Monitoring nutritional status in the critically ill adult.

Nutritional support is an important aspect of the multidisciplinary approach to critical care medicine. During stress, visceral protein turnover is increased. However, muscle and connective tissue proteolysis is obligatory if the stressful condition persists. Through nutritional support, peripheral protein breakdown is minimized and visceral protein synthesis maximized. A delivery system of 15% to 20% dietary protein, 30% fat, 50% to 55% carbohydrate, complemented by moderate amounts of vitamins and minerals, is considered best. Optimal nutritional care depends on objective assessment of the patient's nutritional status before and during nutritional support, particularly the nutritional status of the body cell mass and the energy required for maintenance and support of reparative processes. Indicators least disturbed by factors should be selected for assessment. Individual indicators vary in critical states. After resuscitation, excess body water may increase body weight; after surgery, stress may depress albumin levels. Biometric markers of nutritional status and measurements that adequately validate and evaluate response to nutritional support are discussed.