AVALIAÇÃO DE UM NOVO ÍNDICE DE EFICIÊNCIA VENTILATÓRIA EM PACIENTES COM DOENÇA PULMONAR OBSTRUTIVA CRÔNICA E INSUFICIÊNCIA CARDÍACA CRÔNICA

Abstract

Currently, excess ventilation is based on the minute ventilation/carbon dioxide removal ratio (⩒E-⩒CO2). A new proposal for ventilatory efficiency (η⩒E) was developed and propagated in the international literature, and our main hypothesis is that when equated with long-established methods (⩒E-⩒CO2 slope and ⩒E-⩒CO2 intercept) for maximal and submaximal aerobic performance, it provides comparatively low levels for η⩒E between chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD). Individuals with COPD or CHF were recruited and underwent pulmonary function tests, echocardiography and cardiopulmonary exercise testing, 19 patients with COPD and 19 with HF who completed the study being eligible. The significance level adopted in the analysis statistical was 5%.Comparisons were made between integral values of ⩒E-⩒CO2 and η⩒E for the total period of exercise (100%), and correlations with smaller fractions (90% and 75% of the maximum values). Our results showed thatthe two groups had identical characteristics for age (62±6 vs 59±9 years, p>0.05), sex (10/9 vs 14/5, p>0.05), BMI (26±4 vs 27± 3 Kg m2, p>0.05), and ⩒O2 peak (72±19 vs 74±20, %pred, p>0.05), respectively. The ⩒E-⩒CO2 slope and ⩒E-⩒CO2 intercept were significantly different for COPD and CHF (27.2±1.4 vs 33.1±5.7 and 5.3±1.9 vs 1 .7±3.6, p0.850 for both). We concluded that the new approach to assessing ventilatory efficiency is more appropriate for comparing cardiopulmonary diseases with different pathophysiological mechanisms, including ventilatory restrictions in COPD.