FACTORS CONTRIBUTING TO INCREASED ENERGY-EXPENDITURE IN THERMAL-INJURY - A REVIEW OF STUDIES EMPLOYING INDIRECT CALORIMETRY

In summary, a remarkably close agreement exists for the mean MEE measured in 28 studies of severe burn trauma (Table I). This is especially surprising given the variability in sample sizes, measurement techniques, study designs, and DPBs studied. The mean MEE calculated from the data published in these reports is listed in the final column of Table I. For more than 450 cases, an unweighted MEE is 2750 ± 85 kcal/day. For those studies prior to 1980, the mean MEE exceeds 3000 kcal/day in eight of 14 reports vs only two of 14 published after 1980. Even so, the mean MEE for the pre-1980 reports differs by only 200 kcal/day (2960 ± 120, n = 14). The accepted notion that the degree of elevation in MEE is in proportion to the % BSAB up to about 60% BSAB is useful in a general sense but must be applied with caution. The recent studies, which include proportionately more burns exceeding 80% BSAB, suggest an elevation in MEE in these cases. Nevertheless, a physiologic plateau apparently exists at or slightly below 2 x normal RMR at the peak of MEE. The magnitude of the MEE response results from an undefined interaction among several factors of which some have been examined while others such as inflammatory mediators are only beginning to receive study. The contributions to reduction in MEE from interventions to control cardiac output and peripheral cooling, core temperature, evaporative water (heat) loss, and substrate cycling have been reviewed. The importance of indirect calorimetry in patient care is highlighted by the large variability in similarly injured individuals and in the unexplained component of regression analyses. Finally, of the several most often applied prediction equations for MEE in the absence of measurement, the CEE has been repeatedly shown to overestimate MEE substantially and be of little value while the calculation of either 2 x HBEE or 2000 kcal/m2 BSA provides a more reasonable estimation of the MEE with an added safety factor. Indeed, in adults such as those of our series40 with an average BSA of 1.73 m2, 1800 x BSA is equivalent to 2 x HBEE and may represent the most useful equation when MEE is unmeasured.