In Chapter 1 I have demonstrated that survival rates following out-of-hospital cardiac arrest (OHCA) remain low, despite significant efforts to improve care. The current standard of care in the United Kingdom (UK) and most modern emergency medical services (EMS) is Advanced Life Support (ALS). In some areas of the UK, prehospital critical care is provided in addition to ALS, but this is inconsistent and frequently funded by charities. Prehospital critical care can be defined as interventions beyond ALS, delivered by a group of specialised prehospital providers. There is little evidence for benefit from prehospital critical care for OHCA, and practice in the UK varies. Unanswered questions are the impact of prehospital critical care on patient outcomes, how exactly it differs from ALS, its costs and even how these questions should be addressed in research.
The aim of this thesis is to provide key stakeholders in prehospital care with the information required to guide the funding and configuration of prehospital critical care for OHCA, within the complex setting of mixed charity and National Health Service (NHS) funding.
2.1 Objective 1
Objective: To search and critically appraise the current literature regarding the impact of
prehospital critical care on patient outcomes following OHCA.
Rationale: There are a number of publications which address the research question, but
critical appraisal and synthesis of this literature is required to evaluate their validity and generalisability.
Methods: Systematic review of the literature.
2.2. Objective 2
Objective: To estimate the effect of prehospital critical care on survival following OHCA when
Rationale: Prehospital critical care is a complex intervention of largely unproven benefit in
OHCA. Studying its effects on a patient-centred outcomes in the UK setting is required to support funding decisions.
Methods: Prospective, multi-centre observational study of cases of OHCA with the primary
outcome of survival to hospital discharge following either ALS or prehospital critical care.
2.3 Objective 3
Objective: To understand what interventions are being delivered by prehospital critical care
practitioners during their management of OHCA patients and their potential effects on survival.
Rationale: Prehospital critical care can be seen as a bundle of interventions, which vary
significantly in their application between EMS provider organisations but also between individual cases within the same system. Understanding exactly what happens during the care of patients with OHCA and which interventions are associated with improved survival can help inform the optimal configuration of EMS responses to OHCA.
Methods: Prospective, multi-centre observational study recording prehospital critical care
interventions used during the management of people with OHCA and their association with survival.
2.4 Objective 4
Objective: To describe the costs of prehospital critical care for OHCA, with reference to the
costs of ALS.
Rationale: Prehospital critical care for OHCA patients comes at an increased cost, which is
currently shared between NHS and charity funding, and also depends largely on the transport platform used (helicopter or car based).
Methods: Cost analysis of different models of prehospital critical care, from a funder’s
2.5 Objective 5
Objective: To examine stakeholders’ views on research and randomisation of prehospital
critical care for patients with OHCA.
Rationale: Prehospital critical care exists in a complex environment due to its unique funding
structure and uncertainty around it being required or beneficial. Informal discussions with stakeholders during the planning phase of this PhD demonstrated a wide and often opposing range of views as to how prehospital critical care for patients with OHCA should be researched.
Methods: Qualitative interviews and focus group discussions with key stakeholders.
2.6 Presentation of results
Due to the practical aspects of the methods used for each of these objectives, I was not able to address the objectives in the order outlined above. The prospective nature of the data collection for Objectives 2 and 3 meant that the relevant analyses could only be undertaken towards the end of the PhD project. An important aspect of this thesis is to demonstrate my “capacity to adjust the project design in the light of emergent issues and understandings” (University of the West of England, 2018). In order to support this doctoral qualification descriptor and to maintain a logical flow throughout the thesis, I have therefore decided to present Chapters 4 to 8 in the chronological order in which the relevant research was undertaken. Given that each objective can be seen as a distinct research project, I will present methods, results and discussion for each research phase separately, before then synthesising and appraising the overall thesis in Chapters 9 and 10. At that point, I hope to be able to answer the following questions:
1. What is the best estimate of the effect of prehospital critical care on survival following OHCA? And what are the best and worst case estimates?
2. Which prehospital critical care interventions are frequently delivered? Which interventions are associated with improved survival?
4. Can stakeholders agree on an ideal way to research this and similar questions in a way that is satisfactory for all stakeholders? Is randomisation of prehospital critical care feasible?