Brain DeathNCT06983990
ORI and ETCO₂ Relationship With Arterial Blood Gas During Apnea Test
An observational study of Brain Death, run by Bursa Yuksek Ihtisas Training and Research Hospital at 1 site in Turkey (Türkiye).
Trial summary
This observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO2) values with arterial blood gas parameters in patients undergoing the apnea test for the diagnosis of brain death. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Brain Death
- How many people
- 35 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Jul 2023to 1 Jun 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
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: The study will include adult patients (aged 18 and over) who are being monitored in the intensive care units of the University of Health Sciences Bursa Yuksek Ihtisas Training and Research Hospital and are suspected of brain death, for whom an apnea test has been scheduled by their physician as part of the brain death diagnosis process. The study population will consist of patients who meet the inclusion criteria and for whom written informed consent has been obtained from a legally authorized representative. Patients whose first-degree relatives have declined participation, and those in whom the Oxygen Reserve Index (ORI) probe cannot be used due to circulatory disorders in the extremities, will be excluded from the study.
Who may be able to join
- Patients who meet all the prerequisites for initiating the brain death diagnosis process and for whom the decision to perform the apnea test for diagnosis of brain death.
- Patients aged 18 years or older.
- Patients who have provided verbal and written consent from their first-degree relatives.
Who cannot join
- Patients whose first-degree relatives do not consent to participation in the study.
- Patients in whom the ORI probe cannot be used due to circulatory disturbances in the extremities
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Health Sciences University Bursa Yüksek İhtisas Training and Research Hospital
Bursa
About this study
Official title: Evaluation of the Relationship of Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO₂) With Arterial Blood Gas Parameters During the Apnea Test
This observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO2) values with arterial blood gas parameters in patients undergoing the apnea test for the diagnosis of brain death. The study will examine the correlation between ORI and PaO2, as well as between ETCO2 and PaCO2. The primary objective is to assess the effectiveness of ORI in evaluating oxygenation and its applicability in the apnea test. The study will also evaluate the routine use of ORI in monitoring PaO2 and its potential benefits compared to traditional methods.
Read the detailed description
This observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and partial arterial oxygen pressure (PaO2), as well as between End-Tidal Carbon Dioxide (ETCO2) and partial arterial carbon dioxide pressure (PaCO2) in patients undergoing an apnea test for the diagnosis of brain death. ORI is a relatively new, non-invasive monitoring tool that allows continuous and real-time assessment of oxygenation status. It is a dimensionless parameter with values ranging from 0 to 1. ORI is based on a multi-wavelength pulse co-oximeter that detects light absorption in both arterial and venous blood through a probe. It is designed to estimate PaO2 values in the 100-200 mmHg range, as SpO2 typically reaches ≥97% when PaO2 exceeds 80 mmHg, making it unable to reflect higher PaO2 levels accurately. The apnea test is a critical procedure for the diagnosis of brain death, in which the presence or absence of spontaneous breathing in response to carbon dioxide accumulation is evaluated. During the test, arterial blood gas (ABG) measurements are taken to monitor the rise in PaCO2. Before the test begins, the patient is ventilated with 100% oxygen to raise PaO2 above 200 mmHg, which is confirmed with a pre-test ABG sample. The patient must also be normocapnic prior to testing.
As arterial blood sampling is an invasive procedure, this study aims to assess the predictability of PaO2 and PaCO2 using ORI and ETCO2 in the pre-test phase. The primary objective is to determine the capability of ORI to monitor oxygenation status and evaluate its potential to detect hypoxia earlier. Moreover, by comparing ORI to conventional methods, this study seeks to explore its potential routine use in clinical settings for PaO2 monitoring and its possible advantages. In patients undergoing apnea testing for suspected brain death, this study may help determine whether ORI offers benefits over current monitoring approaches and whether it can reduce dependence on invasive ABG sampling. Furthermore, hyperoxia, like hypoxia, poses various clinical risks. The clinical use of ORI alongside SpO2 may help prevent hyperoxia and enable earlier detection of hypoxia. This may enhance patient safety and improve clinical decision-making in critical care environments.
