RT Journal Article SR Electronic T1 Fat intravasation, fat emboli and fat embolism syndrome in adult major trauma patients with intraosseous catheters: a systematic review JF BMJ Military Health JO BMJ Mil Health FD British Medical Journal Publishing Group SP e002645 DO 10.1136/military-2023-002645 A1 Ellington, Matt A1 Hibberd, O A1 Aylwin, C YR 2024 UL http://militaryhealth.bmj.com/content/early/2024/08/13/military-2023-002645.abstract AB Introduction Intraosseous (IO) administration of medication, fluids and blood products is accepted practice for critically injured patients in whom intravenous access is not immediately available. However, there are concerns that 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) following IO infusion.Methods A systematic search of CINAHL, MEDLINE and Embase was undertaken using the search terms “intraosseous”, “fat embolism”, “fat intravasation” and “fat embolism syndrome”. Two authors independently screened abstracts and full texts, against eligibility criteria and assessed risk of bias. A grey literature search (including references) was undertaken. Inclusion criteria were: all human and animal studies reporting novel data on IO-associated fat emboli. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis.Results 22 papers were identified from the search, with a further 5 found from reference lists. N=7 full papers met inclusion criteria. These papers were all translational animal studies. The overall risk of bias was high. Studies demonstrated that fat intravasation and fat embolisation are near universal after IO infusion, but of uncertain clinical significance. The initial IO flush appears to cause the highest intramedullary pressure and highest chance of fat intravasation and embolisation. No conclusions could be drawn on FES.Conclusions IO catheters remain a useful intervention in the armamentarium of trauma clinicians. Although their use is widely accepted, there is a paucity of evidence investigating fat embolisation in IO infusions. Despite this, pulmonary fat emboli after IO infusion are very common. The existing data are of low quality with a high risk of bias. More research is needed to address this important subject.PROSPERO registration number CRD42023399333.Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplemental information.