An observational study in Brain Death, sponsored by Bursa Yuksek Ihtisas Training and Research Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-04-22.
Sponsored by Bursa Yuksek Ihtisas Training and Research Hospital · Observational
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.
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.
74 studies on the registry are indexed under Brain Death; 10 are open to participants now.
This study's enrollment of 35 is below the median of 80 across 33 observational studies indexed under Brain Death.
Browse Brain Death studies →Bursa Yuksek Ihtisas Training and Research Hospital is the lead sponsor of 52 studies on the registry; 22 are open to participants now.
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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.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
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.
Other: 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.
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.
Time frame: Before and at specific intervals during the apnea test
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)
Time frame: Before the apnea test, at the start of the test, and end of the test
Plan to share: No
Ran from Jul 2023 to primary completion in Jun 2025, 23 months.
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This study is completed, as verified in Apr 2026. You cannot join it, but the record below documents what was studied.
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Bursa Yuksek Ihtisas Training and Research Hospital