Comparative characteristics of some methods for estimating energy expenditure in critically ill mechanically ventilated patients

Aim: To compare the energy expenditure (EE) assessed by ventilator-derived carbon dioxide production (EE–VCO2-ventilator) and the energy expenditure calculated from six predictive equations with the gold standard energy expenditure measured with indirect calorimetry (IC) in mechanically ventilated patients. Materials and methods: This is a prospective, non-randomized, one-month study which included six mechanically ventilated patients with FiO2 <60% and PEEP <10 mbar. Thirty-minute measurements were taken using a Cosmed Q-NRG+ metabolic monitor. The average ventilator-derived VCO2 from the Drager Evita Infinity V500 respirator (VʹCO2, ml/min) was calculated for the same period. The IC-measured EE (MEE-IC) was compared with EE–VCO2-ventilator by a formula proposed in ESPEN (8.19×VCO2) and with six predictive equations. Results: Mean MEE-IC was 1650±365 kcal. Mean measured EE–VCO2-ventilator was 1669±340 kcal. A statistically nonsignificant difference was found between the two measurements (p=0.84, correlation coefficient 0.98). Of the predictive equations we compared, the best correlation to the reference method was the Penn State 3 with mean EE of 1679±356 (p=0.81, correlation coefficient of 0.78). Conclusions: In critically ill mechanically ventilated patients, the assessment of EE based on a ventilator-derived VCO2 is an alternative to IC and is more accurate than most predictive equations

Bioimpedance analysis for fluid status assessment in critically ill septic patients

Aim: The aim of this study was to assess the usefulness of bioimpedance analysis in fluid status evaluation in patients with sepsis and septic shock admitted to the adult ICU. Materials and methods: This is a prospective, observational, clinician-blind study. The inclusion criteria were a diagnosis of sepsis at admission to ICU, a stay in ICU of at least 72 hours, and the first BIA measurement to be conducted within the first three hours of ICU admission. We took whole-body BIA measurements upon admission and every 24 hours thereafter for at least four consecutive measurements. All enteral and parenteral fluids administered to the patients were recorded, as well as the loses through drains, tubes, aspiration, and urine. The cumulative fluid balance (CFB) was calculated every 24 hours. Results: A total of 51 patients with a mean age of 62 years were included in the final analysis. CFB gradually increased during the first 72 hours of ICU stay from 2003±1331 mL at 24 hours to 3680±2368 mL at 48 hours and 5217±2642 mL at 72 hours. There was a statistically significant positive correlation between the increase in CFB and the increase in total body water, extracellular water, and overhydration. The daily changes of vector length and impedance ratio, as well as the overall 72-hour changes showed statistically significant correlation with the CFB. Conclusion: Bioimpedance analysis is a non-invasive, easy-to-use, inexpensive, portable, and fast tool for fluid status assessment. In critically ill septic patients it can be a useful tool in fluid therapy management