Arterial Cannulation

Indications

• Arterial pressure measurement

• Drug delivery (e.g. intra-arterial thrombolysis)

• Procedural access (e.g. coronary angiography)

• Blood sampling

Where can you insert an A-Line?

What are the pros / cons for each site?

What are the relative contraindications to insertion of

an A-line?

And the absolute……?

Allen’s test

• What is it?

• How do you do it?

• What was it designed for?

• Is it useful?

Allen described his original test to assess the circulation in the presence of thromboangiitis obliterans in 1929.

It has been extensively studied and modified. It has a high negative predictive value, but a very low positive predictive value. Its use has all but been abandoned in routine clinical practice.

The patient clenches his or her fist for one minute. While the patient is doing this, the physician presses on the radial and ulna arteries with sufficient pressure to occlude them. After one minute, the patient releases their fist. The ulna circulation is deemed patent if colour returns to the palm and fingers immediately after the pressure applied over the ulna artery is removed.

In modern practice, the cut off for the return of colour is six seconds though Allen gave no such figure.

What are the complications of A-Line insertion?

Medical

Equipment Related

Local Anaesthetics

Mechanism of action