Efficacy of High-Flow Humidified Oxygen (HFHO) in Apneic Oxygenation for Apnea Testing: A Comparison With Continuous Positive Airway Pressure (CPAP)

NCT07640009 | Not Yet Recruiting DMC

• 1 other identifier: CHUO-2025-05
• Study Type: interventional
• Target: 28
• Locations: 1 country
• Sites: 4

Brief Summary

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.

Conditions

Death, Brain

Keywords

Intensive Care Unit; Humidified high-flow oxygen therapy; Continuous positive airway pressure; Apnea testing; Brain death

Outcome Measures

Primary Outcomes (1)

• 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.

  From ventilator disconnection to 10th minute of the apnea test

Secondary Outcomes (9)

• Evolution of arterial blood PaO2 parameters during the apnea test under HHFO and the apnea test with CPAP

  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

  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

  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

  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

  At 2-minute intervals from ventilator disconnection to the 10th minute of each apnea test

Study Arms (2)

Arm HHFO in first

EXPERIMENTAL

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.

Arm CPAP in first.

EXPERIMENTAL

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.

Interventions

Apnea test under HHFO followed by an apnea test under CPAP. OTHER

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.

Arm CPAP in first.; Arm HHFO in first

Apnea test under CPAP followed by an apnea test under HHFO. OTHER

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.

Arm CPAP in first.; Arm HHFO in first

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult intensive care unit patients
• fulfilling all criteria for clinical brain death, for whom confirmation of the absence of spontaneous breathing requires performance of an apnea test
• And for whom consent to participate in the study was sought from a trusted person or a family member

You may not qualify if:

• History of chronic obstructive pulmonary disease (COPD) classified as GOLD stage III or IV.
• Current extracorporeal life support, including veno-arterial (VA) or veno-venous (VV) extracorporeal membrane oxygenation (ECMO).
• PaO₂/FiO₂ ratio ≤ 150 on the most recent arterial blood gas analysis, obtained within 24 hours prior to the screening visit.
• Presence of at least one clear or absolute contraindication to the procurement of at least one organ.
• Presence of a high cervical spinal cord injury.
• Patient in the prone position and/or with a contraindication to placement in the supine position at 30°.
• Minor patient.
• Protected adult under legal guardianship or curatorship.
• Individual under judicial protection (safeguard of justice).
• Individuals deprived of liberty.
• Individual not covered by a social security or health insurance system.
• Pregnant or breastfeeding woman.

Sponsors & Collaborators

• Fisher and Paykel Healthcare: collaborator
• Centre Hospitalier Régional d'Orléans: lead

Study Sites (4)

Chu Angers

Angers, France

Location

Chu de Nantes

Nantes, France

Location

Chu Orleans

Orléans, France

Location

Chru de Tours

Tours, France

Location

MeSH Terms

Conditions

Brain Death

Condition Hierarchy (Ancestors)

Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Coma; Unconsciousness; Consciousness Disorders; Neurobehavioral Manifestations; Neurologic Manifestations; Death; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Randomized controlled crossover multi-center trial

Study Record Dates

• First Submitted: June 5, 2026
• First Posted: June 10, 2026
• Study Start (Estimated): September 15, 2026
• Primary Completion (Estimated): September 15, 2028
• Study Completion (Estimated): September 15, 2028
• Last Updated: June 10, 2026

Record last verified: 2026-06

Locations

FR (4)