Annals of Burns and Fire Disasters - vol. XVIII - n. 1 - March 2005

COMPARISON OF ESTIMATED ENERGY REQUIREMENTS IN SEVERELY BURNED PATIENTS WITH MEASUREMENTS BY USING INDIRECT CALORIMETRY

Tancheva D., Arabadziev J., Gergov G., Lachev N., Todorova S., Hristova A.

Centre for Burns and Plastic Surgery, Pirogov Emergency Medicine Hospital, Sofia, Bulgaria

SUMMARY. Severe burn injuries give rise to an extreme state of physiological stress. No other trauma results in such an accelerated rate of tissue catabolism, loss of lean body mass, and depletion of energy and protein reserves. A heightened attention to energy needs is essential, and the significance of adequate nutritional support in the complex management of patients with major burns is very important. The purpose of this study is to compare the results obtained by three of the most popular methods of estimating energy requirements in severely burned adult patients with the measurements of resting energy (REE) expenditure by indirect calorimetry (IC). A prospective study was carried out of 20 patients (male/female ratio, 17/3; mean age, 37.83 ± 10.86 yr), without accompanying morbidities, with burn injuries covering a mean body surface area of 34.27 ± 11.55% and a mean abbreviated burn severity index of 7.44 ± 1.58. During the first 30 days after trauma, the energy requirements were estimated using the Curreri, Long, and Toronto formulas. Twice weekly measurements of REE by IC were obtained. It was found that the Curreri and Long formulas overestimated the energy requirements in severely burned patients, as found by other investigators. However, no significant difference was found between the daily energy requirements calculated by the Toronto formula and the measured REE values by IC. It is concluded that the Toronto formula can be used as an alternative method for estimating the energy requirements of patients with major burns in cases where IC is not available or not applicable.

Introduction

Severe burn injuries give rise to an extreme state of physiological stress. No other trauma results in such an accelerated rate of tissue catabolism, loss of lean body mass, and depletion of energy and protein reserves. A heightened attention to energy needs is therefore essential and the significance of adequate nutritional support in the complex management of patients with major burns is very important. Many formulas are available for the calculation of daily energy requirements, and the resting energy expenditure (REE) at the bedside of the patient can be measured by indirect calorimetry (IC). Most of these formulas are not exact because they do not take into account many factors affecting energy metabolism: type of thermal trauma, extent of burned body surface, depth and localization of burn, accompanying inhalatory lesions, degree of analgesia, surgical procedures, etc.

The purpose of this study is to make a comparison between the results using three of the most popular methods of estimating adult energy requirements in severely burned patients and the results of measurements of REE by IC.

Materials and methods

A prospective study was carried out on 20 consecutive patients treated in the intensive care unit in the Centre for Burns and Plastic Surgery, Pirogov Emergency Medicine Hospital, Sofia, Bulgaria. The patients’ mean age was 37.83 ± 10.86 yr (range, 21-58 yr) and the male/female ratio was 17/3. There were no accompanying morbidities. The mean body surface area burned (BSAB) was 34.27 ± 11.55% (range, 20-60%) and the mean abbreviated burn severity index (ABSI) was 7.44 ± 1.58 (Table I). The monitoring of caloric expenditure was carried out using the functional respiratory diagnostics device (Critical Care Management System-Med Graphics-USA). A protocol for applying IC was elaborated and used (Table II).

During the first 30 days post-trauma, the energy requirements were estimated using the Curreri formula,1,2 the Long formula,3 and the Toronto formula4,5 (Table III). Twice weekly measurements of REE values by IC were obtained and compared with the energy requirements estimated by the three formulas.

All statistical analyses were performed by computer using the statistical software package SPSS-11.01 for Windows.

Results and discussion

Table IV shows the mean values of the results obtained in the course of 30 days post-burn. No significant difference was observed between the daily energy requirements calculated by the Toronto formula and the measured REE values by IC. However, a statistically significant difference was found between the estimated amount of kcal/24 h when using the Toronto formula and the data measured by IC, on the one hand, and that estimated by the Curreri formula and the Long formula, on the other. The daily energy needs calculated by the Curreri and Long formulas significantly exceeded (by up to 40%) the values estimated by the Toronto formula. The Curreri and Long formulas overestimated the energy requirements in severely burned patients, as also found by other investigators.6 Neither of these two formulas takes into consideration the dynamic changes in the course of burn treatment, and this can lead to undesired overnutrition of the patients.7,8 The energy requirements estimated by using the Toronto formula corresponded closely (no significant difference) to the REE values measured by IC.9 These data are shown in Fig. 1.

Same index letters on the horizontal lines designate lack of significant statistical difference, while different index letters confirm presence of statistical difference

Conclusions

This study suggests that the Toronto formula can be used as an alternative method for estimating the energy requirements of patients with major burns in cases where indirect calorimetry is not available or not applicable.

RESUME. Les brûlures graves causent un état extrême de stress physiologique. Aucun autre traumatisme ne provoque un taux tellement accéléré du catabolisme des tissus, la perte de la masse corporelle maigre et la déplétion des réserves d’énergie et de protéines. Il faut prêter majeure attention aux besoins énergétiques du patient, et l’importance d’un support nutritionnel approprié dans la gestion très complexe des grands brûlés est considérable. Le but des Auteurs de cette étude est de comparer les résultats obtenus moyennant trois des méthodes les plus utilisés pour évaluer les besoins énergétiques des grands brûlés adultes avec les résultats en mesurant la dépense d’énergie au repos utilisant la calorimétrie indirecte. Une étude prospective a été effectuée de vingt patients (rapport mâle/femelle, 17/3; âge moyen, 37,3 ± 10,86 ans), sans aucune autre forme de morbidité, atteints de brûlures dans la mesure de 34,27 ± 11,55% de la surface corporelle et présentant un indexe abrévié moyen de la sévérité de la brûlure de 7,44 ± 1,58. Pendant les 30 premiers jours après la brûlure les besoins énergétiques ont été évalués en utilisant les formules de Curreri, de Long et de Toronto. Deux fois par semaine la dépense d’énergie au repos a été obtenue avec la calorimétrie indirecte. Les Auteurs ont trouvé que les formules de Curreri et de Long surestiment les besoins énergétiques des grands brûlés, comme d’autres chercheurs ont confirmé. Au contraire, aucune différence significative n’a été observée entre les besoins quotidiens énergétiques calculés avec la formule de Toronto et les valeurs de dépense d’énergie au repos obtenues avec la calorimétrie indirecte. Les Auteurs concluent que la formule de Toronto peut être utilisée comme méthode alternative pour évaluer les besoins énergétiques des grands brûlés dans les cas où la calorimétrie indirecte n’est pas disponible ou n’est pas applicable.

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