Inadvertent intra-arterial catheterisation using ultrasound guidance and endocavitary electrocardiography in a paediatric patient

Venous access in small infants is difficult and central venous catheter placed into the brachiocephalic vein is often the preferred approach. Ultrasound guided vein cannulation is standard practice and endocavitary electrocardiography is a reliable catheter tip location method. We report a not immediately recognised 2 month old case of inadvertent intra-arterial catheterisation with a 3 Fr - 8 cm catheter during right innominate vein cannulation under ultrasound guidance. Endocavitary electrocardiography showed an increased amplitude P wave with a low P/R wave ratio but further insertion of the catheter resulted in a reduction of the P wave amplitude. At ultrasound re-evaluation of the innominate vein, the catheter seemed to be inside the vessel into the proximal part of the vein, but distally appeared to surpass the vein to get into the brachiocephalic artery at the level of the bifurcation of the right common carotid artery and the right subclavian artery. Cardiac ultrasound from the suprasternal notch view identified the catheter into the aortic arch. Contrast-enhanced CT scan with 3D reconstruction confirmed the intra-arterial catheterisation and showed that the innominate vein was shifted and partially compressed but not transfixed by the catheter. The catheter was non-surgically removed uneventfully. During innominate vein cannulation the catheter cannot always be visualised into the distal tract of the vein and the maximal P wave may have a low P/R ratio; a chest X-ray can identify intra-arterial but false negative results are possible. We recommend always using a real time ultrasound tip navigation and location protocol, like the Neo-ECHOTIP protocol, to confirm the correct position of the guidewire and the catheter. If the catheter cannot be identified inside the venous system, we suggest systematically visualising the aortic arch from the suprasternal notch view and the aortic root from the parasternal view to identify arterial malposition.