Accuracy of Computed Equations for Predicting the Resting Energy Requirements in Patients with Generalized Secondary Peritonitis

Abstract

Nutritional support is central to prompt treatment of patients with generalized secondary peritonitis (GSP).These patients desperately need a simple and affordable solution to evaluate their daily energy need.Objective: to determine accuracy of estimating the Resting Energy Expenditure (REE) in GSP patients.Materials and methods. Study design: a prospective, single center study. The inclusion criteria: diagnosed GSP and stay at the Intensive Care Unit (ICU). Three treatment arms were formed. The first arm included all patients (n=61), the second arm included patients capable to breath spontaneously and adequately (n=29), and the third arm included patients on artificial ventilation (n=32). Reference values of REE were calculated by Indirect Calorimetry (IC) method using Engstrom Carestation Lung Ventilator and Metabolic (General Electric,USA). Six equations were used to predict REE values: Ideal Body Weight multiplied by 25 (IBWX25); Actual Body Weight multiplied by 25 (ABWX25); J. A. Harris, F. Benedict (HB); HB with corrective ratio 1.25 (HBX1.25); C. Ireton-Jones, 1992 (IJ); PennState, 2003 equation, in modification (PS). SPSS Software Package was used for statistical analysis of the results. The zero hypothesis was rejected at P<0.05.Results. In patients with GSP, the REE value determined by means of Indirect Calorimetry method was equal to 25.78±1.37 kcal/kg/day. If compared with Indirect Calorimetry results, predictive accuracy of calculation equations in the second and third arm, respectively, were as follows: IBWX25: 30 and 0%, HB: 36.7 and 9.9%, HBX1.25: 49.9 and 45.5%, IJ: 51.8 and 53.2%, ABWX25: 63.4 and 60.6%, PS (as determined in patients on mechanical ventilation only): 42.4%.Conclusion. Indirect Calorimetry method is the only accurate way of REE evaluation in GSP patients. ABWX25 and IJ showed the highest predictive accuracy. IBWX25 and HB had the lowest predictive accuracy.