- Conditions
- Brain Death
- Being tested
- No intervention (observational monitoring only)
- Keywords
- Oxygen Reserve Index, ORI, Apnea test, Brain Death, End-Tidal Carbon Dioxide, ETCO2, Hyperoxia, Hypoxia
- Medical subject headings
- Brain Death, Hyperoxia, Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No intervention (observational monitoring only)Other
No intervention is applied. This is an observational study evaluating the correlation between non-invasive monitoring parameters and arterial blood gas values during apnea testing.
| Study group | Role | What they receive |
|---|---|---|
| Apnea test group | Patients undergoing an apnea test as part of brain death evaluation are monitored for correlation analysis of oxygen reserve index (ORI), end-tidal CO₂ (ETCO₂), and arterial blood gas parameters (PaO₂, PaCO₂). No intervention is applied in this observational study. Receives: Other: No intervention (observational monitoring only) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Correlation between Oxygen Reserve Index (ORI) and arterial PaO2 during apnea test
Assess the correlation between non-invasive ORI values obtained from Masimo pulse CO-oximeter and arterial partial pressure of oxygen (PaO2) measured from arterial blood gases during the apnea test.
Measured: Before and at specific intervals during the apnea test
Secondary outcomes (1)
Correlation between End-Tidal Carbon Dioxide (ETCO2) and arterial PaCO2 during apnea test
Assess the correlation between ETCO2 values from capnography and arterial partial pressure of carbon dioxide (PaCO2)
Measured: Before the apnea test, at the start of the test, and end of the test
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 May 2025
- Study start1 Jul 2023
- Primary completion1 Jun 2025
- Study completion1 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Brain DeathStudies of the same condition, open and under way.
- 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
- 35 participants (actual)
Sponsor and investigators
- Lead sponsor
- Bursa Yuksek Ihtisas Training and Research Hospital
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Nilay Sertdemir, Bursa Yuksek Ihtisas Training and Research Hospital
- Investigators
- Nilay SERTDEMIR, MD, Principal investigator, Health Sciences University Bursa Yüksek İhtisas Training and Research Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06983990
- Sponsor's protocol ID
- 2011-KAEK-25 2023/05-06
- Status last verified
- Apr 2026
- First submitted
- 14 May 2025
- Last updated
- 22 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Vivien B, Amour J, Nicolas-Robin A, Vesque M, Langeron O, Coriat P, Riou B. An evaluation of capnography monitoring during the apnoea test in brain-dead patients. Eur J Anaesthesiol. 2007 Oct;24(10):868-75. doi: 10.1017/S0265021507000725. Epub 2007 Jun 20.
PubMed 17579950Applegate RL 2nd, Dorotta IL, Wells B, Juma D, Applegate PM. The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery. Anesth Analg. 2016 Sep;123(3):626-33. doi: 10.1213/ANE.0000000000001262.
PubMed 27007078
Study at a glance
From the registry record, last updated by the sponsor on 22 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluation of the Relationship of Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO₂) With Arterial Blood Gas Parameters During the Apnea Test
- ClinicalTrials.gov ID
- NCT06983990
- Acronym / sponsor ID
- 2011-KAEK-25 2023/05-06
- Conditions
- Brain Death
- Keywords
- Oxygen Reserve Index, ORI, Apnea test, Brain Death, End-Tidal Carbon Dioxide, ETCO2, Hyperoxia, Hypoxia
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 35 participants (actual)
- Lead sponsor
- Bursa Yuksek Ihtisas Training and Research HospitalOther government
- Study start
- 1 Jul 2023 (actual)
- Primary completion
- 1 Jun 2025 (actual)
- Study completion
- 1 Jun 2025 (actual)
- First posted
- 22 May 2025 (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 observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and End-Tidal Carbon Dioxide (ETCO2) values with arterial blood gas parameters in patients undergoing the apnea test for the diagnosis of brain death. The study will examine the correlation between ORI and PaO2, as well as between ETCO2 and PaCO2. The primary objective is to assess the effectiveness of ORI in evaluating oxygenation and its applicability in the apnea test. The study will also evaluate the routine use of ORI in monitoring PaO2 and its potential benefits compared to traditional methods.
Detailed description
This observational study aims to evaluate the relationship between the Oxygen Reserve Index (ORI) and partial arterial oxygen pressure (PaO2), as well as between End-Tidal Carbon Dioxide (ETCO2) and partial arterial carbon dioxide pressure (PaCO2) in patients undergoing an apnea test for the diagnosis of brain death. ORI is a relatively new, non-invasive monitoring tool that allows continuous and real-time assessment of oxygenation status. It is a dimensionless parameter with values ranging from 0 to 1. ORI is based on a multi-wavelength pulse co-oximeter that detects light absorption in both arterial and venous blood through a probe. It is designed to estimate PaO2 values in the 100-200 mmHg range, as SpO2 typically reaches ≥97% when PaO2 exceeds 80 mmHg, making it unable to reflect higher PaO2 levels accurately. The apnea test is a critical procedure for the diagnosis of brain death, in which the presence or absence of spontaneous breathing in response to carbon dioxide accumulation is evaluated. During the test, arterial blood gas (ABG) measurements are taken to monitor the rise in PaCO2. Before the test begins, the patient is ventilated with 100% oxygen to raise PaO2 above 200 mmHg, which is confirmed with a pre-test ABG sample. The patient must also be normocapnic prior to testing.
