Indirect CalorimetryIC-PEEPNCT07796698
Effect of PEEP on Indirect Calorimetry in Critically Ill Patients
A study testing Protocolized PEEP Adjustment in people with Indirect Calorimetry and Mechanical Ventilation, run by Vastra Gotaland Region.
Trial summary
Indirect calorimetry is used in intensive care to measure how much oxygen a patient consumes and how much carbon dioxide is produced. These measurements are used to estimate energy expenditure and help guide nutritional treatment. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Indirect Calorimetry, Mechanical Ventilation, Positive End-Expiratory Pressure
- What is being tested?
- Protocolized PEEP Adjustment
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- No sites listed yet
- Study dates
- 1 Nov 2026to 1 Oct 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 18 years or older.
- Admitted to CIVA or NIVA at Sahlgrenska University Hospital.
- Receiving invasive mechanical ventilation.
- Expected intensive care stay longer than 72 hours.
- Arterial catheter in place.
- Clinical condition considered sufficiently stable by the responsible physician and research nurse to undergo the study-specific PEEP sequence.
- PEEP levels of 8, 12, and 16 cmH2O considered clinically acceptable for the participant during the study measurement period.
Who cannot join
- Ongoing or planned continuous renal replacement therapy or intermittent hemodialysis (CRRT/iHD).
- Extracorporeal membrane oxygenation (ECMO).
- Fraction of inspired oxygen (FiO2) >0.70.
- Severe renal failure or rapidly increasing creatinine where metabolic measurements may be difficult to interpret.
- Terminal illness or decision for end-of-life care.
- Previous participation in the study during the same ICU admission.
- Clinical instability or other condition judged by the responsible physician to make the PEEP measurement sequence unsafe or inappropriate.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Effect of Positive End-Expiratory Pressure on Indirect Calorimetry Measurements in Mechanically Ventilated Critically Ill Patients: A Prospective Physiological Study
Indirect calorimetry is used in intensive care to measure how much oxygen a patient consumes and how much carbon dioxide is produced. These measurements are used to estimate energy expenditure and help guide nutritional treatment. In mechanically ventilated patients, however, ventilator settings may potentially influence the accuracy of indirect calorimetry.
This study will investigate whether changes in positive end-expiratory pressure (PEEP), a routinely used ventilator setting, affect measurements obtained by indirect calorimetry in critically ill mechanically ventilated adults.
Read more
Each participant will undergo indirect calorimetry at three PEEP levels: 8, 12, and 16 cmH2O. Each PEEP level will be maintained for a stabilization period before measurements are obtained. Other ventilator settings will be kept unchanged during the measurement sequence whenever clinically feasible.
The study will compare oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient (RQ), and resting energy expenditure (REE) across the three PEEP levels. The aim is to determine whether clinically relevant changes in PEEP systematically influence indirect calorimetry measurements and their interpretation.
Read the detailed description
Indirect calorimetry (IC) is considered a reference method for assessment of energy expenditure in critically ill patients. It measures oxygen consumption (VO2) and carbon dioxide production (VCO2), from which respiratory quotient (RQ) and resting energy expenditure (REE) are calculated. Reliable measurements are important when IC is used to guide nutritional therapy in mechanically ventilated intensive care patients.
Measurement accuracy may potentially be influenced by ventilator settings and changes in respiratory mechanics. Positive end-expiratory pressure (PEEP) is frequently adjusted during intensive care, but there is limited clinical evidence regarding whether changes in PEEP within commonly used ranges systematically affect contemporary indirect calorimetry measurements. The approved research project therefore includes a physiological substudy specifically examining the influence of PEEP on VO2, VCO2, RQ, and REE.
This is a prospective, single-center, repeated-measures physiological study conducted in mechanically ventilated adult intensive care patients at Sahlgrenska University Hospital. Participants undergo indirect calorimetry during a standardized sequence of three PEEP levels: 8, 12, and 16 cmH2O. Each participant therefore serves as their own control.
