Arterial cannulation

Summary

Indications

1. ▪ Continuous blood pressure monitoring

2. ▪ Arterial blood gas analysis.

Complications

1. ▪ Infection

2. ▪ Thrombosis with distal ischaemia (risk factors are: size of catheter, multiple attempts, duration in situ, ischaemia, and pre-existing hypertension)

3. ▪ False aneurysm.

Equipment

1. ▪ Sterile drape and gloves

2. ▪ Aseptic solution

3. ▪ Local anaesthetic with needle and syringe

4. ▪ Clear dressing

5. ▪ Continuous flushing device

6. ▪ 20 g Teflon cannula (e.g. Abbocath) and 2 ml syringe (plunger removed) or Seldinger arterial kit.

Sites

1. ▪ Radial artery: accessible site, with good collateral flow. 10% have either poor collateral flow or incomplete palmar arch, therefore Allen's test (see Examination of the Vascular System Chapter) is used to confirm ulnar artery blood supply. Position for insertion of arterial line: hyper-extending the wrist with thumb abducted.

2. ▪ Brachial artery: generally avoided, as if occluded, the collateral supply around the elbow may be insufficient.

3. ▪ Axillary artery: generally avoided as difficult and uncomfortable for patient.

4. ▪ Femoral artery: Higher infection risk.

5. ▪ Dorsalis pedis: small calibre vessel, difficult cannulation.

Technique

Three techniques are commonly practiced:

1. Direct cannulation: similar to peripheral intravenous access:

1. ▪ Palpate the artery and its course.

2. ▪ Insert local anaesthetic subcutaneously.

3. ▪ Aseptic precautions.

4. ▪ Attach the 2 ml syringe to the cannula.

5. ▪ Insert as per an intravenous cannula (the 2 ml syringe acts as a reservoir for blood and confirms that the bevel is still within the artery).

6. ▪ Attach to continuous flushing device (see Figure 126).

7. ▪ Apply dressing to secure.

8. ▪ Discard sharps appropriately.