the dialysis

Dialysis
In medicine, dialysis is a type of renal replacement therapy which is used to provide an artificial replacement for lost kidney function due to renal failure. It is a life support treatment and does not treat any kidney diseases. Dialysis may be used for very sick patients who have suddenly lost their kidney function (acute renal failure) or for quite stable patients who have permanently lost their kidney function (end stage renal failure). When healthy, the kidneys remove waste products (for example potassium, acid and urea) from the blood and also remove excess fluid in the form of urine. Dialysis treatments have to duplicate both of these functions as dialysis (waste removal) and ultrafiltration (fluid removal).
Dialysis works on the principle of the diffusion of solutes across a semipermeable membrane. Blood flows by one side of a semipermeable membrane, and a dialysis solution or fluid flows by the opposite side. Smaller solutes pass through the membrane. The concentrations of undesired solutes (for example potassium, urea, and phosphorus) are high in the blood, but low or absent in the dialysis solution and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like sodium and chloride that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to neutralise the acidosis that is often present in these patients.
Dialysis is a method of removing toxic substances (impurities or wastes) from the blood when the kidneys are unable to do so. Dialysis is most frequently used for patients who have kidney failure, but may also be used to quickly remove drugs or poisons in acute situations. This technique can be life saving in people with acute or chronic kidney failure.


>>>> Types Of Dialysis
There are two main types of dialysis, hemodialysis and peritoneal dialysis. Hemofiltration is not strictly speaking a dialysis treatment, but is extremely similar.
1. Hemodialysis
In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing it to a semipermeable membrane. Dialysis solution is pumped through the dialysate compartment of the dialyzer, which is configured so that the blood and dialysis solutions flow on opposite sides of the semipermeable membrane. The cleansed blood is then returned via the circuit back to the body. Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This usually is done by applying a negative pressure to the dialysate compartment of the dialyzer. This pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows removal of several liters of excess salt and water during a typical 3-4 hour treatment. Hemodialysis treatments are typically given three times per week, but more frequent sessions, which are usually 2-3 hours in duration given 5-6 times per week can be sometimes perscribed. Hemodialysis treatments can be given either in outpatient dialysis centers or can be done by a patient at home, providing they have suitable help and accommodation.
2. Peritoneal dialysis
In peritoneal dialysis, a sterile solution containing minerals and glucose is run through a tube into the peritoneal cavity, the abdominal body cavity around the intestine, where the peritoneal membrane acts as a semipermeable membrane. The dialysate is left there for a period of time to absorb waste products, and then it is drained out through the tube and discarded. This cycle or "exchange" is normally repeated 4-5 times during the day, (sometimes more often overnight with an automated system). Ultrafiltration occurs via osmosis; the dialysis solution used contains a high concentration of glucose, and the resulting osmotic pressure causes fluid to move from the blood into the dialysate. As a result, more fluid is drained than was instilled. Peritoneal dialysis is less efficient than hemodialysis, but because it is carried out for a longer period of time the net effect in terms of removal of waste products and of salt and water are similar to hemodialysis. Peritoneal dialysis is carried out at home by the patient and it requires a substantial degree of motivation and support to perform. It does free patients from the routine of having to go to a dialysis clinic on a fixed schedule multiple times per week, and it can be done while traveling with a minimum of specialized equipment.
3. Hemofiltration
Hemofiltration is a similar treatment to hemodialysis, but it makes use of a different principle. The blood is pumped through a dialyzer or "hemofilter" as in dialysis, but no dialysate is used. A pressure gradient is applied; as a result, water moves across the very permeable membrane rapidly, facilitating the transport of dissolved substances, importantly ones with large molecular weights, which are cleared less well by hemodialysis. Salts and water lost from the blood during this process are replaced with a "substitution fluid" that is infused into the extracorporeal circuit during the treatment. Hemodiafiltration is a term used to describe several methods of combining hemodialysis and hemofiltration in one process.


