Submaximal exercise in emphysema and malnutrition at two levels of carbohydrate and fat intake

Eight malnourished patients with emphysema (EMPH) and eight malnourished patients without evidence of lung disease (MALN) received an infusion of 5% dextrose plus electrolytes (D₅W) for 48 h and were then randomly assigned to a hypercaloric diet with either 53% of the calories as carbohydrate (CB) or with 55% as fat (FB) for the 1st wk, maintaining a constant protein intake. The alternate diet was given the following week. Ventilation and gas exchange were measured during supine cycle ergometry at 0, 12, and 25 W during the D₅W, CB, and FB diet periods. At each exerice intensity, the EMPH group demonstrated a 12-15% greater O₂ consumption, a lower respiratory quotient, and an O₂ debt larger than that of the MALN group. Resting ventilation was higher during the CB than FB regimen in both groups of patients, but during the CB diet the EMPH group had a more exaggerated ventilatory response than the MALN group. The results demonstrate that EMPH patients have an unusual metabolic pattern during hypercaloric feeding and exercise. Furthermore in EMPH patients a FB regimen does not appear to create the additional stress on the respiratory system during exercise that is generated with a CB regimen.