Assessement of resting energy expenditure of obese patients: comparison of indirect calorimetry with formulae.

BACKGROUND & AIMS: Determining the caloric expenditure of overweight (Body mass index - BMI from 25-29.9 kg/m(2)) or obese (BMI> or =30 kg/m(2)) patients is a difficult task. The importance of the measurement using indirect calorimetry (IC) is to avoid the administration of an inadequate caloric load, which can increase clinical morbidity. The aim of this study was to compare the resting energy expenditure (REE) obtained by IC with that estimated by the Harris-Benedict (HB) and the Ireton-Jones (IJ) equations and a fixed amount of 21 kcal/kg of body weight, using actual, average and adjusted weights. METHODS: A total of 71 IC measurements were prospectively performed in 44 patients using the "DELTATRAC II" calorimeter. In 53 of the measurements the patients were on mechanical ventilation and 18 were performed using the canopy, in the fasting state and 24h after achieving calculated caloric requirements. RESULTS: The best REE prediction value in the fasting state was obtained with the HB equation using the actual body weight (HB/ABW), 1873+/-484 kcal/day (p=0.49) when compared to the REE of 1798+/-495 kcal/day measured by IC. After achieving caloric needs, the best REE prediction values were using the HB/ABW equation, 1873+/-484 kcal/day (p=0.56) and the IJ equation with the adjusted body weight, 2103+/-580 kcal/day (p=0.19) when compared to 1948+/-507 kcal/day measured by IC. Although, when the above results were plotted on the Bland and Altman limits of agreement test their average bias were low, but the ranges of their absolute values from the observed average agreement were large, > or =531 kcal. CONCLUSION: From these data we can conclude that even though the average values obtained with the equations utilized to predict the REE for this population, showed good correlation with those by IC, as they had the best comparative absolute results, however they demonstrated an unacceptable variability when matched to the measured REE values.

Can measured resting energy expenditure be estimated by formulae in daily clinical nutrition practice?

PURPOSE OF REVIEW: To recognize the fundamental factors that alter energy expenditure on a daily basis and the impact they have on the measurement of caloric consumption by the human body, through respiratory indirect calorimetry, and thus to try to determine which predictive equation best correlates with total energy expenditure generated from energy measurements. RECENT FINDINGS: The most important compartment of the body, for its metabolic activity and influence upon resting metabolic rate, is fat-free mass. Other variables affecting energy expenditure are sex, weight, height, age, body surface area, fat mass and ethnicity. Metabolic and activity factors such as the thermic effect of nutrients, facultative thermogenesis, anabolism/growth and physical activity, also contribute, comprising total daily energy expenditure. Following the pioneering work of Harris and Benedict for the estimation of energy expenditure, several authors turned their experimental interest to this area, and various recent predictive formulae were derived. These are useful and easy to apply in daily clinical nutrition practice. However, because of the cited variables upon energy expenditure, the final daily caloric estimates show inherent errors ranging from -23.5 to +22.5% upon measured caloric expenditure. These are particularly remarkable in critically ill patients who are exposed to medical and surgical interventions. SUMMARY: One has to be careful in choosing, understanding and clinically applying the results from predictive equations, bearing in mind that the original population from which the equation was derived does not always correspond to that currently being evaluated.

Complicaçöes do suporte nutricional em pacientes cardiopatas numa unidade de terapia intensiva / Nutritional support complications in cardiac patients in an intensive care unit

Objetivando avaliar portadores de cardiopatia quanto as complicaçöes decorrentes de nutricäo enteral e/ou parenteral, realizado estudo retrospectivo entre 64 pacientes com doencas cardíacas admitidos consecutivamente no Centro de Terapia Intensiva (CTI)da Clínica Säo Vicente, entre outubro de 1994 e dezembro de 1996. A maioria (n=50) encontrava-se em pós-operatório de cirurgia cardíaca ou vascular complicadas. O APACHE ll foi 13, 75+ou-4, 95. A via enteral foi utilizada em 100 por cento dos pacientes, com associaçäo de nutriçäo parenteral em nove deles (14 por cento). O sitio gastrico foi o mais utilizado (57,8 por cento),com boa tolerância. As dietas poliméricas,hiperproteicas,foram utilizadas em 82 por cento dos casos. O percentual diário de administraçäo das dietas foi de 84 +ou-11 ,3 por cento. As complicaçöes mais frequentemente encontradas durante a nutriçäo enteral foram a constipaçäo (50 por cento),a distensäo abdominal (29 por cento), a hiperglicemia (26 por cento) a diarreia (20 por cento) e os vômitos (11 por cento). Houve desposicionamento da sonda em 18 pacientes (29 por cento) e obstruçäo de sonda em apenas tres ocasiöes (4 por cento). As complicaçöes que predominam com a nutriçäo parenteral foram a hiperglicemia em três pacientes (33 por cento), a colonizaçäo do catéter, que ocorreu em três dos catéteres implantados (23 por cento),e a hipertriglicemia, em dois casos (22 por cento). A mortabilidade foi elevada: 39,7 por cento (n=25). A causa mortis mais frequente foi o choque refratário (n=8) e a falência de múltiplos orgäos (n=7). Concluimos que a nutriçäo enteral e bem tolerada em pacientes graves portadores de cardiopatia, com administraçäo satisfatória em sitio gástrico, utilizando-se formulaçöes poliméricas