Use of indirect calorimetry in the nutritional management of burned patients.

Abstract

The use of indirect calorimetry in assessing and monitoring nutritional support in burn patients is reported. Twenty-nine patients with a mean burn size of 35% TBSA were monitored with 228 measurements of resting energy expenditure (REE), calculations of respiratory quotient (RQ), and substrate metabolism. Daily weights, nitrogen balance determinations, and routine laboratory tests were also obtained. Oxygen consumption (VO2) was 186 +/- 39 ml/min/M2, corresponding to REE of 2,506 +/- 543 kcal/day. REE varied during the course of wound healing, demonstrating a biphasic course. Metabolic rate was also significantly increased with the performance of routine procedures such as dressings and surgery. Measurements of REE were a mean 76% of predictions based on the Curreri formula, and 1.47 times basal energy expenditure (BEE) calculated by the Harris-Benedict equation. Neither formula provided for the great variations observed in daily, and individual, measurements of REE. During the study, patients consumed 2,900 +/- 811 kcal/day, which exceeded REE by 1.14. This was associated with mean weight loss of 3.2% (range, -16 to 9%). RQ was less than 0.85 in 9% of determinations, but exceeded 1.0 24% of the time. Protein accounted for 17 +/- 3% of total metabolism, corresponding to a calorie:nitrogen ratio of 128:1. Practically, however, provision of this much protein proved difficult. Routine use of indirect calorimetry permits tailoring of nutritional support for burn patients, and is valuable in the early detection of significant under- or overnutrition.