INDIRECT CALORIMETRY IN CRITICALLY ILL PATIENTS - ROLE OF THE CLINICAL DIETITIAN IN INTERPRETING RESULTS

Evaluation and interpretation of energy needs of critically ill patien ts require the expertise of clinical dietitians. Dietitians must be kn owledgeable about the methods available to quantify energy needs and a ble to communicate effectively with physicians and nurses regarding nu tritional requirements. Several prediction equations are available for calculating energy needs of critically ill patients. Indirect calorim etry is also used frequently to measure energy requirements in this pa tient population. This article defines when energy expenditure measure d by indirect calorimetry may provide clinically useful information. D ata obtained by indirect calorimetry must be interpreted carefully. In direct calorimetry is based on the equations for oxidation of carbohyd rate, protein, and fat. Errors in interpretation can be made when meta bolic pathways other than oxidation dominate or when clinical conditio ns exist that affect carbon dioxide excretion hom the lungs. Before in corporating data obtained from indirect calorimetry into a nutrition c are plan, the clinical dietitian should carefully evaluate the followi ng factors for a patient: clinical conditions when the measurement was made, desired weight loss or gain, tolerance to food or nutrition sup port, relationship between protein intake and energy need, and need fo r anabolism or growth. This article provides clinical examples illustr ating how measured values compare with calculated values and recommend ations for how to incorporate measured values into nutrition care plan s.