Central line placement allows us to gain access to the vasculature in order to administer fluid therapy and medications, perform serial blood sampling, and monitor haemodynamic parameters. Careful vessel selection and catheter placement are of paramount importance. Central venous catheters (CVC) are most commonly inserted via the jugular vein, with the tip of the catheter sitting in the cranial vena cava. PICC (peripherally inserted central catheter) lines can be used, especially if there is a suspicion of increased intracranial pressure or where the access to the jugular vein is limited. In this case, long catheters are inserted through the medial or lateral saphenous veins and the tip sits in the caudal vena cava.^1,2

When choosing the appropriate site, several factors should be taken into account, like the patient size and species, vein accessibility, physical barriers (wounds, fractures, neoplasia, neurologic insufficiencies), restraint requirements, patient temperament, haemodynamic stability, coagulation abnormalities (CVC may be contraindicated in hyper- or hypocoagulable states) and sources of contamination like urine, vomit, diarrhoea or faeces.^1,2

Indications for CVC or PICC line placement include prolonged hospitalization, administration of hypertonic fluids or hyperosmolar medications, frequent blood sampling, delivery of total parenteral nutrition (TPN), central venous pressure (CVP) monitoring and when maintaining a peripheral catheter is expected to be challenging.^1,2

There are several disadvantages in the use of a CVC/PICC line, like longer placement time, which increases the risk of infection, greater expense, patient discomfort during placement which requires the patient to be sedated/anaesthetised, longer length may make rapid fluid administration problematic and difficulty in monitoring for extravasation of fluid.^1,2

The use of CVC should be avoided in cases where there is suspicion of thromboembolic disease, coagulopathy, increased intracranial pressure, respiratory disease (prolonged time for its placement could be an issue), immune mediated haemolytic anaemia and cervical disease/pain.

Several different types of catheters can be used for CVC/PICC lines, such as:

• Long over-the-needle catheters are cheaper, available in various diameters and lengths, made of a stiff material which can cause discomfort, prone to kinking and as made of Teflon should be replaced every 72 hours.^1,2
• Through-the-needle catheters are longer than long over-the-needle, are available in various diameters and lengths, placement is faster, they can be placed in peripheral vein if the jugular cannot be used, they are cheaper and require a bandage to secure them.^1,2
• Over-the-wire catheters are available in single or multi lumen. They are designed to stay in place for longer periods (soft, flexible and made of anti-thrombogenic material). Available in various lengths and diameters. Placement requires a longer procedure time, and they are more expensive.^1,2

Placement

The most commonly used CVC placement technique is the over-the-wire (Seldinger) technique. PICC lines may require through-the-needle techniques. A few steps are common to both techniques and are very important:

• Determine the appropriate length of CVC before scrubbing by measuring (tape measure) from the approximate site of insertion to where the tip of the catheter should lie. For jugular lines the tip should lie just outside the right atrium which usually approximates to the caudal border of the scapula when measuring.
• Prepare all equipment needed for CVC placement.
• Attach patient to monitoring equipment.
• The catheterisation site is clipped and surgical preparation performed.
• Aseptic technique is essential and the operator and assistant should wear a gown, face mask and sterile gloves.

Through-the-Needle (Peel-Away) Catheter

• Insert the peel-away over-the-needle sheath into the vein.
• Remove the needle, leaving the sheath in the vein.
• Insert the catheter through the sheath into the vein.
• Grasp and pull the sheath, peeling it up out of the vein, leaving the catheter in place.
• Aspirate catheter and flush with 0.9% NaCl or heparinised saline.
• Suture at the anchor points and bandage.²

Through-the-Needle Catheter

• A plastic sleeve around the catheter prevents contamination during placement.
• Once the catheter has been fed entirely into the vessel, the needle is backed out of the skin and a protective guard is snapped over the needle.²

Over-the-Wire Catheter (Seldinger Technique)

Material

1.  Mayo stand or a table with sterile field

2.  CVC single or multi-lumen (multi-lumen preferably)

3.  Sterile swabs

4.  Suture material

5.  Sterile NaCl 0.9% 100 ml bag

6.  Sterile syringes (5 ml and 10 ml quantity depending on number of lumens x 2)

7.  Sterile needles (ideally 21 G 5/8”) equal to number of syringes

8.  Intravenous catheters (size depending on the size of guide wire)

9.  ECG monitor

10.  Lidocaine 2% with 2 ml syringe and 21–23 G needle

11.  Needle free valves for each lumen³

Placement

1.  Ask assistant to open the required equipment in a sterile manner.

2.  Prepare syringes with sterile NaCl 0.9% (do not fill them completely as some available volume is required for aspiration of blood from CVC once it is in place).

3.  Prepare CVC by attaching needle-free valves and pre-flushing the lumens with 0.9% NaCl and clamping them off immediately after flushing before the syringe is detached. Return catheter to the pack.

