Placing and managing central lines (Proceedings)

Central lines have become a necessity in the majority of hospitalized patients in the critical care setting. Despite the many uses they provide, there is an increase in patient compliance and comfort when used appropriately. Central lines are not just for fluid administration; they can provide us with additional patient parameters which affect patient care and treatment plans.

Indications

Total Parenteral Nutrition, or TPN, must have a dedicated route for administration. Due to the risk for bacterial contamination, and vaso-irritation/phlebitis due to its' high osmolality, TPN should always be administered through a central line. Partial/Peripheral Parenteral Nutrition, or PPN such as Procalamine, should also be administered via central line. PPN is also in jeopardy of bacterial contamination, in addition to vaso-iritation due to its high osmolality. In addition to nutrition, multi-lumen central lines allow incompatible fluids, additives, blood components and drugs to be given simultaneously without interference.  Patients who require multiple blood samplings, such as a DKA (diabetic ketoacidosis), will also benefit from a central line, as blood sampling can be performed using a three syringe technique. This decreases frequency and discomfort from multiple peripheral venipunctures. Central venous pressures, or CVP, can be obtained through a central line using a manometer. Central venous pressures give us an estimate of right atrial blood pressure. This tells us how well patients are tolerating fluid therapy through CVP trends, and if there is an increased risk for fluid overload. Cardiac patients, trauma patients, septic and acute renal failure patients, and those requiring high volume diuresis are examples of candidates for CVP monitoring. Also, patients who are fractious often benefit from central lines. Central lines allow access to the line without being in a compromised position, such as at the animals' feet. Instead it allows catheter management and blood sampling without restraint, and the discomfort of phlebotomy.

Contraindications

It is contraindicated to place central lines in patients who are coagulopathic, are hypercoagulopathic (such as Immune Mediated Hemolytic Anemia), or where skin infection is evident at the site of insertion. It is important to note which disease processes cause an increased risk of thrombosis prior to placing a central line. Jugular central lines are contraindicated in patients who have suffered head or neck trauma, such as A-A luxation or traumatic brain injury. Avoid jugular central lines in patients who are in respiratory distress, have laryngeal paralysis, cerebral edema or cranial disease. It may be beneficial in a select group of these patients to place a central line via the femoral vein into the caudal vena cava, instead of the jugular.

Products

There are a few different methods and products available for placing central lines.

Peel-away sheath technique

This technique requires the peel-away sheath introducer/catheter. It is an over the needle sheath that is gently peeled away, after inserting the catheter through the sheath. (ex: MILA cath)

Guide wire seldinger technique

This method incorporates the use of a needle or peripheral catheter, guide wire, vasodilator, and central line catheter. It involves the use of a guide wire to pass the vasodilator and central line into the vessel. (ex: Aarrow)

Through the needle catheter

Requires a through the needle catheter unit. After placing the needle in the vessel, the catheter is fed through the needle and the needle is backed out and covered with a guard. (ex: Intracath)

The silicone/polyurethane material that constructs central lines will allow long-term placement and are less thrombogenic, as opposed to peripheral catheters which are made up of polypropylene/polyethylene/polyvinylchloride.

Placement

Regardless of placement technique, it is imperative the process be treated in a sterile manner. This requires sterile gloves, a sterile central line kit, hair removal, three scrub prep, and patient draping.

Measurement

Because central lines are available in a variety of sizes and lengths, measurement is crucial when placing a central line. For jugular central lines, accurate measurement can be achieved by measuring from the desired site of insertion to the caudal aspect of the shoulder. Ideal placement is in the cranial vena cava within the thoracic inlet, cranial to the right atrium. This allows accurate CVP monitoring. Femoral placed central lines should be long enough to enter the caudal vena cava to allow CVP monitoring.

Anesthesia

Most critical patients will not require chemical intervention for central line placement. However, more alert and stable patients may require some form of injectable sedation, or combination of sedation and pain medication (Neuroleptanalgesia). Commonly used medications for placement are: Propofol, Fentanyl, torbugesic, butorphanol, midazolam, and valium. Please keep in mind these are titrated to effect. An assistant should be administering drugs, flow by oxygen, as well as monitoring the patient throughout the procedure. Flow by oxygen is recommended during the procedure due to the respiratory depressant effects of opiods, as well as the compromised state of critically ill patients.

Supplies

Be sure to have all supplies ready prior to placement. Clippers, scrub and alcohol scrub, assistant, monitoring equipment, central line kit, bandage materials, patients own bag of saline flush and heparin/saline flush (500u heparin/250cc 0.9% NaCl), sterile gloves, oxygen, and sedative if needed.

Placement

Locate desired point of insertion by having an assistant hold off the vein. Prepare site by clipping a large area of hair, roughly 4”x4”. Using a three scrub technique, alternating a chlorhexadine solution and alcohol, clean site thoroughly and let air dry. (Dirtier patients may require more cleaning.) Open pack and, wearing sterile gloves, familiarize yourself with the contents of the central line kit. Once familiarized, apply drape to patient, and if indicated administer sedation. Ask assistant to hold off again, locate desired point of insertion, and begin placement of central line. (Techniques may vary). After central line placement, be sure to obtain blood back in all lumens of the central line, to clear air from the lines. Then flush all lines with saline, clamp, and cap. Be sure to suture in place using 3 points of contact. 

Bandaging

Keeping the central line clean is a necessity. Applying a bandage to prevent nosocomial infections while hospitalized is mandatory. Using gauze squares around the insertion site can not only act as a barrier, but it also provides cushion between the patient and the port of the central line. After applying gauze squares, cast padding can be wrapped around neck/leg 2-3 times, followed by 2-3 rows of roll gauze. This not only protects the central line, it also keeps the central line stable. A few rows of vet wrap will help hold everything together. Then secure all lumens with tape, and be sure to label all lumens for IVF, blood sampling, or TPN. (It is highly recommended a lumen be preserved for TPN only.) Lastly, be sure 2-3 fingers can easily fit under the bandage, to avoid constricting the patient's airway. Remember, bandaging is an art!

Confirmation

Be sure to verify accurate central line placement with a radiograph. This will allow the determination of accurate CVP's. It will also prevent arrhythmias if the central line requires backing out and the use of a spacer. Often, measurement is inaccurate, and the central line can end up in the right atrium, leading to arrhythmias.

Maintenance

Now that the central line is in place and ready for use, it is crucial maintenance is not overlooked. Bandage changes daily, using aseptic technique while wearing gloves, is recommended. During bandage changes monitor for fever, swelling, phlebitis, thrombosis formation, leaking, and redness. If noted, central line removal may be indicated. Monitor all lumens and lines for remnants of blood, as this can serve as a bacterial medium. It is also important to change out caps, t-sets, and lines daily. Routine alcohol swabbing of injection ports, personal fluid bag ports, and IV line connections is also warranted. Due to the requirements of central line cleanliness, patients should have their own bag of plain saline, heparin/saline flush and sterile water (if reconstituted medications are ordered). It is also recommended to fit canine patients with a harness, and avoid the use of neck leads while a central line is in place.

Central lines allow ease of treatment, patient compliance and comfort, as well as diagnostic capabilities. They allow advanced care, and require a higher standard of skill and patient management.