>>>> Hemodialysis
In medicine, hemodialysis, also haemodialysis, is a method for removing waste products such as potassium and urea, as well as free water from the blood when the kidneys are incapable of this (i.e. in renal failure). It is a form of renal dialysis and is therefore a renal replacement therapy.
Hemodialysis is typically conducted in a dedicated facility, either a special room in a hospital or a clinic (with specialized nurses and technicians) that specializes in hemodialysis. Although less typical, dialysis can also be done in a patient's home as home hemodialysis.
Principle



Semipermeable membrane
The principle of hemodialysis is the same as other methods of dialysis; 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 the extracorporeal 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 is a sterilized solution of mineral ions. Urea and other waste products, and also, potassium and phosphate, diffuse into the dialysis solution. However, concentrations of sodium and chloride are similar to those of normal plasma to prevent loss. 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 of hemofiltration.

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 they will need. In the North America and 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" dialysis, which is comprised of 1.5 - 3 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 8-10 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.

Side-effects and complications
Hemodialysis usually also involves the removal (ultrafiltration) of extra fluid, because most patients with end-stage renal failure pass little or no urine. The sudden removal of fluid on dialysis may cause side effects, which are usually proportionate to the amount of fluid which is removed. These potential side effects include low blood pressure, fatigue, chest pains, leg-cramps and headaches.
Since hemodialysis requires access to the circulatory system, patients undergoing hemodialysis have a portal of entry for microbes, which could lead to septicemia or an infection affecting the heart valves (endocarditis) or bone (osteomyelitis). The risk of infection depends on the type of access used (see below). Bleeding may also occur, again the risk depending on the type of access used.
Heparin is the most commonly used anticoagulant in hemodialysis patients, as it is generally well tolerated and can be quickly reversed with protamine. Heparin allergy can 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 very rare but severe anaphylactic reaction to the dialyzer. Its symptoms include sneezing, wheezing, shortness of breath, back pain, chest pain, or sudden death. It can be caused by residual sterilant in the dialyzer or the material of the membrane itself. In recent years, the incidence of First Use Syndrome has fallen off, due to an increased use of gamma irradiation, steam sterilization, or electron-beam radiation instead of chemical sterilants, and the development of new dialyzer membranes of higher biocompatibility.
There are specific complications associated with different types of hemodialysis access, listed below.

Access
There are three primary modes of access to the blood in hemodialysis: an intravenous catheter, an arteriovenous (AV) Cimino fistula, or 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.
A. 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 go into 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.
They 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. They are 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 and as such tunnelled catheters are designed for short to medium term access (weeks to months only), as 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, which results in scarring and narrowing of the vein, often to the point where it occludes. 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 the formation of a fistula or graft at a later date. Patients on longterm 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 patients with end-stage renal failure, who are either waiting for alternative access to mature, or those who are unable to have alternative access.
Catheter access is often popular with patients, as attachment to the dialysis machine doesn't require needles. However the serious risks of catheter access noted above mean that such access should only be contemplated as a long term solution in the most desperate access situation.
B. AV fistula
AV (arteriovenous) cimino fistulas are recognized as the preferred access method. To create a fistula, a vascular surgeon joins an artery and a vein together through anastomosis. Since this bypasses the capillaries, blood flows at a very high rate through the fistula. One can feel this by placing one's finger over a mature fistula. This is called feeling for "thrill", and feels like a distinct 'buzzing' feeling over the fistula. Fistulas are usually created in the non-dominant arm, and may be situated on the hand (the 'snuffbox' fistula'), the forearm (usually a radiocephalic 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 4-6 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, as there is no foreign material involved in their formation, higher blood flow rates (which translates to more effective dialysis), and a lower incidence of thrombosis. The complications are few, but if a fistula has a very high flow in it, and the vasculature that supplies the rest of the limb is poor, then a steal syndrome can occur, where blood entering the limb is drawn into the fistula and returned to the general circulation without entering the capillaries of the limb. 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 a bulging in the wall of the vein, or aneurysm, where the vessel wall is weakend by the repeated insertion of needles over time. To a large extent the risk of developing an aneurysm can be reduced by careful needling technique. Aneurysms may necessitate corrective surgery and may shorten the useful life of a fistula.
C. AV graft
AV (arteriovenous) grafts are much like fistulas in most respects, except that an artificial vessel is used to join the artery and vein, made of a synthetic material, often PTFE (Gore-Tex). Grafts are used when the patient's native vasculature does not permit a fistula. They mature faster than fistulas, and may be ready to use days after formation. However, they are at high risk for developing narrowing where the graft is sewn to the vein. As a result of the narrowing, clotting or thrombosis often occurs. As foreign material, they are at greater risk for becoming infected. The options for sites to place a graft are larger, due to the fact that the graft can be fashioned quite long. Thus they can be placed in the thigh or even the neck (the 'necklace graft').
D. Fistula First project
Because of the greatly increased survival rates with AV fistulas as opposed to venous catheters (survival with AV grafts is somewhere in between), The Centers for Medicare & Medicaid (CMS) has set up a Fistula First Initiative, the object of which is to increase the utilization of AV fistulas in dialysis patients.
Equipment

