Vascular access is the circulatory site that makes the linkage between the patient’s circulation and the hemodialysis machine possible. Blood is pulled out of the body by the blood pump through the vascular access. The pump will then force the blood through the dialyzer and back to the patient’s bloodstream. During dialysis, the total volume of blood pulled out of the body is approximately 300ml. Choosing the optimal access site may be restricted to certain limits. The distal portion of the non-dominant arm is normally the preferred location for access placement. However, the final choice will be determined by the vascular surgeon based on confirmatory tests and studies. Some patient may have more limited choices for access placement than others. For instance, patients with underlying diabetes may have problems with peripheral vascular disease since this condition damages blood vessels progressively. There are two basic types of vascular accesses that need to be cared for dialysis technicians. While there are proven pros and cons accompanying both, the type to be used will always depend on what the patient prefers.
The Two Types of Vascular Accesses That Dialysis Technicians Should Know
- Internal – these accesses are usually permanent, and are ideal for patients who will be on long-term hemodialysis. An Internal access is usually placed in the early stages of chronic renal failure, even before the patient needs it. This is done so it will be ready to use when the patient actually starts treatment. Internal accesses require that dialysis technicians know how to care for them so they’ll last longer.
- External – these are temporary accesses placed while the internal access is still maturing. An external access may come in the form of a straight hemodialysis catheter or a cuffed and tunneled hemodialysis catheter. This type of access is usually done when the patient only needs dialysis for a short while. Dialysis technicians will still need to provide proper care even if this access is used transitorily.
Getting a fistula or graft placed is part of preparing the patient for hemodialysis. A fistula or graft is the ideal access for dialysis. If your patient is right handed, the surgeon’s first choice is to place the access in the patient’s left arm. If he’s left handed, the right arm will be the surgeon’s first choice. However, there are instances when this will not be the case. The surgeon will always inform the patient which arm to protect. In this regard, dialysis technicians should be well aware that the designated arm should not be compromised by IV’s, needle sticks for lab work, or even checking the blood pressure. In some cases, patients may require additional studies to verify the size of their blood vessels before the placement of the access. Ultrasound mapping is typically the most effective tool a surgeon can use to plan for access. Normally, there are no needles involved when mapping is done. On the other hand, some patients may also need a venogram done. During this study, a small needle is used to inject sterile dye into the blood vessels. The surgeon and access team will decide which study is best for the patient. The placement of an internal vascular access requires a trip to the Outpatient Surgery Department. A fistula or graft will then be placed in the operating room.
The Types of Internal Vascular Accesses
- The Arterial-Venous (AV) Fistula – The AV fistula uses the patient’s native vein and artery to make a connection. A fistula is usually situated in the patient’s upper or lower arm. When the link is made, the artery’s higher pressure pushes blood into the vein. After a few months, the vein will become larger and its walls will become thicker. The blood from these vessels can then be used for dialysis. The fistula normally matures in about 4-6 weeks. When this happens, it will now be possible to insert two needles for treatment. One needle will be used to pull blood from the patient’s body through the dialysis tubing. The blood will then flow through the dialyzer, filtering it in the process. Clean blood will be returned to the patient’s body through the second needle. The AV fistula is the most popular type of internal vascular access for hemodialysis. Since it doesn’t utilize foreign material to make, it is less likely to become infected or clotted. It is also more flexible because it is made of native tissues. When well-cared for by dialysis technicians, the AV fistula will provide the patient with better dialysis, resulting to better prognoses. Unfortunately, there are still risks involved. If a fistula may not develop successfully, a graft will then be utilized.
- The Graft – A graft is highly similar to an AV fistula. It still connects artery to a vein. It is also used for dialysis in the same way as a fistula. However, what differentiates the graft is the material it uses. Unlike a fistula, a graft utilizes a thin, hollow, semi-rigid tube of a man-made material. A graft is ideal for patients with veins that can’t or didn’t develop a fistula. Grafts are usually placed in the upper or lower arm, or the upper leg of the patient. This type of access can either be straight or looped, which are literally named after their design. Since grafts are larger and more rigid than a natural vein, dialysis technicians can insert needles through them with less trouble than with a fistula. However, grafts can become infected or clotted more easily than a fistula since they are not naturally part of the patient’s body tissue. Grafts can be used in about 2 weeks after its first placement.
Arteriovenous Fistula and Arteriovenous Graft Care for Dialysis Technicians
- Thoroughly inspect the AVF or AVG, and be vigilant for any abnormalities.
- “Feel” the thrill. “Hear” the bruit. The thrill is a vibration that you can palpate. It is normally continuous and soft. Assessing the thrill will confirm the direction of the blood flow in the access. Meanwhile, the bruit is a continuous, soft, and low-pitched sound that you can hear with a stethoscope. If the sound becomes discontinuous, harsh, and high-pitched, the access may be abnormally constricting. If noted, immediately note and report your findings to the nurse.
