Precise analysis of energy requirements and prevention of energy imbalance are important for critical patients. Indeed, these measures can reduce the risk of complications following inadequate nutritional support. Although indirect calorimetry is the “gold standard” for measuring actual energy expenditure (AEE), some factors may limit the accuracy and feasibility of “breath-by-breath” gas analysis. Sedation procedure is one of the most significant factor determining the accuracy and interpretation of metabolic monitoring results.
OBJECTIVE. T
O determine the level of agreement in indirect calorimetry data between the integrated metabolic monitor «ZISLIN» (ZISLIN Metabolic Module) of the Löwenstein ELISA ventilator (Löwenstein Medical, Germany) and Q-NRG calorimeter (COSMED, Italy) in patients on mechanical ventilation and propofol or dexmedetomidine sedation.
MATERIAL AND METHODS
A single-center prospective open cohort study included 20 ICU patients on mechanical ventilation and propofol or dexmedetomidine sedation for at least postoperative 24 hours. Simultaneous measurements using the “ZISLIN” metabolograph of the Löwenstein ELISA respirator (Löwenstein Medical, Germany) and the Q-NRG autonomous calorimeter (COSMED, Italy) were performed synchronously four times in each patient: 1, 4, 8 and 12 hours after the patient's admission to the ICU. Mean values of VO2, VCO2, AEE and RQ were obtained from the processed data. Limits of agreement and bias between VO2, VCO2, AEE and RQ measured with the «ZISLIN» metabolic unit and the Q-NRG reference device were compared using the Bland—Altman method.
RESULTS
Mean difference in patients sedated with propofol or dexmedetomidine was as follows: AEE -84.52 with limits of agreement ±171.4 kcal, VO2 — 10.42 ±26.6 ml, VCO2 — 12.03±26.76 ml, RQ — 0.011±0.1. Analysis in three subgroups (propofol sedation, dexmedetomidine sedation, mixed group) showed that difference of measurements did not depend significantly on the value of the parameter when comparing all values of AEE, VO2, VCO2 obtained by two devices. This indicates no systematic discrepancy of data and good comparability of results. When comparing RQ values, we found systematic discrepancy of data.
CONCLUSION
Indirect calorimetry performed with the ZISLIN Metabolic Module module is highly precise, as demonstrated by comparison with the new “gold standard”, the Q-NRG calorimeter. The “breath-by-breath” devices can be as accurate as those using a gas mixing chamber for analysis in patients on invasive MV during medical sedation.
