Plain English Summary
Background and study aims
A cardiac arrest occurs when the heartbeat and breathing stop suddenly. It is one of the most extreme medical emergencies. Health outcomes are poor; less than 1 in 10 patients survive to be discharged from hospital. The best initial treatment is cardiopulmonary resuscitation (CPR); a combination of rescue breathing and chest compressions. Prompt and effective CPR prevents damage to the brain and other organs, and maximises the chance that the heart will start beating again. Ensuring a clear airway, whilst interrupting chest compressions as little as possible, is essential for survival. At the moment, we do not know the best way for NHS ambulance staff to provide rescue breathing during an out of hospital cardiac arrest. Placing a breathing tube in the windpipe (tracheal intubation) has been considered the best method of airway management, but this can cause complications as well as interruptions in chest compressions. Recently national recommendations suggested using a newer method of airway management: the insertion of a supraglottic airway device (SAD). A SAD is a tube that sits on top of the voice box. These devices are already used during routine anaesthesia in hospitals and in emergency care. They are quicker to insert and cause less interruption to chest compressions compared to intubation, however the SAD may not stay in place as securely as a breathing tube and, if a patient vomits, stomach contents may get into their lungs causing further complications. The aim of the AIRWAYS-2 trial is to determine whether intubation or the best available SAD (called the i-gel) gives the best chance of recovery following a cardiac arrest that takes place out of hospital (out of hospital cardiac arrest - OHCA).
Who can participate?
Paramedics employed by one of the four ambulance trusts who have agreed to support the study (South Western Ambulance Service NHS Foundation Trust, East of England Ambulance Service NHS Trust, East Midlands Ambulance Service NHS Trust , Yorkshire Ambulance Service NHS Trust). All out of hospital cardiac arrest patients attend by an AIRWAYS-2 paramedic are automatically enrolled in the study.
What does the study involve?
Paramedics who consent to take part in the study are allocated into one of two airway management pathway groups. Those in group A use intubation (where a breathing tube is placed in the windpipe) when administrating CPR. Those in group B use the i-gel device (where the breathing tube sits on top of the voice box). Patients that survive the cardiac arrest are taken into hospital and information on their functional status and quality of life when they are discharged from hospital, and then three and six months after the cardiac arrest; patients that agree to active follow up are asked to complete patient questionnaires. At the end of the study we will compare treatment costs.
What are the possible benefits and risks of participating?
Paramedics will benefit from additional training in resuscitation, airway management and evidence based practice during the trial. We do not know whether the study will benefit OHCA patients but the information we get from this study will help improve the treatment of people who have an OHCA in the future.
Where is the study run from?
The University of the West of England and the Clinical Trial and Evaluation Unit, Bristol in collaboration with South Western Ambulance Service NHS Trust.
When is the study starting and how long is it expected to run for?
February 2015 to October 2018
Who is funding the study?
National Institute for Health Research, Health Technology Assessment (UK)
Who is the main contact?
Professor Jonathan Benger
Prof Jonathan Benger
Academic Department of Emergency Care
University Hospitals Bristol NHS Foundation Trust
Bristol Royal Infirmary
+44 (0) 117 3421498
HTA 12/167/102; Sponsor: 13-034; Protocol Version: 1.0
Cluster randomised trial of the clinical and cost effectiveness of the i-gel supraglottic airway device versus tracheal intubation in the initial airway management of out of hospital cardiac arrest
The hypothesis is that the i-gel, a second-generation supra-glottic airway device, is superior to tracheal intubation in non-traumatic out of hospital cardiac arrest in adults, in terms of both clinical and cost effectiveness.
More details can be found at: http://www.nets.nihr.ac.uk/projects/hta/12167102
Protocol can be found at: http://www.nets.nihr.ac.uk/__data/assets/pdf_file/0003/130665/PRO-12-167-102.pdf
NRES Committee South Central - Oxford C, 24/09/2014, ref: 14/SC/1219
Parallel two-group multi-centre cluster randomised controlled trial and accompanying cost-effectiveness analysis
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Website details to follow
Out of hospital cardiac arrest (OHCA)
The current standard care pathway is tracheal intubation: the placement of a cuffed tube in the patient's trachea (windpipe) to provide oxygen to the lungs and remove carbon dioxide. Tracheal intubation is considered the gold standard of airway management, and is used universally in comatose survivors of cardiac arrest following their admission to hospital.
The intervention being studied is the insertion of an i-gel, a second-generation SAD, as an alternative to tracheal intubation.
Aspects of management common to both groups:
For both the intubation and intervention group care will proceed as normal for OHCA patients enrolled in the trial, aside from the initial airway management. The trial intervention will cease after care is handed over to the medical team in hospital or the patient is recognised as life extinct by ambulance clinicians at scene. This will be a period of between 30 and 90 minutes.
Patients will then be followed up at hospital discharge, 3 and six months following the patients cardiac arrest.
