Total energy expenditure during total parenteral nutrition: ambulatory patients at home versus patients with sepsis in surgical intensive care.

BACKGROUND

To avoid the complications associated with overfeeding or underfeeding, the energy requirements of patients receiving total parenteral nutrition (TPN) must be accurately prescribed. However, until recently it has not been possible to directly measure the rates of total energy expenditure (TEE) in surgical patients receiving TPN.

METHODS

Values for total body water and TEE in four patients with sepsis (mean Acute Physiology and Chronic Health Evaluation [APACHE] score, 10) receiving TPN in surgical intensive care unit and in four patients with chronic intestinal failure receiving long-term TPN at home (HPN) have been determined by using the doubly labeled water technique. The values for TEE have been compared with those of resting energy expenditure obtained with indirect calorimetry (REE CAL) and calculated by using the Harris-Benedict equation (REE HB).

RESULTS

In both the patients with sepsis and the patients receiving HPN the proportion of body weight made up of water was normal for patient age and gender. In patients with sepsis the REE HB significantly (p < 0.05) underestimated the REE CAL (15.39 +/- 3.80 kcal/kg/day-1 versus 31.3 +/- 1.23 kcal/kg/day-1) and was significantly less than the TEE derived by using doubly labeled water (44.62 +/- 1.09 kcal/kg/day-1; p < 0.001). In the ambulatory patients receiving HPN no difference was noted between the REE HB and the REE CAL (18.02 +/- 0.41 kcal/kg/day-1 versus 21.37 +/- 0.94 kcal/kg/day-1). The average TEE for these patients was 30.25 +/- 3.42 kcal/kg/day-1, and this was significantly greater (p < 0.006) than both REE CAL and REE HB:

CONCLUSIONS

This investigation has shown that in patients with sepsis TEE constitutes 1.4 times the REE CAL or approximately 40 kcal/kg/day, whereas in HPN patients TEE can be estimated by supplying 1.4 times the REE or approximately 30 kcal/kg/day-1.