BackgroundIn the United Kingdom, hospital patients suffer preventable deaths (failure to rescue) and delayed admission to the Intensive Care Unit because of poor illness recognition. This problem has consistently been identified in care reviews. Strategies to improve deteriorating ward patient care, such as early warning systems and specialist care teams (Critical Care Outreach or Rapid Response), have not reliably demonstrated reductions to patient deaths. Current research focuses on failure to rescue, but further reductions to patient deaths are possible, by examining care of unwell hospital patients who are rescued (successfully treated). Our primary objective is to develop a framework of care escalation success factors that can be developed into a complex intervention to reduce patient mortality and unnecessary admissions to the Intensive Care Unit (ICU).Methods and AnalysisSUFFICE is a multicentre mixed-methods, exploratory sequential study examining rescue events in the acutely unwell ward patient in two National Health Service Trusts with Teaching Hospital status. The study will constitute four key phases. Firstly, we will observe ward care escalation events to generate a theoretical understanding of the process of rescue. Secondly, we will review care records from unwell ward patients in whom an ICU admission was avoided to identify care success factors. Thirdly, we will conduct staff interviews with expert doctors, nurses, and Allied Health Professionals to identify how rescue is achieved and further explore care escalation success factors identified in the first two study phases. The final phase involves integrating the study data to generate the theoretical basis for the framework of care escalation success factors.Ethics and DisseminationEthical approval has been obtained through the Queen Square London Research and Ethics committee (REC Ref 20/HRA/3828; CAG-20CAG0106). Study results will be of interest to critical care, nursing and medical professions and results will be disseminated at national and international conferences.Trial Registration NumberISRCTN 38850