Condition category
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
Not yet recruiting

Plain English Summary

Background and study aims
Acute respiratory failure is a common and life-threatening medical emergency that often results in long hospital stays or expensive intensive care admissions. It occurs when heart or lung disease suddenly develops or worsens and leads to the patient being unable to maintain oxygen levels in their blood. When this happens the patient is at high risk of death and needs emergency treatment. Paramedics currently provide oxygen delivered at normal pressure by a loose fitting face mask. Continuous positive airway pressure (CPAP) is a potentially useful treatment that could be delivered by paramedics in an ambulance. It involves delivering oxygen under increased pressure through a tight-fitting face mask. Its use in hospital can reduce the risk of death in people with lung disease and improve breathing in people with heart disease. Small studies undertaken outside the UK have suggested that using CPAP in an ambulance may save more lives than delaying its use until arrival at hospital. However, it is uncertain whether this treatment could work effectively in NHS ambulance services, and if it represents good value for money. The aim of this study is to see whether it is possible and worthwhile to undertake a full-scale study comparing CPAP and standard oxygen treatment delivered by paramedics for acute respiratory failure, and if so, how we should do it.

Who can participate?
Adults aged over 18 with acute respiratory failure

What does the study involve?
Paramedics identify adults with acute respiratory failure when attending 999 emergency calls. Participants are randomly allocated to either receive CPAP or standard oxygen treatment. All the participants then undergo normal hospital treatment and are followed up for a month to see if they survive. The participants’ quality of life, need for admission to intensive care, and length of stay in hospital are also measured. Additionally, the study measures how many adults are attended with acute respiratory failure, how many are entered into the study, the number who correctly receive CPAP treatment, and how many patients we can follow up to the end of the study. Paramedics are also surveyed to understand their experience of delivering CPAP and aspects of the research. Together these results indicate whether it is feasible and affordable to conduct a full-scale study of CPAP for acute respiratory failure, and inform how to design it.

What are the possible benefits and risks of participating?
CPAP may improve acute respiratory failure symptoms and outcomes. Also, the study may help to improve the treatment of people with acute respiratory failure in the future, making participation a positive experience. CPAP can cause feelings of claustrophobia. In rare cases CPAP can contribute to aspiration (vomiting, with vomit entering the lungs) or pneumothorax (collapsed lung). There are strict criteria for entering people into the study to minimise the chance of these risks. Any side effects occurring during the study are carefully monitored. Participants receive usual clinical care following random allocation and treatment. No further clinical risks are therefore expected during the study.

Where is the study run from?
West Midlands Ambulance Service NHS Foundation Trust (UK)

When is the study starting and how long is it expected to run for?
July 2016 to October 2018

Who is funding the study?
Health Technology Assessment Programme (UK)

Who is the main contact?
1. Dr Sam Keating (
2. Dr Gordon Fuller

Trial website

Contact information



Primary contact

Dr Sam Keating


Contact details

Clinical Trials Research Unit
University of Sheffield
Regent Court
30 Regent Street
S1 4DA
United Kingdom
+44 (0)114 22 25156



Additional contact

Dr Gordon Fuller


Contact details

Clinical Trials Research Unit
University of Sheffield
Regent Court
30 Regent Street
S1 4DA
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number

HTA 15/08/40

Study information

Scientific title

The ACUTE (Ambulance CPAP: Use, Treatment Effect and Economics) feasibility study: a pilot randomised controlled trial of prehospital CPAP for acute respiratory failure



Study hypothesis

Is it possible and worthwhile to undertake a full-scale study comparing continuous positive airway pressure (CPAP) delivered by paramedics to standard oxygen treatment for adults with acute respiratory failure? And if so, how should we do it?

More details can be found at:

Ethics approval

Not provided at time of registration – submission pending

Study design

Stand-alone randomised controlled pilot trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

See additional files


Acute respiratory failure (ARF)


A stand-alone randomised controlled pilot trial will be conducted. Patients with acute respiratory failure will be identified by paramedics responding to 999 ambulance call and enrolled in the study.