Schematic of a hemodialysis circuit
The hemodialysis machine performs the function of pumping 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, blood pressure, heart rate, conductivity, pH, etc. If any reading is out of normal range, an audible alarm will sound to alert the patient-care technician who is monitoring the patient. Manufacturers of dialysis machines include companies such as Fresenius, Gambro, Baxter, B. Braun, and Bellco.
A. Water system
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 are not able to perform their intended function of removing impurities, ions that are introduced into the blood stream via water can build up to hazardous levels, causing numerous symptoms including death. Aluminum, chloramine, fluoride, copper, and zinc, as well as bacterial fragments and endotoxins, have all cause problems in this regard.
For this reason, water used in hemodialysis carefully purified prior to use. Initially it is filtered and temperature-adjusted, and its pH is corrected by addition of 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 left over electrolytes is done by running the water through a tanks with ion-exchange resins, that basically take up any left over anions or cations and replace them with hydroxyl and hydrogen molecules, respectively, leaving ultrapure water.
Ultrapure dialysate
Even this degree of water purification may not be enough. The trend lately is to pass this final purified water (after mixing with dialysate concentrate) through a dialyzer membrane, to have another layer of protection in terms of removing impurities, especially those of bacterial origin that may have accumulated in the water after its passage through the original water purification system.
On-line monitoring of dialysis solution during dialysis Once purified water is mixed with dialysate concentrate, its conductivity increases, since water tha contains charged ions conducts electricity. During dialysis, the conductivity of dialysis solution is continuously monitored, to make sure 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.
B. Dialyzer
Basic construction: 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, the walls of which are composed of semi-permeable membrane, is anchored at each end into potting compound (a sort of glue), and then this assembly is put into a clear plastic cylindrical shell with 4 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 in order to move fluid from the blood to the dialysate compartment.
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, for example, beta-2-microglobulin are not removed at all with low-flux dialyzers, and the trend has been to use high-flux dialyzers lately. However, then newer dialysis machines and high-quality dialysis solution needs to be used, 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 lintels). The surface of such membranes was not very biocompatible, because exposed hydroxyl groups would activate complement in the blood passing by the membrane. Modifications of the basic, "unsubstituted" cellulose membrane were then developed. One was to cover these hydroxyl groups with acetate groups (cellulose acetate); another was to mixing 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, made of polymers such as polyarylethersulfone, polyamide, polyvinylpyrrolidone, polycarbonate, or 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 of them tend to be high-flux.
Nanotechnology is being used in some of the most recent high-flux membranes in order to have 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 to not pass albumin (MW ~66,400 daltons). Whenever a membrane is made, there is a size distribution range of the pores, and as larger pore sizes are approached, 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 believes that some albumin removal may be beneficial in terms of removing protein-bound uremic toxins.
Membrane flux and outcome: Whether use of a high-flux dialyzer results in better patient outcomes is somewhat controversial, but several important studies have suggested that there are clinical benefits to doing so. The NIH funded HEMO trial compard survival and hospitalizations in a randomized trial in patients being dialyzed with low-flux vs. high-flux membranes. Although the primary outcome was not quite statistically significant, several secondary outcomes did suggest a benefit. A recent Cochrane analysis concluded that benefit of membrane choice on outcomes has not yet been demonstrated.
Membrane flux and beta-2-microglobulin amyloidosis: Another area where use of high-flux dialysis membranes, and/or use of intermittent on-line hemodiafiltration (IHDF) may be of benefit has to do with complications of beta-2-microglobulin accumulation. Beta-2-microglobulin is a large molecule, with a molecular weight of about 11,600 daltons. This large molecule 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 have passed (usually at least 5-7), patients on hemodialysis begin to develop complications from the accumulation of beta-2-M, including carpal tunnel syndrome, bone cysts, and accumulation of this amyloid in joints and other tissues. Beta-2-M amyloidosis can cause very serious complications, including a spondylarthropathy, and often is associated with shoulder joint problems. Observational studies from Europe and Japan have suggested a lower incidence of beta-2-M complications when high-flux membranes are used in dialysis mode, or when IHDF is used, as opposed to regular dialysis using a low-flux membrane.
Dialyzer size and efficiency: Dialyzers come in many different sizes. A larger dialyzer with an increased 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 of K0A ranging from about 500 to 1500 ml/min. K0A, expressed in ml/min can be thought of the maximum clearance of a dialyzer at very high blood and dialysate flow rates.
Reuse of dialyzers: The dialyzer may either be discarded after each treatment or reused. If it is reused, there is an extensive procedure of high-level disinfection. Dialyzers are not shared between patients in the practice of reuse. There was initially controversy about whether reuse of dialyzers resulted in worse patient outcomes. The consensus today is, that dialyzer reuse, done carefully and properly, is associated with similar outcomes to single-use of dialyzers.




