Background In the UK the EZ-IO® Intraosseous Infusion System is a paramedic delivered technique involving the placement of the Intraosseous (IO) needle into the patient's bone marrow via an EZ-IO driver. The primary use for EZ-IO is when intravenous (IV) access is not possible, mainly for patients in cardiac arrest but may include severely unwell/injured patients. This study aimed to determine EZ-IO success rate, including impact on return of spontaneous circulation (ROSC).

Methods One hundred and ninety-five cardiac arrest patient records where EZ-IO placement was attempted were retrospectively examined to determine whether ROSC was achieved at any point. Findings were compared to records where resuscitation was attempted and patients were administered drugs IV and tested for association using Pearson's Chi-Square Test.

In addition, patients' records were assessed for their compliance to best practice guidance issued by the Joint Royal Colleges Ambulance Liaison Committee for use in UK Ambulance Services and manufacturer's guidelines.

Results ROSC was achieved for 29% of the patients who had an EZ-IO inserted (n=57), therefore for 71% (n=138) ROSC was not achieved. This compares to 46% (n=338) and 54% (n=399) retrospectively for patients administered drugs IV. We observed a strong association between method of access and patient's outcome (χ² (1)=17.465, p=.000).

Where an EZ-IO was attempted 100% (n=195) were identified as having a successful IO placement, although certain areas of documentation were highlighted as requiring improvement, specifically: insertion site (recorded for 26%, n=51); needle size (74%, n=145), and saline flush (93%, n=182).

Conclusions Although, this shows that the practice of pre-hospital EZ-IO insertion is successful, it compares less favourably to administering resuscitation drugs IV. However, there may be other factors associated with achieving ROSC that have not been taken into account, including the reasons IV access was not possible and whether this was an influencing factor.