Central Lines

Central Lines

A central line (aka central venous catheter, CVL, CVC) is a large bore cannla or catheter which is inserted into a large vein in the body. The tip of the cannula may lie in either the superior or inferior vena cava (SVC or IVC) or into the right atrium (RA).

Below is a picture of a CVL.

There are a number of indications for inserting a central line, including:

• Measuring central venous pressure (CVP)
• Administering drugs or products which could damage smaller vessels, i.e. chemotherapy or parenteral nutrition
• Obtaining venous access in an individual whose peripheral veins have shut down, for example a patient in shock
• Administering high slow fluids - larger vessels required, as flow in a vessel is relative to the radius of that vessel to the power of 4
• Haemodialysis in renal failure
• Ease of IV access if required for a number of days, for example post-operatively

A central line can be inserted into the following veins, with those in bold used most frequently:

• Internal jugular vein
• Subclavian vein
• Femoral vein
• External jugular vein

Most central lines inserted in the region of the neck are placed into the right hand side if possible, as this provides the most direct route to the atrium, and avoids the possibility of injury to the thoracic duct.

Below are examples of CVL placement.


Inserting a CVL

Firstly, the site of insertion should be cleansed, and a sterile field prepared. The following video shows a version of the procedure:


Central lines are inserted with the patient in the 'Trendelenberg position'; lying down and facing away from the site of insertion. This is to aid identification of the required vein. Guidelines now advise ultrasound to be used to ensure the needle is placed correctly, and not inserted into the internal carotid or subclavian arteries. Studies have shown that ultrasound guidance increases the success rate of correct CVL insertion and reduces liklihood of any complication.

After the vein has been correctly located a guide wire is pased through the needle into the vein. The cannula or catheter is then passed over the guide wire into the vein and the guide wire can be removed.

Below is an X-ray showing a CVL correctly inserted:




Complications

• Pneumothorax
• Haemothorax
• Arterial cannulation
• Injury to the thoracic duct
• Air embolism
• Infection
• Thrombus formation