Oral nutrition in patients receiving home cyclic parenteral nutrition: pattern of substrate utilization

Patients receiving cyclic home parenteral nutrition (PN) often have a significant oral caloric intake. This study describes the metabolic use of fuels, as assessed by indirect calorimetry, in eight stable, ambulatory, noncancerous, adult patients receiving glucose-based PN with (PN + oral) or without (PN only) a self-selected oral intake. Patients' weight was 91 +/- 2% (mean +/- SE) of ideal body weight, and fat mass was 22 +/- 5 and 31 +/- 2% of actual body weight in males and females, respectively. Under the PN-only regimen, providing 104 +/- 5% of predicted basal energy expenditure (BEE), patients were in equilibrium for energy and nitrogen balances. Oral supplementation (absorbed oral intake 80 +/- 5% of BEE) was associated with positive energy and nitrogen balances but also with nearly continuous net fat synthesis. We conclude that the glucose-based PN + mixed oral regimen enables the patients to face the increased energy requirements of everyday ambulatory life but is not associated with an optimal body composition in long-term PN patients.