The ICALIC Accuracy Validation in Geneva Study

Study Overview
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Brief Summary
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This study aims at validating the accuracy of the new indirect calorimeter (Q-NRG, COSMED, Italy), developed for the ICALIC multicenter study. The validation of accuracy will only be conducted in Geneva center. The measurements made with the new calorimeter will be compared to the measurements by the mixing chamber method using a mass spectrometer (MAX300-LG, Extrel, USA) for gas composition analysis.

Detailed Description
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Indirect calorimetry is a method to measure energy expenditure of human subjects by analyzing patient breath gas to measure the amount (volume) of oxygen consumption (VO2) and CO2 production (VCO2). Energy expenditure is calculated by the Weir's equation using the measured VO2 and VCO2 values. The new calorimeter is equipped with a disposable in-line pneumotach flowmeter, which measures the flow of exhaled gas of patients directly within the mechanical ventilator circuit. It also samples small amount of inhaled and exhaled gas to measure the inhaled and exhaled O2 and CO2 compositions. The new dynamic micro-mixing chamber technique is used to meaure VO2 and VCO2 to derive the energy expenditure. The mass spectrometer measures the inhaled and exhaled gas compositions. The mass spectrometer samples inhaled gas from the mechanical ventilator circuit. A mixing chamber system is used to collect the expired gas from the outlet of the mechanical ventilator. The collected gas is measured for the second time after diluting with a constant flow of ambient air, which is monitored by an independent mass flow meter. The volume of the expired gas is calculated by comparison of the concentrations of exhaled gas before and after the dilution. The measurements will be used to calculate the VO2 and VCO2 to derive the energy expenditure.

Official Title
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Clinical Evaluation of the Ease of Use of a New Indirect Calorimeter for Energy Expenditure Measurement in ICU Patients: The ICALIC International Multicentric Study

Conditions
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Critical Illness

Intervention / Treatment
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* Other: Indirect calorimetry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: • Mechanically ventilated adult ICU patients Exclusion Criteria: Fraction of inhaled oxygen (FIO2) > 70% Positive end expiratory pressure (PEEP) >10cmH2O Peak ventilatory pressure > 30cmH2O Presence of air leaks from thoracic drain tube Changes in vasoactive agent dose (>20%, <1 hr before and/or during IC) Agitation or change in sedative dose (>20%, <1 hr before and/or during IC) Change in body temperature (>0.5°C, <1 hr before and/or during IC) Expected duration of ICU stay < 24 hours Expected survival of the patient < 24 hours

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Mechanically ventilated ICU patient<br>Indirect calorimetry measurements will be conducted using the new calorimeter and the mass spectrometer system at the same time for all enrolled patients. | Other: Indirect calorimetry<br>* Indirect calorimetry will be conducted using the new calorimeter and mixing chamber method using the mass spectrometer.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy of Energy expenditure | Energy expenditure calculated as a result of VO2 and VCO2 measurements | immediately after the measurement | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy of VO2 | Volume of oxygen consumption | immediately after the measurement | 
| Accuracy of VCO2 | Volume of CO2 production | immediately after the measurement | 
| Respiratory quotient (RQ) | RQ calculated as a ratio of VCO2 to VO2 | immediately after the measurement | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Indirect calorimetry, ICALIC Study, Energy expenditure, VO2, VCO2, Respiratory quotient