4.  Drape the patient.

5.  Ask assistant to raise the vein and determine the venepuncture site.

6.  Use a peripheral intravenous catheter of an appropriate size, or the catheter supplied with the CVC pack for initial venepuncture (skin incision using a scalpel blade can be performed for ease).

7.  Once catheter is placed in the jugular vein, remove the stylet, leaving the catheter in place and then introduce the guide wire. Use the J ending of the guide wire which should be retracted back into the sheath and then fed through the catheter into the vessel (at this point monitor patient for any changes on the ECG monitor as this might indicate introduction of the wire into the heart which can cause cardiac arrhythmias).

8.  Once the guide wire is in, remove the catheter ensuring the guide wire is held at all times and that it does not move deeper into or completely out of the vessel.

9.  Once only the wire remains in the vessel, a dilator is fed over the wire and should be introduced into the vessel by a slight rotating motion. Some force might be required to pass through the tissues and the vessel wall.

10.  Remove dilator while holding the wire and ensuring it remains in the vessel.

11.  Remove the dilator and feed the CVC over the guide wire unclamping the distal (brown) lumen to allow free passage of the guide wire (the guide wire should always be held by operator or assistant and must be retracted out of the vessel enough to enable firm hold of it at the distal CVC lumen while introducing CVC into the vein).

12.  Once the CVC is inserted to the pre-measured length the guide wire can be removed.

13.  Attach sterile syringe preloaded with NaCl 0.9% and aspirate each lumen until blood is visible. If any air remains it should be aspirated into the syringe. Flush lumens until cleared of any remaining blood.

14.  Secure the CVC in place by placing sutures through its wings.

15.  Radiograph chest to confirm positioning. If the catheter is sitting within the right atrium or is not parallel to the vessel, it should be repositioned and reconfirmed. Inappropriate positioning of the CVC could lead to life threatening complications.

16.  Place a sterile dressing (Allevyn adhesive for example, size depending on size of animal) over the insertion site, followed by padding such as Soffban, and conforming bandages respectively. Take care to keep bandages around the neck very loose to avoid restricting breathing.³

Maintenance

Appropriate maintenance is of extreme importance and it is paramount that aseptic technique is used at all times:

Catheter Check

• Flush unused ports with sterile saline (q 8–12 h).
• More frequent checks if any concerns or high rates of fluid therapy.
• Check for swelling, if there is swelling cranial to the insertion site, the tape might be too tight or there might be oedema formation. If the swelling is caudal to the insertion site, fluid extravasation may have occurred.
• Check for signs of inflammation (pain, redness, malodour, discharge).
• If complications are noted when doing the catheter check:
• Record findings and inform clinician.
• Consider removing the catheter if appropriate.
• Consider sending the tip for culture and sensitivity.
• Replace in another site if necessary.
• The bandage should be removed and changed at least once daily as well as any dressing covering the incision port.^1-3

Blood Collection

One of the ports should be reserved for blood collection only. The port should be swabbed with alcohol impregnated solution for 15 seconds allowing 15 seconds to dry.³ Then, the line should be flushed with heparinised saline and 2–2.5 ml of blood should be drawn and not discarded.³ The samples can be collected and the amount of blood firstly drawn be re-introduced. The line should then be flushed with saline and the port swabbed again.

Administration of Medications/Intravenous Fluid Therapy (IVFT)

One port should be dedicated to this purpose. The port should be swabbed with alcohol impregnated solution for 15 seconds allowing 15 seconds to dry.³ The fluid line can then be connected or medication administered. In case of medication being administered, the used port should be flushed. The port should then be swabbed again.²

Total Parenteral Nutrition (TPN)

One port should be dedicated to this purpose even if patients are not on it. The port should be swabbed with alcohol impregnated solution for 15 seconds allowing 15 seconds to dry. Disconnection of the line from the port should be avoided as can increase the infection risk.³

Central Venous Pressure (CVP)

Use the IVFT or blood collection port, swab port with alcohol impregnated solution for 15 seconds allowing 15 seconds to dry. Then, connect the CVP measurement tubing. After the measurement is performed, swab the port again.^2,3

Complications

Complications may include displacement, extravasation of fluid or medication, phlebitis/thrombophlebitis, infection, dislodgement/catheter embolism, air embolism or exsanguination.^1,2

References

1.  Adamantos S, Alwood A. Vascular access. In: BSAVA Manual of Canine and Feline Emergency and Critical Care. BSAVA Library; 2015:8–17.

2.  Creedon JMB, Davis H. Advanced Monitoring and Procedures for Small Animal Emergency and Critical Care. John Wiley & Sons; 2012.

3.  Aspinall V. The Complete Textbook of Veterinary Nursing. 2nd ed. Elsevier Health Sciences; 2011.

4.  SOP folder from the ICU at the Royal (Dick) School of Veterinary Studies.

5.  Dodd L. Critical patient care (venous catheters, urinary catheters, drains). In: Proceedings from the 13th EVECCS Congress. EVECCS; 2014.