Residual flow of the radial artery in the presence of an arterial catheter: A single-centre retrospective observational study

Arterial catheterisation is a common procedure used to manage critically ill patients. The radial artery, both for its favourable anatomical position and the presence of ulnar collateral circulation, is the most used. While there is a consensus for a catheter/vein ratio of ⩽33% for venous catheterisation, there are no strong indications for arterial catheterisation. Some authors have hypothesised that a catheter/artery ratio of less than 45% is advisable. This study aimed to explore the relationship between residual flow in the Radial Artery, the catheter/artery ratio, and ulnar compensation.