Metabolic and ventilatory response pattern to arm elevation in patients with COPD and healthy age-matched subjects

Many patients with chronic obstructive pulmonary disease (COPD) experience problems in those activities of daily living which involve so-called unsupported arm elevations (AE). In this study, possible differences in the metabolic and ventilatory response pattern to three types of arm elevation were compared between 13 COPD patients (forced expiratory volume in one second (FEV1) (mean (SD)) 38 (13)% of predicted) and 13 age-matched healthy subjects. Each subject consecutively performed three types of arm elevation for 2 min, with 3 min rest periods in between. Breath-by-breath metabolic and ventilatory parameters and heart rate (HR) were registered during a 3 min baseline period and throughout the measurement period. Adjusted for significantly greater baseline test results in COPD patients, it was found that AE (arm elevation including recovery) tended to be more demanding with respect to metabolic and ventilatory response for patients with COPD than for the age-matched healthy subjects. Arm elevation resulted in an increase in oxygen consumption (V'O2) (COPD 12%; healthy 6%), carbon dioxide elimination V'CO2 (COPD 15%; healthy 10%), minute ventilation V'E (COPD 13%; healthy 7%) and heart rate (COPD 2%; healthy 5%). A pronounced difference was found in the pattern of metabolic and ventilatory response to arm elevation, i.e. there was an earlier but sluggish V'O2 onset in COPD patients, whereas the healthy subjects demonstrated a sudden peak approximately 30 s after arm elevations. Mutual comparison of the three different types of arm elevation demonstrated a comparable response pattern. Knowledge of the specific response to arm elevations in COPD patients seems essential for interpretation of arm elevation tests in upper extremity rehabilitation programmes.