ABSTRACT
At least nine different equations have been published for calculating metabolic expenditure by indirect calorimetry. This study examined the differences between equations when they are used for the nutritional assessment in an intensive care unit (ICU). Oxygen consumption and carbon dioxide production were measured in 36 ICU patients and used to calculate metabolic expenditure with the nine equations. The equations produced differences in metabolic expenditure which averaged from 0.8-96 kcal/day. The largest difference produced by any two of the nine equations was 189 kcal/day. Although differences in original stoichiometric data have resulted in numerous different equations for the calculation of metabolic expenditure, these differences are not clinically important. It makes little difference which equation is used for nutritional assessment in an ICU.
Subject(s)
Dietary Carbohydrates/metabolism , Dietary Fats/metabolism , Dietary Proteins/metabolism , Energy Metabolism , Mathematical Computing , Pulmonary Gas Exchange , Humans , Nitrogen/metabolism , Nitrogen/urine , Oxygen ConsumptionABSTRACT
Patients who undergo gastric partitioning for morbid obesity lose weight rapidly in the first year after surgery. This study measured changes in body composition and dietary intake at 3 months, 6 months, and 1 year after gastric partitioning. Body composition was determined by total-body gamma-ray spectrometry. Records of dietary intake were computer analyzed for nutritional content with the Ohio State Nutrient Analysis Data Base. All patients lost a significant amount of weight at 3, 6, and 12 months after surgery. Loss of lean tissue comprised 25% of the total weight loss at 3 months but only 20% of the total at 1 year. Before surgery the mean energy intake was 2592 kcal and the mean protein intake was 92 gm. After 3 months, energy intake was 745 kcal and protein 32 gm. One year after surgery energy intake was 1089 kcal and protein 41 gm per day. We conclude that patients lose a significant amount of lean body tissue in the first 3 months after gastric partitioning but the loss does not continue, and 1 year after surgery some lean tissue is actually regained. This initial loss is due to a combination of a very restrictive dietary regimen and the body's metabolic response to surgery. After the first 3 months adaptation occurs and lean tissue is spared.
