Arterial Cannula: Indications, Procedure, Sites, Complications by Nursesnote

 Arterial Cannula

Arterial cannula indications

Performed correctly, arterial cannula is a safe technique allowing continuous monitoring of blood pressure and frequent sampling of blood. It is indicated in any patient with unstable or potentially unstable haemodynamic or respiratory status.

Arterial Cannulation Radial 

The radial artery is most frequently chosen because it is accessible and has good collateral blood flow. Allen's test, used to confirm the ulnar blood supply, is not reliable.

Cannulation procedure

Use aseptic technique. Hyperextend wrist and abduct the thumb. After skin cleansing, local anaesthetic (1% lidocaine) is injected into the skin and subcutaneous tissue over the most prominent pulsation. The course of the artery is noted and a 20 G Teflon cannula inserted along the line of the vessel. The vessel is usually entered in similar fashion to an intravenous cannula. There is usually some resistance to skin puncture. To avoid accidentally puncturing the posterior wall of the artery, the skin and artery should be punctured as two distinct manoeuvres. Alternatively, a small skin Nick may be made to facilitate skin entry.

In the case of elderly patients with mobile, atheromatous vessels, a technique involving deliberate transfixation of the artery may be used. The cannula is passed through the anterior and posterior walls of the vessel, this immobilising it. The needle is removed and the cannula withdrawn slowly into the vessel lumen before being advanced.

Seldinger - type kits are available for arterial Cannulation. A guidewire is first inserted through a rigid steel needle. The indwelling plastic cannula is then placed over the guidewire.

The cannula should be connected to a continuous flushing device after successful puncture. Flushing with a syringe should be avoided since the high pressures generated may lead to a retrograde cerebral embolus.

Other sites for Cannulation

Brachial artery

End artery supplying a large volume of tissue. Thus thrombosis has potentially severe consequences. 

Femoral artery

May be difficult to keep clean. Also supplies a large volume of tissue. A longer catheter should be used to avoid displacement.

Complications

• Digital ischaemia due to arterial spasm, thrombosis, or embolus.
• Bleeding
• Infection
• False aneurysm