ABC | Volume 114, Nº4, April 2020

Original Article Marchese et al. Inspiratory exercise in heart failure Arq Bras Cardiol. 2020; 114(4):656-663 tested, this study, until then, is the only one to verify the central hemodynamic response of different IE loads in patients with HFREF. To assess hemodynamic response, a cardiothoracic bioimpedance device was used, which is a noninvasive hemodynamic assessment method that, when compared to thermodilution methods, showed high correlation. 12 Even when used to assess cardiac patients, as shown in the study by Villacorta et al., 13 CTB showed accuracy in the calculation of CO, cardiac index and SV when compared to cardiac magnetic resonance. Therefore, in our study, a method of hemodynamic evaluation capable of reliably recording the changes occurred during IE was used. Inspiratory muscle weakness, present in about 30 to 50% of patients with HFREF, has been acknowledged as a factor that contributes to exercise limitation, in addition to having an independent prognostic value. 3-5 One of the main studies with IMT in HF was carried out by Dall'ago et al., 9 in which 32 patients were randomized into two groups (IMT-placebo and IMT 30%). After 12 weeks of sessions (7 times a week, for 30 minutes), the patients in the intervention group showed a significant increase of 115% in MIP, 17% increase in peak oxygen uptake, and 19% increase in the distance covered in six minutes, in addition to an improvement in quality of life. Table 1 – Sample characteristics n=20 Gender 13M\7F Age (years) 65 ± 11 Weight (kg) 72 ± 14 Height (cm) 164 ± 11 BMI (kg/m2) 26.7 ± 4.4 Ethnicity Caucasian (7). Brown (6). Afrodescendants (7) NYHA Class II (14). Class III (6) LVEF (%) 37.2 ± 6.3 MIP (cm\H2O) - 101 ± - 43 MEP (cm\H2O) 95 ± 42 30% load IMT (cm\H2O) 31 ± 11 60% load IMT (cm\H2O) 61 ± 25 Pharmacological therapy ACE inhibitor, % 55 Diuretics, % 75 β-blocker, % 80 M: male; F: female; kg: kilogram; cm: centimeters; BMI: body mass index; kg/m²: kilograms per square meter; LVEF: left ventricular ejection fraction; MIP: maximum inspiratory pressure; MEP: maximal expiratory pressure; IMT: inspiratory muscle training; cm/H 2 O: centimeters of water; ACE: angiotensin-converting enzyme. Figure 2 – HR behavior before and at 15 min. of IE with the different loads. HR: heart rate; IE: inspiratory exercise; bpm: beats per minute; plac: placebo; min: minutes. (Source: The author) Figure 3 – Behavior of the SV before and at 15 min. of IE with the different loads. SV: systolic volume; IE: inspiratory exercise; ml: milliliter; plac: placebo; min: minutes. (Source: The author) Figure 4 – Behavior of CO before and at 15 min. of IE with the different loads. CO: cardiac output; IE: inspiratory exercise; ml: milliliter; plac: placebo; min: minutes. (Source: The author) 659