UNIT NINE
716
Understanding the Urinary System
access is used until a fistula or graft is placed and usable. A central venous catheter with two or three ports (the third port can be used for medications by trained staff) is placed in a central vein for temporary access. Central catheters should not be used long term because of the risk of infection. An AV fistula is made by opening and joining a vein and artery together under the skin to create an area with greater blood volume for the dialysis machine to pull from (Fig. 37.9). AV fistulas may take several weeks to mature. The vascular surgeon determines when the fistula is mature for use. An AV graft uses a tube made of synthetic material to attach to an artery and a vein. Two needles are inserted into the graft to access the patient’s blood. Traditional graft mate- rial is not self-sealing and requires time for tissue growth to serve as a plug for the hole that the needles make before it can be used. This may take 1 to 2 weeks. Immediate-access vascular access grafts are self-sealing and do not require tis- sue growth, so they can be used often within 24 hours after surgical implantation. This self-sealing property decreases postdialysis bleeding, which reduces the time required for the dialysis session. Vascular Access Care. Postoperatively, neurovascular checks are performed hourly. Neurovascular checks include extremity movement and sensation, presence of numbness or tingling, pulses, temperature, color, and capillary refill (normally less than 3 seconds). The extremity is elevated postoperatively. Range-of-motion exercises are encouraged. Vascular surgery pain is usually mild unless there is an occlusion. Dressings or incisions are checked, and any drain- age, hematoma, or infection is documented and reported as needed. If a pulse is absent or weak or the extremity is cool or dusky, the HCP is notified immediately. AV fistulas or grafts can cause distal ischemia or “steal syndrome” because
too much arterial blood is being “stolen” from the distal extremity. This is usually observed postoperatively and may require surgical correction to restore blood flow. AV fistulas and grafts are checked every 4 hours for patency by the nurse by palpating to feel the thrill (a vibra- tion) and auscultating to hear the bruit (swishing sound) at the site of the graft or fistula. Decrease or cessation of bruit or thrill indicates an occlusion. If a thrill or bruit is diminished or not present, the HCP is notified immediately. The site must be carefully monitored per institution policy to detect clotting or problems. Early detection of clotting allows the surgeon an opportunity to save the access by per- forming a declotting procedure rather than a total revision. The extremity in which the access is placed should be protected. Do not use it for blood draws or IV fluids. Special care of the access is taught to the patient, as it is the patient’s only way to eliminate waste (Box 37.3). The patient is taught to check patency daily. PERITONEAL DIALYSIS. Peritoneal dialysis is continuous dialysis performed by the patient or family in the home. The peritoneal membrane is the semipermeable membrane across which excess wastes and fluids move from blood in perito- neal vessels into a dialysate solution that has been instilled into the peritoneal cavity. A peritoneal catheter is placed into the peritoneal space between the two layers of the perito- neum below the waistline. This catheter is used to perform an exchange process with three steps: (1) filling, (2) dwell time, and (3) draining. The fill step involves instilling sterile dialyzing solution (dialysate) into the patient’s peritoneal cavity through the catheter. The amount of solution is individualized by body weight. The solution is left to dwell in the abdomen as pre- scribed for several hours, allowing time for the waste prod- ucts from the blood to pass through the peritoneal membrane into the dialysate solution (Fig. 37.10). The solution is then drained from the body and discarded. Several treatment plans use this exchange process. The treatment plan that best suits the patient’s needs is deter- mined by the patient and the dialysis team. Continuous ambulatory peritoneal dialysis is most common. Usually, three exchanges are done during the day and one before bed. Other treatment plans use a computerized machine called a cycler to regulate exchanges during sleep. Sometimes, med- ications are added to dialyzing solutions, such as heparin to prevent clotting of the catheter, insulin for the patient with diabetes, or antibiotics to treat infection. Patient and family education is extremely important for peritoneal dialysis to be successful. The patient must be taught and able to demonstrate ability to do a successful exchange. Sterile technique while performing exchanges is imperative, and the exchanges should be done in a clean
Artery
Anastomosis
Vein
A
• WORD • BUILDING • peritoneal dialysis: peritoneal—peritoneum + dialysis— passage of a solution through a membrane
B FIGURE 37.9 Hemodialysis access sites. (A) Arteriovenous fistula. (B) Arteriovenous graft.
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