At each PEEP level, the patient is allowed to reach a stable condition before indirect calorimetry measurements are obtained. The ethics protocol specifies a stabilization period before measurement and that other ventilator settings should remain unchanged during the PEEP sequence. The final operational study protocol uses PEEP levels of 8, 12, and 16 cmH2O.
Indirect calorimetry measurements will include VO2, VCO2, RQ, and REE. Measurements will be performed under standardized conditions, with attention to measurement stability and ventilator leakage. In the underlying research protocol, acceptable IC measurement periods are defined using steady-state criteria and controlled ventilator conditions.
The primary objective is to determine whether VO2, VCO2, RQ, and REE change systematically across PEEP levels of 8, 12, and 16 cmH2O. Repeated measurements will be analyzed using mixed-effects models accounting for clustering of observations within participants.
PEEP changes are performed within clinically accepted ranges under continuous intensive care monitoring. The measurement sequence will be interrupted if clinically relevant deterioration in hemodynamics, oxygenation, or other physiological parameters occurs. The ethics protocol specifically requires PEEP changes to remain within clinically acceptable levels and to be discontinued if adverse physiological effects are observed.
A relative difference of 10% in indirect calorimetry-derived measurements between PEEP levels was considered clinically meaningful. Assuming a within-participant standard deviation of approximately 12.5%, corresponding to a standardized paired effect size of 0.8, approximately 15 evaluable participants are required to achieve 80% power at a two-sided alpha level of 0.05. To account for incomplete measurement sequences and technically inadequate indirect calorimetry measurements, 20 participants are planned for enrollment.
- Being tested
- Protocolized PEEP Adjustment
- Keywords
- Indirect calorimetry, PEEP, Positive end-expiratory pressure, Critical illness, Intensive care, Oxygen consumption, VO2, Carbon dioxide production, VCO2, Respiratory quotient, RQ, Resting energy expenditure, REE
- Medical subject headings
- Critical Illness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Protocolized PEEP AdjustmentOther
Positive end-expiratory pressure (PEEP) is adjusted sequentially to 8, 12, and 16 cmH2O during a single study session. Each level is maintained until the predefined stabilization criteria are met before indirect calorimetry measurements are obtained. The sequence is performed under continuous intensive care monitoring and is discontinued if clinically relevant deterioration occurs.
| Study group | Role | What they receive |
|---|---|---|
| Sequential PEEP Levels | Experimental | All participants undergo indirect calorimetry measurements during a standardized sequence of PEEP levels at 8, 12, and 16 cmH2O. Each PEEP level is maintained for a predefined stabilization period before measurement. Other ventilator settings are kept unchanged whenever clinically feasible. Each participant therefore serves as their own control. Receives: Other: Protocolized PEEP Adjustment |
What is being measured
The primary outcome is the main question the study is designed to answer.
Resting Energy Expenditure Across PEEP Levels
Resting energy expenditure (REE), measured by indirect calorimetry and expressed in kcal/day, will be compared within participants across PEEP levels of 8, 12, and 16 cmH2O. The primary objective is to determine whether changes in PEEP produce systematic and clinically meaningful changes in measured REE.
Measured: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Secondary outcomes (3)
Oxygen Consumption Across PEEP Levels
VO₂ in mL/min compared within participants at PEEP 8, 12, and 16 cmH₂O.
Measured: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Carbon Dioxide Production Across PEEP Levels
VCO₂ in mL/min compared within participants at the three PEEP levels.
Measured: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Respiratory Quotient Across PEEP Levels
RQ calculated as VCO₂/VO₂ and compared within participants at the three PEEP levels.
Measured: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Sep 2026
- Study start1 Nov 2026 (estimated)
- Primary completion1 Jun 2028 (estimated)
- Study completion1 Oct 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Indirect CalorimetryStudies of the same condition, open and under way.
- More trials run by Vastra Gotaland RegionThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Sequential
- Model description
- All participants undergo repeated indirect calorimetry measurements during a standardized sequence of PEEP levels at 8, 12, and 16 cmH2O. Each PEEP level is maintained for a predefined stabilization period before measurement, while other ventilator settings are kept unchanged whenever clinically feasible. Each participant therefore serves as their own control for comparison of indirect calorimetry variables across PEEP levels.
