NUTRITIONAL STATE AND EXERCISE TOLERANCE IN PATIENTS WITH COPD

We hypothesized that in patients with COPD, poor nutritional status ad versely influences exercise tolerance by limiting aerobic capacity of exercising muscles. In 28 patients with stable COPD, we correlated nut ritional status with gas exchange indexes obtained during maximal incr emental cycle ergometer exercise and with respiratory function paramet ers. On the basis of percent of ideal body weight (%IBW), patients wer e divided into three groups (GP): GP1 (n=8, %IBW <90); GP2 (n=13, %IBW greater than or equal to 90<110); and GP3 (n=7, %IBW greater than or equal to 110). When compared with normally nourished individuals (GPs 2 and 3), malnourished GP1 patients showed greater reduction in maxima l workload and in peak O-2 uptake (VO2 peak), with earlier onset of me tabolic acidosis (anaerobic threshold [AT]; in addition, indexes refle cting O-2 cost of ventilation were higher in GP1. Nutritional status c ould be correlated with exercise tolerance (VO (2) peak, r=0.82, p<0.0 001), with onset of metabolic acidosis (AT, r=0.69, p<0.0001) and with dead space/tidal volume ratio (VD/VT, r=-0.59, p<0.001). Body weight was inversely correlated with indexes that are likely to reflect the i ncrease in O-2 cost of ventilation. We conclude that in patients with stable COPD, (1) malnutrition significantly affects muscle aerobic cap acity and exercise tolerance, and (2) high wasted ventilation and O-2 cost of ventilation may be responsible for the weight loss.