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Key information


Airway Pressure Release Ventilation (APRV) vs conventional ventilation for patients with moderate to severe acute hypoxemic respiratory failure (RELEASE).

Chief Investigators: Prof Luigi Camporota, Prof Danny McAuley

Sponsor: University of Warwick

Funder: NIHR HTA programme (NIHR154501)

Registration Number: ISRCTN17158033


Approximately 130,000 adults are admitted to critical care units (CCUs) in the UK each year, 40-45% of whom require invasive mechanical ventilation (IMV). Acute hypoxaemic respiratory failure (AHRF) is the most common reason for IMV and is associated with serious morbidity and a mortality which remains high at ~40%. Although lifesaving, IMV can cause additional lung injury (termed ventilator induced lung injury - VILI).
Airway Pressure Release Ventilation (APRV) is a method of IMV which uses longer inspiration times followed by a brief expiration. The longer inspiration time enables alveolar recruitment and oxygenation while the short expiration time maintains lung volume. This reduces shear-stress damage to the alveoli, whilst maintaining adequate ventilation.

RELEASE aims to investigate, using a multi-centre, parallel group, pragmatic, randomised controlled trial design, the clinical and cost effectiveness of early APRV compared to conventional lung protective invasive mechanical ventilation(IMV) in patients with moderate-severe acute hypoxic respiratory failure (AHRF).

Sample size:

We aim to recruit 710 participants.

Primary outcome:

Duration of invasive mechanical ventilation (time from randomisation to first successful unassisted breathing or death).


The total planned project duration is 52 months. Recruitment is anticipated to commence October 2024 for 32 months.


If you have any questions, please contact the study team via email.



RELEASE Study Team
Warwick Clinical Trials Unit,
Warwick Medical School,
University of Warwick,

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