- Masking
- None (open label)
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Vastra Gotaland Region
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Carl Sjödin, Vastra Gotaland Region
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07796698
- Sponsor's protocol ID
- IC-PEEP-01
- Acronym
- IC-PEEP
- Status last verified
- Aug 2026
- First submitted
- 25 Aug 2026
- Last updated
- 1 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: The feasibility and conditions for sharing de-identified individual participant data have not yet been determined. Any future data sharing will be subject to applicable ethical approvals, data protection regulations, institutional policies, and appropriate data-sharing agreements.
Study at a glance
From the registry record, last updated by the sponsor on 1 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Positive End-Expiratory Pressure on Indirect Calorimetry Measurements in Mechanically Ventilated Critically Ill Patients: A Prospective Physiological Study
- ClinicalTrials.gov ID
- NCT07796698
- Acronym / sponsor ID
- IC-PEEP / IC-PEEP-01
- Keywords
- Indirect calorimetry, PEEP, Positive end-expiratory pressure, Critical illness, Intensive care, Oxygen consumption, VO2, Carbon dioxide production
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 20 participants (estimated)
- Lead sponsor
- Vastra Gotaland RegionOther government
- Study start
- 1 Nov 2026 (estimated)
- Primary completion
- 1 Jun 2028 (estimated)
- Study completion
- 1 Oct 2028 (estimated)
- First posted
- 1 Sep 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Indirect calorimetry is used in intensive care to measure how much oxygen a patient consumes and how much carbon dioxide is produced. These measurements are used to estimate energy expenditure and help guide nutritional treatment. In mechanically ventilated patients, however, ventilator settings may potentially influence the accuracy of indirect calorimetry.
This study will investigate whether changes in positive end-expiratory pressure (PEEP), a routinely used ventilator setting, affect measurements obtained by indirect calorimetry in critically ill mechanically ventilated adults.
Each participant will undergo indirect calorimetry at three PEEP levels: 8, 12, and 16 cmH2O. Each PEEP level will be maintained for a stabilization period before measurements are obtained. Other ventilator settings will be kept unchanged during the measurement sequence whenever clinically feasible.
The study will compare oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory quotient (RQ), and resting energy expenditure (REE) across the three PEEP levels. The aim is to determine whether clinically relevant changes in PEEP systematically influence indirect calorimetry measurements and their interpretation.
Detailed description
Indirect calorimetry (IC) is considered a reference method for assessment of energy expenditure in critically ill patients. It measures oxygen consumption (VO2) and carbon dioxide production (VCO2), from which respiratory quotient (RQ) and resting energy expenditure (REE) are calculated. Reliable measurements are important when IC is used to guide nutritional therapy in mechanically ventilated intensive care patients.
Measurement accuracy may potentially be influenced by ventilator settings and changes in respiratory mechanics. Positive end-expiratory pressure (PEEP) is frequently adjusted during intensive care, but there is limited clinical evidence regarding whether changes in PEEP within commonly used ranges systematically affect contemporary indirect calorimetry measurements. The approved research project therefore includes a physiological substudy specifically examining the influence of PEEP on VO2, VCO2, RQ, and REE.
This is a prospective, single-center, repeated-measures physiological study conducted in mechanically ventilated adult intensive care patients at Sahlgrenska University Hospital. Participants undergo indirect calorimetry during a standardized sequence of three PEEP levels: 8, 12, and 16 cmH2O. Each participant therefore serves as their own control.
At each PEEP level, the patient is allowed to reach a stable condition before indirect calorimetry measurements are obtained. The ethics protocol specifies a stabilization period before measurement and that other ventilator settings should remain unchanged during the PEEP sequence. The final operational study protocol uses PEEP levels of 8, 12, and 16 cmH2O.
Indirect calorimetry measurements will include VO2, VCO2, RQ, and REE. Measurements will be performed under standardized conditions, with attention to measurement stability and ventilator leakage. In the underlying research protocol, acceptable IC measurement periods are defined using steady-state criteria and controlled ventilator conditions.