- Locate the physical location of the access. Assess its depth and direction of flow. Feel the entire length of the access by gently compressing it lightly with your two middle fingers. Once you feel the pulse and/or thrill on both sides of the area being compressed, hold your position and observe. Always remember that you will feel the strongest pulse on the arterial side. The pulse of thrill will be gentle or can’t be felt at the venous end.
- Assess the condition of the incision(s). For newly placed accesses or revised accesses, dialysis technicians should describe their condition, color and temperature. Proper assessment of the incision is a vital component of effective wound management, and needs high quality observational skills, knowledge and judgment.
- Is the site swelling or edematous? Bear in mind that new accesses may be swollen, red, and painful for the first few days after surgical placement. The patient’s body normally prepares to protect against infection before healing begins. This swelling may be caused by the body’s immune system working to protect the incision from infection.
- Know the signs and symptoms of infection. This should include an abnormally-high temperature, redness around the site, pain, increased swelling, and drainage. Also assess for any bruising. When any of these are present, dialysis technicians should reported them immediately as infections can be life threatening. They must be treated as soon as possible.
- Assess for aneurysms or pseudoaneurysms. Aneurysms are the abnormal bulging of a blood vessel. A true aneurysm is involves all three layers of the wall of an artery, while a false aneurysm is caused by the collection of blood leaking out of the artery or vein. Either of these cases require immediate care. When an aneurysm increases in size, the risk of rupture increases. Ruptured aneurysms can cause heavy bleeding, subsequently leading to hypovolemic shock, or even death.
- How are the previous cannulation sites? Light scab formation and scarring are normal.
- Inspect the entire access extremity. Include the hands and feet, and compare their definition to the opposite extremity. The presence of swelling and enlarged veins on the access extremity may signify a narrowing or blockage of veins. Veins typically swell or enlarge when the drainage of blood from the certain area is occluded.
- Dialysis technicians should carefully inspect the access and access extremity before, during, and after each treatment. Ideally, the sooner a complication is identified the easier it is to treat.
- Clean the skin. Patients are highly encouraged to wash the skin over the AVF or AVG daily, as well as prior to each dialysis session with hypoallergenic soap and lukewarm water. If patient is unable to do so, the dialysis technician may do so, using a skin cleansing agent. Keeping this area clean will dramatically reduce the risk of infection.
- Patient education is an effective tool for long-term treatment. Dialysis is a life-sustaining measure. Without providing non-judgmental comfort and long-term patient education, the entire treatment process will most likely be ineffective. Dialysis technicians should sensitively teach patients how to recognize the signs and symptoms of infection. As much as possible, let patients avoid activities that could block or negatively affect the blood flow within their accesses. Patient should avoid having their blood pressures monitored on the access extremity. Carrying or resting heavy objects on their access extremity should also be prohibited. Dialysis technicians should teach patients how to check for the patency of their accesses, including the presence of a thrill, on a daily basis. Appropriately, temperature extremes must be avoided at all times since this can cause blood vessels to expand or constrict abnormally.
- Teach patients with AVF how to exercise their immature access. With the surgeon’s approval, dialysis technicians may lightly place a tourniquet above the access and have the patient squeeze a soft ball in a prescribed amount of time and frequency. However, this should not be done during or immediately after dialysis treatment. Lifting light 2-pound hand held dumbbells with sets of 5-10 repetitions may also be acceptable. This light exercise may be repeated up to 4 times a day or according to physician’s orders.
- Dialysis technicians may use germicidal/disinfectant solutions when cleaning the access. Solutions, such as Isopropyl 70% alcohol, povidone iodine, and ExSept Plus, are acceptable.
- On the other hand, the local anesthetics that can be used by dialysis technicians should be limited to Xylocaine and Pain Ease®, or any similar topical creams. Local anesthetics may be used by dialysis technicians at least one hour before needle placement.
- Two needles will need to be inserted in the access at each treatment. The sites can be rotated if the patient has a graft. If the patient has a fistula the sites may rotate. The buttonhole technique can also be used, where the same hole is used each time. Choose a site for cannulation. The site used should be at least half an inch away from any previous needle sites. Also, do not cannulate near the surgical connection of the vein and artery. New insertions should be made at least one inch from obstructions, or restrictions. Keep the distance between the arterial and venous needles to at least 2 inches apart.
- A tourniquet may be helpful for cannulation. Place it on the extremity above the access immediately before cannulation and removed immediately after needle insertion.
- Except in very rare occasions with a physician’s order, tourniquets should never be left on the access extremity during treatment. Doing so can occlude blood flow, making the treatment process less desirable. If it should be left in place, the tourniquet must be situated between the arterial and venous needles. Dialysis technicians should not forget to periodically check the access flow above and below the lightly placed tourniquet.
- A detailed history of the access for each patient must be maintained in the medical record by dialysis technicians. Include a diagram of the current access with direction of flow. If there are prior cases of infection, clotting, and other interventions or revision procedures done on the access present, chart this in the patient’s medical record.
- The sites of cannulation and blood tubing connections are normally verified by the nurse and the physician for accuracy, patency and security. They should be made readily visible throughout treatment by dialysis technicians.
- Document all findings and properly chart accordingly.