Central Venous Catheters for Veterinary Technicians

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1 Central Venous Catheters for Veterinary Technicians Erica Mattox, CVT, VTS (ECC) Central venous catheterization is passing a long catheter into a large vein, such as the jugular or caudal vena cava. This can be achieved using a peripheral vein: a peripherally inserted central catheter or PICC. The peripheral vein used in cats and dog is the saphenous vein. Due to the difficulty of passing beyond the axilla into the larger anterior vena cava, central catheters are not inserted into the cephalic vein. Indications for central catheter placement include long-term administration of IV fluids and medication, use of hyperosmolar solutions (greater then 600mOsm/L), parenteral nutrition, potentially irritating drugs known to cause phlebitis and tissue sloughing (diazepam, pentobarbital, mannitol, vasopressor CRI), blood sample collection, and central venous pressure measurement. Central venous catheters can cause complications in animals with coagulation abnormalities, or in patients at risk of thrombus, such as those with immune mediated hemolytic anemia or Hyperadrenocorticism. Central catheters are technically harder to place than peripheral catheters but with practice they can be a quickly learned skill. Over the needle catheters are the most commonly used type of peripheral catheter. It is inexpensive and easy to place. However, they are not long enough to reach into the vena cava so are not used for central venous catheterization. However in a very small patient, when used for jugular catheterization they may be appropriate. Through-the-needle catheters are passed through or inside the needle. These catheters are usually longer than over the needle catheters and come in a variety of diameters. They are often too short to use as a true central catheter in the saphenous vein but usually long enough for jugular central catheterization. Most central catheter placement utilizes long single-lumen or multilumen catheters inserted using a Seldinger guidewire technique or a peel-off sheathed needle technique. A multilumen catheter has more than one chamber which allows simultaneous infusions of otherwise incompatible fluids via one catheter reducing the number of catheters that need to be placed. Multilumen catheters may be double, triple or quadruple lumen. Multilumen catheters are more expensive then single lumen catheters. Central vein insertion sites include the jugular vein and the lateral and medical saphenous veins. The jugular vein may be more visible than peripheral veins in hemodynamically challenged patients. In patients with vomiting, diarrhea, or polyuria jugular catheters, bandages, and attached IV tubing are less likely than saphenous catheters to become contaminated. Jugular

2 catheters are usually well tolerated and less likely than peripheral catheters to be chewed or removed by the patient. The jugular vein is catheterized directly into the cervical region. It lies along the jugular groove between the point of the mandible and the thoracic inlet. Jugular catheters are placed with the tip of the catheter always directed toward the heart. The jugular vein is surrounded by a large amount of skin that can make immobilization difficult. The peripheral veins used in dogs and cats are the medial or lateral saphenous veins. The cranial branch of the lateral saphenous obliquely crosses the lateral aspect of the distal tibia. The lateral saphenous vein is larger than the medial saphenous in the dog, and the medial saphenous is larger than the lateral and is more commonly catheterized in the cat. To achieve central vein catheterization using the saphenous vein, long catheters must be used. There are many choices in how the catheter can be placed. The through the needle catheter has been the traditional way in which central venous catheters have been placed. The Seldinger method has replaced the traditional method of placing central catheters in veterinary and human medicine, as it is technically easier to do but there are more steps involved. The Seldinger method uses an introducer needle or over the needle catheter and the placement of a guide wire to feed the long catheter into the vein. Introduction of foreign material or infectious agents into the central circulation can have far more serious consequences than peripheral vessel contamination. Maintenance of aseptic technique when placing and using central venous catheters is of utmost importance. This includes sterile preparation, drape and wearing sterile gloves. Before beginning any central catheter placement the required distance for catheter insertion should be measured. The aim for a jugular catheter is to have the tip lying within the thoracic cavity, just cranial to the right atrium. For PICC lines the distance from the insertion site to the vena cava is measured. Supplies include; central catheter kit, peripheral over the needle catheter, clippers, antiseptic scrub, sterile drapes, sterile gloves, suture, needle driver, sterile adhesive pad or non-adhesive pad, tape, 4x4 gauze pads, roll gauze, three syringes of heparinized saline, T-connector, a lovely assistant, and exam gloves for your lovely assistant. Placement of the jugular catheter is best done with the patient in lateral recumbency. The patient s head is extended and its forelimbs positioned caudally by your lovely assistant. A rolled towel can be placed under the neck to help accessibility of the vessel. Placement of the Saphenous catheter is also done in lateral recumbency just as when placing a peripheral saphenous catheter. The key to a through the needle jugular catheter placement (or any central venous catheter) is patient positioning and vein stabilization. Gently place the patient in lateral recumbency and have your lovely assistant restrain appropriately. Clip a wide area around the venipuncture site. Locate and visualize the vein. Skin should be prepared as for surgical procedure with aseptic scrub. Infiltrate insertion site with local anesthetic if indicated. Put on sterile gloves. Remove the catheter from packaging. Do not remove the protective pouch or white clip from the hub of the blue needle guard. Slide the clear plastic ring at the end of the blue needle guard toward the

