Aims and Objectives Intraosseous (IO) administration of medication, fluids and blood products is accepted practice for critically injured patients in whom intravenous (IV) access is not immediately available. However, there are concerns that the high intramedullary pressures resulting from IO infusion may cause bone marrow intravasation and subsequent fat embolisation. The aim of this Systematic Review is to synthesise the existing evidence describing fat intravasation, fat embolism, and Fat Embolism Syndrome (FES) in IO infusion for major trauma patients.

Method and Design A systematic search of MEDLINE, CINAHL and Embase was conducted using the terms “intraosseous” “fat embolism” “fat intravasation” and “fat embolism syndrome”. Two authors independently screened studies for eligibility and risk of bias. All studies reporting novel data on IO-associated fat emboli were included. PROSPERO number CRD42023399333. Adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA).

Results and Conclusion In total, twenty-seven abstracts were identified and n=7 met full inclusion criteria (table 1). All papers were large animal translational studies. The overall risk of bias was high. Fat intravasation and fat embolisation were observed to be near-universal following IO infusion, but of uncertain clinical significance. In one study, high infusion pressures were associated with immediate cardiovascular instability which was attributed to FES. The initial IO flush appeared to be the procedure with the highest intramedullary pressure. No conclusions could be made on FES from the study methodologies.

Intraosseous catheters remain a useful intervention in the armamentarium of trauma clinicians. Although their use is widely accepted, there is a paucity of evidence exploring the risks of fat embolisation in IO infusions. The existing data is of low quality with a high risk of bias. Despite this, pulmonary fat emboli after IO infusion are common. More research is needed to quantify the clinical significance of fat embolism and FES after IO infusion in adult major trauma patients.