LECTURE 7 (Cannulation) Flashcards
What is a cannula?
A flexible tube containing a needle (stylet) which may be inserted into a blood vessel
What are the main factors prior to inserting a peripheral cannula?
- Location of sitting
- Condition of the vein
- Purpose of the device
What are the properties of the Cephalic vein?
- Size + position -> excellent for transfusions
- Accommodates a large-gauge cannula
- Provides a natural splint
What are the properties of the Basilic vein?
- A large vessel
- Ulnar border or hand and forearm
What are the properties of the Digital veins?
- Small
- Can accommodate a small-gauze needle
- Last resort for fluid administration
What are the properties of Metacarpal veins?
- Accessible
- Easily visualised and palpated
- Well suited for cannulation
What are the Indications for cannulas?
- Short-term therapy (less than a week)
- Bolus injections/short infusions in the outpatient/day unit setting
What are the Contraindications for cannulas?
- Long-term intravenous therapy
- Longer/continuous infusions of medications that are vesicant or those that have a pH > 9
What does application of the tourniquet promote?
Venous distension
What is the difference between the Direct method and the Indirect method?
Direct method = when the device enters through skin and immediately enters the vein
Indirect method = When the device is inserted through the skin and vein is relocated and device is advanced into the vessel
Why shouldn’t the stylet be reintroduced after unsuccessful cannulation?
Could result in
- catheter fragmentation
- embolism
What is the measurement used for needles and cannulas?
Standard wire gauge
Measures the internal diameter (the smaller the gauze size, the larger the diameter)
How do you prepare the skin?
An antiseptic solution (e.g 2% chlorhexidine solution or 70% alcohol) should be applied with repeated back-and-forth strokes with friction for 30-60 seconds for an area of 4-5cm
When should cannulas be resited?
48-72 hours
What are the complications of Cannula insertion?
- Pain
- Hematoma
- Phlebitis
- Irritation/damage due to large cannulas or movement
- Chemical irritation from drugs
- Bacterial infection
What is Phlebitis?
Inflammation of the intima of the vein
CHARACTERISED BY:
- pain and tenderness along cannulated vein
- erythema
- warmth and streak formation with/without palpable cord
What are the three types of Phlebitis?
- Mechanical
- Chemical
- Bacterial
What are Arterial cannulas?
Plastic tube inserted and secured in a peripheral or central artery
Where are Arterial cannulas most commonly used?
In intensive care units and during surgery to
- Provide a means for continuous intra-arterial pressure monitoring
- Facilitate frequent blood sampling for blood gas and lab analysis
What are safest and most common sites for arterial cannulation?
- Radial artery
- Dorsalis pedis
Where is the central site of choice if peripheral arterial cannulation is not possible?
Femoral cannulation
What are the Indications for Arterial cannulation?
- During/following major anaesthesia
- Monitoring of acid/base balance and respiratory status in: acute respiratory failure, mechanical ventilation, during and after CPR, critically ill patients, severe sepsis and shock conditions
What are the Contraindications for Arterial cannulation?
- Previous upper extremity surgery
- Previous axillary clearance
- Peripheral vascular disease
- Raynaud’s disease (decreased blood flow to fingers)
- Diabetes
- Collagen vascular disease
- Active upper or lower limb infection
