Vascular Access Techniques
Jennifer J. Devey, DVM, Diplomate ACVECC
Saanichton, British Columbia
Access Points
Typically peripheral catheters are placed in the cephalic veins. Lateral saphenous veins can be used in dogs and medial saphenous veins can be used in cats. In larger animals the dorsal pedal vein can be accessed. Peripherally inserted central catheters (PICC) can be inserted via the saphenous veins. Central lines can be inserted via the external jugular veins. When no other access points exist catheters can be inserted via the maxillary or the femoral veins.
Catheter Materials
Catheters can be made of many different types of materials. Most over-the-needle catheters are made of Teflon which is rigid and moderately reactive. Central catheters are typically made of polyurethane which is soft and flexible and moderately reactive. Silicone is chemically inert, soft, flexible and only mildly reactive. Polyvinylchloride, polypropylene, polyethyleneare more rigid and more reactive than other materials, and typically should be avoided as vascular access catheters or long term indwelling catheters.
General Peripheral Catheter Care
Fur should be clipped circumferentially around the limb for peripheral catheters. Individual packets of triple antibiotic ointment should be used to apply ointment over the venotomy site followed by placement of a Band-Aid or a sterile 4x4. The site should be monitored continuously for signs of swelling or discomfort. The dressing should be changed every 24 hours or when it becomes wet or soiled although disturbing the catheter at the venotomy site should be avoided.
Catheters should be removed whenever there is sign of significant inflammation (pain, redness, heat, swelling) or infection. These complications are going to be more likely with serious underlying disease, immunocompromised patients, infusion of hyperosmolar fluids or irritating medications, and excessive movement of the catheter. With proper care a catheter may easily last as long as 5 days.
Facilitative Maneuver
A facilitative maneuver involves making a small nick in skin with edge of hypodermic needle. This reduces the resistance to passage of the catheter allowing less painful placement, less likelihood of burring, and usually allows a catheter one size larger than normal to be placed.
Mini-Cutdown – Peripheral
A mini-cutdown is indicated when the cephalic or saphenous vein cannot be visualized and there is a need to establish IV access with absolute certainty on the first attempt.
method:
surgical prep of catheter site as for routine percutaneous catheter placement
use edge of bevel (rim) of 20g or 18g hypodermic needle as “scalpel”
cut over vein across skin tension line; i.e., craniomedial to caudolateral direction at 15-30 degrees off horizontal
visualize vein and insert catheter
dissect vessel further as needed using needle as ‘mini scalpel’ with bevel directed parallel to vein
place triple antibiotic over cutdown site
tape in catheter as normal and place sterile dressing
Central Catheters
Central catheters are catheters whose tip is in the vena cava. They are indicated whenever central venous pressure monitoring is indicated, when frequent blood sampling is necessary, or when hypertonic fluids need to be administered. Central catheters can be placed using a through the needle, peel-away, Seldinger or feeding tube technique. Through the needle catheters function far less effectively than catheters placed via a peel-away or Seldinger technique in the author’s experience and so will not be discussed here.
General Placement Principles
For jugular catheters the skin should be clipped from the dorsal midline to the opposite jugular. Aseptic technique must be used including the wearing of surgical gloves,placement of a drape and use of sterile instruments and suture material. Patients are typically placed in lateral or dorsal recumbency but can be placed with the animal sitting. The neck is extended and the catheter is measured from the site of entry to level of 4th intercostal space for placement at level of right atrium. The jugular vein is always located along line between angle of mandible and thoracic inlet. The skin is punctured first and then the vein.
Peel-Away Sheath Introducer
This technique typically is used to place PICC lines but can be used to place central lines.
method:
make small skin nick
insert sheath-needle assembly into vessel
stabilize needle to prevent from advancing or retracting and advance sheath
remove needle leaving sheath in vessel (a sterile gloved finger can be placed over end of sheath to prevent excessive hemorrhage)
introduce catheter through sheath, cap and flush
remove sheath by pulling tabs up and out
suture catheter to skin and bandage
Seldinger Technique
The Seldinger technique was developed by Dr Seldinger, a Swedish radiologist, in 1953. The catheter is threaded over a wire that has been introduced into the vessel. The wire is known as a J-wire due to the presence of a hook in the tip of the wire.
method:
place over-the-needle catheter in vein using percutaneous venipuncture
remove catheter stylet and feed in J-wire using introducer
in narrow diameter veins (if diameter smaller than J) use blunt end of wire rather than J end
remove catheter while holding on to wire
place dilator over wire - insert through skin with rotating motion
remove dilator and insert long catheter over wire
remove wire
suture catheter and bandage
Feeding Tube Through Percutaneous Catheter
This technique was first published in veterinary medicine by Rivera and Spreng. It allows for placement of PICC lines or long central lines and can be used when commercial catheters are not available.
method:
place 16g or 14g 1over-the-needle catheter into vein
attach 3-way stopcock to end of 3.5Fr (16g) or 5Fr (14g) feeding tube, prime tube with saline
lubricate outside of feeding tube with 50% dextrose
insert feeding tube through catheter to pre-measured level
remove percutaneous catheter from vein sliding as far proximally as possible
secure catheter and bandage as for other catheters
Intravenous Cutdown – Central
Central cutdowns are indicated for patients in severe hypovolemic shock or during CPR.
method:
surgical prep of jugular (ideal)
attach 3-way stopcock to end of 3.5Fr (16g) or 5Fr (14g) feeding tube, prime tube with saline
make skin incision with #10 or #15 scalpel
use blunt dissection to expose vein
dissect vein with curved hemostats so minimal fascia attached to vein
slide hemostats under vein to level of handles - this provides a platform to work from
tie off vein proximally using monofilament suture; keep ends long to use as traction
place second suture around vein distally but do not tie
insert #11 blade parallel to vessel through centre of vessel, turn 90 degrees and cut outwards
using catheter introducer or blunt end of curved needle open vessel and slide in catheter
tie second suture trapping vein to catheter; ensure at least 3 mm tissue bumper
suture incision (leave partially open if not done under aseptic conditions)
place sterile dressing
Complications
Most catheter complications relate to phlebitis. This can be simple inflammation related to movement of a stiff catheter in a vein or as serious as infection that can lead to bacteremia. Aseptic technique should be used whenever possible. If sterility was broken the wound should be cleaned thoroughly, antibiotic ointment applied and a sterile dressing placed. Forceful aspiration should be avoided in all small peripheral catheters since it tends to suck the wall of the vessel against a burred edge. Infusion of hyperosmolar solutions should be avoided through peripheral vessels unless there is very good blood flow around the catheter. Thromboembolic complications are also possible and are often associated with the underlying disease. Ensuring that catheters made of nonthrombogenic materials are used whenever possible will minimize this complication.