75°) was standardized based on the length of the thigh and leg to minimize individual differences. Correction for the effect of gravity on neuromuscular performance was accomplished by incorporating limb mass into the calculation of torque production. Previous warm-up was repeated five time with an angular velocity of 400°/s. All patients randomly performed two maximal isokinetic tests: 6 repetitions at 60°/s and 20 repetitions at 300°/s. Measurements of torque, work (J), power (W) maximum (peak), and fatigue index were obtained in both tests. In addition, data were analysed at percent of prediction (percent pred) by reference values previously described for the Brazilian population, corrected by muscle mass and peak values.

DIAGNOSTIC_TEST

Cardiopulmonary Exercise Test

All exercise tests were performed on an electronically braked cycle ergometer. Standard metabolic and ventilatory responses were measured breath-by-breath using a calibrated, computer-based system. The incremental exercise test started with 2-min unloaded cycling and increments of 3-10 Watts per min until exhaustion. The anaerobic threshold was estimated by the ventilatory equivalents and V-slope methods and it was determined in agreement by a cardiologist and pulmonologist. Heart rate was determined using the 12-lead electrocardiogram. Throughout the experiment, the pulse hemoglobin saturation (SpO2) was assessed with a pulse oximeter and the 'shortness of breath' was asked at exercise cessation using the 0-10 Borg category ratio scale. All measurements were expressed as percentage predicted for the Brazilian population.

DIAGNOSTIC_TEST

Functional Capacity Tests

The six-minute walk test (6MWT) was in accordance with the American Thoracic Society (ATS). The four-minute step test (4MST) consisted of going up and down a 20-cm high, 40-cm wide and 40-cm long step for 4 minutes. The investigators measured the heart rate and pulse hemoglobin saturation at rest before each test and every minute of both tests. The investigators assessed dyspnoea and leg fatigue at rest and with the modified Borg scale immediately after finishing the test.

DIAGNOSTIC_TEST

Lung Function Test

Spirometry, gas transfer, and static lung volumes were measured in all patients, and airflow was measured using a "Pitot-tube" based on the American Thoracic Society/European Respiratory Society guidelines. Measurement of maximal inspiratory and expiratory pressures was performed from the residual volume and total lung capacity. Resting blood gases were obtained by samples from the radial artery.

DIAGNOSTIC_TEST

Doppler Echocardiography

The same medical doctor performed all echocardiograms and all patients underwent comprehensive echocardiography.

DIAGNOSTIC_TEST

Anthropometry and Body Composition

Body composition was assessed using a body composition analyzer. Percent body fat was estimated from the resistance and reactance values. Resistance values and the subject's height (meters), weight (kg), sex, and age (years) were entered into a computer program to estimate percentage of fat, fat mass (FM), and muscle mass (MM).

Sponsors & Collaborators

• Coordination for the Improvement of Higher Education Personnel

  collaborator OTHER

• Mayron Faria de Oliveira

  lead OTHER

Study Design

Allocation

NON_RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

FACTORIAL

Eligibility

Min Age

30 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2014-08-01

Primary Completion

2017-12-01

Completion

2018-12-01