Rob Mostert

Efficacy of Nutritional Supplementation Therapy in Depleted Patients With Chronic Obstructive Pulmonary Disease

OBJECTIVE Weight loss and muscle wasting adversely affect morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD). Maintenance systemic glucocorticosteroids, prescribed in a substantial number of patients, further contribute to muscle weakness. We investigated the efficacy of oral nutritional supplementation therapy in depleted patients with COPD. METHODS The therapy consisted of daily two to three oral liquid nutritional supplements (mean +/- standard deviation: 2812 +/- 523 kJ/24 h) incorporated into an 8-wk inpatient pulmonary rehabilitation program in 64 (49 men) depleted patients with COPD. Endpoints were body weight, fat-free mass by bioelectrical impedance analysis, respiratory and peripheral muscle function (maximal inspiratory mouth pressure and handgrip strength, respectively), exercise performance (incremental bicycle ergometry), and disease-specific health status by St. Georges Respiratory Questionnaire. Forty-eight percent of the patients were treated with low-dose oral glucocorticosteroids as maintenance medication (dose equivalent to 7.6 +/- 2.5 mg of methylprednisolone per day). RESULTS Increases in body weight (2.1 +/- 2.1 kg, P < 0.001) and fat-free mass (1.1 +/- 2.0 kg, P < 0.001) were seen. Further, maximal inspiratory mouth pressure (4 +/- 10 cm of H(2)O, P = 0.001), handgrip strength (1.2 +/- 3.1 kg, P = 0.004), and peak workload (7 +/- 11 W, P = 0.001) significantly improved. Clinically significant improvements in the items symptoms (9 +/- 16 points, P < 0.001) and impact (4 +/- 15 points, P = 0.043) of St. Georges Respiratory Questionnaire were achieved. Oral glucocorticosteroid treatment significantly impaired the response to nutritional supplementation therapy with respect to maximal inspiratory mouth pressure, peak workload, and St. Georges Respiratory Questionnaire symptom score. CONCLUSIONS Nutritional supplementation therapy implemented in a pulmonary rehabilitation program was effective in depleted patients with COPD. However, oral glucocorticosteroid treatment attenuated the anabolic response to nutritional supplementation.

Analysis of the Metabolic and Ventilatory Response to Self-Paced 12-Minute Treadmill Walking in Patients With Severe Chronic Obstructive Pulmonary Disease

BACKGROUND The 12-minute walking test is frequently used to measure exercise capacity in patients with severe chronic obstructive pulmonary disease. However, the physiological response to this test has been the subject of limited investigation. METHODS In this study, the metabolic and ventilatory consequences of a self-paced 12-minute treadmill walking test (WT) were measured in 17 patients with severe chronic obstructive pulmonary disease (FEV1: 40 +/- 9%) and evaluated using the physiological response to symptom-limited cycle ergometry (CE). During exercise testing, heart rate, transcutaneous oxygen saturation, and lactate concentration were measured, and oxygen consumption, carbon dioxide production, tidal volume, and breathing frequency were recorded breath by breath. RESULTS After 4 minutes walking, the peak oxygen consumption (VO2) was already 99 +/- 11% of last-minute walking VO2. Walking speed was chosen within 2 minutes and remained stable throughout the test. The WT and CE showed similar (end-) test results for all measurements, except for a higher carbon dioxide production, venous lactate concentration, and respiratory quotient after CE. However, lactate concentration was also significantly increased after WT. Severe and prolonged desaturation was shown during walking in most patients. CONCLUSIONS The physiological stress evoked during the WT is close to the stress developed at an incremental symptom-limited test and the relatively high metabolic and ventilatory stress is sustained from at least 4 to 12 minutes during the WT. This study has shown that anaerobic metabolism not only occurs during incremental cycle ergometry, but also during the WT.