Question For Hemodialysis

>> What is hemodialysis?
Hemodialysis is a procedure in which a machine filters harmful waste and excess salt and fluid from your blood. A needle is inserted into your arm through a special access point. Your blood is then directed through the needle to a machine called a dialyzer, which filters your blood a few ounces at a time. The filtered blood returns to your body through another needle.
>> Who needs hemodialysis?
If your kidneys are failing, you may need dialysis to help control your blood pressure and maintain the proper balance of fluid and various chemicals — such as potassium and sodium — in your body. Dialysis also helps your body maintain the proper acid-base balance.
Sometimes kidney failure is caused by a specific kidney disease. In other cases, it's a complication of another condition, such as:
 Diabetes
 High blood pressure (hypertension)
 Kidney inflammation (glomerulonephritis)
 Inflammation of blood vessels (vasculitis)
 Polycystic kidney disease
>> How do you prepare for hemodialysis?
Before you start hemodialysis, a surgeon creates a vascular access point for blood to leave for cleansing and then re-enter your body during treatment. There are three types of access points:
 Temporary access. If you need emergency hemodialysis, the surgeon may insert a plastic tube (catheter) into a large vein in your neck or near your groin. The catheter is temporary. If it's left in place for too long, you face a risk of infection, clotting in the catheter and stenosis (narrowing) of surrounding blood vessels.
 Arteriovenous (AV) fistula. A surgically created AV fistula is a connection between an artery and a vein, usually in the forearm. Once the connection is made, faster flowing arterial blood flows into the vein -causing it to grow larger and stronger. This makes repeated needle placements for hemodialysis easier. An AV fistula may take six weeks or longer to heal, but it can last for many years. An AV fistula is less likely than other types of access points to form clots or become infected.
 Arteriovenous (AV) graft. If your blood vessels are too small to form an AV fistula, the surgeon may instead connect an artery and a vein with a synthetic tube. This tube functions like an artificial vein, usually in your forearm or upper arm. An AV graft often heals within two to three weeks. With proper care, an AV graft may last several years — but it's more likely to form clots and become infected than is an AV fistula.
Ideally, the access point is created weeks or even months before you need hemodialysis.
>> How do you care for the access point?
Vascular access is a vital part of hemodialysis. Take special care to prevent injury and infection:
 Keep the access area clean.
 Don't use the arm with the access point for blood pressure readings or to draw blood samples not associated with the dialysis treatment.
 Don't lift heavy objects or put pressure on the arm with the access point.
 Don't cover the access point with tight clothing or jewelry.
 Check the pulse in the access point every day.
 Ask the nurse or technician to check the access point before each treatment.
 Don't sleep with the access arm under your head or body.
If your access point stops working, the surgeon can create a new access point in your other forearm, your upper arm or your groin. Or you may consider peritoneal dialysis, another type of dialysis done through a catheter inserted in your abdomen.
>> How often is treatment needed?
Most people receive hemodialysis three times a week, about three to five hours at each session. This type of hemodialysis, known as conventional hemodialysis, is usually done in a dialysis center. During each session you can read, watch TV, or do crossword puzzles or other sedentary activities.
At some dialysis centers, you can choose shorter but more frequent treatments. This is known as daily dialysis. It's usually done six days a week for about two to two and a half hours. Although conventional hemodialysis is more common, people who choose daily hemodialysis often report greater improvements in blood pressure and quality of life.
>> Can hemodialysis be done at home?
With special training and someone to help you, it's possible to do hemodialysis at home. If you're comfortable doing the procedure yourself and keeping records for your health care team, the benefits are appealing. Your quality of life will likely improve, you'll save yourself travel time to and from the dialysis center, and you'll have more flexibility about when to do your treatments — perhaps even at night while you sleep.
>> Is there a special diet for people on hemodialysis?
Eating the right foods can improve your dialysis results and your overall health. While you're receiving hemodialysis, you'll need to carefully monitor your intake of fluids, protein, sodium, potassium and phosphorus. Your dietitian will help you develop an individualized meal plan based on:
 Your weight
 Your personal preferences
 How well your kidneys still function
 Other medical conditions you might have, such as diabetes or high blood pressure
>> What about medication?
While you're receiving hemodialysis, you'll likely need various medications:
 Blood thinners to prevent clots in the hemodialysis machine and tubing
 Blood pressure medication to control your blood pressure
 Erythropoietin to stimulate your bone marrow to produce new red blood cells
 Calcium, iron and other nutritional supplements to control the level of certain nutrients in your blood
 Phosphate binders to prevent the buildup of phosphorus in your blood
 Stool softeners and laxatives to manage constipation
Your doctor will do frequent blood tests to monitor your condition.


>> What are the potential complications of hemodialysis?
Your kidneys play a role in many of your body's systems. When your kidneys stop working, these other systems don't work as well as they did before. This can lead to various complications, including:
 Lack of red blood cells (anemia)
 Bone diseases
 High blood pressure
 Fluid overload
 Inflammation of the membrane surrounding the heart (pericarditis)
 High potassium levels, which can affect your heart rhythm
 Nerve damage
 Infection
 Heart disease
Dialysis of any type is a serious responsibility. Whether you choose to have hemodialysis at home or in a dialysis center — or you opt for peritoneal dialysis — your health is in your hands. Weigh the pros and cons of each treatment option with your health care team to help decide what's best for you.