3 hub just past the point where the needle guard wings will open. Expose the needle by opening the wings and removing the inner needle cover. Hold the catheter at the bevel hub with the thumb and forefingers of the dominant hand. Choose a point of insertion over the vein just cranially to mid neck. Insertion should be done in two steps. Place the catheter with the needle bevel facing up just into the skin. Locate the middle of the vein using the tip of the needle, and advance the needle into the vein. As you advance into the vein, decrease the angle of the needle to mimic the vein and feed it into the vessel a few millimeters. Blood should flow into the catheter lumen. Ask your assistant to stop occluding the vein. Feed the catheter, along with the stylet, into the vein from the end through the plastic pouch. Continue to feed until the white adapter at catheter end meets the blue needle guard hub and secure these pieces together. The catheter should feed easily. If it feeds easily at first and then resistance is met, try popping the stylet free from the catheter and feed just the catheter. In some animals, the stylet is too stiff to pass easily to the end point of insertion. Once the catheter is successfully threaded, and the white hub connected to the blue needle guard hub, withdraw the needle from the vein, close the needle guard wings over the needle, and slide the clear plastic ring to the end to secure. Make sure the catheter is not pinched in the sides of the needle guard wings. This can lacerate the catheter causing a catheter embolism. Remove the plastic clip and protective pouch from the blue needle guard. Carefully remove the stylet and attach a t-connector. Attach a flush syringe. Aspirate blood to ensure successful placement, and flush, cap with male adaptor plug. Clean the area. Secure the catheter with tape or suture and Bandage. The Seldinger technique is a method in which a small introducer catheter and guide wire are used to access vessels or cavities for catheterization. Prepare the area around the venipuncture site. Locate and visualize the vein. Open the catheter pack, keeping contents sterile. Flush each port with sterile saline. Put on sterile gloves. Using sterile technique, drape the site with sterile towels. Measure the appropriate distance for catheter insertion. Infiltrate insertion site with local anesthetic if indicated. Hold off the vein and insert the introducing needle or catheter under the skin. Then direct into the vein, confirming correct placement by observing blood flow. If using a catheter, remove the stylet. Introduce the guide wire system into the introducer needle or catheter and thread through the needle or catheter into the vein. Many guide wires have a flexible J-tip at the distal end to prevent vessel puncture. In some smaller patients, it may be easier to feed the straight end instead, but use care never to force the wire or puncture the vessel. Pass approximately two thirds the length of the guide wire into the vein. Keeping hold of the guide wire withdraw the introducing needle or catheter over the wire. Pass the vascular dilator over the wire and using a twisting motion guide it into the vessel to accommodate the catheter, keeping hold of the end of the guide wire. A small nick incision in the skin may need to be made using a scalpel blade to advance the vascular dilator. Withdraw the dilator back off of the wire keeping the wire in place. Pass the catheter over the wire. Advance the catheter and pull the wire out just until the guide wire begins to extend out the proximal port. Holding the guide wire securely, feed the catheter into the vein the desired distance. Holding the catheter in place, withdraw the guide wire. Withdraw any air from the port just vacated by the wire, flush, clamp and cap. Suture the catheter to the skin via the butterfly wings on the catheter or its positioning adapter. Suture to skin around the base of the catheter in the groove provided, being careful not to suture through the catheter itself. Clean area and bandage the catheter in place. Be sure to incorporate ports into the bandage to avoid contamination and tension when connected to IV tubing.

4 The peel-off sheathed method is similar to an over the needle catheter placement with a few additional steps. Once the needle and sheath placement is confirmed the needle is removed leaving the sheath in the vessel. The catheter contains a stylet. The catheter and stylet are threaded into the sheath. The sheath has two tabs on the proximal end near the hub of the needle; when the tabs are pulled the sheath will split or peel away. The peel-off sheath technique can be used to place long catheters and is often used for PICC lines. Secure and bandage. Being in a large vein as well as being coupled with the large gauge of the catheter, a central venous catheter gives veterinary technicians the ability to remove blood from the catheter. This is accomplished by using 3 syringes to remove the blood and flush the catheter, referred to as the 3 syringe technique. The first syringe is used to remove residual substances from the catheter lumen. The second syringe is used to actually remove the blood sample. The contents of the first syringe are usually then given back to the patient or discarded. The third syringe has heparinized saline flush in it and is administered to remove any residual blood from the catheter lumen. Catheter care is an important part of central venous catheter success. Keep insertion sites clean and bandaged. The dressing should be removed and the catheter site inspected as needed or at least every 12 hours. Look for clinical signs of phlebitis, infection, and thrombosis. To prevent contamination injection ports should be wiped with antiseptic before needle puncture. It has been recommended to replace catheters every 72 hours. These recommendations come from human medicine. The likelihood of complications increases the longer a catheter is left in place. If catheter care is performed and there are no complications noted the catheter can remain in place for longer than 72 hours. Phlebitis is inflammation of the vessel wall occurring as a result of damage to the endothelial lining. Phlebitis is characterized by swelling, tenderness on palpation, and erythema of the skin over the vessel. Phlebitis is often caused by mechanical damage to the vessel by movement of the catheter, so it should be well stabilized. Catheter related bloodstream has been implicated in morbidity and mortality in small animal intensive care units. Infection may be initiated by phlebitis and cellulitis. Aseptic technique in catheter placement and maintenance will help to decrease the risk of infection. Fever of unknown origin in a critically ill patient should prompt consideration of replacement of all indwelling catheters. Thrombosis is the formation of a thrombus on the catheter or vessel wall. Thrombosis can result from endothelial trauma or an inflammatory reaction to the catheter material. A vein that feels thick and cordlike characterizes thrombosis. Catheter embolism occurs when a fragment of the catheter breaks off and enters the circulation. The fragment may be severed when withdrawing an inside the needle catheter. It can occur if the catheter is cut during bandage change or the patient chews the bandage. If it becomes difficult to aspirate blood from a central venous catheter the patient s perfusion status should be evaluated. In rare situations a central venous catheter may need to be replaced. As long as the vein is still healthy, this can be accomplished by feeding a guidewire into the existing catheter, removing that catheter and replacing with the new catheter. Again be sure to use aseptic technique, secure and bandage.

5 Central venous catheter placement can be done by skilled technicians. It not only helps our patients by allowing for pain free serial blood collection and CVP measurements but it increases our job satisfaction. All you need is a central catheter kit, a lovely assistant, and some practice.