As arterial blood sampling is an invasive procedure, this study aims to assess the predictability of PaO2 and PaCO2 using ORI and ETCO2 in the pre-test phase. The primary objective is to determine the capability of ORI to monitor oxygenation status and evaluate its potential to detect hypoxia earlier. Moreover, by comparing ORI to conventional methods, this study seeks to explore its potential routine use in clinical settings for PaO2 monitoring and its possible advantages. In patients undergoing apnea testing for suspected brain death, this study may help determine whether ORI offers benefits over current monitoring approaches and whether it can reduce dependence on invasive ABG sampling. Furthermore, hyperoxia, like hypoxia, poses various clinical risks. The clinical use of ORI alongside SpO2 may help prevent hyperoxia and enable earlier detection of hypoxia. This may enhance patient safety and improve clinical decision-making in critical care environments.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Apnea test group | – | Other: No intervention (observational monitoring only)Patients undergoing an apnea test as part of brain death evaluation are monitored for correlation analysis of oxygen reserve index (ORI), end-tidal CO₂ (ETCO₂), and arterial blood gas parameters (PaO₂, PaCO₂). No intervention is applied in this observational study. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The study will include adult patients (aged 18 and over) who are being monitored in the intensive care units of the University of Health Sciences Bursa Yuksek Ihtisas Training and Research Hospital and are suspected of brain death, for whom an apnea test has been scheduled by their physician as part of the brain death diagnosis process. The study population will consist of patients who meet the inclusion criteria and for whom written informed consent has been obtained from a legally authorized representative. Patients whose first-degree relatives have declined participation, and those in whom the Oxygen Reserve Index (ORI) probe cannot be used due to circulatory disorders in the extremities, will be excluded from the study.
Key inclusion criteria (3 listed)
- Patients who meet all the prerequisites for initiating the brain death diagnosis process and for whom the decision to perform the apnea test for diagnosis of brain death.
- Patients aged 18 years or older.
- Patients who have provided verbal and written consent from their first-degree relatives.
Key exclusion criteria (2 listed)
- Patients whose first-degree relatives do not consent to participation in the study.
- Patients in whom the ORI probe cannot be used due to circulatory disturbances in the extremities
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 |
|---|---|---|
| No intervention (observational monitoring only)No intervention is applied. This is an observational study evaluating the correlation between non-invasive monitoring parameters and arterial blood gas values during apnea testing. | Other | Apnea test group |
Primary outcome
Correlation between Oxygen Reserve Index (ORI) and arterial PaO2 during apnea test
Time frame: Before and at specific intervals during the apnea test
Assess the correlation between non-invasive ORI values obtained from Masimo pulse CO-oximeter and arterial partial pressure of oxygen (PaO2) measured from arterial blood gases during the apnea test.
1 secondary outcome
Correlation between End-Tidal Carbon Dioxide (ETCO2) and arterial PaCO2 during apnea test
Time frame: Before the apnea test, at the start of the test, and end of the test
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Apr 2026.
- Results publication: PubMed 17579950Vivien B, Amour J, Nicolas-Robin A, Vesque M, Langeron O, Coriat P, Riou B. An evaluation of capnography monitoring during the apnoea test in brain-dead patients. Eur J Anaesthesiol. 2007 Oct;24(10):868-75. doi: 10.1017/S0265021507000725. Epub 2007 Jun 20.
- Results publication: PubMed 27007078Applegate RL 2nd, Dorotta IL, Wells B, Juma D, Applegate PM. The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery. Anesth Analg. 2016 Sep;123(3):626-33. doi: 10.1213/ANE.0000000000001262.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Nilay SERTDEMIR, MD principal investigator
Health Sciences University Bursa Yüksek İhtisas Training and Research Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Brain Death, run by Bursa Yuksek Ihtisas Training and Research Hospital at 1 site in Turkey (Türkiye).
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 3 inclusion and 2 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: finished, as of the sponsor's last update on 22 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Correlation between Oxygen Reserve Index (ORI) and arterial PaO2 during apnea test (time frame: Before and at specific intervals during the apnea test). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06983990, which also lists 2 linked publications.
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 22 Apr 2026.