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7/29/2019 Introduction to Hemodialysis
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Introduction to hemodialysis
Hemodialysis is the most common method used to treat advanced and permanent kidney failure. Since the
1960s, when hemodialysis first became a practical treatment for kidney failure, we've learned much about
how to make hemodialysis treatments more effective and minimize side effects. In recent years, more
compact and simpler dialysis machines have made home dialysis increasingly attractive. But even with
better procedures and equipment, hemodialysis is still a complicated and inconvenient therapy that
requires a coordinated effort from your whole health care team, including your nephrologist, dialysis
nurse, dialysis technician, dietitian, and social worker. The most important members of your health care
team are you and your family. By learning about your treatment, you can work with your health care team
to give yourself the best possible results, and you can lead a full, active life.
When Your Kidneys Fail
Healthy kidneys clean your blood by removing excess fluid, minerals, and wastes. They also make
hormones that keep your bones strong and your blood healthy. When your kidneys fail, harmful wastes
build up in your body, your blood pressure may rise, and your body may retain excess fluid and not make
enough red blood cells. When this happens, you need treatment to replace the work of your failed
kidneys.
How Hemodialysis Works
In hemodialysis, your blood is allowed to flow, a few ounces at a time, through a special filter that
removes wastes and extra fluids. The clean blood is then returned to your body. Removing the harmful
wastes and extra salt and fluids helps control your blood pressure and keep the proper balance of
chemicals like potassium and sodium in your body.
One of the biggest adjustments you must make when you start hemodialysis treatments is following a
strict schedule. Most patients go to a clinic-a dialysis center-three times a week for 3 to 5 or more hours
each visit. For example, you may be on a Monday-Wednesday-Friday schedule or a Tuesday-Thursday-
Saturday schedule. You may be asked to choose a morning, afternoon, or evening shift, depending on
availability and capacity at the dialysis unit. Your dialysis center will explain your options for scheduling
regular treatments.
Researchers are exploring whether shorter daily sessions, or longer sessions performed overnight while
the patient sleeps, are more effective in removing wastes. Newer dialysis machines make these
alternatives more practical with home dialysis. But the Federal Government has not yet established a
policy to pay for more than three hemodialysis sessions a week.
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Picture of Hemodialysis
Several centers around the country teach people how to perform their own hemodialysis treatments at
home. A family member or friend who will be your helper must also take the training, which usually takes
at least 4 to 6 weeks. Home dialysis gives you more flexibility in your dialysis schedule. With homehemodialysis, the time for each session and the number of sessions per week may vary, but you must
maintain a regular schedule by giving yourself dialysis treatments as often as you would receive them in a
dialysis unit.
Adjusting to Changes
Even in the best situations, adjusting to the effects of kidney failure and the time you spend on dialysis
can be difficult. Aside from the "lost time," you may have less energy. You may need to make changes in
your work or home life, giving up some activities and responsibilities. Keeping the same schedule you kept
when your kidneys were working can be very difficult now that your kidneys have failed. Accepting this
new reality can be very hard on you and your family. A counselor or social worker can answer your
questions and help you cope.
Many patients feel depressed when starting dialysis, or after several months of treatment. If you feel
depressed, you should talk with your social worker, nurse, or doctor because
this is a common problem that can often be treated effectively.
Getting Your Vascular Access Ready
One important step before starting hemodialysis is preparing a vascular access,
a site on your body from which your blood is removed and returned. A vascular
access should be prepared weeks or months before you start dialysis. It will
allow easier and more efficient removal and replacement of your blood with
fewer complications. For more information about the different kinds of vascular
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accesses and how to care for them, see the National Institute of Diabetes and Digestive and Kidney
Diseases (NIDDK) fact sheet Vascular Access for Hemodialysis.
Equipment and Procedures
When you first visit a hemodialysis center, it may seem like a complicated mix of machines and people.
But once you learn how the procedure works and become familiar with the equipment, you'll be more
comfortable.
Picture of a Graft
Dialysis Machine
The dialysis machine is about the size of a dishwasher. This machine has three main jobs:
pump blood and watch flow for safety
clean wastes from blood
watch your blood pressure and the rate of fluid removal from your body
Dialyzer
The dialyzer is a large canister containing thousands of small fibers
through which your blood is passed. Dialysis solution, the cleansing fluid,
is pumped around these fibers. The fibers allow wastes and extra fluids to
pass from your blood into the solution, which carries them away. The
dialyzer is sometimes called an artificial kidney.
Reuse. Your dialysis center may use the same dialyzer more than once for
your treatments. Reuse is considered safe as long as the dialyzer is
cleaned before each use. The dialyzer is tested each time to make sure it's
still working, and it should never be used for anyone but you. Before each
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session, you should be sure that the dialyzer is labeled with your name and check to see that it has
been cleaned, disinfected, and tested.
Dialysis Solution
Dialysis solution, also known as dialysate, is the fluid in the dialyzer that helps remove wastes and extra
fluid from your blood. It contains chemicals that make it act like a sponge. Your doctor will give you aspecific dialysis solution for your treatments. This formula can be adjusted based on how well you handle
the treatments and on your blood tests.
Needles
Many people find the needle sticks to be one of the hardest parts of hemodialysis treatments. Most people
however, report getting used to them after a few sessions. If you find the needle insertion painful, an
anesthetic cream or spray can be applied to the skin. The cream or spray will numb your skin briefly so
you won't feel the needle.
Most dialysis centers use two needles-one to carry blood to the dialyzer and one to return the cleaned
blood to your body. Some specialized needles are designed with two openings for two-way flow of blood,
but these needles are less efficient and require longer sessions. Needles for high-flux or high-efficiency
dialysis need to be a little larger than those used with regular dialyzers.
Picture of arterial and venous needles
Some people prefer to insert their own needles. You'll need training on inserting needles properly to
prevent infection and protect your vascular access. You may also learn a "ladder" strategy for needle
placement in which you "climb" up the entire length of the access session by session so that you don't
weaken an area with a grouping of needle sticks. A different approach is the "buttonhole" strategy in
which you use a limited number of sites but insert the needle back into the same hole made by the
previous needle stick. Whether you insert your own needles or not, you should know these techniques to
better care for your access.
Tests to See How Well Your Dialysis Is Working
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About once a month, your dialysis care team will test your blood by using one of two formulas-URR or
Kt/V-to see whether your treatments are removing enough wastes. Both tests look at one specific waste
product, called blood urea nitrogen (BUN), as an indicator for the overall level of waste products in your
system. For more information about these measurements, see the NIDDK fact sheet Hemodialysis Dose
and Adequacy.
Conditions Related to Kidney Failure and Their Treatments
Your kidneys do much more than remove wastes and extra fluid. They also make hormones and balance
chemicals in your system. When your kidneys stop working, you may have problems with anemia and
conditions that affect your bones, nerves, and skin. Some of the more common conditions caused by
kidney failure are extreme tiredness, bone problems, joint problems, itching, and "restless legs." Restless
legs will keep you awake as you feel them twitching and jumping.
Anemia and Erythropoietin (EPO)
Anemia is a condition in which the volume of red blood cells is low. Red blood cells carry oxygen to cells
throughout the body. Without oxygen, cells can't use the energy from food, so someone with anemia may
tire easily and look pale. Anemia can also contribute to heart problems.
Anemia is common in people with kidney disease because the kidneys produce the hormone
erythropoietin, or EPO, which stimulates the bone marrow to produce red blood cells. Diseased kidneys
often don't make enough EPO, and so the bone marrow makes fewer red blood cells. EPO is available
commercially and is commonly given to patients on dialysis.
For more information about the causes of and treatments for anemia in kidney failure, see the NIDDK fact
sheet Anemia in Kidney Disease and Dialysis.
Renal Osteodystrophy
The term "renal" describes things related to the kidneys. Renal osteodystrophy, or bone disease of kidney
failure, affects 90 percent of dialysis patients. It causes bones to become thin and weak or formed
incorrectly and affects both children and adults. Symptoms can be seen in growing children with kidney
disease even before they start dialysis. Older patients and women who have gone through menopause are
at greater risk for this disease.
Itching (Pruritus)
Many people treated with hemodialysis complain of itchy skin, which is often worse during or just after
treatment. Itching is common even in people who don't have kidney disease; in kidney failure, however,
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itching can be made worse by wastes in the bloodstream that current dialyzer membranes can't remove
from the blood.
The problem can also be related to high levels of parathyroid hormone (PTH). Some people have found
dramatic relief after having theirparathyroid glands removed. The four parathyroid glands sit on the outer
surface of the thyroid gland, which is located on the windpipe in the base of your neck, just above the
collarbone. The parathyroid glands help control the levels of calcium and phosphorus in the blood.
But a cure for itching that works for everyone has not been found. Phosphate binders seem to help some
people; these medications act like sponges to soak up, or bind, phosphorus while it is in the stomach.
Others find relief after exposure to ultraviolet light. Still others improve with EPO shots. A few
antihistamines (Benadryl, Atarax, Vistaril) have been found to help; also, capsaicin cream applied to the
skin may relieve itching by deadening nerve impulses. In any case, taking care of dry skin is important.
Applying creams with lanolin or camphor may help.
Sleep Disorders
Patients on dialysis often have insomnia, and some people have a specific problem called the sleep
apnea syndrome, which is often signaled bysnoring and breaks in snoring. Episodes of apnea are actually
breaks in breathing during sleep. Over time, these sleep disturbances can lead to "day-night reversal"
(insomnia at night, sleepiness during the day),headache, depression, and decreased alertness. The apnea
may be related to the effects of advanced kidney failure on the control of breathing. Treatments that work
with people who have sleep apnea, whether they have kidney failure or not, include losing weight,
changing sleeping position, and wearing a mask that gently pumps air continuously into the nose (nasal
continuous positive airway pressure, or CPAP).
Many people on dialysis have trouble sleeping at night because of aching, uncomfortable, jittery, or
"restless" legs. You may feel a strong impulse to kick or thrash your legs. Kicking may occur during sleep
and disturb a bed partner throughout the night. The causes of restless legs may include nerve damage or
chemical imbalances.
Moderate exercise during the day may help, but exercising a few hours before bedtime can make it worse.
People with restless leg syndrome should reduce or avoid caffeine, alcohol, and tobacco; some people also
find relief with massages or warm baths. A class of drugs called benzodiazepines, often used to treat
insomnia or anxiety, may help as well. These prescription drugs include Klonopin, Librium, Valium,
and Halcion. A newer and sometimes more effective therapy is levodopa (Sinemet), a drug used to
treat Parkinson's disease.
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Sleep disorders may seem unimportant, but they can impair your quality of life. Don't hesitate to raise
these problems with your nurse, doctor, or social worker.
Amyloidosis
Dialysis-related amyloidosis (DRA) is common in people who have been on dialysis for more than 5 years.
DRA develops when proteins in the blood deposit on joints and tendons, causing pain, stiffness, and fluid
in the joints, as is the case with arthritis. Working kidneys filter out these proteins, but dialysis filters are
not as effective.
How Diet Can Help
Eating the right foods can help improve your dialysis and your health. Your clinic has a dietitian to help
you plan meals. Follow the dietitian's advice closely to get the most from your hemodialysis treatments.
Here are a few general guidelines.
Fluids. Your dietitian will help you determine how much fluid to drink each day. Extra fluid can
raise your blood pressure, make your heart work harder, and increase the stress of dialysis
treatments. Remember that many foods-such as soup, ice cream, and fruits-contain plenty of water.
Ask your dietitian for tips on controlling your thirst.
Potassium. The mineral potassium is found in many foods, especially fruits and vegetables.
Potassium affects how steadily your heart beats, so eating foods with too much of it can be very
dangerous to your heart. To control potassium levels in your blood, avoid foods like oranges, bananas,
tomatoes, potatoes, and dried fruits. You can remove some of the potassium from potatoes and other
vegetables by peeling and soaking them in a large container of water for several hours, then cooking
them in fresh water.
Phosphorus. The mineral phosphorus can weaken your bones and make your skin itch if you
consume too much. Control of phosphorus may be even more important than calcium itself in
preventing bone disease and related complications. Foods like milk and cheese, dried beans, peas,
colas, nuts, and peanut butter are high in phosphorus and should be avoided. You'll probably need to
take a phosphate binder with your food to control the phosphorus in your blood between dialysis
sessions.
Salt (sodium chloride). Most canned foods and frozen dinners contain high amounts of sodium.
Too much of it makes you thirsty, and when you drink more fluid, your heart has to work harder to
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pump the fluid through your body. Over time, this can cause high blood pressureand congestive heart
failure. Try to eat fresh foods that are naturally low in sodium, and look for products labeled "low
sodium."
Protein. Before you were on dialysis, your doctor may have told you to follow a low-protein diet to
preserve kidney function. But now you have different nutritional priorities. Most people on dialysis are
encouraged to eat as much high-quality protein as they can. Protein helps you keep muscle and repair
tissue, but protein breaks down into urea (blood urea nitrogen, or BUN) in your body. Some sources of
protein, called high-quality proteins, produce less waste than others. High-quality proteins come from
meat, fish, poultry, and eggs. Getting most of your protein from these sources can reduce the amount
of urea in your blood.
Calories. Calories provide your body with energy. Some people on dialysis need to gain weight.
You may need to find ways to add calories to your diet. Vegetable oils-like olive, canola, and safflower
oils-are good sources of calories and do not contribute to problems controlling your cholesterol. Hard
candy, sugar, honey, jam, and jelly also provide calories and energy. If you have diabetes, however,
be very careful about eating sweets. A dietitian's guidance is especially important for people
with diabetes.
Supplements. Vitamins and minerals may be missing from your diet because you have to avoid somany foods. Dialysis also removes some vitamins from your body. Your doctor may prescribe a
vitamin and mineral supplement designed specifically for people with kidney failure. Take your
prescribed supplement after treatment on the days you have hemodialysis. Never take vitamins
that you can buy off the store shelf, since they may contain vitamins or minerals that are
harmful to you.
You can also ask your dietitian for recipes and titles of cookbooks for patients with kidney disease.
Following the restrictions of a diet for kidney disease might be hard at first, but with a little creativity, you
can make tasty and satisfying meals. For more information, see the NIDDK booklet Eat Right to Feel Right
on Hemodialysis.
Financial Issues
Treatment for kidney failure is expensive, but Federal health insurance plans pay much of the cost, usually
up to 80 percent. Often, private insurance or State programs pay the rest. Your social worker can help you
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locate resources for financial assistance. For more information, see the NIDDK fact sheetFinancial Help for
Treatment of Kidney Failure.
Hope Through Research
The NIDDK, through its Division of Kidney, Urologic, and Hematologic Diseases, supports several
programs and studies devoted to improving treatment for patients with progressive kidney disease and
permanent kidney failure, including patients on hemodialysis.
The End-Stage Renal Disease Program promotes research to reduce medical problems from
bone, blood, nervous system, metabolic, gastrointestinal, cardiovascular, and endocrine abnormalities
in kidney failure and to improve the effectiveness of dialysis and transplantation. The research focuses
on evaluating different hemodialysis schedules and on finding the most useful information for
measuring dialysis adequacy. The program also seeks to increase kidney graft and patient survival
and to maximize quality of life.
The HEMO Study, completed in 2002, tested the theory that a higher dialysis dose and/or high-
flux membranes would reduce patient mortality (death) and morbidity (medical problems). Doctors at
15 medical centers recruited more than 1,800 hemodialysis patients and randomly assigned them to
high or standard dialysis doses and high- or low-flux filters. The study found no increase in the health
or survival of patients who had a higher dialysis dose, who dialyzed with high-flux filters, or who did
both.
The U.S. Renal Data System (USRDS) collects, analyzes, and distributes information about the
use of dialysis and transplantation to treat kidney failure in the United States. The USRDS is funded
directly by the NIDDK in conjunction with the Centers for Medicare & Medicaid Services. The USRDS
publishes an Annual Data Report, which identifies the total population of people being treated for
kidney failure; reports on incidence, prevalence, death rates, and trends over time; and develops data
on the effects of various treatment approaches. The report also helps identify problems and
opportunities for more focused special studies of renal research issues.
The Hemodialysis Vascular Access Clinical Trials Consortium is conducting a series of
multicenter, clinical trials of drug therapies to reduce the failure and complication rate of
arteriovenous (AV) grafts and fistulas in hemodialysis. These studies are randomized and placebo
controlled, which means the studies meet the highest standard for scientific accuracy. AV grafts and
fistulas prepare the arteries and veins for regular dialysis. See the NIDDK fact sheet Vascular Access
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for Hemodialysis for more information. Recently developed drugs to prevent blood clots may be
evaluated in these large clinical trials.
The U.S. Government does not endorse or favor any specific commercial product or company. Trade,
proprietary, or company names appearing in this document are used only because they are considered
necessary in the context of the information provided. If a product is not mentioned, the omission does not
mean or imply that the product is unsatisfactory.
Hemodialysis in progress
Hemodialysis machine
In medicine, hemodialysis (also haemodialysis) is a method for removing waste products such
as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure.
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Hemodialysis is one of three renal replacement therapies (the other two being renal transplant; peritoneal
dialysis).
Hemodialysis can be an outpatient or inpatient therapy. Routine hemodialysis is conducted in a dialysis
outpatient facility, either a purpose built room in a hospital or a dedicated, stand alone clinic. Less
frequently hemodialysis is done at home. Dialysis treatments in a clinic are initiated and managed by
specialized staff made up of nurses and technicians; dialysis treatments at home can be self initiated and
managed or done jointly with the assistance of a trained helper who is usually a family member.[1]
[edit]Principle
Semipermeable membrane
The principle of hemodialysis is the same as other methods ofdialysis; it involves diffusion of solutes
across a semipermeable membrane. Hemodialysis utilizes counter current flow, where the dialysate is
flowing in the opposite direction to blood flow in theextracorporeal circuit. Counter-current flow maintains
the concentration gradient across the membrane at a maximum and increases the efficiency of the
dialysis.
Fluid removal (ultrafiltration) is achieved by altering the hydrostatic pressure of the dialysate
compartment, causing free water and some dissolved solutes to move across the membrane along a
created pressure gradient.
The dialysis solution that is used may be a sterilized solution of mineral ions or comply with British
Pharmacopoeia. Urea and other waste products, potassium, and phosphate diffuse into the dialysis
solution. However, concentrations ofsodium and chloride are similar to those of normal plasma to prevent
loss. Sodium bicarbonate is added in a higher concentration than plasma to correct blood acidity. A small
amount of glucose is also commonly used.
Note that this is a different process to the related technique ofhemofiltration.
[edit]History
Many have played a role in developing dialysis as a practical treatment for renal failure, starting with
Thomas Graham ofGlasgow, who first presented the principles of solute transport across a semipermeable
membrane in 1854.[2] The artificial kidney was first developed by Abel, Rountree and Turner in 1913,[3] the
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first hemodialysis in a human being was by Hass(February 28, 1924)[4] and the artificial kidney was
developed into a clinically useful apparatus by Kolffin 1943 - 1945.[5] This research showed that life could
be prolonged in patients dying ofrenal failure.
Dr. Willem Kolffwas the first to construct a working dialyzer in 1943. The first successfully treated
patient was a 67-year-old woman in uremic coma who regained consciousness after 11 hours of
hemodialysis with Kolffs dialyzer in 1945. At the time of its creation, Kolffs goal was to provide life
support during recovery from acute renal failure. After World War II ended, Kolff donated the five
dialyzers he had made to hospitals around the world, including Mount Sinai Hospital, New York. Kolff gave
a set of blueprints for his hemodialysis machine to George Thorn at the Peter Bent Brigham
Hospital in Boston. This led to the manufacture of the next generation of Kolffs dialyzer, a stainless
steel Kolff-Brigham dialysis machine.
By the 1950s, Willem Kolffs invention of the dialyzer was used for acute renal failure, but it was not seen
as a viable treatment for patients with stage 5 chronic kidney disease (CKD). At the time, doctors believed
it was impossible for patients to have dialysis indefinitely for two reasons. First, they thought no man-
made device could replace the function of kidneys over the long term. In addition, a patient undergoing
dialysis suffered from damaged veins and arteries, so that after several treatments, it became difficult to
find a vessel to access the patients blood.
Dr. Nils Alwall: The original Kolff kidney was not very useful clinically, because it did not allow for
removal of excess fluid. Dr. Nils Alwall [6] encased a modified version of this kidney inside a stainless steel
canister, to which a negative pressure could be applied, in this way effecting the first truly practical
application of hemodialysis, which was done in 1946 at theUniversity of Lund. Alwall also was arguably the
inventor of the arteriovenous shunt for dialysis. He reported this first in 1948 where he used such an
arteriovenous shunt in rabbits. Subsequently he used such shunts, made of glass, as well as his canister-
enclosed dialyzer, to treat 1500 patients in renal failure between 1946 and 1960, as reported to the First
International Congress of Nephrology held in Evian in September 1960. Alwall was appointed to a newly-
created Chair of Nephrology at the University of Lund in 1957. Subsequently, he collaborated with
Swedish businessman Holger Crafoord to found one of the key companies that would manufacture dialysis
equipment in the past 50 years, Gambro. The early history of dialysis has been reviewed by Stanley
Shaldon.[7]
Dr. Belding H. Scribner working with a surgeon, Dr. Wayne Quinton, modified the glass shunts used by
Alwall by making them from Teflon. Another key improvement was to connect them to a short piece of
silicone elastomer tubing. This formed the basis of the so-called Scribner shunt, perhaps more properly
called the Quinton-Scribner shunt. After treatment, the circulatory access would be kept open by
connecting the two tubes outside the body using a small U-shaped Teflon tube, which would shunt the
blood from the tube in the artery back to the tube in the vein.[8]
In 1962, Scribner started the worlds first outpatient dialysis facility, the Seattle Artificial Kidney Center,
later renamed the Northwest Kidney Centers. Immediately the problem arose of who should be given
dialysis, since demand far exceeded the capacity of the six dialysis machines at the center. Scribner
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decided that the decision about who would receive dialysis and who wouldnt, would not be made by him.
Instead, the choices would be made by an anonymous committee, which could be viewed as one of the
first bioethics committees.
For a detailed history of successful and unsuccessful attempts at dialysis, including pioneers such as Abel
and Roundtree, Haas, and Necheles, see this review by Kjellstrand.[9]
[edit]Prescription
A prescription for dialysis by a nephrologist (a medical kidney specialist) will specify various parameters
for a dialysis treatment. These include frequency (how many treatments per week), length of each
treatment, and the blood and dialysis solution flow rates, as well as the size of the dialyzer. The
composition of the dialysis solution is also sometimes adjusted in terms of its sodium and potassium and
bicarbonate levels. In general, the larger the body size of an individual, the more dialysis he/she will need.
In North America and the UK, 3-4 hour treatments (sometimes up to 5 hours for larger patients) given 3
times a week are typical. Twice-a-week sessions are limited to patients who have a substantial residual
kidney function. Four sessions per week are often prescribed for larger patients, as well as patients who
have trouble with fluid overload. Finally, there is growing interest in short daily home hemodialysis, which
is 1.5 - 4 hr sessions given 5-7 times per week, usually at home. There also is interest in nocturnal
dialysis, which involves dialyzing a patient, usually at home, for 810 hours per night, 3-6 nights per
week. Nocturnal in-center dialysis, 3-4 times per week, is also offered at a handful of dialysis units in
the United States.
[edit]Side effects and complications
Hemodialysis often involves fluid removal (through ultrafiltration), because most patients with renal
failure pass little or no urine. Side effects caused by removing too much fluid and/or removing fluid too
rapidly include low blood pressure, fatigue, chest pains, leg-cramps, nausea and headaches. These
symptoms can occur during the treatment and can persist post treatment; they are sometimes collectively
referred to as the dialysis hangover or dialysis washout. The severity of these symptoms is usually
proportionate to the amount and speed of fluid removal. However, the impact of a given amount or rate of
fluid removal can vary greatly from person to person and day to day. These side effects can be avoided
and/or their severity lessened by limiting fluid intake between treatments or increasing the dose of dialysis
e.g. dialyzing more often or longer per treatment than the standard three times a week, 34 hours per
treatment schedule.
Since hemodialysis requires access to the circulatory system, patients undergoing hemodialysis may
expose their circulatory system to microbes, which can lead to sepsis, an infection affecting the heart
valves (endocarditis) or an infection affecting the bones (osteomyelitis). The risk of infection varies
depending on the type of access used (see below). Bleeding may also occur, again the risk varies
depending on the type of access used. Infections can be minimized by strictly adhering to infection
control best practices.
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Heparin is the most commonly used anticoagulant in hemodialysis, as it is generally well tolerated and can
be quickly reversed with protamine sulfate. Heparin allergy can infrequently be a problem and can cause a
low platelet count. In such patients, alternative anticoagulants can be used. In patients at high risk of
bleeding, dialysis can be done without anticoagulation.
First Use Syndrome is a rare but severe anaphylactic reaction to the artificial kidney. Its symptoms include
sneezing, wheezing, shortness of breath, back pain, chest pain, or sudden death. It can be caused by
residual sterilant in the artificial kidney or the material of the membrane itself. In recent years, the
incidence of First Use Syndrome has decreased, due to an increased use ofgamma irradiation, steam
sterilization, or electron-beam radiation instead of chemical sterilants, and the development of new
semipermeable membranes of higherbiocompatibility. New methods of processing previously acceptable
components of dialysis must always be considered. For example, in 2008, a series of first-use type or
reactions, including deaths occurred due to heparin contaminated during the manufacturing process with
oversulfated chondroitin sulfate.[10]
Longterm complications of hemodialysis include amyloidosis, neuropathy and various forms ofheart
disease. Increasing the frequency and length of treatments have been shown to improve fluid overload
and enlargement of the heart that is commonly seen in such patients.[11][12]
Listed below are specific complications associated with different types of hemodialysis access.
[edit]Access
In hemodialysis, three primary methods are used to gain access to the blood: an intravenous catheter,
an arteriovenous fistula (AV) and a synthetic graft. The type of access is influenced by factors such as the
expected time course of a patient's renal failure and the condition of his or her vasculature. Patients may
have multiple accesses, usually because an AV fistula or graft is maturing and a catheter is still being
used. The creation of all these three major types of vascular accesses requires surgery.[13]
[edit]Catheter
Catheter access, sometimes called a CVC (Central Venous Catheter), consists of a plastic catheter with
two lumens (or occasionally two separate catheters) which is inserted into a large vein (usually the vena
cava, via the internal jugular vein or the femoral vein) to allow large flows of blood to be withdrawn from
one lumen, to enter the dialysis circuit, and to be returned via the other lumen. However, blood flow is
almost always less than that of a well functioning fistula or graft.
Catheters are usually found in two general varieties, tunnelled and non-tunnelled.
Non-tunnelled catheter access is for short-term access (up to about 10 days, but often for one dialysis
session only), and the catheter emerges from the skin at the site of entry into the vein.
Tunnelled catheter access involves a longer catheter, which is tunnelled under the skin from the point of
insertion in the vein to an exit site some distance away. It is usually placed in the internal jugular vein in
the neck and the exit site is usually on the chest wall. The tunnel acts as a barrier to invading microbes,
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and as such, tunnelled catheters are designed for short- to medium-term access (weeks to months only),
because infection is still a frequent problem.
Aside from infection, venous stenosis is another serious problem with catheter access. The catheter is a
foreign body in the vein and often provokes an inflammatory reaction in the vein wall. This results
in scarring and narrowing of the vein, often to the point of occlusion. This can cause problems with severe
venous congestion in the area drained by the vein and may also render the vein, and the veins drained by
it, useless for creating a fistula or graft at a later date. Patients on long-term hemodialysis can literally
'run out' of access, so this can be a fatal problem.
Catheter access is usually used for rapid access for immediate dialysis, for tunnelled access in patients
who are deemed likely to recover from acute renal failure, and for patients withend-stage renal
failure who are either waiting for alternative access to mature or who are unable to have alternative
access.
Catheter access is often popular with patients, because attachment to the dialysis machine doesn't require
needles. However, the serious risks of catheter access noted above mean that such access should becontemplated only as a long-term solution in the most desperate access situation.
[edit]AV fistula
A radiocephalic fistula.
AV (arteriovenous) fistulas are recognized as the preferred access method. To create a fistula, a vascular
surgeon joins an artery and a veintogether through anastomosis. Since this bypasses the capillaries, blood
flows rapidly through the fistula. One can feel this by placing one's finger over a mature fistula. This is
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called feeling for "thrill" and produces a distinct 'buzzing' feeling over the fistula. One can also listen
through a stethoscope for the sound of the blood "whooshing" through the fistula, a sound called bruit.
Fistulas are usually created in the nondominant arm and may be situated on the hand (the 'snuffbox'
fistula'), the forearm (usually aradiocephalic fistula, or so-called Brescia-Cimino fistula, in which
the radial artery is anastomosed to the cephalic vein), or the elbow (usually a brachiocephalic fistula,
where the brachial artery is anastomosed to the cephalic vein). A fistula will take a number of weeks to
mature, on average perhaps 46 weeks. During treatment, two needles are inserted into the fistula, one
to draw blood and one to return it.
The advantages of the AV fistula use are lower infection rates, because no foreign material is involved in
their formation, higher blood flow rates (which translates to more effective dialysis), and a lower incidence
ofthrombosis. The complications are few, but if a fistula has a very high blood flow and the vasculature
that supplies the rest of the limb is poor, a steal syndrome can occur, where blood entering the limb is
drawn into the fistula and returned to the general circulation without entering the limb's capillaries. This
results in cold extremities of that limb, cramping pains, and, if severe, tissue damage. One long-term
complication of an AV fistula can be the development of an aneurysm, a bulging in the wall of the vein
where it is weakened by the repeated insertion of needles over time. To a large extent the risk of
developing an aneurysm can be reduced by carefully rotating needle sites over the entire fistula, or using
the "buttonhole"(constant site) technique. Aneurysms may necessitate corrective surgery and may
shorten the useful life of a fistula. To prevent damage to the fistula and aneurysm or pseudoaneurysm
formation, it is recommended that the needle be inserted at different points in a rotating fashion. Another
approach is to cannulate the fistula with a blunted needle, in exactly the same place. This is called a
'buttonhole' approach. Often two or three buttonhole places are available on a given fistula. This also can
prolong fistula life and help prevent damage to the fistula.
[edit]AV graft
An arteriovenous graft.
AV (arteriovenous) grafts are much like fistulas in most respects, except that an artificial vessel is used to
join the artery and vein. The graft usually is made of a synthetic material, often PTFE, but sometimes
chemically treated, sterilized veins from animals are used. Grafts are inserted when the patient's native
vasculature does not permit a fistula. They mature faster than fistulas, and may be ready for use several
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weeks after formation (some newer grafts may be used even sooner). However, AV grafts are at high risk
to develop narrowing, especially in the vein just downstream from where the graft has been sewn to the
vein. Narrowing often leads to clotting or thrombosis. As foreign material, they are at greater risk for
becoming infected. More options for sites to place a graft are available, because the graft can be made
quite long. Thus a graft can be placed in the thigh or even the neck (the 'necklace graft').
[edit]Fistula First project
AV fistulas have a much better access patency and survival than do venous catheters or grafts. They also
produce better patient survival and have far fewer complications compared to grafts or venous catheters.
For this reason, the Centers for Medicare & Medicaid (CMS) has set up a Fistula First Initiative,[14] whose
goal is to increase the use of AV fistulas in dialysis patients.
There is ongoing research to make bio-engineered blood vessels, which may be of immense importance in
creating AV fistulas for patients on hemodialysis, who do not have good blood vessels for creation of one.
It involves growing cells which produce collagen and other proteins on a biodegradable micromesh tube
followed by removal of those cells to make the 'blood vessels' storable in refrigerators.[15]
[edit]Types
There are three types of hemodialysis: conventional hemodialysis, daily hemodialysis, and nocturnal
hemodialysis. Below is the adaption and summary from a brochure of The Ottawa Hospital.
[edit]Conventional hemodialysis
Chronic hemodialysis is usually done three times per week, for about 34 hours for each treatment, during
which the patient's blood is drawn out through a tube at a rate of 200-400 mL/min. The tube is connected
to a 15, 16, or 17 gauge needle inserted in the dialysis fistula or graft, or connected to one port of a
dialysis [[catheter] without needles]. The blood is then pumped through the dialyzer, and then the
processed blood is pumped back into the patient's bloodstream through another tube (connected to a
second needle or port). During the procedure, the patient's blood pressure is closely monitored, and if it
becomes low, or the patient develops any other signs of low blood volume such as nausea, the dialysis
attendant can administer extra fluid through the machine. During the treatment, the patient's entire blood
volume (about 5000 cc) circulates through the machine every 15 minutes. During this process, the dialysis
patient is exposed to a weeks worth of water for the average person.
[edit]Daily hemodialysis
Daily hemodialysis is typically used by those patients who do their own dialysis at home. It is less stressfu
(more gentle) but does require more frequent access. This is simple with catheters, but more problematic
with fistulas or grafts. The "buttonhole technique" can be used for fistulas requiring frequent access. Daily
hemodialysis is usually done for 2 hours six days a week.
[edit]Nocturnal hemodialysis
The procedure of nocturnal hemodialysis is similar to conventional hemodialysis except it is performed
three to six nights a week and six-ten hours per session while the patient sleeps.[16]
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[edit]Advantages and disadvantages
[edit]Advantages
Low mortality rate
Better control of blood pressure and abdominal cramps
Less diet restriction
Better solute clearance effect for the daily hemodialysis: better tolerance and fewer
complications with more frequent dialysis [17]
[edit]Disadvantages
Restricts independence, as people undergoing this procedure cannot travel around
because of supplies availability
Requires more supplies such as high water quality and electricity
Requires reliable technology like dialysis machines The procedure is complicated and requires that care givers have more knowledge
Requires time to set up and clean dialysis machines, and expense with machines and
associated staff[17]
[edit]Equipment
Schematic of a hemodialysis circuit
The hemodialysis machine pumps the patient's blood and the dialysate through the dialyzer. The newest
dialysis machines on the market are highly computerized and continuously monitor an array of safety-
critical parameters, including blood and dialysate flow rates; dialysis solution conductivity, temperature,
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and pH; and analysis of the dialysate for evidence of blood leakage or presence of air. Any reading that is
out of normal range triggers an audible alarm to alert the patient-care technician who is monitoring the
patient. Manufacturers of dialysis machines include companies such as Nipro, Fresenius, Gambro, Baxter,
B. Braun, NxStage and Bellco.
[edit]Water system
A hemodialysis unit's dialysate solution tanks
An extensive water purification system is absolutely critical for hemodialysis. Since dialysis patients are
exposed to vast quantities of water, which is mixed with dialysate concentrate to form the dialysate, even
trace mineral contaminants or bacterial endotoxins can filter into the patient's blood. Because the
damaged kidneys cannot perform their intended function of removing impurities, ions introduced into the
bloodstream via water can build up to hazardous levels, causing numerous symptoms or death.
Aluminum, chloramine, fluoride, copper, and zinc, as well as bacterial fragments and endotoxins, have all
caused problems in this regard.
For this reason, water used in hemodialysis is carefully purified before use. Initially it is filtered and
temperature-adjusted and its pH is corrected by adding an acid or base. Then it is softened. Next the
water is run through a tank containing activated charcoal to adsorb organic contaminants. Primary
purification is then done by forcing water through a membrane with very tiny pores, a so-called reverse
osmosis membrane. This lets the water pass, but holds back even very small solutes such as electrolytes.
Final removal of leftover electrolytes is done by passing the water through a tank with ion-exchange
resins, which remove any leftover anions or cations and replace them with hydroxyl and hydrogen
molecules, respectively, leaving ultrapure water.
Even this degree of water purification may be insufficient. The trend lately is to pass this final purified
water (after mixing with dialysate concentrate) through a dialyzer membrane. This provides another layer
of protection by removing impurities, especially those of bacterial origin, that may have accumulated in
the water after its passage through the original water purification system.
Once purified water is mixed with dialysate concentrate, its conductivity increases, since water that
contains charged ions conducts electricity. During dialysis, the conductivity of dialysis solution is
continuously monitored to ensure that the water and dialysate concentrate are being mixed in the proper
proportions. Both excessively concentrated dialysis solution and excessively dilute solution can cause
severe clinical problems.
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[edit]Dialyzer
The dialyzer is the piece of equipment that actually filters the blood. Almost all dialyzers in use today are
of the hollow-fiber variety. A cylindrical bundle of hollow fibers, whose walls are composed of semi-
permeable membrane, is anchored at each end into potting compound (a sort of glue). This assembly is
then put into a clear plastic cylindrical shell with four openings. One opening or blood port at each end of
the cylinder communicates with each end of the bundle of hollow fibers. This forms the "blood
compartment" of the dialyzer. Two other ports are cut into the side of the cylinder. These communicate
with the space around the hollow fibers, the "dialysate compartment." Blood is pumped via the blood ports
through this bundle of very thin capillary-like tubes, and the dialysate is pumped through the space
surrounding the fibers. Pressure gradients are applied when necessary to move fluid from the blood to the
dialysate compartment.
[edit]Membrane and flux
Dialyzer membranes come with different pore sizes. Those with smaller pore size are called "low-flux" and
those with larger pore sizes are called "high-flux." Some larger molecules, such as beta-2-microglobulin,are not removed at all with low-flux dialyzers; lately, the trend has been to use high-flux dialyzers.
However, such dialyzers require newer dialysis machines and high-quality dialysis solution to control the
rate of fluid removal properly and to prevent backflow of dialysis solution impurities into the patient
through the membrane.
Dialyzer membranes used to be made primarily of cellulose (derived from cotton linter). The surface of
such membranes was not very biocompatible, because exposed hydroxyl groups would
activate complement in the blood passing by the membrane. Therefore, the basic, "unsubstituted"
cellulose membrane was modified. One change was to cover these hydroxyl groups with acetate groups(cellulose acetate); another was to mix in some compounds that would inhibit complement activation at
the membrane surface (modified cellulose). The original "unsubstituted cellulose" membranes are no
longer in wide use, whereas cellulose acetate and modified cellulose dialyzers are still used. Cellulosic
membranes can be made in either low-flux or high-flux configuration, depending on their pore size.
Another group of membranes is made from synthetic materials, using polymers such
as polyarylethersulfone, polyamide, polyvinylpyrrolidone, polycarbonate, and polyacrylonitrile. These
synthetic membranes activate complement to a lesser degree than unsubstituted cellulose membranes.
Synthetic membranes can be made in either low- or high-flux configuration, but most are high-flux.
Nanotechnology is being used in some of the most recent high-flux membranes to create a uniform pore
size. The goal of high-flux membranes is to pass relatively large molecules such as beta-2-microglobulin
(MW 11,600 daltons), but not to pass albumin (MW ~66,400 daltons). Every membrane has pores in a
range of sizes. As pore size increases, some high-flux dialyzers begin to let albumin pass out of the blood
into the dialysate. This is thought to be undesirable, although one school of thought holds that removing
some albumin may be beneficial in terms of removing protein-bound uremic toxins.
[edit]Membrane flux and outcome
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Whether using a high-flux dialyzer improves patient outcomes is somewhat controversial, but several
important studies have suggested that it has clinical benefits. The NIH-funded HEMO trial compared
survival and hospitalizations in patients randomized to dialysis with either low-flux or high-flux
membranes. Although the primary outcome (all-cause mortality) did not reach statistical significance in
the group randomized to use high-flux membranes, several secondary outcomes were better in the high-
flux group.[18][19] A recent Cochrane analysis concluded that benefit of membrane choice on outcomes has
not yet been demonstrated.[20] A collaborative randomized trial from Europe, the MPO (Membrane
Permeabilities Outcomes) study,[21] comparing mortality in patients just starting dialysis using either high-
flux or low-flux membranes, found a nonsignificant trend to improved survival in those using high-flux
membranes, and a survival benefit in patients with lower serum albumin levels or in diabetics.
[edit]Membrane flux and beta-2-microglobulin amyloidosis
High-flux dialysis membranes and/or intermittent on-line hemodiafiltration (IHDF) may also be beneficial
in reducing complications of beta-2-microglobulin accumulation. Because beta-2-microglobulin is a large
molecule, with a molecular weight of about 11,600 daltons, it does not pass at all through low-flux dialysis
membranes. Beta-2-M is removed with high-flux dialysis, but is removed even more efficiently with IHDF.
After several years (usually at least 5-7), patients on hemodialysis begin to develop complications from
beta-2-M accumulation, including carpal tunnel syndrome, bone cysts, and deposits of this amyloid in
joints and other tissues. Beta-2-M amyloidosis can cause very serious complications,
includingspondyloarthropathy, and often is associated with shoulder joint problems. Observational studies
from Europe and Japan have suggested that using high-flux membranes in dialysis mode, or IHDF,
reduces beta-2-M complications in comparison to regular dialysis using a low-flux membrane.[22][23][24][25][26]
[edit]Dialyzer size and efficiency
Dialyzers come in many different sizes. A larger dialyzer with a larger membrane area (A) will usually
remove more solutes than a smaller dialyzer, especially at high blood flow rates. This also depends on the
membrane permeability coefficient K0 for the solute in question. So dialyzer efficiency is usually expressed
as the K0A - the product of permeability coefficient and area. Most dialyzers have membrane surface areas
of 0.8 to 2.2 square meters, and values ofK0A ranging from about 500 to 1500 mL/min. K0A, expressed in
mL/min, can be thought of as the maximum clearance of a dialyzer at very high blood and dialysate flow
rates.
[edit]Reuse of dialyzers
The dialyzer may either be discarded after each treatment or be reused. Reuse requires an extensive
procedure of high-level disinfection. Reused dialyzers are not shared between patients. There was an
initial controversy about whether reusing dialyzers worsened patient outcomes. The consensus today is
that reuse of dialyzers, if done carefully and properly, produces similar outcomes to single use of
dialyzers.[27]
Dialyzer Reuse is a practice that has been around since the invention of the product. This practice includes
the cleaning of a used dialyzer to be reused multiple times for the same patient. Dialysis clinics reuse
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dialyzers to become more economical and reduce the high costs of single-use dialysis which can be
extremely expensive and wasteful. Single used dialyzers are initiated just once and then thrown out
creating a large amount of bio-medical waste with no mercy for cost savings. If done right, dialyzer reuse
can be very safe for dialysis patients.
There are two ways of reusing dialyzers. Firstly, there is manual reuse, which involves the cleaning of the
used dialyzer by hand. The dialyzer is semi-disassembled then flushed repeatedly before being rinsed with
water. It is then stored with a liquid disinfectant for 18+ hours until its next use. Secondly, there is the
newer method of automated reuse by means of a medical device. These devices are beneficial to dialysis
clinics that practice reuse especially for large dialysis clinical entities because they allow for several
back to back cycles per day. The dialyzer is automatically cleaned by machine then filled with liquid
disinfectant for storage. Automated reuse is more effective than manual reuse, but when reused over 15
times with current methodology, the dialyzer can lose B2m, middle molecule clearance and fiber pore
structure integrity, reducing the effectiveness of the patients dialysis session.[citation needed]
[edit]Nursing care for hemodialysis patient
Adapt from nephrology nursing practice recommendations developed by Canadian Association of
Nephrology and Technology (CANNT) based on best available evidence and clinical practice guidelines, a
nephrology nurse should perform [28]:
Hemodialysis Vascular Access: Assess the fistula/graft and arm before, after each dialysis or every
shift: the access flow, complications Assess the complication of central venous catheter: the tip
placement, exit site, complications document and notify appropriate health care provider regarding any
concerns. educates the patient with appropriate cleaning of fistula/graft and exit site; with recognizing and
reporting signs and symptoms of infection and complication.
Hemodialysis adequacy: Assesses patient constantly for signs and symptoms of inadequate dialysis.
Assesses possible causes of inadequate dialysis. Educations patients the importance of receiving adequate
dialysis.
Hemodialysis treatment and complications: Performs head to toe physical assessment before, during
and after hemodialysis regarding complications and accesss security. Confirm and deliver dialysis
prescription after review most update lab results. Address any concerns of the patient and educate patient
when recognizing the learning gap.
Medication management and infection control practice: Collaborate with the patient to develop a
medication regimen. Follow infection control guidelines as per unit protocol
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