Objectives & Background Inadvertent intra-arterial cannulation (IIAC) is a recognised complication of peripheral cannulation with the potential for severe consequences including limb ischaemia and amputation. Patients presenting to EDs are often complex, frail or obese (known risk factors for difficult cannulation) meaning the overall incidence may be much higher than that suggested by existing evidence.

Objectives:

• ▸ To report the rate of IIAC in our Emergency Department.

• ▸ To assess whether blood gas analysis can be used to screen for IIAC.

Methods A prospective observational study was undertaken over a two week period. Every cannula inserted in the ED during hours of recruitment had blood drawn and blood gas analysis performed. The results were analysed by a senior ED clinician who assessed whether the blood gas values represented arterial or venous blood. Ultrasound assessment was performed on every cannula to confirm placement and, if there was any degree of uncertainty, transduced pressure readings were obtained.

Results Two IIACs were confirmed out of the 83 cannulae analysed, a rate of 2.4%. Both of these IIACs were detected by the senior clinician interpreting the blood gas. Two further cannulae were incorrectly identified as potentially arterial on the blood gas, but were proven to be venous using ultrasound. Both patients experiencing IIACs had multiple risk factors for difficult cannulation and 44% of all subjects had at least one risk factor.

Conclusion IIAC occurs more frequently than previously reported in our ED. A high proportion of ED patients have risk factors that make IIAC more likely. Point of care blood gas analysis may be a useful screening tool for detecting IIAC, particularly when used in conjunction with ultrasound +/− transduction. The results of this study justify further research to confirm and extend these observations. Implications for everyday practice within the ED include increased awareness and recognition of IIAC.