What Is A Central Line? A Complete Guide To Central Venous Catheters

A breakdown of what central lines are, how they work, insertion technique, removal and documentation.

Central venous catheters, commonly called central lines, are one of the most important vascular access devices used in modern healthcare.

They are commonly inserted in theatres, intensive care units and emergency departments to allow safe administration of medications, fluids and monitoring.

For Operating Department Practitioners, anaesthetic staff and critical care teams, understanding how central lines work is essential.

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1. What Is A Central Line?

A central line is a long sterile catheter inserted into a large central vein, usually the:

• Internal jugular vein
• Subclavian vein
• Femoral vein

The tip of the catheter sits within the superior vena cava close to the heart. This allows rapid dilution of medications and accurate central venous access.

Central lines are used for:

• Vasoactive infusions
• Long term IV therapy
• Total parenteral nutrition (TPN)
• Difficult IV access
• Central venous pressure monitoring
• Rapid fluid administration
• Frequent blood sampling

Unlike peripheral cannulas, central lines can safely deliver irritant medications directly into high blood flow vessels. For example Noradrenaline/ Norepinephrine

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2. How Does A Central Line Work & What Equipment Is Needed?

Central lines work by providing direct access into the central venous circulation.

Most central lines are inserted using the Seldinger technique, where a guidewire is first inserted into the vein before the catheter is passed over it. (

Equipment commonly required includes:

• Central line insertion kit
• Ultrasound machine
• Sterile ultrasound probe cover
• Sterile gown and gloves
• Large sterile drapes
• Chlorhexidine skin prep
• Local anaesthetic
• Scalpel
• Guidewire
• Dilator
• Syringes and saline flushes
• Transparent dressing
• Monitoring equipment
• Three way Taps or Smartsite devices to add onto the Lumens.

Strict aseptic technique and maximal sterile barrier precautions are essential during insertion to reduce bloodstream infection risk. 

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3. How Is A Central Line Inserted?

Insertion is normally performed using ultrasound guidance to visualise the target vein and reduce complications.

The patient is positioned appropriately depending on the insertion site. Internal jugular lines are often inserted with the patient head down slightly to reduce air embolism risk. A simplified insertion process includes:

1. Consent and patient explanation
2. Monitoring attached including ECG, oxygen saturation and blood pressure
3. Sterile gowning and draping
4. Skin preparation using chlorhexidine
5. Ultrasound identification of the vein
6. Needle insertion into the vessel
7. Guidewire insertion
8. Needle removal
9. Small skin incision using scalpel
10. Dilator advanced over the wire
11. Central line threaded over guidewire
12. Guidewire removed and confirmed intact
13. Line flushed and secured
14. Sterile dressing applied
15. Chest X-ray confirmation where appropriate

Potential complications include:

• Pneumothorax
• Arterial puncture
• Bleeding
• Air embolism
• Catheter infection
• Arrhythmias
• Incorrect placement

 

*ALLWAYS watch the ECG for rhythm changes/ectopics when inserting the guide wire and Cather. Ectopic beats or change in rhythm usually mean the wire/catheter is too far into the heart.

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4. How To Remove A Central Line Properly

Central lines should be removed as soon as they are no longer clinically required to reduce infection risk. 

Proper removal technique is extremely important because complications such as bleeding or air embolism can occur if the procedure is performed incorrectly.

Typical removal steps include:

1. Explain the procedure to the patient
2. Position the patient flat if possible
3. Perform hand hygiene and apply PPE
4. Remove dressing using aseptic technique
5. Ask the patient to perform a Valsalva manoeuvre or exhale during removal
6. Slowly withdraw the catheter smoothly
7. Apply immediate pressure to the site
8. Inspect the catheter tip to ensure it is intact
9. Apply an occlusive sterile dressing
10. Monitor for bleeding or respiratory symptoms

Patients are normally observed after removal for signs of bleeding, air embolism or infection. 

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5. Documentation

Accurate documentation is essential throughout the life of a central line.

Documentation should include:

• Date and time of insertion
• Insertion site
• Type of catheter inserted
• Number of insertion attempts
• Clinician performing insertion
• Use of ultrasound guidance
• Confirmation of guidewire removal
• Dressing applied
• Chest X-ray confirmation if required
• Line removal date and time
• Condition of catheter on removal
• Any complications

Daily assessment of whether the line is still clinically necessary is recommended to reduce catheter related bloodstream infections. 

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Common Complications Of Central Lines

Although central lines are extremely useful, they are not without risk.

Common complications include:

• Central line associated bloodstream infections (CLABSI)
• Pneumothorax
• Air embolism
• Venous thrombosis
• Occlusion
• Catheter migration
• Bleeding or haematoma formation

Strict aseptic technique, proper dressing care and early removal all help reduce complication rates.

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