>>>> Peritoneal dialysis

In medicine, peritoneal dialysis is a method for removing waste such as urea and potassium from the blood, as well as excess fluid, when the kidneys are incapable of this (i.e. in renal failure). It is a form of renal dialysis, and is thus a renal replacement therapy.
Peritoneal dialysis works on the principle that the peritoneal membrane that surrounds the intestine, can act as a natural semipermeable membrane (see dialysis), and that if a specially formulated dialysis fluid is instilled around the membrane then dialysis can occur, by diffusion. Excess fluid can also be removed by osmosis, by altering the concentration of glucose in the fluid.
Dialysis fluid is instilled via a peritoneal dialysis catheter, (the most common type is called a Tenckhoff Catheter) which is placed in the patient's abdomen, running from the peritoneum out to the surface, near the navel. Peritoneal dialysis catheters may also be tunnelled under the skin and exit alternate locations such as near the rib margin or sternum (called a presternal catheter), or even up near the clavicle. This is done as a short surgery. The exit site is chosen based on surgeon's or patient's preference and can be influenced by anatomy or hygiene issues.
Peritoneal dialysis is typically done in the patient's home and workplace, but can be done almost anywhere; a clean area to work, a way to elevate the bag of dialysis fluid and a method of warming the fluid are all that is needed. The main consideration is the potential for infection. Peritonitis is the most common serious complication. Infections of the catheter's exit site or "tunnel" (path from the peritoneum to the exit site) are less serious but more frequent. Because of this, patients are advised to take a number of precautions against infection.
>> Types of peritoneal dialysis
There are three types of peritoneal dialysis.
• Continuous ambulatory peritoneal dialysis (CAPD), the most common type, needs no machine and can be done at home. Exchanges of fluid are done throughout the day, usually four exchanges a day.
• Continuous cyclic peritoneal dialysis (CCPD) uses a machine and is usually performed at night when the person is sleeping.
• Intermittent peritoneal dialysis (IPD) uses the same type of machine as CCPD - if done overnight is called Nocturnal intermittent peritoneal dialysis (NIPD).
>> Advantages and disadvantages of peritoneal dialysis
Advantages
• Can be done at home.
• Relatively easy to learn.
• Easy to travel with, bags of solution are easy to take on holiday.
• Fluid balance is usually easier than on hemodialysis
• Theoretically better to start dialysis on, as native urine output is maintained for longer than on hemodialysis.
• PD is method of the first choice in treating chronical kidney failure
• It is proven, that patients on PD has 50% longer life during observation period of 5 yrs, than on hemodialysis.
Disadvantages
• Requires a degree of motivation and attention to cleanliness whilst performing exchanges.
• Possible complications.
>> Side-effects and complications
Peritoneal dialysis requires access to the peritoneum. As this access breaks normal skin barriers, and as people with renal failure generally have a slightly suppressed immune system, infection is a relatively common problem. The infections can be localised, as in an exit-site or tunnel infection, where the infection is limited to the skin or soft tissue around the catheter, or potentially more severe, if the infection reaches the peritoneum, in which case it is termed PD peritonitis; which may require antibiotics and supportive care, or, if the peritonitis is severe, removal of the catheter and a change of renal replacement therapy modality to hemodialysis. Occasionally, severe peritonitis may be life-threatening. Long term peritoneal dialysis can cause changes in the peritoneal membrane, making it less permeable and causing it to no longer act as a dialysis membrane as well as it used to. This loss of function can manifest as a loss of dialysis adequacy, or poorer fluid exchange (also known as ultrafiltration failure)
Other complications that can occur are fluid leaks into surrounding soft tissue, often the scrotum in males. Hernias are another problem that can occur due to the abdominal fluid load.These often require repair before peritoneal dialysis is recommenced.
