An interventional study of Apnea test under HHFO followed by an apnea test under CPAP. and Apnea test under CPAP followed by an apnea test under HHFO. in Death, Brain, sponsored by Centre Hospitalier Régional d'Orléans. Not yet recruiting at 4 sites in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-10.
Sponsored by Centre Hospitalier Régional d'Orléans · Not applicable, Interventional, and Other
Brain death (BD) is characterized by a severe brain injury resulting in irreversible loss of all brain and brainstem functions, while other organs may remain viable. The diagnosis of BD is based on the presence of coma, absence of brainstem reflexes, and absence of spontaneous breathing confirmed by an apnea test. In France, the apnea test is mandatory prior to organ procurement. The apnea test aims to demonstrate that hypercapnia, a strong ventilatory stimulus, does not induce any respiratory movements.
In current practice, the apnea test is performed by disconnecting the patient from mechanical ventilation for 8-10 minutes while administering oxygen. Oxygenation strategies during apnea vary across French centers. Although the use of continuous positive airway pressure (CPAP) is recommended, a substantial proportion of tests are still performed without positive end-expiratory pressure (PEEP) effect, using either an open T-piece or an intratracheal oxygen catheter. These methods are associated with a higher risk of complications, such as hypoxemia, and potential adverse effects on organ function, which is particularly relevant in the context of organ donation.
Humidified high-flow oxygen (HHFO), delivered via a specialized device connected to the endotracheal tube, provides high flow rates (up to 60 L/min), allows precise adjustment of the fraction of inspired oxygen (FiO₂ up to 1.0), and generates a minimal PEEP effect. HHFO is routinely used in intensive care units. While its feasibility during apnea testing has been reported, its efficacy during BD diagnosis has not been well evaluated.
Preliminary observations in intensive care patients with clinical brain death suggest that HHFO can be safely used during the apnea test, allowing achievement of hypercapnia and confirmation of absence of spontaneous respiration while maintaining better oxygenation compared with conventional oxygen delivery via an open T-piece.
This study aims to evaluate the efficacy of HHFO for apneic oxygenation during the apnea test, in comparison with the recommended method using CPAP.
The study strategy is based on performing two consecutive apnea tests in patients with clinical brain death, conducted in a randomized order. Only patients in whom the first apnea test confirms the absence of spontaneous breathing will proceed to the second apnea test. Consistency of clinical brain death at the end of the first apnea test are defined by the absence of any respiratory movement and the presence of either an arterial partial pressure of carbon dioxide (PaCO₂) ≥ 60 mmHg or an increase in PaCO₂ > 20 mmHg compared with the PaCO₂ measured at the end of the preoxygenation period.
Each of the two apnea tests will be preceded by a standardized 15-minute preoxygenation period using assisted controlled ventilation with a tidal volume of 6mL/kg of predicted body weight.
The two consecutive apnea tests will be performed in randomized order under CPAP and under HHFO with standardized parameters.
As per routine clinical practice, an arterial blood gas sample will be obtained before disconnection from the ventilator at the end of the preoxygenation period to confirm normocapnia, defined as 35 mmHg ≤ PaCO₂ ≤ 45 mmHg. A second arterial blood gas sample will be obtained at the end of the apnea test, prior to reconnection to the ventilator, to measure PaCO₂ and arterial partial pressure of oxygen (PaO₂).
Specifically for the purposes of the study, during each apnea test, the investigator will perform arterial blood gas sampling every 2 minutes to measure PaO₂, PaCO₂, and pH. At the same time points, arterial blood pressure, heart rate, pulse oximetry, and catecholamine infusion doses will be recorded.
In addition to these measurements required to meet the study objectives, demographic and clinical data will be collected primarily from the medical records to characterize the study population.
74 studies on the registry are indexed under Brain Death; 10 are open to participants now.
This study's planned enrollment of 28 is below the median of 154 across 39 interventional studies indexed under Brain Death.
