Estudo de dois dispositivos de suporte ventilatório não invasivo sobre a tolerância ao exercício em esteira rolante na DPOC com hiperinsuflação dinâmica

Abstract

The intolerance to exercise in patients with Chronic Obstructive Pulmonary Disease (COPD) is complex and multifactorial. In this context, there is the use of noninvasive ventilatory support (SVNI) as an aid to improve endurance in patients with COPD. This benefit for a given level of external work may delay the development of lung dynamic hyperinflation (HD), which assumes an unfavorable major role especially in the later stages of the disease. The objective of this research was to evaluate the effects of using a BiPAP system (bilevel positive airway pressure) with "inverted" pressure levels (BiPAP "inverted" - BIPAPi) compared to the EPAP (Expiratory Positive Airway Pressure) on exercise tolerance (Tlim) in treadmill in COPD with HD. A total of 16 patients of both sexes (12 males) with COPD (GOLDII-IV) and stable, able to demonstrate HD for during the exercise ΔCI(peak-rest)>150mL, without acute coronary disease or arrhythmia known and without using continuous supplemental oxygen or SpO2<90% at rest. They underwent pulmonary function tests, transthoracic Doppler echocardiography, cardiopulmonary exercise testing (CPET) incremental and three tests at a constant speed and high intensity treadmill, with random sequence, one without intervention (control), another with facial mask EPAP (spring-load) and a one-way valve with an expiratory resistance between 5-10 (~ 7.5) cmH2O and a device called BiPAPi (IPAP: 4cmH2O and EPAP 5-10 (~ 7.5) cmH2O). There was a minimum of 24 hours between tests. We used the program Sigma Plot 12.0. The results were expressed as mean and standard deviation (SD). The Shapiro-Wilks test to check normality and distribution was used. Non-normal variables were log-transformed. The one-way analysis of variance (1-way ANOVA) was used in the comparison between the two devices under control in CPET at a constant speed and significance set at α = 5%. Twelve men (75%) and 4 women (25%) with a mean age of 64.5 ± 7.3 years. There was a reduction in walking distance and Tlim with the use of EPAP in relation to BiPAPi and control (p=0.001). In isotime analysis (200s) of the two devices compared with the control, there was a reduction in tidal volume (VT) for the EPAP mode compared to BiPAPi and control (p =0.018). A reduction in oxygen pulse of EPAP compared to control (p=0.046). The results indicated that the proposed NIV less IPAP to EPAP to reduce inspiratory resistance and to avoid alveolar collapse brought no advantage in increasing Tlim on a treadmill compared to control, and the EPAP alone showed up, with pressures between 5-10 (~7.5) cmH2O, proved to be deleterious.