>> Step-by-step description of peritoneal dialysis (a CAPD exchange)
1. The supplies and materials needed for an exchange are gathered in one clean location. Notable amongst these is a bag of dialysis fluid (also called dialysis solution), a solution comprised of a known amount of a glucose dissolved in water. The strength of this solution determines the osmotic gradient, and therefore the amount of water that diffuses out of the bloodstream. Common strengths of glucose are 0.5%, 1.5%, 2.5% and 4.25%. 1.5% is approximately fluid-neutral; it neither adds nor removes fluid and is used for patients who are primarily concerned with waste removal rather than fluid regulation. Higher concentrations lead to greater water removal. A higher dextrose concentration moves fluid and more wastes into the abdominal cavity, increasing both early and long-dwell exchange efficiency. Eventually, however, the body absorbs dextrose from the solution. As the concentration of dextrose in the body comes closer to that in the solution, dialysis becomes less effective, and fluid is slowly absorbed from the abdominal cavity. Electrolytes are also present in the fluid to maintain proper body levels. Patients weigh themselves, and measure temperature and blood pressure daily to determine whether the body is retaining fluid and, thus, what strength of fluid to use. Dialysis fluid typically comes premixed in a disposable bag-and-tube apparatus; no additional equipment is needed. The apparatus consists of two bags, one empty and one with the fluid, connected via flexible tubing to a Y-shaped fitting. The bag is heated to body temperature, to avoid causing cramping. Dry heat is used; common methods include microwaves, heating pads and solar radiation (often using the dashboard of a car, for instance while travelling).
2. The patient, who performs the entire procedure themselves, dons a disposable surgical mask, scrubs their hands using antibacterial soap, and tucks a clean towel into the waistband of their pants to protect their clothing. The bag of dialysis fluid is removed from the protective packaging, and is hung from an IV stand or other elevated location, such as a coat hook. The tubing attached to the bag of fluid is uncoiled, and the second (empty) bag is placed on the floor. The Y-shaped connector is attached to the catheter tip; a protective cap must be removed from both of these before the connection is made, and the two portions of the connector are not permitted to touch anything, to avoid possible contamination.
3. Once connected to the system, the patient clamps the tubing connected to the full bag of dialysis fluid and then releases the twist valve located in the tip of their catheter; this permits fluid to flow into or out of the peritoneal cavity. Because the full bag of fluid is clamped off but the empty bag is not, the effluent (used dialysis fluid) from within the peritoneum can drain out of the catheter and into the lower, waste bag. Emptying the abdomen of fluid takes approximately fifteen minutes, and the patient is free to perform tasks such as reading, watching television and browsing the internet.
4. When the abdomen has drained, the lower drain-bag is clamped off. The twist valve in the catheter is also closed. The clamp is then removed from the upper tubing, permitting dialysis fluid to drain out into the abdomen. The clamp to the drain bag is briefly opened and some fluid is drained directly from the upper bag into the lower bag. This clears the line of air and other impurities. The drain line is then clamped off and the twist valve on the catheter end is opened. This permits fluid to enter the peritoneum. Filling the abdomen with fresh fluid takes about fifteen minutes, and the patient enjoys the same freedoms as while draining.
5. Once the entire bag of fluid (an amount varying primarily based on body size, ranging from 1500 to 3000 mL) has been introduced to the abdomen, the patient then cleans their hands again (typically using an antiseptic alcohol-based cleanser) and puts the surgical mask on. The Y-connector is detached from the catheter tip and a protective cap is placed on the end of the catheter.


6. The effluent is inspected after a dialysis exchange is complete; a cloudy effluent indicates probable peritoneal infection. The effluent is drained into a toilet, and the various dialysis supplies are discarded with normal garbage.

>>>> Hemofiltration
Hemofiltration is a similar treatment to hemodialysis, but it makes use of a different principle. The blood is pumped through a dialyzer or "hemofilter" as in dialysis, but no dialysate is used. A pressure gradient is applied; as a result, water moves across the very permeable membrane rapidly, facilitating the transport of dissolved substances, importantly ones with large molecular weights, which are cleared less well by hemodialysis. Salts and water lost from the blood during this process are replaced with a "substitution fluid" that is infused into the extracorporeal circuit during the treatment. Hemodiafiltration is a term used to describe several methods of combining hemodialysis and hemofiltration in one process.
>> Starting indications
The decision to initiate dialysis or hemofiltration in patients with renal failure can depend on several factors, which can be divided into acute or chronic indications.
• Acute Indications for Dialysis/Hemofiltration:
o 1) Hyperkalemia
o 2) Metabolic Acidosis
o 3) Fluid overload (which usually manifests as pulmonary oedema)
o 4) Uremic pericarditis, a potentially life threatening complication of renal failure
o 5) And in patients without renal failure, acute poisoning with a dialyzable drug, such as lithium, or toxin.
• Chronic Indications for Dialysis:
o 1) Symptomatic renal failure.
o 2) Low glomerular filtration rate (GFR) (RRT often recommended to commence at a GFR of less than 10-15 mls/min/1.73m2)
o 3) Difficulty in medically controlling serum phosphorus or anaemia when the GFR is very low