ABC | Volume 110, Nº5, May 2018

Original Article Oliveira et al Exercise in acute heart failure Arq Bras Cardiol. 2018; 110(5):467-475 Therefore, in the present study, we aimed to investigate in acute/decompensated HF patients, (i) the safety of in-hospital aerobic ET; and (ii) the effectiveness of aerobic ET combined with NIV during hospitalization in patients with acute HF. Methods This was a controlled, prospective and randomized study. A convenience sample of 29 patients was recruited from the acute HF ward of a cardiology hospital. These patients had an established diagnosis of acute HF and a previous Doppler echocardiography with left ventricle ejection fraction (LVEF) < 30%. All of them were in NYHA class IV. Patients were excluded from the study if they had unstable angina, complex cardiac arrhythmias, pacemaker, cardiac resynchronization therapy or left ventricular assist device, myocardial infarction within the previous 12 months, oxyhemoglobin saturation by pulse oximetry (SpO 2 ) at rest <88% without oxygen supplementation, or acute pulmonary edema with clinical indications for mechanical ventilation. In addition, patients with clinical indication of NIV besides the proposed by this protocol were excluded. Study protocol All of the subjects underwent an individualized clinical evaluation after hospital admission on day 1 (D1) by the cardiologist and physiotherapist involved in the study. Pulmonary function tests (spirometry), blood sample (brain natriuretic peptide [NT-proBNP] and high sensitivity C-reactive protein [hs-CRP]), six-minute walk test (6MWT), and maximal inspiratory pressure (MIP) test were performed. All patients received standard medical treatment 7 and after clinical and laboratorial tests they were randomized into three groups: ET+NIV, ET+Sham and Control. We decided to include a placebo NIV group to test the hypothesis that exercise alone (ET+Sham) or exercise associated to NIV (ET+NIV) were better than conventional treatment (Control group) in acute heart failure patients. The ET+NIV group performed aerobic ET associated with NIV once a day, for 8 consecutive days; and the ET+Sham group performed aerobic exercise with placebo NIV once a day, also for 8 consecutive days. The control group (Control) received only medical treatment and did not perform aerobic exercise training. At D10 all patients underwent the same clinical evaluation as D1. After the protocol, all patients continued receiving only medical treatment, and were followed-up until hospital discharge or transfer to the intensive care unit. Exercise protocol The ET+NIV and ET+Sham groups performed aerobic exercise on an unloaded in-bed cycle ergometer (Cajumoro, Brazil) for 20 minutes or less, until limit of tolerance. The exercise groups were blinded to pressure applied to NIV or Sham. SpO 2 (Nonin ® Medical, USA) and heart rate (HR) were continuously measured with a heart rate monitor (Polar ® RS800, Finland). Systolic and diastolic arterial pressures (SAP and DAP) were obtained by the auscultatory method (Unilec TM sphygmomanometer and Littmann Quality stethoscope; USA). Blood lactate (Accutrend Plus ® , Germany) was collected during the exercise protocol, at rest, every two minutes, and at the end of exercise. The patients were asked to rate their “shortness of breath” at exercise cessation by the 0–10 Borg’s category ratio scale. 23 Noninvasive positive pressure ventilation Noninvasive ventilation was delivered using the bi-level ventilator (BiPAP Vision ® ; Respironics, USA), applied via oronasal mask in two conditions: bi-level positive airway pressure ventilation – inspiratory positive airway pressure: 14 cmH 2 O, and expiratory positive airway pressure: 8 cmH 2 O, without supplementary oxygen (FiO 2 0.21) and sham ventilation – inspiratory positive airway pressure: 4 cmH 2 O, and expiratory positive airway pressure: 4 cmH 2 O, without supplementary oxygen (FiO 2 0.21). The pressure values were selected based on previous evidence that an inspiratory positive pressure range of 8–20 cmH 2 O and a positive end-expiratory pressure range of 4–10 cmH 2 O were associated with positive clinical effects in a population with similar levels of acute HF. 24,25 The inspiratory positive pressure and positive end‑expiratory pressure values in the sham NIV were set to minimum value (4 cmH 2 O), since the BiPAP Vision cannot be reduced below 4 cmH 2 O. Those values in sham NIV were able to overcome the resistance imposed by the ventilator circuit (as directed by the manufacturer) and to ensure that patients remained blinded to the intervention being applied. Pulmonary function test and maximal inspiratory pressure Spirometric tests were performed, and forced expiratory volume in 1 second (FEV 1 ), forced vital capacity (FVC), and FEV 1 /FVC ratio were measured (EasyOne ® Plus Diagnostic spirometer, Switzerland). MIP was measured with a digital manometer (MVD-300 ® V.1.1 Microhard System; Globalmed, Brazil). Patients were instructed to perform a maximum inspiration from residual volume; each patient performed five maximum inspirations with differences smaller than 10% between them, and the highest result was used for the analysis. Therefore, all results were compared to predicted values. 26 Six-minute walk test The 6MWT was performed on a 30-m flat corridor, according to the American Thoracic Society. 27 Blood pressure, HR, and SpO 2 were measured, and the modified dyspnea Borg scale was applied. All measurements were performed before and immediately after completion of the tests, and after a two-minute recovery period. HR and SpO 2 were monitored throughout the test (Nonin TM portable oximeter – USA). 468