Critical Illness
Conditions
Keywords
Indirect calorimetry, ICALIC Study, Energy expenditure, VO2, VCO2, Respiratory quotient
Brief summary
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
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.
Interventions
OTHERIndirect calorimetry
Indirect calorimetry will be conducted using the new calorimeter and mixing chamber method using the mass spectrometer.
Sponsors
University Hospital, Geneva
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Accuracy of Energy expenditure | immediately after the measurement | Energy expenditure calculated as a result of VO2 and VCO2 measurements |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Accuracy of VO2 | immediately after the measurement | Volume of oxygen consumption |
| Accuracy of VCO2 | immediately after the measurement | Volume of CO2 production |
| Respiratory quotient (RQ) | immediately after the measurement | RQ calculated as a ratio of VCO2 to VO2 |
Countries
Switzerland
Contacts
Primary ContactTaku Oshima, MD,PhD
Backup ContactSeverine Graf
Outcome results
None listed