GASTRIC-EMPTYING, PULMONARY-FUNCTION, GAS-EXCHANGE, AND RESPIRATORY QUOTIENT AFTER FEEDING A MODERATE VERSUS HIGH-FAT ENTERAL FORMULA MEAL IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE PATIENTS

High fat enteral formulas have advocated for the nutritional support o f chronic obstructive pulmonary disease (COPD) patients because dietar y fat utilization under ideal conditions produces less CO2 per O-2 con sumed than carbohydrate. No data exist for these patients comparing th e effects of a moderate fat vs. a high fat enteral formula on gastric emptying times (GE) and subsequent CO2 production (V over dot CO2), ox ygen consumption (V over dot O-2), respiratory quotient (RQ), and pulm onary function. Our double-blind crossover study compared these parame ters after feeding a 355 mL (530 kcal) meal with either 41% fat calori es (Respalor(R)) or 55% fat calories (Pulmocare(R)). Thirty-six COPD o utpatients with a forced expiratory volume in 1 s (FEV(1)) <60% of pre dicted were studied after an overnight fast. Gastric emptying half-tim e (GE t(1/2)) was measured using the Tc-99M-radionuclide technique; V over dot CO2 , Vover dot O-2 RQ, and other pulmonary functions were me asured at 0, 30, 90, and 150 min postprandial using the Canopy Mode of the Deltatrac Metabolic Monitor and the Renaissance Spirometry System . We observed a significantly (p = 0.0001) longer GE postprandial, the V over dot CO2 and V over dot O-2 for patients fed the moderate-fat f ormula were significantly (P = 0.005) higher than for those fed the hi gh-fat formula; no differences were observed for the other pulmonary f unctions. Although RQ increased significantly (p = 0.01) after both me als, no differences between formulas were noted at all postprandial ti mes tested. Compared to the high-fat meal, the moderate-fat meal signi ficantly enhanced gastric emptying. The earlier rise in V over dot CO2 and V over dot O-2 after the moderate-fat meal did not impact pulmona ry function and reflected the earlier utilization of the moderate-fat meal. The fact that RQ was not different was most likely due to earlie r gastric emptying of the moderate-fat meal rather than the difference of the fat-to-carbohydrate ratio between the two tested meals. The im pact of these findings on long-term management of COPD patients awaits long-term prospective studies.