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Intravenous Catheterization

Elisa M. Mazzaferro, MS, DVM, PhD, Diplomate ACVECC, Wheat Ridge Veterinary Specialists, Wheat Ridge, Colorado

Internal Medicine

November 2007
Peer Reviewed

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Intravenous catheterization is used to administer drugs, intravenous fluids, parenteral nutrition, and blood products during illness and also in routine elective procedures. Expertise is required to ensure that the procedure does not contribute to increased morbidity.

Deciding where to place an intravenous catheter is largely dependent on the condition(s) being treated and the practitioner's experience and expertise. For example, the potential for contamination with vomitus, epistaxis, urine, or feces would help determine whether to place a catheter in a forelimb or a hindlimb, but a hindlimb would be used to minimize risk of injury to personnel when dealing with a fractious animal or one with a seizure disorder.1

Intravenous catheters come in a variety of types and sizes for long- and short-term use, including butterfly catheters, over-the-needle short catheters, and through-the-needle long central venous catheters (Figure A).

A butterfly catheter is used for short-term infusion of drugs such as chemotherapeutic or anesthetic agents. Butterfly catheters are not designed to remain in place for chronic use because of the risk that the needle's sharp edge will lacerate the vessel.

Short, over-the-needle polypropylene catheters are most commonly used to infuse drugs, fluids, or blood products. Because the rate of flow through a catheter is inversely proportional to its length and radius, the flow through a short, large-bore catheter is much faster than that through a smaller gauge,
long one.

A long catheter that enters a central vein is used to infuse drugs, fluids, or blood products and is also used for blood sample collection and administration of hyperosmolar solutions (eg, parenteral nutrition). Large-bore central venous catheters are less desirable in animals with coagulation abnormalities (eg, vitamin K antagonist/rodenticide intoxication), or in patients at risk of thrombosis, such as those with immune-mediated hemolytic anemia or hyperadrenocorticism.

Patient Preparation
It is essential to wash hands and don a pair of gloves prior to the procedure. For peripheral catheter placement, nonsterile gloves are sufficient. Restrain the animal in a position that is comfortable for both patient and handler. In most cases, sedation is not necessary. Clip hair from the site of insertion circumferentially around the limb where the catheter will be inserted (Figure). Remove long hair on the caudal aspect of the limb to prevent contaminating the site with debris once the catheter is secured with tape. Scrub the area with an antimicrobial solution, such as chlorhexidine or povidone-iodine, and rinse with isopropyl alcohol, sterile saline, or water.

Clipping helps adhesive tape cling to the patient's skin, which in turn secures the catheter in the vessel.

Peripheral Venous Catheter Placement
Peripheral catheters can be placed in the cephalic, accessory cephalic, auricular, lateral, or medial saphenous veins. After the catheter site has been clipped and aseptically scrubbed, have an assistant occlude the vessel proximal to the proposed site of insertion.

Insert the over-the-needle catheter through the skin and into the vessel at approximately a 15º to 30º angle. Place a 4 × 4 gauze square distal to the clipped area to avoid dragging the catheter through the hair coat (A).

In some instances, such as in an intact male cat or an extremely dehydrated animal, the skin will be tough and cause the catheter to become jagged as it is pushed through the skin. Percutaneous facilitation is a technique in which a small nick incision is made through the skin over the vessel. The catheter and stylet can be inserted through the incision to prevent burring of the catheter through the tough skin.

Once the catheter and stylet have been inserted into the vessel, watch carefully for a "flash" of blood in the catheter hub, then push the needle and catheter an additional 2 mm to 3 mm into the vessel.

Have an assistant place a thumb over the catheter in the vein while the stylet is removed (B). This will occlude the vessel sufficiently so blood will not flow back and contaminate the site.

Next, place a T-port or male adapter that has been flushed with heparinized saline into the hub of the catheter. The catheter can now be secured in place with adhesive tape.

Use the largest bore catheter possible in a peripheral application to optimize the rate of fluid flow.

