Introduction A new prognostic model has been developed and externally validated, the aim of which is to assist in the management of the blunt chest wall trauma patient in the Emergency Department (ED). A definitive randomised controlled trial (impact trial), is required to assess the clinical and cost effectiveness of the new model, before it can be accepted in clinical practice. The purpose of this trial is to assess the feasibility and acceptability of such a definitive trial and inform its design.

Methods and analysis This feasibility trial is designed to test the methods of a multi-centre, cluster-randomised (stepped wedge) trial, with a substantial qualitative component. Four EDs in England and Wales will collect data for all blunt chest wall trauma patients over a five month period; in the initial period acting as the controls (normal care) and the second period, acting as the interventions (in which the new model will be used). Baseline measurements including completion of the SF-12v2 will be obtained on initial assessment in the ED. Patient outcome data will then be collected for any subsequent hospitalisations. Data collection will conclude with a six week follow-up completion of two surveys (SF-12v2 and Client Services Receipt Inventory).

Analysis of outcomes will focus on feasibility, acceptability and trial processes and will include recruitment and retention rates, attendance at clinician training rates and use of model in the ED. Qualitative feedback will be obtained through clinician interviews and a research nurse focus group. An evaluation of the feasibility of health economics outcomes data will be completed.

Ethics and dissemination Wales Research Ethics Committee 6 granted approval for the trial in September 2016. Health Care Research Wales Research Permissions and the HRA have granted approval for the study. Patient recruitment commenced in February 2017. Planned dissemination is through publication in a peer-reviewed Emergency Medicine Journal, presentation at appropriate conferences and to stakeholders at Professional Meetings.