Patients randomised to the intervention arm will receive treatment with CPAP, a form of noninvasive ventilation where oxygen is supplied to the upper airways at increased pressure through a tight-fitting mask. The O_two CPAP unit will be used: a lightweight, single use, low flow system. Patients randomised to the control arm will receive oxygen delivered at normal atmospheric pressure via nasal cannula, an air entrainment ‘Venturi’ mask, a simple face mask, or a non-rebreathing reservoir face mask. Patients in both trial arms will receive other standard pre-hospital and hospital treatments.

Intervention type



Drug names

Primary outcome measures

The following feasibility outcomes will be reported descriptively together with their 95% confidence interval:
1. Recruitment rate per 100,000 population per year (target 8, i.e. 120 across 1.5 million)
2. Proportion recruited in error and classified as violations or deviations (target 0% and ≤10%)
3. Adherence to the allocation schedule (target ≥90%)
4. Adherence to treatment in the CPAP arm (target ≥75%)
5. Retention at 30 days (target ≥90%)
6. Data completeness (target ≥90%)

Secondary outcome measures

Summary estimates of effectiveness outcomes will also be reported with 95% confidence intervals across the whole trial population using an as randomised analysis:
1. Proportion surviving to 30 days
2. Proportion undergoing endotracheal intubation by 30 days
3. Proportion admitted to critical care at any point up to 30 days
4. Mean and median length of hospital stay
5. Mean EQ-5D-3L (measured for each participant at baseline and at the 30-day follow-up)
6. Key elements of health-care resource use up to 30 days

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Adults aged over 18
2. Acute respiratory failure defined as respiratory distress with peripheral oxygen saturation below BTS target levels (88% for patients with COPD, 94% for other conditions), despite supplemental oxygen

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. The time difference between being able to start prehospital CPAP and being able to start in-hospital CPAP is expected to be less than 15 minutes
2. Age < 18 years
3. Known to have terminal illness
4. Known pre-existing lack of capacity (confirmed by relatives, carers or documentary evidence, such as Lasting Power of Attorney)
5. Documented not for resuscitation status
6. Acutely incapacitated patients with valid advanced directive declining non-invasive ventilation or participation in research
7. The patient has an oxygen alert card
8. Anticipated inability to apply CPAP (e.g. facial deformity)
9. Respiratory failure due to chest trauma
10. Contraindication to CPAP (suspected pneumothorax, respiratory arrest, epistaxis, vomiting, hypotension)

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

West Midlands Ambulance Service NHS Foundation Trust
Trust Headquarters, Millennium Point Waterfront Business Park Waterfront Way Brierley Hill West Midlands
United Kingdom

Sponsor information


University of Sheffield

Sponsor details

Western Bank
S10 2TN
United Kingdom

Sponsor type




Funder type


Funder name

Health Technology Assessment Programme

Alternative name(s)

NIHR Health Technology Assessment Programme, HTA

Funding Body Type

government organisation

Funding Body Subtype

Federal/National Government


United Kingdom

Results and Publications

Publication and dissemination plan

The trial protocol will be submitted for open access publication and presented at relevant conferences. Results of the study and the updated economic model will be disseminated in high-profile peer-reviewed scientific journals and relevant academic conferences. Authorship will include funding co-applicants, research paramedics and the study manager, according to International Committee of Medical Journal Editors (ICMJE) guidelines.

Details of the trial, including regularly updated progress reports, will be available on a dedicated study website hosted by the CTRU. Plain English study progress reports will be provided to participants, patient advocacy groups, local PPI panels and our service user advisory group. Study developments will also be communicated through social media including twitter and podcasts. The lay TMG member and service user advisory group will contribute to writing any scientific publications, particularly plain English summaries and conference presentations.

At the end of the study a report will be submitted to the trial funders with full details of study progress and study findings. It is anticipated that this report will be independently peer reviewed and the final accepted report published as a “gold” open access monograph in the Health Technology Assessment journal.

Intention to publish date


Participant level data

Available on request

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes