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Focus on Dialysis
(Relates to Chapter 47, “Nursing Management: Acute Kidney Injury and Chronic Kidney Disease,” in the textbook)
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Dialysis
Movement of fluid/molecules across a semipermeable membrane from one compartment to another
Used to correct fluid/electrolyte imbalances and to remove waste products in renal failure
Treat drug overdoses
Clinically, dialysis is a technique by which substances move from the blood through a semipermeable membrane and into a dialysis solution (dialysate).
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Dialysis
Two methods of dialysis available
Peritoneal dialysis (PD)
Hemodialysis (HD)
In PD, the peritoneal membrane acts as the semipermeable membrane. In HD, an artificial membrane (usually made of cellulose-based or synthetic materials) is used as the semipermeable membrane and is in contact with the patient’s blood.
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Dialysis
Begun when patient’s uremia can no longer be adequately managed conservatively
Initiated when GFR (or creatinine clearance) <15 mL/min
This criterion can vary widely in different clinical situations, and the physician will determine when to start dialysis on the basis of the patient’s clinical status.
Certain uremic complications, including encephalopathy, neuropathies, uncontrolled hyperkalemia, pericarditis, and accelerated hypertension, indicate a need for immediate dialysis.
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5. General Principles of Dialysis
Diffusion
Movement of solutes from an area of greater concentration to an area of lesser
{See next slide for figure.}
Hemodialysis patients are exposed to 120 to 130 L of water during each dialysis treatment. Small-molecular-weight substances can pass from the dialysate into a patient’s blood, so the purity of the water used for dialysis is monitored and controlled.
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6. Osmosis and Diffusion Across Semipermeable Membrane
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7. General Principles of Dialysis
Osmosis
Movement of fluid from an area of lesser to an area of greater concentration of solutes
Glucose is added to the dialysate and creates an osmotic gradient across the membrane, pulling excess fluid from the blood.
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8. General Principles of Dialysis
Ultrafiltration
Water and fluid removal
Results when an osmotic gradient occurs across the membrane
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Peritoneal Dialysis
Peritoneal access is obtained by inserting a catheter through the anterior wall.
Technique for catheter placement varies.
Usually done via surgery
In the United States, approximately 12% of patients receiving dialysis treatments are on PD.
Preparation of the patient for catheter insertion includes emptying the bladder and bowel, weighing the patient, and obtaining a signed consent form.
{See next slide for figure.}
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Tenckhoff Catheter
Fig Peritoneal dialysis showing peritoneal catheter inserted into peritoneal cavity.
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Peritoneal Dialysis
After catheter is inserted, skin is cleaned with antiseptic solution and sterile dressing applied.
Connected to sterile tubing system
Secured to abdomen with tape
Catheter irrigated immediately
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Peritoneal Dialysis
Waiting period of 7 to 14 days preferable
2 to 4 weeks after implantation, exit site should be clean, dry, and free of redness/tenderness.
Once site has healed, patient may shower and pat dry.
Some patients just wash with soap and water and go without a dressing; others require daily dressing changes.
However, teach all patients to examine their catheter site for signs of infection.
Showering is preferred, as the exit site should not be submerged in bath water.
{See next slide for figure.}
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13. Peritoneal Catheter Exit Site
Fig Peritoneal catheter exit site.
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14. Peritoneal Dialysis Dialysis Solutions and Cycles
Available in 1- or 2-L plastic bags with glucose concentrations of 1.5%, 2.5%, and 4.25%
Electrolyte composition similar to plasma
Solution warmed to body temperature
Dialysis solutions vary, and the choice of exchange volume is primarily determined by the size of the peritoneal cavity. A larger person may tolerate a 3-liter exchange volume without any difficulty, whereas an average-size person usually tolerates a 2-liter exchange.
Ultrafiltration (fluid removal) during PD depends on osmotic forces, with glucose being the most effective osmotic agent currently available.
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15. Peritoneal Dialysis Dialysis Solutions and Cycles
Three phases of PD cycle
Inflow (fill)
Dwell (equilibration)
Drain
Called an exchange
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16. Peritoneal Dialysis Dialysis Solutions and Cycles
Inflow
Prescribed amount of solution infused through established catheter over about 10 minutes
After solution infused, inflow clamp closed to prevent air from entering tubing
The flow rate may be decreased if the patient has pain.
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17. Peritoneal Dialysis Dialysis Solutions and Cycles
Dwell
Diffusion and osmosis occur between patient’s blood and peritoneal cavity.
Duration of time varies, depending on the method.
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18. Peritoneal Dialysis Dialysis Solutions and Cycles
Drain
15 to 30 minutes
May be facilitated by gently massaging abdomen or changing position
The cycle starts again with the infusion of another 2 L of solution. For manual PD, a period of about 30 to 50 minutes is required to complete an exchange.
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19. Peritoneal Dialysis Systems
Automated peritoneal dialysis (APD)
Cycler delivers the dialysate.
Times and controls fill, dwell, and drain.
Continuous ambulatory peritoneal dialysis (CAPD)
Manual exchange
APD is the most popular form of PD, as it allows patients to accomplish dialysis while they sleep. The machine cycles four or more exchanges per night with 1 to 2 hours per exchange.
{See next slide for APD figure.}
CAPD: Exchanges are carried out manually by exchanging 1.5 to 3 L of peritoneal dialysate at least 4 times daily, with dwell times averaging 4 hours. For example, one schedule starts exchanges at 7 AM, 12 noon, 5 PM, and 10 PM.
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20. Automated Peritoneal Dialysis
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21. Peritoneal Dialysis Complications
Exit site infection
Peritonitis
Hernias
Infection of the peritoneal catheter exit site is most commonly caused by Staphylococcus aureus or S. epidermidis (from skin flora).
Most frequently, peritonitis occurs because of improper technique in making or breaking connections for exchanges.
Because of increased intraabdominal pressure secondary to dialysate infusion, hernias can develop in predisposed individuals such as multiparous women and older men.
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22. Peritoneal Dialysis Complications
Lower back problems
Bleeding
Pulmonary complications
Protein loss
Increased intraabdominal pressure can cause or aggravate lower back pain.
Bloody effluent over several days or the new appearance of blood in the effluent can indicate active intraperitoneal bleeding.
Atelectasis, pneumonia, and bronchitis may occur from repeated upward displacement of the diaphragm, resulting in decreased lung expansion.
The amount of protein loss is usually about 0.5 g/L of dialysate drainage, but it can be as high as 10 to 20 grams per day.
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23. Peritoneal Dialysis Effectiveness and Adaptation
Short training program
Independence
Ease of traveling
Fewer dietary restrictions
Greater mobility than with HD
Learning the self-management skills required to do peritoneal dialysis is usually accomplished in a 3- to 7-day training program.
Mortality rates are about equal between in-center hemodialysis patients and peritoneal dialysis patients for the first few years. However, after about 2 years, mortality rates for patients receiving PD are higher, especially for the elderly with diabetes and patients with a prior history of cardiovascular disease.
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24. Hemodialysis Vascular Access Sites
Obtaining vascular access is one of the most difficult problems.
Types of access include
Arteriovenous fistulae and grafts
Temporary vascular access
AVF have the best overall patency rates and the least number of complications (e.g., thrombosis, infection) of all vascular accesses.
In some situations when immediate vascular access is required, percutaneous cannulation of the internal jugular or femoral vein is performed.
{See next 4 slides for figures.}
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25. Vascular Access for Hemodialysis
A, Arteriovenous fistula.
B, Arteriovenous graft.
Fig Vascular access for hemodialysis. A, Arteriovenous fistula. B, Arteriovenous graft.
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26. Arteriovenous Fistula
Arteriovenous fistula created by anastomosing an artery and vein.
A subcutaneous arteriovenous fistula (AVF) is most commonly created in the forearm with an anastomosis between an artery and a vein (usually cephalic).
Fig Arteriovenous fistula created by anastomosing an artery and vein.
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27. Vascular Access Catheter
Temporary double-lumen vascular access catheter for acute hemodialysis.
A, Soft, flexible dual-lumen tube is attached to a Y hub.
B, The distance between arterial intake and venous return lumina typically provides recirculation rates of 5% or less.
Fig Temporary double-lumen vascular access catheter for acute hemodialysis. A, Soft, flexible
double-lumen tube is attached to a Y hub. B, The distance between the arterial intake and the venous
return lumina typically provides recirculation rates of 5% or less.
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28. Vascular Access Catheter
A, Right internal jugular placement for a tunneled, cuffed semipermanent catheter.
B, Temporary hemodialysis catheter in place.
C, Long-term cuffed hemodialysis catheter.
Fig A, Right internal jugular placement for a tunneled, cuffed semipermanent catheter.
B, Temporary hemodialysis catheter in place. C, Long-term cuffed hemodialysis catheter.
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29. Hemodialysis Dialyzers
Long plastic cartridge that contains thousands of parallel hollow tubes or fibers
Fibers are the semipermeable membrane.
The blood is pumped into the top of the cartridge and is dispersed into all of the fibers.
Dialysis fluid (dialysate) is pumped into the bottom of the cartridge and bathes the outside of the fibers with dialysis fluid.
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30. Hemodialysis Procedure
Two needles placed in fistula or graft
Needle closer to fistula or red catheter lumen pulls blood from patient and sends to dialyzer.
Blood is returned from dialyzer to patient through second needle or blue catheter.
Heparin is added to the blood as it flows into the dialyzer because any time blood contacts a foreign substance, it has a tendency to clot.
{See next slide for figure.}
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31. Components of Hemodialysis
Blood is removed via a needle inserted into a fistula or via catheter lumen. It is propelled to the dialyzer by a blood pump. Heparin may be infused as a bolus predialysis or through a heparin pump continuously to prevent clotting. Dialysate is pumped in and flows in the opposite direction of the blood. The dialyzed blood is returned to the patient through a second needle or catheter lumen. Old dialysate and ultrafiltrate are drained and discarded.
Fig Components of a hemodialysis system. Blood is removed via a needle inserted in a fistula or via
catheter lumen. It is propelled to the dialyzer by a blood pump. Heparin is infused either as a bolus
predialysis or through a heparin pump continuously to prevent clotting. Dialysate is pumped in and
Flows in the opposite direction of the blood. The dialyzed blood is returned to the patient through a
Second needle or catheter lumen. Old dialysate and ultrafiltrate are drained and discarded.
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32. Hemodialysis Procedure
Dialyzer/blood lines primed with saline solution to eliminate air
Terminated by flushing dialyzer with saline to remove all blood
Needles removed and firm pressure applied
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33. Hemodialysis Procedure
Before treatment, nurse should
Complete assessment of fluid status, condition of access, temperature, and skin condition
During treatment, nurse should
Be alert to changes in condition
Perform vital signs every 30 to 60 minutes
The difference between the last postdialysis weight and the present predialysis weight determines the ultrafiltration, or the amount of weight to be removed.
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34. Hemodialysis Complications
Hypotension
Muscle cramps
Loss of blood
Hepatitis
Hypotension that occurs during HD primarily results from rapid removal of vascular volume (hypovolemia), decreased cardiac output, and decreased systemic intravascular resistance.
Factors associated with the development of muscle cramps include hypotension, hypovolemia, high ultrafiltration rate (large interdialytic weight gain), and use of low-sodium dialysis solution.
Blood loss may result from blood not being completely rinsed from the dialyzer, accidental separation of blood tubing, dialysis membrane rupture, or bleeding after the removal of needles at the end of dialysis.
At one time, hepatitis B had an unusually high prevalence in dialysis patients, but the incidence today is quite low.
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35. Hemodialysis Effectiveness and Adaptation
Cannot fully replace metabolic and hormonal functions of kidneys
Can ease many of the symptoms
Can prevent certain complications
HD does not alter the accelerated rate of development of cardiovascular disease and the related high mortality.
The yearly death rate of patients receiving maintenance dialysis remains high and is estimated to be between 19% and 24%.
Individual adaptation to maintenance HD varies considerably. Initially, many patients feel positive about the dialysis because it makes them feel better and keeps them alive, but often great ambivalence is expressed about whether it is worthwhile.
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36. Continual Renal Replacement Therapy (CRRT)
Alternative or adjunctive method for treating AKI
Means by which uremic toxins and fluids are removed
Acid-base status/electrolytes adjusted slowly and continuously
Patients selected are usually those who do not respond to dietary interventions and drug therapy. The principle of CRRT is to dialyze patients in a more physiologic way over 24 hours, just as the kidneys do.
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37. Continual Renal Replacement Therapy (CRRT)
Can be used in conjunction with HD
Contraindication
Presence of manifestations of uremia requiring rapid resolution
Continued for 30 to 40 days
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38. Continual Renal Replacement Therapy (CRRT)
Hemofilter change every 24 to 48 hours
Ultrafiltrate should be clear yellow.
Specimens may be obtained for evaluation.
{Discuss ultrafiltration therapies.}
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39. Continual Renal Replacement Therapy (CRRT)
Two types of CRRT
Venous access
Arterial access
See Table for more information.
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40. Continual Renal Replacement Therapy (CRRT)
Most common: Venovenous approaches
Continuous venovenous hemofiltration (CVVH)
Continuous venovenous hemodialysis (CVVHD)
See Table for more information.
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41. Continuous Vevovenous Therapies
Basic schematic of continuous venovenous therapies. Blood pump is required to pump blood through the circuit. Replacement ports are used for CVVH and CVVHD only and can be given prefilter or postfilter. Dialysate port is used for CVVHD only. Regardless of modality, ultrafiltrate is drained via the ultrafiltration drain port.
Fig Basic schematic of continuous venovenous therapies. Blood pump is required to pump blood
through the circuit. Replacement ports are used for instilling replacement fluids and can be given prefilter
or postfilter. Dialysate port is used for infusing distillate. Regardless of modality, ultrafiltrate is drained
via the ultrafiltration drain port.
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42. Continual Renal Replacement Therapy (CRRT)
Continuous venovenous hemofiltration (CVVH)
Large volumes of fluid removed hourly, then replaced
Fluid replacement dependent on stability/individualized needs of patient
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43. Continual Renal Replacement Therapy (CRRT)
Continuous venovenous hemodialysis (CVVHD)
Uses dialysate
Dialysate bags attached to distal end of hemofilter
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44. Continual Renal Replacement Therapy (CRRT)
Continuous venovenous hemodialysis (CVVHD)
Fluid pumped countercurrent to blood flow
Ideal treatment for patient who needs fluid/solute control but cannot tolerate rapid fluid shifts with HD
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45. Continual Renal Replacement Therapy (CRRT)
Highly permeable, hollow fiber hemofilter
Uses double-lumen catheter placed in femoral, jugular, or subclavian vein.
Removes plasma water and nonprotein solutes
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46. Continual Renal Replacement Therapy (CRRT)
CRRT versus HD
Continuous rather than intermittent
Solute removal by convection (no dialysate required), in addition to osmosis and diffusion
Less hemodynamic instability
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47. Continual Renal Replacement Therapy (CRRT)
CRRT versus HD (cont’d)
Does not require constant monitoring by HD nurse
Does not require complicated HD equipment
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Audience Response Question
When implementing care for the patient on peritoneal dialysis, the nurse recognizes that dietary needs include an increased quantity of:
1. Fat.
2. Protein.
3. Calories.
4. Carbohydrates.
Answer: 2
Rationale: Dietary protein guidelines for peritoneal dialysis (PD) differ from those for hemodialysis because of protein loss in the dialysate. During PD, protein intake must be high enough to compensate for the losses, so the nitrogen balance is maintained. The recommended protein intake is at least 1.2 g/kg of ideal body weight per day and is increased on the basis of individual needs of the patient.
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Case Study
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Case Study
65-year-old woman with history of progressive renal failure for 5 years
Diagnosed with type 1 diabetes mellitus when 15 years old
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Case Study
She has diabetic retinopathy with macular degeneration.
Gives herself insulin using an insulin pen
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Case Study
Lab values
BUN 72 mg/dL
Serum creatinine 7.5 mg/dL
GFR 12 mL/min
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Discussion Questions
What are her options for renal replacement therapy?
Which one would be the best choice for her?
HD, PD, kidney transplant
Kidney transplant restores renal function, but resources for obtaining kidneys for transplant are limited. PD is probably a better choice than HD. The person with diabetes does better on PD than on HD.
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