Nitrogen and energy relationships in malnourished patients with emphysema

The purpose of this study was to examine the impact of nutritional support on nitrogen-energy relationships and functional parameters in malnourished patients with emphysema. Malnourished patients without lung disease served as the control group. Ten ambulatory, stable patients with emphysema and six patients without lung disease received an infusion of 5% dextrose (baseline) plus electrolytes (D₅W) for two days, which was followed by an enteral or a parenteral infusion of either a carbohydrate-based (CB, 53% carbohydrate) or a fat-based diet (FB, 55% fat) for 1 wk each, in a randomized cross-over design. All patients had greater than 10% weight loss. Caloric intake was set at 1.7 times the resting energy expenditure (REE) as measured during the baseline period. The REE of patients with emphysema was 23 and 27% above that of the control group during baseline and refeeding periods, respectively. The increased REE was met primarily by an increased carbohydrate oxidation. During the infusion of D₅W, N balance was lower in patients with emphysema, but during repletion N balance was similar in both groups of patients. Two weeks of nutritional support with either a CB or a FB diet increased body weight, N balance, and arm muscle area and improved maximal inspiratory pressure, skeletal muscle strength, and endurance-strength (using quadriceps, hamstring, and handgrip) to a similar degree in malnourished patients with and without lung disease. In other stress states, such as infection, it has been shown that hypermetabolism, hypercatabolism, and preferential fat oxidation occur concomitantly. Patients with emphysema are unusual because, althouth they are hypermetabolic, they are not hypercatabolic and do not demonstrate preferential fat oxidation.