Primary outcome measure
The modified Rankin scale (mRS) score at hospital discharge, which incorporates survival to discharge and is widely used in OHCA research. Death scores 6, and mRS is usually presented dichotomously as good recovery (0-3) or poor recovery/death (4-6). We will collect survival and mRS at hospital discharge from routinely available clinical data with the prior permission of the Health Research Authority Confidentiality Advisory Group (CAG). However, other and longer-term outcomes are also important, and we will therefore seek consent from survivors (or a consultee according to the requirements of the Mental Capacity Act 2005 if the patient lacks capacity) to collect additional data at hospital discharge and 3 and 6 months after OHCA. We have chosen a 6-month final follow-up (compared to 3 in our feasibility study) because, whilst there are very few additional deaths between 3 and 6 months, cognitive function and quality of life continue to improve during this time.
Secondary outcome measures
We will seek consent from survivors (or a consultee according to the requirements of the Mental Capacity Act 2005 if the patient lacks capacity) to collect additional data at hospital discharge and 3 and 6 months after OHCA.
All enrolled patients
1. Initial ventilation success, defined as visible chest rise.
3. Loss of a previously established airway.
4. Actual sequence of airway interventions delivered.
5. Chest compression fraction.
6. Return of spontaneous circulation (ROSC).
7. Airway management in place when ROSC was achieved or the resuscitation was discontinued.
8. Economic data regarding expenditure and further healthcare contacts.
Patients who survive to admission to hospital (estimated 20% of enrolled patients)
9. Length of intensive care stay.
10. Length of hospital stay.
Patients who survive to hospital discharge (estimated 9% of enrolled patients)
11. Quality of life at hospital discharge.
Patients who survive beyond hospital discharge (estimated 8% of enrolled patients)
12. Modified Rankin scale at 3 and 6 months following OHCA.
13. Quality of life (using the EQ5D) at 3 and 6 months following OHCA.
14. Cognitive function (using the cerebral performance category) 3 and 6 months following OHCA.
15. Date of death, where this occurs during the trial.
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Paramedic inclusion criteria:
1. Employed by one of the four participating ambulance trusts in general operational duties, and could therefore be despatched to attend an OHCA as the first or second paramedic to arrive on scene.
Patient inclusion criteria:
1. Patient known or believed to be 18 years of age or older
2. Must be in non-traumatic cardiac arrest outside hospital
3. Patient must be attended by a paramedic who is participating in the trial and is either the 1st or 2nd paramedic to arrive at scene.*1
4. Resuscitation is attempted by ambulance staff.*2
*1 The time and order of staff arrival is routinely collected by ambulance services. The participating paramedic will manage the patients airway, according to their allocation. If both the 1st and 2nd paramedic are participating in the trial, the patients airway will be managed according to the allocation of the 1st paramedic to arrive (usually designated as the attendant within the ambulance service).
*2 Circumstances in which resuscitation should and should not be attempted are described in national guidelines, but the frequency of attempted resuscitation in both arms will be regularly examined by the DMSC to identify any bias in the commencement of resuscitation attempts
Target number of participants
We estimate each paramedic will attend 7 OHCA over a two-year recruitment period. We aim to recruit 1,300 paramedics to give approximately 9,070 OHCA patients enrolled in the trial.
Participant exclusion criteria
Paramedic exclusion criteria:
1. Paramedics working in non-clinical and managerial roles not routinely attending OHCA
Patient exclusion criteria:
1. Patient detained by Her Majesty's Prison Service
2. Previously recruited to the trial
3. Estimated weight <50 kg
4. Mouth opening <2 cm
The latter two exclusions have been applied because SADs are not designed for use in patients with low bodyweight or significantly reduced mouth opening. There is a risk of post-randomisation bias being introduced by these two exclusion criteria, but in our feasibility study only 2/711 patients (0.3%) were excluded on these grounds. We will monitor these exclusions, under the supervision of the DMSC, and should the exclusion rate exceed 1% we will take action to address this through enhanced training and supervision.
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Bristol Royal Infirmary
South Western Ambulance Service NHS Foundation Trust (UK)
c/o Ms Sarah Black
South Western Ambulance Services NHS Foundation Trust
+44 (0) 1392 261640
Health Technology Assessment Programme
NIHR Health Technology Assessment Programme, HTA
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
We intend to disseminate our primary outcome in late Spring 2018. This will take the form of publication in a high-impact peer reviewed journal, as well as presentation at relevant conferences.
Our long term and secondary outcomes will also be published in high-impact peer reviewed journals in late 2018, with presentation at relevant conferences.
IPD sharing statement:
The datasets generated during and/or analysed during the current study are/will be available upon request from email@example.com.
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
2016 protocol in: https://www.ncbi.nlm.nih.gov/pubmed/27697605
2018 results in: https://www.ncbi.nlm.nih.gov/pubmed/30167701
2019 trial design and implementation in: https://www.ncbi.nlm.nih.gov/pubmed/30736841