The primary objective is to determine whether VO2, VCO2, RQ, and REE change systematically across PEEP levels of 8, 12, and 16 cmH2O. Repeated measurements will be analyzed using mixed-effects models accounting for clustering of observations within participants.
PEEP changes are performed within clinically accepted ranges under continuous intensive care monitoring. The measurement sequence will be interrupted if clinically relevant deterioration in hemodynamics, oxygenation, or other physiological parameters occurs. The ethics protocol specifically requires PEEP changes to remain within clinically acceptable levels and to be discontinued if adverse physiological effects are observed.
A relative difference of 10% in indirect calorimetry-derived measurements between PEEP levels was considered clinically meaningful. Assuming a within-participant standard deviation of approximately 12.5%, corresponding to a standardized paired effect size of 0.8, approximately 15 evaluable participants are required to achieve 80% power at a two-sided alpha level of 0.05. To account for incomplete measurement sequences and technically inadequate indirect calorimetry measurements, 20 participants are planned for enrollment.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- All participants undergo repeated indirect calorimetry measurements during a standardized sequence of PEEP levels at 8, 12, and 16 cmH2O. Each PEEP level is maintained for a predefined stabilization period before measurement, while other ventilator settings are kept unchanged whenever clinically feasible. Each participant therefore serves as their own control for comparison of indirect calorimetry variables across PEEP levels.
| Arm | Type | Receives |
|---|---|---|
| Sequential PEEP Levels | Experimental | Other: Protocolized PEEP AdjustmentAll participants undergo indirect calorimetry measurements during a standardized sequence of PEEP levels at 8, 12, and 16 cmH2O. Each PEEP level is maintained for a predefined stabilization period before measurement. Other ventilator settings are kept unchanged whenever clinically feasible. Each participant therefore serves as their own control. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Age 18 years or older.
- Admitted to CIVA or NIVA at Sahlgrenska University Hospital.
- Receiving invasive mechanical ventilation.
- Expected intensive care stay longer than 72 hours.
- Arterial catheter in place.
Key exclusion criteria (7 listed)
- Ongoing or planned continuous renal replacement therapy or intermittent hemodialysis (CRRT/iHD).
- Extracorporeal membrane oxygenation (ECMO).
- Fraction of inspired oxygen (FiO2) >0.70.
- Severe renal failure or rapidly increasing creatinine where metabolic measurements may be difficult to interpret.
- Terminal illness or decision for end-of-life care.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Protocolized PEEP AdjustmentPositive end-expiratory pressure (PEEP) is adjusted sequentially to 8, 12, and 16 cmH2O during a single study session. Each level is maintained until the predefined stabilization criteria are met before indirect calorimetry measurements are obtained. The sequence is performed under continuous intensive care monitoring and is discontinued if clinically relevant deterioration occurs. | Other | Sequential PEEP Levels |
Primary outcome
Resting Energy Expenditure Across PEEP Levels
Time frame: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Resting energy expenditure (REE), measured by indirect calorimetry and expressed in kcal/day, will be compared within participants across PEEP levels of 8, 12, and 16 cmH2O. The primary objective is to determine whether changes in PEEP produce systematic and clinically meaningful changes in measured REE.
3 secondary outcomes
Oxygen Consumption Across PEEP Levels
Time frame: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Carbon Dioxide Production Across PEEP Levels
Time frame: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Respiratory Quotient Across PEEP Levels
Time frame: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Sep 2026.
- Individual participant dataSharing planned: Undecided. The feasibility and conditions for sharing de-identified individual participant data have not yet been determined. Any future data sharing will be subject to applicable ethical approvals, data protection regulations, institutional policies, and appropriate data-sharing agreements.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Questions about this trial
What is this clinical trial studying?
A study testing Protocolized PEEP Adjustment in people with Indirect Calorimetry and Mechanical Ventilation, run by Vastra Gotaland Region.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 1 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Carl Sjödin, PhD student (0707163277, carl.sjodin@vgregion.se), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Resting Energy Expenditure Across PEEP Levels (time frame: During a single study session: after approximately 20 minutes at each PEEP level (8, 12, and 16 cmH2O)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Sep 2026.