Central venous catheterisation - 2
Sites of insertion
Usual sites of insertion include :
- internal jugular veins
- subclavian veins
- femoral veins
Femoral insertion is associated with increased complications.
Assess the patient before you start
All patients should be assessed for factors that might increase the difficulty of catheter insertion such as :
- history of failed attempts or difficult access
- skeletal deformity
- scarring or previous surgery at insertion site
If you think you will have trouble inserting the catheter, either do it under supervision, or get someone more experienced to do it whilst you observe.
As with all invasive procedures, positioning the patient is critical to success. The head down (Trendelenburg) position fills the veins, making them easier to cannulate, and reducing the risk of air embolus.
Internal jugular insertion
1. Identify landmarks - the apex of the triangle formed by the two heads of the sternocleidomastoid muscle and the clavicle serves as a landmark. The internal jugular vein runs deep to the sternocleidomastoid muscle and then through this triangle before it joins the subclavian vein to become the brachiocephalic vein.
2. After the landmarks have been identified, sterile barriers have been prepared, and local anesthesia has been administered, the patient is placed in mild head down position with the head rotated 45 degrees away from the site of cannulation. Rotation of the head more than 45 degrees can result in the veins being compressed by the strap muscles in the neck.
3. Places your index and middle finger the nondominant hand on the carotid artery and inserts a 22-gauge 'finder' needle through the skin, immediately lateral to the carotid pulse and slightly superior to the apex of the triangle.
4. The needle is advanced past the apex of the triangle, in the direction of the ipsilateral nipple, at an angle of 20 degrees above the plane of the skin.
5. The vein is usually located near the surface of the skin and is often encountered after less than 0.5 in. (1.3 cm) of the needle has been inserted.
6. If the first pass is unsuccessful, the needle should be directed slightly more medially on the next insertion attempt. With the finder needle in place, an 18-gauge introducer needle is then inserted alongside it and into the vein.
Insertion site for internal jugular vein
Subclavian vein insertion
1. Locate the vein - the subclavian vein arises from the axillary vein at the point where it crosses the lateral border of the first rib. It is usually 1 to 2 cm in diameter and is fixed in position directly beneath the clavicle. It is separated from the subclavian artery by the anterior scalene muscle.
2. For catherization, the patient is placed in a mild head down position. Some people find a small rolled towel between the patient's shoulder blades helps positioning.
3.After identification of the landmarks, sterile preparation, and administration of local anesthesia, the skin is punctured approximately 2 cm below to the midpoint of the clavicle with an 18-gauge introducer needle.
4.The needle is advanced in the direction of the sternal notch until the tip of the needle hits the clavicle at the junction of its medial and middle thirds.
5.The needle is then passed beneath the clavicle, with the needle hugging the underside of the clavicle.
6. If the first pass is unsuccessful, the needle should be angled slightly more towards the sternal notch on the next insertion attempt.
Choosing the site - points to remember
- all lines, but particularly internal jugular catheterisation is often difficult in morbidly obese patients as it is difficult to determine landmarks.
- subclavian vein catheterisation should be avoided in patients with severe hypoxaemia due to increased risk of pneumothorax associated with this location.
- femoral catheterisation should be avoided in patients who have grossly contaminated inguinal regions due to increased risk of infection.
- the femoral vein should be considered if central venous access is required in resuscitation as it is quicker to insert and identify landmarks. The catheter can always be replaced at a more appropriate site when the patient is more stable.