Validation of predictive equations for resting energy expenditure in adult outpatients and inpatients.

BACKGROUND & AIMS: When individual energy requirements of adult patients cannot be measured by indirect calorimetry, they have to be predicted with an equation. The aim of this study was to analyze which resting energy expenditure (REE) predictive equation was the best alternative to indirect calorimetry in adult patients. METHODS: Predictive equations were included when based on weight, height, gender and/or age. REE was measured with indirect calorimetry. The mean squared prediction error was used to evaluate how well the equations fitted the REE measurement. RESULTS: Eighteen predictive equations were included. Indirect calorimetry data were available for 48 outpatients and 45 inpatients. Also a subgroup of 42 underweight patients (BMI<18.5) was analyzed. The mean squared prediction error was 233-426 kcal/d and the percentage of patients with acceptable prediction was 28-52% for adult patients depending on the equation used. The FAO/WHO/UNU (1985) equation including both weight and height had the smallest prediction error in adult patients (233 kcal/d), outpatients (182 kcal/d), inpatients (277 kcal/d) as well as underweight patients (219 kcal/d). CONCLUSIONS: The REE of adult outpatients, inpatients and underweight patients can best be estimated with the FAO/WHO/UNU equation including weight and height, when indirect calorimetry is not available.

Population pharmacokinetics of lorazepam and midazolam and their metabolites in intensive care patients on continuous venovenous hemofiltration.

BACKGROUND: The objective is to study the population pharmacokinetics of lorazepam and midazolam in critically ill patients with acute renal failure who are treated with continuous venovenous hemofiltration (CVVH). METHODS: Twenty critically ill patients with acute renal failure on CVVH therapy were administered either lorazepam (n = 10) or midazolam (n = 10) by continuous infusion. CVVH was performed with an ultrafiltrate flow of 2 L/h with filtrate substitution in the predilution or postdilution mode. Blood flow through the 1.9-m 2 cellulose triacetate membrane filter was 180 mL/min. For 48 hours, multiple blood and ultrafiltrate samples were obtained for determination of concentrations of the drug and its metabolites. RESULTS: The pharmacokinetics of lorazepam is described best by a 1-compartment model. No significant covariates were identified. Total-body clearance was 6.4 L/h, and volume of distribution was 376 L. Ultrafiltration clearance was 0.31 L/h, equivalent to approximately 5% of total clearance. Average degree of plasma protein binding was 82.9% for lorazepam, with a sieving coefficient of 0.16 +/- 0.03. For lorazepamglucuronide, degree of plasma protein binding was 39.5%, and sieving coefficient was 0.48 +/- 0.07. The pharmacokinetics of midazolam is described best by a 1-compartment model. No significant covariates were identified. Total-body clearance was 8.5 L/h, and volume of distribution was 157 L. Clearance by ultrafiltration was 0.055 L/h, equivalent to approximately 0.7% of total clearance. Average degree of plasma protein binding was 95.8%, with a sieving coefficient of 0.04 +/- 0.03. For the metabolite 1-hydroxymidazolamglucuronide, average degree of plasma protein binding was 43.4%, with a sieving coefficient of 0.45 +/- 0.06. CONCLUSION: Neither lorazepam nor midazolam is removed efficiently by CVVH. CVVH contributes significantly to the removal of the glucuronide metabolites lorazepamglucuronide and 1-hydroxymidazolamglucuronide.