Arterial Access

What is it?
Cannulation of a peripheral artery
- allows constant BP monitoring
- repeated ABG sampling

Where?
Usually via radial or dorsalis pedis
- avoid femoral and brachial (lack collaterals)
- femoral has sepsis risk

Contraindications?
Local sepsis and coagulopathy

Complications?
Haematoma, thrombosis, distal ischaemia, intimal damage, aneurysm formation, disconnection and injection of irritant drugs.

How?
Test collateral circulation with Allen's Test
Use a 20-22g cannula.
Ensure light, comfort and assistance
Palpate the artery with two fingers
- feel and imagine its course
Insert at 45o
Puncture the artery
- advance guidewire
- railroad the cannula
- check backflow and secure the cannula
Connect transducer and flush

For BP measurement
Connect via a short rigid length to a 3-way tap, flush device and transducer
- zero and calibrate the transducer
- the shape of the wave is important, eg sharp peaked upswing and low dicrotic notched downswing may indicate hypovolaemia.

Care of the line

Connect to a hep saline continuous flush device
- this keeps it patent
- and allows BP measurement without letting blood out into the line.