You folks know that if there’s one thing I’m passionate about, it’s us nurses doing more with our skills. One fantastic example of how we can do more to support our critical medical patients is through placing and maintaining central venous catheters. These are incredibly fun to place, allow us to administer multiple drugs and fluids easily, and collect samples without the need for repeated venipuncture - what’s not to like?

In today’s post, we’re talking all about what central venous catheters are, how they are placed, when to use (and when not to use!) them, and how to nurse the CVC patient.

What is a central venous catheter?

Central venous catheters (CVCs, or central lines) are catheters placed in such a way that the tip of the catheter sits in the vena cava. These are generally large-bore catheters and can be multi-lumen, allowing multiple fluids to be administered simultaneously.

Why use one?

CVCs have several benefits and specific indications, including:

• The administration of multiple (incompatible) agents at once through multi-lumen catheters (two or three separate lines, allowing for complete separation of incompatible substances through the same catheter) 

• The administration of hyperosmolar solutions which would not be suitable for peripheral veins, due to an increased risk of phlebitis; these solutions include concentrated glucose (>7.5%) solutions and parenteral nutrition solution

•  Allowing measurement of central venous pressure (CVP)

• Collection of multiple blood samples through the sampling port, without performing repeated venipuncture

• They are suitable for longer-term use than peripheral catheters – and can be left in situ for up to 14-21 days.

When wouldn’t we use one?

CVCs do carry increased risks and special considerations when compared with standard peripheral IV catheters, and as nurses, we need to be aware of these to plan our nursing care effectively. These include:

• CVCs are not suitable for use in coagulopathic or thrombocytopenic patients

• CVCs are not suitable for patients with increased intracranial pressure

• CVCs are not suitable for patients with wounds, cellulitis, vasculitis or other lesions in the region of the jugular vein

• CVCs have a higher cost than standard catheters

• CVCs require more intensive monitoring and care, compared with peripheral catheters (24-hour care and monitoring must be available on-site)

Complications associated with CVC use include:

• Bacterial contamination – introduction of infection into the central circulation has more significant consequences than peripheral circulation. This is especially important at the time of placement, as this carries the highest risk of introducing contamination. Sepsis and/or cellulitis can result if they are improperly placed or managed.

• Thrombus formation – this can cause complete occlusion of the catheter lumen(s) in severe cases, and careful management is required to prevent thrombosis.

• Cardiac arrhythmias may be seen at the time of catheter placement (usually self-limiting)

• Phlebitis

•  Haematoma formation

• Haemorrhage

• Self-trauma, interference or removal

• Kinking of the catheter, complicating administration of fluids or medications – careful selection of the placement and suture site is advised to minimise this.

Central Venous Catheter Placement

Equipment Required

• Jugular catheter kit of appropriate size and length, based on patient

  • Two versions are available; Seldinger (guidewire) technique or peel-away technique

• Sterile gloves

• Clippers

• Chlorhexidine scrub solution

• Chloraprep or final skin preparation applicator

• 100ml Saline x 1

• Needle-free bag spike x 1

• 5ml syringes x 2-3

• Alcohol disinfecting caps

• Dressing material

Placement Technique

• A 10x10 cm area is clipped over the right jugular vein (typically the left is not used if possible, as oesophagostomy tubes are placed on this side) and aseptically prepared.

• An assistant raises the vein.

• A small stab incision is made in the skin over the jugular vein.

• Using the large-bore peripheral IV catheter supplied in the jugular catheter kit, the jugular vein is cannulated, the stylet removed, and the catheter bunged.

•  If using the Seldinger technique, the guidewire introducer is placed into the catheter hub, and the guidewire advanced using the measuring markers on the wire as a guide. Approximately 20-30cm of guidewire should remain outside of the patient’s vein, depending on the length of the guidewire and catheter being used.

  • The anaesthetist should monitor the patient’s ECG closely during this time, as cardiac arrhythmias can be seen if the guidewire is advanced too far into the cranial vena cava.

  • The introducer and peripheral IV catheter are removed, leaving the guidewire in situ.

  •  A dilator is placed over the top of the guidewire, to facilitate the introduction of the catheter. This is then removed again, leaving the guidewire in situ.

  • The catheter ports are flushed with sterile saline and the catheter is introduced over the top of the guidewire, holding the guidewire with one hand, and advancing the catheter over it with the other. The gate clamp over the lumen where the guidewire is emerging is released, to allow the guidewire to pass through the catheter lumen.

  • The catheter is advanced off of the guidewire to the level of the multi-lumen port, and the guidewire is withdrawn.

• If using the peel-away technique, the peel-away introducer, with its stylet, is placed directly into the jugular vein through the stab incision.

  • The stylet is removed, and the catheter advanced directly through the introducer to the multi-lumen port.

  • The peel-away introducer is pulled apart and peeled off of the catheter, as the catheter’s position within the neck is simultaneously maintained.

