COMPARISON OF LOW, MEDIUM, AND HIGH-CARBOHYDRATE FORMULAS FOR NIGHTTIME ENTERAL FEEDINGS IN CYSTIC-FIBROSIS PATIENTS

This study examined whether the increase in CO2 production (VCO2) and ventilatory demands by carbohydrate loading with different formulas during nighttime enteral feedings could be detrimental in young adult cystic fibrosis patients with moderate to advanced lung disease. Ten patients age 17 to 24 (mean 21.4 years) received 1000 kcal/M2 of a low (Pulmocare), medium (Ensure Plus), and high (Vivonex HN) carbohydrate formula in random order. Eight patients had severe, and two moderate obstructive pulmonary disease; nine used nighttime oxygen therapy. Basal energy expenditure (BEE) without feedings averaged 120% of that predicted by the Harris-Benedict equation. The metabolic expenditure by indirect calorimetry during nighttime feedings was 25 to 36% greater than the BEE. Oxygen consumption (VO2) increased 21 to 27% during nighttime feedings with no difference between formulas. VCO2 increased 29% for Pulmocare, 46% with Ensure Plus, and 53% with Vivonex HN. The increase in VCO2 with Pulmocare was significantly less than Ensure Plus (p < 0.05) and Vivonex HN (p < 0.005). The respiratory quotient (RQ) (VCO2-/VO2) for Pulmocare (0.88) was the same as the BEE, but increased with Ensure Plus (1.00), and Vivonex HN (1.08). The 41% increase in minute ventilation with Vivonex HN was greater than the 25 to 28% increase observed for Pulmocare and Ensure Plus (p < 0.05). Transcutaneous oxygen saturation fell no more than 2% with all formulas. PCO2 changed ±5 torr during enteral feedings with similar changes in any patient with all formulas. We concluded that nighttime enteral feedings in cystic fibrosis patients did not result in significant increased carbon dioxide retention or oxygen desaturation despite increased VCO2, VO2, minute ventilation and metabolic expenditure. Pulmocare resulted in the lowest VCO2, RQ, and minute ventilation.