Critical Illness； Intensive Care Unit PatientsNCT07454057
Prospective Observational Study of Exhaled Carbon MonoxideTrajectories and Outcomes in ICU Patients
An observational study of Critical Illness； Intensive Care Unit Patients, run by Shanghai Zhongshan Hospital.
Trial summary
This is a single-center, prospective, observational study in adult intensive care unit (ICU) patients. The study will measure exhaled carbon monoxide (eCO) once daily for up to 7 days after ICU admission using a red blood cell lifespan breath analyzer, which simultaneously estimates erythrocyte lifespan. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Critical Illness； Intensive Care Unit Patients
- How many people
- 220 participants
- Where
- No sites listed yet
- Study dates
- 15 Mar 2026to 30 Nov 2027
- Phase
- Observational
- 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
Study population: Adult intensive care unit (ICU) patients (≥18 years) admitted to the study site will be screened consecutively. Eligible participants are those expected to remain in the ICU for at least 48 hours and able to complete daily exhaled carbon monoxide (eCO) measurements (spontaneously breathing or mechanically ventilated). Written informed consent will be obtained from the patient or a legally authorized representative. Patients meeting any exclusion criteria (e.g., carbon monoxide poisoning, active smoking within 24 hours, inability to perform breath sampling, pregnancy/breastfeeding, hereditary hemoglobinopathies) will not be enrolled. Participants may be withdrawn if informed consent is revoked, if continued data collection is judged clinically inappropriate, if the patient is transferred and lost to follow-up, or if eCO data are missing for more than 50% of the 7-day collection period (fewer than 4 valid measurements).
Who may be able to join
- Age ≥ 18 years
- Admitted to the intensive care unit (ICU) at the study site
- Expected ICU length of stay ≥ 48 hours
- Able to complete exhaled carbon monoxide (eCO) measurement (spontaneously breathing or mechanically ventilated)
- Written informed consent provided by the patient or a legally authorized representative
Who cannot join
- Carbon monoxide poisoning
- Active smoking within 24 hours prior to ICU admission
- Unable to perform breath sampling (e.g., massive airway bleeding, severe airway obstruction, extracorporeal membrane oxygenation)
- Ineffective sampling due to poor mask seal or special ventilation modes
- Pregnant or breastfeeding
- Known hereditary hemoglobinopathies (e.g., sickle cell disease, thalassemia)
- Patient or family refusal
- Other conditions deemed unsuitable by investigators
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: Prospective Observational Study of Exhaled Carbon Monoxide Trajectories and Outcomes in ICU Patients
This is a single-center, prospective, observational study in adult intensive care unit (ICU) patients. The study will measure exhaled carbon monoxide (eCO) once daily for up to 7 days after ICU admission using a red blood cell lifespan breath analyzer, which simultaneously estimates erythrocyte lifespan. eCO is a gas produced endogenously during heme degradation and may reflect hemolysis, oxidative stress, and inflammation in critically ill patients.
The purpose of this study is to describe how eCO changes over time in ICU patients and to determine whether different eCO patterns are associated with clinical outcomes. The primary outcome is all-cause mortality within 28 days after enrollment. Secondary outcomes include 90-day mortality, acute kidney injury, organ dysfunction assessed by SOFA score, transfusion requirement, changes in anemia-related indices, ICU length of stay, and duration of invasive mechanical ventilation. Participation does not change routine clinical care; study procedures involve breath sampling and collection of clinical data from the medical record.
Read the detailed description
Background: Endogenous carbon monoxide is generated in the human body and may increase during critical illness due to hemolysis, oxidative stress, and inflammation. Whether longitudinal patterns of exhaled carbon monoxide (eCO) provide prognostic information in critically ill patients remains unclear.
Design and setting: This is a single-center, prospective, observational cohort study conducted in an adult intensive care unit (ICU). The study is designed to characterize longitudinal eCO patterns and evaluate their clinical significance in critically ill patients without altering routine clinical management.
Study procedures and data collection: eCO will be measured once daily from Day 0 (baseline, within 24 hours of ICU admission/enrollment) through Day 7 when feasible, using a standardized breath analysis device. For patients receiving mechanical ventilation, breath sampling will be performed according to a standardized protocol for ventilated patients. In addition to serial eCO measurements, demographic characteristics, admission diagnosis, comorbidities, severity-of-illness scores, key treatments, and laboratory variables relevant to hemolysis, inflammation, organ function, anemia, and iron metabolism will be collected from the electronic medical record and protocol-defined assessments, as applicable.
Analytic approach: Group-based trajectory modeling (GBTM) will be used to identify distinct eCO trajectory groups from repeated measurements. Associations between eCO trajectories and prespecified clinical outcomes will be evaluated using Kaplan-Meier methods and multivariable Cox proportional hazards models with adjustment for clinically relevant covariates. Additional exploratory analyses will assess relationships between eCO trajectories and laboratory biomarker patterns, including anemia-related, iron metabolism-related, and inflammatory indices. Machine learning methods (e.g., XGBoost with SHAP-based interpretation) may also be used in exploratory analyses to develop risk prediction models incorporating eCO and other clinical variables.