Over-the-Wire Central Venous Catheter Placement
Central venous catheters are essential when a patient will undergo multiple venipunctures over time, for simultaneous infusion of multiple fluids and drugs, or to administer hyperosmolar solutions such as parenteral nutrition.2 Over-the-wire catheter kits are available from a variety of sources but the components are similar. After routinely preparing the animal's catheter site, drape in with sterile field towels and disposable sterile drapes. Infiltrate a small amount (0.5 mg/kg to 1 mg/kg) of lidocaine into the subcutaneous tissue and skin over the proposed site of catheter insertion, being careful to avoid intravenous administration of lidocaine. 

Wearing sterile gloves, make a small nick incision through the skin with a No. 11 scalpel blade, taking care to avoid lacerating the underlying vessel (A). Next, insert the catheter into the vessel at an approximately 30º angle. As with other catheters, watch for a flash of blood in the hub, then push the catheter off the stylet and into the vessel (B).

Insert a large vascular dilator over the J-wire into the vessel. Take care that the stylet of the catheter is completely removed before attempting to insert the J-wire. Straighten out the J portion of the wire into its introducer before attempting to seat it into the catheter hub. Once the J-wire is inserted, pull the catheter out of the vessel and off the J-wire. Be sure NEVER TO LET GO OF THE WIRE.

Place a vascular dilator sheath over the wire and insert into the vessel in a brisk twisting motion. It is not necessary to insert the dilator all the way into the vessel-its role is to create a large hole through the tissues on top of the vessel, including skin and muscle, so that the catheter can easily pass through without getting caught.

Remove the vascular dilator from the vessel and off the J-wire. Once the dilator is removed, blood will flow freely, so be prepared to place the long catheter quickly to avoid excessive blood loss through the expanded hole. Coil the catheter in your hand to prevent contamination and insert it over the wire into the vessel to its hub or predetermined length (A). Most catheters have side holes through which they can be attached to the skin using nonabsorbable sutures (B). After being flushed and wrapped with bandage material, the catheter is ready for use.

If the vessel isn't visible, try "strumming" the area with the needle, pushing back and forth under the skin until it pops over the underlying vessel.

Through-the-Needle Central Venous Catheter Placement
After selecting the type of catheter and proposed site of insertion, carefully clip and aseptically scrub the catheter site. Wash your hands thoroughly and put on sterile gloves. Restrain the animal in a comfortable position and occlude the vessel. Tent the skin over the vessel and insert the needle through the skin but not into the vessel. Insert the needle into the vessel at a 30º angle. While inserting the needle, watch for a flash of blood in the catheter. Once blood is observed, insert the catheter into the vessel.

If the catheter has a stylet and it was not removed to facilitate placement, remove it now (A). Once the catheter is in the vessel, flush with sterile 0.9% saline (B). The catheter can be secured with sutures or adhesive tape, and is ready for use. If the catheter is placed in a jugular vein intended for measuring central venous pressures, a lateral thoracic radiograph should be obtained to make sure that the distal tip of the catheter is located just outside the right atrium.

Securing & Maintaining an Intravenous Catheter
Intravenous catheters can be secured with lengths of 1/2- and 1-inch adhesive medical tape. First, check that the catheter hub and surrounding skin are dry and clear of moisture, blood, or debris. Place a length of tape around the catheter hub, ensuring it adheres securely to the catheter (A)-this piece of tape will prevent the catheter from slipping out of the vessel. Next, place a length of tape under the catheter hub and around the limb or neck. Secure a third length of tape around the T-port or male adapter and wrap it around the limb or neck. (B) Central venous catheters are also wrapped with layers of cotton and self-adhering bandaging material. All catheters should be labeled with the date and type of catheter placement.

Catheter maintenance involves flushing with sterile 0.9% saline, with or without additional heparin, every 4 to 6 hours. Evaluate the catheter site at least once daily for signs of erythema, discharge, difficulty flushing, or pain upon injection. Any of these abnormal signs, or fever in a previously afebrile animal, warrant removal of the catheter and culture of the catheter tip. It was previously thought that intravenous catheters should be removed and rotated every 3 days to prevent catheter-induced infection, but more recent research indicates they can remain in place as long as they are functional without the complications noted, provided that personnel strictly adhere to appropriate aseptic techniques during catheter placement and handling.3,4


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