Doctorate Description: Current international guidelines and the associated “chain of survival” emphasise the recognition of critically unwell patients in the community followed by an efficient response in the hope of preventing out-of-hospital cardiac arrest, which occurs when the heart stops beating suddenly. This thesis investigates how Emergency Medical (ambulance) Services can improve their recognition and response to patients who are at imminent risk of out-of-hospital cardiac arrest to reduce mortality and improve outcomes. Four distinct studies were completed:
a) Systematic mixed studies review;
b) Retrospective observational study of Emergency Medical Services call triage and the outcome of patients at imminent risk of out-of-hospital cardiac arrest;
c) Conversation analysis of the Emergency Medical Services call;
d) Interviews with Emergency Operations Centre staff.