The effects of high-fat and high-carbohydrate diet loads on gas exchange and ventilation in COPD patients and normal subjects.

Reducing the CO2 production (VCO2) is a plausible means to lower the ventilatory demand in the treatment of patients with COPD. The purpose of this study was to examine the effects of high-fat and high-carbohydrate (high-CHO) diet loads on gas exchange and ventilation in the COPD patients and normal subjects. The percentage of changes in the averaged values of VCO2, O2 consumption (VO2), respiratory quotient (RQ), minute ventilation (VE), and end-tidal CO2 (ETCO2) measured by a mass spectrometer for 5 min every 30 min after the diet were compared between diets and between study subjects. Compared with the high-fat diet, the high-CHO diet can lead to significantly higher levels of VCO2, VO2, RQ, and VE in the COPD patients 30 to 60 min after the diet, and the differences can last for about 1.5 h. The comparison between COPD patients and normal control subjects also showed that the high-CHO diet load can result in significantly higher levels of VCO2, VO2, and VE, and significantly lower level of ETCO2 in the COPD patients, whereas the high-fat diet cannot. In addition, enhanced thermic effect of food within 150 min (TEF150) occurred in the COPD patients as compared with that of normal controls, and the increase in TEF150 occurred only with the high-CHO diet. This study suggested that a high-fat diet is more beneficial to the COPD patient than a high-CHO diet, and that the gas exchange and energy utilization of the COPD patients following a high-CHO diet might be different from that of normal control subjects.