Study conduct: No intervention is assigned as part of the study, and all treatment decisions remain at the discretion of the treating clinicians.
- Keywords
- Exhaled carbon monoxide；, Group-based trajectory modeling, Prognosis, Inflammation, ICU outcomes
- Medical subject headings
- Inflammation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Adult ICU Patients | Consecutive adult intensive care unit (ICU) patients enrolled in a single-center, prospective observational cohort. Exhaled carbon monoxide (eCO) is measured once daily for up to 7 days after ICU admission. Clinical data and outcomes are collected from the medical record and follow-up. No treatment is assigned as part of the study. |
What is being measured
The primary outcome is the main question the study is designed to answer.
28-day all-cause mortality
Measured: From enrollment (Day 0) up to Day 28
Secondary outcomes (8)
90-day all-cause mortality
Measured: From enrollment up to Day 90
Acute kidney injury (AKI) (KDIGO)
Incidence and staging of acute kidney injury defined by KDIGO 2012 criteria (serum creatinine increase ≥0.3 mg/dL within 48 hours, or ≥1.5 times baseline within 7 days, or urine output <0.5 mL/kg/h for ≥6 hours) during ICU hospitalization.
Measured: From enrollment through ICU discharge (up to 28 days)
Organ dysfunction assessed by SOFA score
Daily Sequential Organ Failure Assessment (SOFA) score, a composite organ dysfunction scale ranging from 0 to 24, encompassing respiratory, coagulation, liver, cardiovascular, neurological, and renal subsystems. Each of the 6 organ system components is scored from 0 to 4, with higher scores indicating worse organ dysfunction and greater illness severity. Scores will be assessed daily from Day 0 (baseline) through Day 7.
Measured: Daily from Day 0 (baseline) through Day 7
Red blood cell transfusion requirement
Whether red blood cell transfusion was administered (yes/no), number of transfusion episodes, and total units transfused within 28 days after ICU admission.
Measured: Up to 28 days after ICU admission/enrollment
ICU length of stay
Total duration of invasive mechanical ventilation during the ICU stay.
Measured: From ICU admission to ICU discharge (up to 90 days)
Duration of invasive mechanical ventilation
Total duration of invasive mechanical ventilation during the ICU stay.
Measured: From enrollment to liberation from invasive mechanical ventilation or ICU discharge (up to 28 days)
Complete blood count-related panel
Longitudinal changes in complete blood count-related indices, including hemoglobin, reticulocyte count, and red cell distribution width (RDW), and their associations with eCO trajectories.
Measured: Up to 28 days after enrollment
Changes in iron metabolism related indices
Longitudinal changes in iron metabolism- and erythropoietin-related indices, including serum iron, ferritin, transferrin saturation, soluble transferrin receptor, and erythropoietin (EPO), and their associations with eCO trajectories.
Measured: Baseline and up to 28 days after enrollment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Mar 2026
- Study start15 Mar 2026 (estimated)
- Primary completion30 Aug 2027 (estimated)
- Study completion30 Nov 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Critical Illness； Intensive Care Unit PatientsStudies of the same condition, open and under way.
- More trials run by Shanghai Zhongshan HospitalThe 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 220 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Shanghai Zhongshan Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Ming Zhong, Principal investigator, Fudan University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07454057
- Sponsor's protocol ID
- B2026-018
- Status last verified
- Mar 2026
- First submitted
- 10 Feb 2026
- Last updated
- 6 Mar 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared because this is a single-center observational study with a limited sample size. De-identified summary-level data may be made available upon reasonable request to the corresponding investigator.
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prospective Observational Study of Exhaled Carbon Monoxide Trajectories and Outcomes in ICU Patients
- ClinicalTrials.gov ID
- NCT07454057
- Acronym / sponsor ID
- B2026-018
- Keywords
- Exhaled carbon monoxide；, Group-based trajectory modeling, Prognosis, Inflammation, ICU outcomes
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 220 participants (estimated)
- Lead sponsor
- Shanghai Zhongshan HospitalUniversity, hospital or other
- Study start
- 15 Mar 2026 (estimated)
- Primary completion
- 30 Aug 2027 (estimated)
- Study completion
- 30 Nov 2027 (estimated)
- First posted
- 6 Mar 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.
This is a single-center, prospective, observational study in adult intensive care unit (ICU) patients. The study will measure exhaled carbon monoxide (eCO) once daily for up to 7 days after ICU admission using a red blood cell lifespan breath analyzer, which simultaneously estimates erythrocyte lifespan. eCO is a gas produced endogenously during heme degradation and may reflect hemolysis, oxidative stress, and inflammation in critically ill patients.
The purpose of this study is to describe how eCO changes over time in ICU patients and to determine whether different eCO patterns are associated with clinical outcomes. The primary outcome is all-cause mortality within 28 days after enrollment. Secondary outcomes include 90-day mortality, acute kidney injury, organ dysfunction assessed by SOFA score, transfusion requirement, changes in anemia-related indices, ICU length of stay, and duration of invasive mechanical ventilation. Participation does not change routine clinical care; study procedures involve breath sampling and collection of clinical data from the medical record.