Browse Brain Death studies →Centre Hospitalier Régional d'Orléans is the lead sponsor of 132 studies on the registry; 32 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HHFO in first: in this arm, the first of the two consecutive apnea tests is performed under HHFO, followed by a second apnea test under CPAP.
Other: Apnea test under HHFO followed by an apnea test under CPAP. · Other: Apnea test under CPAP followed by an apnea test under HHFO.
CPAP in first: in this arm, the first of the two consecutive apnea tests is performed under CPAP, followed by a second apnea test under HHFO.
Other: Apnea test under HHFO followed by an apnea test under CPAP. · Other: Apnea test under CPAP followed by an apnea test under HHFO.
For each 10-minute apnea test, regardless of the oxygenation device used, arterial blood gas will be analysed and heart rate, arterial pressure, and pulse oximetry will be recorded in 2-minute intervals.
For each 10-minute apnea test, regardless of the oxygenation device used, arterial blood gas will be analysed and heart rate, arterial pressure, and pulse oximetry will be recorded in 2-minute intervals.
Change in PaO₂ (mmHg) between the beginning and the end of an apnea test under HHFO and CPAP
To demonstrate the non-inferiority of humidified high-flow oxygen compared to continuous positive airway pressure in apneic oxygenation for apnea testing.
Time frame: From ventilator disconnection to 10th minute of the apnea test
Evolution of arterial blood PaO2 parameters during the apnea test under HHFO and the apnea test with CPAP
Recording of PaO2 values measured in 2-minute intervals during the apnea test under HHFO and apnea test with CPAP
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Evolution of arterial blood PaCO2 parameters during the apnea test under HHFO and the apnea test with CPAP
Recording of PaCO2 values measured in 2-minute intervals during the apnea test under HHFO and apnea test with CPAP
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Evolution of arterial blood pH parameters during the apnea test under HHFO and the apnea test with CPAP
Recording of pH values measured in 2-minute intervals during the apnea test under HHFO and apnea test with CPAP
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Evolution of arterial blood pressure during the apnea test under HHFO and the apnea test with CPAP
Recording of arterial blood pressure measured in 2-minute intervals during the apnea test under HHFO and with CPAP.
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Evolution of heart rate during the apnea test under HHFO and the apnea test with CPAP
Recording of heart rate measured in 2-minute intervals during the apnea test under HHFO and with CPAP.
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Evolution of pulse oximetry during the apnea test under HHFO and the apnea test with CPAP
Recording of pulse oximetry measured in 2-minute intervals during the apnea test under HHFO and with CPAP.
Time frame: At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test
Time required to reach the hypercapnia thresholds necessary to confirm brain death during an apnea test under HHFO and with CPAP
Time required to exceed 60mmHg of PaCO2 or for which PaCO2 increases by more than 20mmHg compared to the PaCO2 before disconnection during an apnea test under HHFO and with CPAP
Time frame: From ventilator disconnection until the hypercapnia threshold is reached
Occurrence of apnea test interruptions during HHFO and CPAP.
Documentation of apnea test interruptions under HHFO and CPAP.
Time frame: From ventilator disconnection until apnea test termination due to intolerance
Nurse-rated numeric scale evaluations of Humidified High Flow Oxygen and Continuous Positive Airway Pressure use for each enrolled patient
Nurse-rated ease of use will be assessed using a 4-point numeric scale (range: 0-3). The minimum score is 0 and the maximum score is 3. A score of 0 corresponds to very difficult use, and a score of 3 corresponds to very easy use. Higher scores indicate greater ease of use
Time frame: Within 1 hour after each apnea test.
Start is estimated for Sep 2026; primary completion for Sep 2028, 24 months later.
Of 14 interventional studies with no phase under Brain Death, half reached primary completion within 29 months of starting (the median), counting those still running; a quarter within 24 and three quarters within 52. This study's planned 24 months is below that.
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This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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