Invasive (intra-arterial) blood pressure (IBP) monitoring is a commonly used technique in the Intensive Care Unit (ICU) and is also often used in the operating theatre.

This technique involves direct measurement of arterial pressure by inserting a cannula needle in a suitable artery.  The cannula must be connected to a sterile, fluid filled system which is connected to an electronic patient monitor.  The advantage of this system is that a patient’s blood pressure is constantly monitored beat-by-beat, and a waveform can be displayed.