Detailed description
Background: Endogenous carbon monoxide is generated in the human body and may increase during critical illness due to hemolysis, oxidative stress, and inflammation. Whether longitudinal patterns of exhaled carbon monoxide (eCO) provide prognostic information in critically ill patients remains unclear.
Design and setting: This is a single-center, prospective, observational cohort study conducted in an adult intensive care unit (ICU). The study is designed to characterize longitudinal eCO patterns and evaluate their clinical significance in critically ill patients without altering routine clinical management.
Study procedures and data collection: eCO will be measured once daily from Day 0 (baseline, within 24 hours of ICU admission/enrollment) through Day 7 when feasible, using a standardized breath analysis device. For patients receiving mechanical ventilation, breath sampling will be performed according to a standardized protocol for ventilated patients. In addition to serial eCO measurements, demographic characteristics, admission diagnosis, comorbidities, severity-of-illness scores, key treatments, and laboratory variables relevant to hemolysis, inflammation, organ function, anemia, and iron metabolism will be collected from the electronic medical record and protocol-defined assessments, as applicable.
Analytic approach: Group-based trajectory modeling (GBTM) will be used to identify distinct eCO trajectory groups from repeated measurements. Associations between eCO trajectories and prespecified clinical outcomes will be evaluated using Kaplan-Meier methods and multivariable Cox proportional hazards models with adjustment for clinically relevant covariates. Additional exploratory analyses will assess relationships between eCO trajectories and laboratory biomarker patterns, including anemia-related, iron metabolism-related, and inflammatory indices. Machine learning methods (e.g., XGBoost with SHAP-based interpretation) may also be used in exploratory analyses to develop risk prediction models incorporating eCO and other clinical variables.
Study conduct: No intervention is assigned as part of the study, and all treatment decisions remain at the discretion of the treating clinicians.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Adult ICU Patients | – | –Consecutive adult intensive care unit (ICU) patients enrolled in a single-center, prospective observational cohort. Exhaled carbon monoxide (eCO) is measured once daily for up to 7 days after ICU admission. Clinical data and outcomes are collected from the medical record and follow-up. No treatment is assigned as part of the study. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult intensive care unit (ICU) patients (≥18 years) admitted to the study site will be screened consecutively. Eligible participants are those expected to remain in the ICU for at least 48 hours and able to complete daily exhaled carbon monoxide (eCO) measurements (spontaneously breathing or mechanically ventilated). Written informed consent will be obtained from the patient or a legally authorized representative. Patients meeting any exclusion criteria (e.g., carbon monoxide poisoning, active smoking within 24 hours, inability to perform breath sampling, pregnancy/breastfeeding, hereditary hemoglobinopathies) will not be enrolled. Participants may be withdrawn if informed consent is revoked, if continued data collection is judged clinically inappropriate, if the patient is transferred and lost to follow-up, or if eCO data are missing for more than 50% of the 7-day collection period (fewer than 4 valid measurements).
Key inclusion criteria (5 listed)
- Age ≥ 18 years
- Admitted to the intensive care unit (ICU) at the study site
- Expected ICU length of stay ≥ 48 hours
- Able to complete exhaled carbon monoxide (eCO) measurement (spontaneously breathing or mechanically ventilated)
- Written informed consent provided by the patient or a legally authorized representative
Key exclusion criteria (8 listed)
- Carbon monoxide poisoning
- Active smoking within 24 hours prior to ICU admission
- Unable to perform breath sampling (e.g., massive airway bleeding, severe airway obstruction, extracorporeal membrane oxygenation)
- Ineffective sampling due to poor mask seal or special ventilation modes
- Pregnant or breastfeeding
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
28-day all-cause mortality
Time frame: From enrollment (Day 0) up to Day 28
8 secondary outcomes
90-day all-cause mortality
Time frame: From enrollment up to Day 90
Acute kidney injury (AKI) (KDIGO)
Time frame: From enrollment through ICU discharge (up to 28 days)
Organ dysfunction assessed by SOFA score
Time frame: Daily from Day 0 (baseline) through Day 7
Red blood cell transfusion requirement
Time frame: Up to 28 days after ICU admission/enrollment
ICU length of stay
Time frame: From ICU admission to ICU discharge (up to 90 days)
Duration of invasive mechanical ventilation
Time frame: From enrollment to liberation from invasive mechanical ventilation or ICU discharge (up to 28 days)
Complete blood count-related panel
Time frame: Up to 28 days after enrollment
Changes in iron metabolism related indices
Time frame: Baseline and up to 28 days after enrollment
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 6 Mar 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be shared because this is a single-center observational study with a limited sample size. De-identified summary-level data may be made available upon reasonable request to the corresponding investigator.
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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.
Ming Zhong principal investigator
Fudan University
Questions about this trial
What is this clinical trial studying?
An observational study of Critical Illness； Intensive Care Unit Patients, run by Shanghai Zhongshan Hospital.
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 5 inclusion and 8 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 6 Mar 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 Fei Leng, MD. (021-64041990, leng.fei@zs-hospital.sh.cn), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
28-day all-cause mortality (time frame: From enrollment (Day 0) up to Day 28). 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 6 Mar 2026.