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 (Airways-2)

Design: This is a parallel two-group multi-centre cluster randomised controlled trial (RCT) and accompanying cost-effectiveness analysis to identify the best approach to initial airway management during out of hospital cardiac arrest (OHCA). Randomisation by patient is impractical; we will therefore randomise by paramedic. Setting: Paramedics will be recruited from four NHS ambulance services with favourable characteristics. The NHS ambulance services are: • South Western Ambulance Service NHS Foundation Trust (SWAST) • East of England Ambulance Service NHS Trust • East Midlands Ambulance Service NHS Trust • Yorkshire Ambulance Service NHS Trust The College of Paramedics is also fully supportive of the study. Hospitals receiving OHCA patients from these ambulance services will also be taking part. Target Population: Adults (18 years or older) who have suffered a non-traumatic out of OHCA. Health technologies being assessed: The i-gel, a second-generation supraglottic airway device (SAD), used as the initial airway management strategy in adult non-traumatic OHCA. We will use the most recent version of this device. In our feasibility study we have examined usual care for airway management during OHCA, and concluded that tracheal intubation (optimised through the use of an intubating bougie and quantitative end-tidal carbon dioxide monitoring) is the best comparator. In both arms a brief period of bag-mask ventilation may precede the allocated airway intervention, and an algorithm to guide subsequent actions if the initial technique is unsuccessful will be provided to all paramedics in research training sessions. Measurement of costs and outcomes: The primary outcome will be the modified Rankin Scale (mRS) score at hospital discharge, which incorporates survival to discharge. 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). Other and longer-term outcomes are also important, and we will therefore seek consent from survivors (or a consultee 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 because cognitive function and quality of life continue to improve up to this time. Sample Size: We estimate that approximately 1,300 paramedics will be required to participate in the trial. Enrolment of patients treated by study paramedics is expected to take place over a 24 month period with 9,070 patients required in total (4,535 in each of the two trial groups). Statistical Analysis: The primary outcome of mRS at discharge (presented dichotomously as good recovery (0-3) or poor recovery/death (4-6)), and other binary outcomes, will be analysed using a multilevel logistic regression model, in which the data are nested within attending paramedic. Repeated mRS scores will be analysed using multilevel logistic regression for repeated measures. Survival to 6 months and other time-to-event outcomes will be analysed using survival analysis methods, again allowing for clustering of patients by paramedic. Quality of life scores and cognitive function will simply be described because these will be available only for survivors. Quality of life and patient survival will be analysed jointly to assess whether the use of the i-gel supraglottic airway device simultaneously improves the patient’s quality of life and reduces the risk of death. Analyses will be done according to the principle of intention-to-treat, and reported according to the CONSORT guidelines. Research Management: The research will be managed by a Trial Management Group which will meet approximately every 4-6 weeks. A Trial Steering Committee, a Data Monitoring Committee and a Patient and Public Involvement Committee will also be set up; these committees will meet approximately every 6 months. The