• Each port is checked for blood flow, flushed, and a needle-free valve is attached.

• The catheter is then sutured in place and covered with a sterile dressing and light neck wrap.

CVC Care and Management

Much of the veterinary nurse’s role in managing these devices is to maintain asepsis and avoid contamination during daily use of the catheter. 

Aseptic Technique

Whenever handling the catheter, lines or ports (e.g. when administering medications or obtaining blood samples), strict hand hygiene should be performed in addition to wearing disposable examination gloves. 

In addition to this, the catheter must be stripped back (i.e. all bandage material removed) and the site examined for signs of phlebitis, haematoma, dislodgement or kinking, or any other abnormality at least once every 12 hours. Any abnormalities should be reported to the veterinary surgeon managing the patient, in case catheter removal is required. 

The site should be cleaned as necessary, and a new dressing should be applied; the site should be covered with a sterile non-adhesive sterile dressing. The catheter should then be bandaged with a soft padded bandage, followed by a conforming bandage. Any catheter ports/lines exposed outside of the dressing should be secured with stockinette or ‘string vest’ material (provided it is not too tight) to avoid ports hanging or dangling, risking contamination. Alcohol disinfecting caps should also be applied over the needle-free ports, and these should be changed each time the catheter ports are flushed.

Sterile gloves should be worn at all times during the catheter strip back, examination and re-dress.

The CVC ports should be carefully managed, with alcohol applied to each port prior to use, and alcohol disinfecting caps covering each port whilst not in use. Ideally, needle-free valves should be utilised, as needle puncture can be associated with increased contamination. 

Whenever any ports are used, particular attention should be paid to the catheter gate clamps, ensuring they are closed whilst the needle-free valve is activated. If a line/syringe is attached to the port with it open, air embolism can result.

All ports not in use require flushing every four hours, with heparinised saline. Ideally, each patient should have their own, labelled, bag of saline made up and replaced every 24 hours.

If any ports are occluded, they should not be used. The author removes the needle-free port and replaces this with a red ‘closed cap’, to prevent syringe attachment and clearly labels the port ‘DO NOT USE’. This avoids the accidental flushing of blood clots into the circulation.

CVC Ports Explained

Most CVCs have 2-3 lumens, with colour-coded ports. Two-lumen catheters have a white and brown (proximal and distal) port, and three-lumen catheters have a white (distal), brown (middle) and blue (proximal) port. Generally, the proximal (white) port is used for fluid therapy (including blood products or colloids). The middle (blue) port is reserved for parenteral nutrition, or if PN is not expected for that patient, it may be used for other purposes – typically the administration of medications. The distal (brown) port is used for medication administration and is also used for blood sample collection.

Sample Collection

When collecting blood samples from a CVC, the following equipment is required:

• Sterile gloves

• 2ml syringe containing 0.3-0.5ml saline x 2

• An empty syringe of appropriate size for blood sample collection

• Alcohol disinfecting caps/swabs

• Required sample tubes

Sample procedure:

1. Following open gloving, the distal port is swabbed and a syringe containing flush is attached. 

2. A volume of saline flush equal to the catheter’s priming volume is infused into the catheter. 

3. Using the same syringe, a blood volume 3x the dead-space volume of the catheter is collected and immediately re-infused back into the patient. 

4. This is repeated three times until the flush is ‘diluted away’ with the patient’s blood. 

5. The sample is then collected in a separate syringe, and the catheter is flushed again. 

Other Considerations for CVC Patients

Dogs with central venous catheters should be walked carefully, with a harness, to avoid neck leads in the jugular region. Patients should be handled carefully, particularly avoiding restraint around the cervical area.

CVC Removal

When the central venous catheter is removed, the following steps should be followed:

• Hands are disinfected and disposable gloves are worn

• Sutures are removed using a disposable stitch cutter blade

• Sterile swabs are placed over the catheter site

• Digital pressure is maintained on the site as the catheter is removed

• Digital pressure remains on the site for a few minutes following removal

• A light bandage is placed over the site (care to ensure the dressing is not tight around the neck) for up to one hour

• A sterile adhesive dressing is placed over the site following bandage removal

So that’s an overview of central line placement, care and nursing! Do you use these in your clinic? Let me know below!

References:

1. Aldridge, P. and O’Dwyer, L. 2013. Practical emergency and critical care veterinary nursing. Wiley-Blackwell.

2. 2. Barr, C. et al. 2017. Effect of blood collection by the push-pull technique from an indwelling catheter versus direct venipuncture on venous blood gas values before and after administration of alfaxalone or propofol in dogs. Journal of the American Veterinary Medical Association, 251(10). Available from: https://avmajournals.avma.org/view/journals/javma/251/10/javma.251.10.1166.xml

3. Kirby, R. and Linklater, A. 2016. Monitoring and intervention for the critically ill small animal: the rule of 20. Wiley-Blackwell.