Venepuncture & Cannulation Flashcards
What is the definition of venepuncture?
The procedure of inserting a needle into a vein, in order to obtain blood samples for haematology and/or microbiology.
What is the definition of peripheral venous cannulation (PVC)?
The insertion of a plastic tube into a patient’s vein in order to administer intravenous medications, fluid or blood.
What are the two main steps to locating a vein?
- Visual inspection
- Palpation
What should a good vein be?
- Be visible
- Be soft and bouncy
- Refill when depressed
- Be straight
- Have a good large (or largest) lumen
- Be well supported
What vein should be considered first?
Metacarpal veins (the veins on the dorsum of the hand). If these veins are not suitable then continue to look further up the arm until you reach the antecubital fossa (located in a depression on the anterior surface of the elbow joint, it lies anteriorly to the elbow).
Why should the metacarpal vein be considered first?
If you insert a cannula in the antecubical fossa area and are unsuccessful, damage will have been caused to the wall of the vein. If you then insert a cannula in the metacarpal veins and administer IV fluids, the fluid could seep out at the ACF vein causing an infiltration or extravasation injury. When re-siting a cannula, the new insertion site must be proximal to the current site to avoid extravasation injury.
What equipment is needed for venepuncture?
- Cleaned tray
- Non-sterile gloves
- Butterfly needle and holder and vacuum collection tubes
- Torniquet
- Gauze
- Tape
- Alcohol swab
- Blood tubes
What is the maximum length tourniquets should be left on?
1 minute
How is skin decontaminated?
Before needed insertion, the skin must be cleaned with 2% chlorohexidine and 70% isopropyl alcohol. It must be applied for 30 seconds then left to dry for 30 seconds.
What are the complications of venepuncture?
- Infection
- Structural damage
- Haematoma
- Prolonged bleeding
- Needle stick injury
- Phobias
What is a haematoma?
A haematoma is a collection of blood which is located outside the blood vessels.
Haematoma can occur during venepuncture if the needle breaks through the opposite vein wall causing blood to leak from the vein into the subcutaneous tissue. The needle will need to be removed, direct pressure applied to the site.
What equipment is needed for cannulation?
- Gather a clean tray
- Non-sterile gloves
- Cannula
- Blunt needle
- Sterile gauze
- Cannula dressing
- 10 mL syringe
- Alcohol swab
- 10 mL 0.9% NaCl solution
- Torniquet
What does selecting a cannula size depend on?
- Size of the patient’s vein
- What you need the medication to do
Why should you use the smallest cannula possible?
To reduce the risk of mechanical phlebitis.
Therefore, patients who only require IV antibiotics, blood or IV fluid, a 20 gauge (pink) cannula will be sufficient.
What are the complications that can occur with a cannula?
- Transfixation
- Phlebitis
- Haematoma
- Cannula fracture and migration
- Vesicant extravasation
