Efeitos da ventilação não invasiva nos modos CPAP e Bi-nível sobre a tolerância ao exercício na insuficiência cardíaca crônica

Abstract

Introduction: Dyspnea and fatigue are the main clinical symptoms of heart failure and primarily responsible for exercise intolerance found in this syndrome. Now, It is known that the use of NIV in CPAP mode applied before exercise increases exercise tolerance in people with heart failure; however, it's not yet known if the bi-level mode is able to generate similar or even better results, due to pressure increase of the ventilatory support in this modality. Moreover, it is possible that there is influence between the pressure levels set in the NIV and the magnitude of its effect on the exercise in this population Objective:1) test for differences between the acute effects of NIV on exercise tolerance in patients with HF, when applied CPAP or bi-level mode; and 2) check for discrepancies in the acute effects of Bi-level mode on the physical performance of these individuals, when applied at different pressure levels. Methodology: This is a controlled, randomized, double-blind and cross-over clinical trial, composed of 14 volunteers (age 63 ± 9 years), with chronic heart failure, functional class II and III (New York Heart Association) in clinical stability. The experiment took place in four different visits, with an minimum interval of 48 hours between them. At the first visit, the volunteers were screened and performed a SWT without prior intervention. Following a randomized sequence, In each of the 3 subsequent visits, the volunteers received a different mode of NIV for 30 minutes immediately before the SWT. The following modes were used: Bi-level with minimal parameters (EPAP = 6 cm H2O and IPAP = 12 cm H2O), Bi-level with maximum parameters (EPAP = 8 cm H2O and IPAP = 14 cm H2O) and CPAP (6 cm H2O). In the tests were observed walking distance (WD), perceived levels of fatigue and dyspnea, affective response and other physiological variables. Statistical analysis was performed using ANOVA for repeated measures followed by Bonferroni post-test, considering p-value less than or equal to 0.05 as statistically significant. Results: No difference was found between the WD obtained in T-CP (440.4 + 72,4m) and T-Bi (441.6 + 79,4m) (p = 1.00). However, the WD was higher after the use of NIV in both the T-CP, as in T-Bi compared to that observed in T-Co (381.2 + 79,8m) (p = 0.004 and p = 0.007, respectively). Conclusion: The use of a non-invasive ventilatory support, regardless of mode, promotes improvement in exercise tolerance in people with heart failure, which can allow this population range, more broadly, the benefits from the exercise of its functionality and quality of life.