Continuous ARterial monitoring in Elderly and Frail patients for hip fractUre surgery to prevent Low blood pressure - the CAREFUL Study Protocol.

Intra-operative hypotension is common and associated with postoperative organ injury and mortality, particularly in older patients living with frailty. Continuous invasive arterial blood pressure monitoring provides real-time measurements and may allow earlier detection and management of hypotension and improve outcomes. Contemporary UK data show that this intervention is rarely used in elderly patients living with frailty who are undergoing urgent hip fracture surgery. The CAREFUL Study (Continuous ARterial monitoring in Elderly and Frail patients for hip fractUre surgery to prevent Low blood pressure) will synthesise evidence to determine the feasibility of a definitive randomised controlled trial evaluating continuous versus intermittent arterial blood pressure monitoring in this population. The study comprises three integrated workstreams: a systematic review and meta-analysis to evaluate existing evidence on continuous arterial blood pressure monitoring and peri-operative outcomes; mixed-methods qualitative analysis to explore clinician attitudes, barriers and facilitators to implementation; a multi-centre external feasibility randomised controlled trial with embedded qualitative research. The feasibility study will randomise 100 patients aged ≥ 65 years with a Clinical Frailty Scale score of ≥ 5 undergoing proximal femoral fracture surgery to either continuous invasive arterial blood pressure monitoring or non-invasive 3- to 5-minute cycle blood pressure monitoring. Data will include recruitment, retention and intervention compliance, exposure to intra-operative hypotension, postoperative complications and quality of life. Findings will inform the design of a definitive effectiveness trial. Results will be shared through peer-reviewed open-access publications, stakeholder events and collaboration with professional bodies and patient partners to guide future peri-operative care for older, frail surgical patients.