PRINCIPLEDialysis works on the principles of thediffusionof solutes andultrafiltrationof fluid across a semi-permeable membrane. Diffusion is a property of substances in water; substances in water tend to move from an area of high concentration to an area of low concentration. Blood flows by one side of a semi-permeable membrane, and a dialysate, or special dialysis fluid, flows by the opposite side. A semipermeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys, when the blood enters the kidneys and the larger substances are separated from the smaller ones in theglomerulus. Thekidneyshave important roles in maintaining health. When healthy, the kidneys maintain the body's internal equilibrium of water and minerals (sodium, in medicine,dialysisis a process for removing waste and excess water from theblood, and is used primarily potassium, chloride, calcium, phosphorus, magnesium, sulfate). The acidicmetabolismend-products that the body cannot get rid of via respiration are also excreted through the kidneys. The kidneys also function as a part of theendocrine system, producingerythropoietin and calcitriol. Erythropoietin is involved in the production of red blood cells and calcitriol plays a role in bone formation. Dialysis is an imperfect treatment to replace kidney function because it does not correct the compromised endocrine functions of the kidney. Dialysis treatments replace some of these functions throughdiffusion(waste removal) andultrafiltration(fluid removal). Blood is diverted from an artery, usually on in wrist into the dialyzer, where it flows either by its own impetus or with aid of mechanical pump along one surface of membrane. Finally blood passes through the trap that removes clots and bubbles and return to the vein in the patients forearms. In patients with chronic kidney failure who require frequent dialysis, repeated surgical access to the blood vessels in treatment is obviated by provision of an external plastic shunt between them. In medicine, is a process for removing waste and excess water from theblood, and is used primarilyas anartificial replacement for lostkidney functionin people withrenal failure. THE TWO MAIN TYPES OF DIALYSIS- HEMODIALYSIS PERITONEAL DIALYSIS

Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called adialyzer, that contains asemipermeable membrane. The blood flows in one direction and thedialysateflows in the opposite. The counter-current flow of thebloodand dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea andcreatininefrom the blood. The concentrations of solutes (for examplepotassium,phosphorus, and urea) are undesirably 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 likepotassiumandcalciumthat 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 ofbicarbonateinto the blood, to act as a pH buffer to neutralize themetabolic acidosisthat is often present in these patients. The levels of the components of dialysate are typically prescribed by anephrologistaccording to the needs of the individual patient.Inperitoneal dialysis, wastes and water are removed from the blood inside the body using theperitoneal membraneof theperitoneumas a natural semipermeable membrane. Wastes and excess water move from the blood, across the peritoneal membrane, and into a special dialysis solution, called dialysate, in theabdominal cavitywhich has a composition similar to the fluid portion of blood.

HEMODIALYSIS In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing it to a partially permeable membrane. The dialyzer is composed of thousands of tiny synthetic hollow fibers. The fiber wall acts as the semipermeable membrane. Blood flows through the fibers, dialysis solution flows around the outside of the fibers, and water and wastes move between these two solutions. 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 the removal of several litres of excess fluid during a typical 4-hour treatment. In the US, hemodialysis treatments are typically given in a dialysis center three times per week (due in the US to Medicare reimbursement rules); however, as of 2007 over 2,500 people in the US are dialyzing at home more frequently for various treatment lengths. Studies have demonstrated the clinical benefits of dialyzing 5 to 7 times a week, for 6 to 8 hours. This type of hemodialysis is usually called "nocturnal daily hemodialysis", which a study has shown a significant improvement in both small and large molecular weight clearance and decrease the requirement of taking phosphate binders. These frequent long treatments are often done at home while sleeping, but home dialysis is a flexible modality and schedules can be changed day to day, week to week. In general, studies have shown that both increased treatment length and frequency are clinically beneficial.

PERITONEAL DIALYSIS

In peritoneal dialysis, a sterile solution containing glucose (called dialysate) is run through a tube into theperitoneal cavity, theabdominalbody cavity around theintestine, where the peritoneal membrane acts as a partially permeable membrane. The peritoneal membrane or peritoneum is a layer of tissue containing blood vessels that lines and surrounds the peritoneal, or abdominal, cavity and the internal abdominal organs (stomach, spleen, liver, and intestines). Diffusion and osmosis drive waste products and excess fluid through the peritoneum into the dialysate until the dialysate approaches equilibrium with the body's fluids. Then the dialysate is drained, discarded, and replaced with fresh dialysate. This exchange is repeated 4-5 times per day; automatic systems can run more frequent exchange cycles overnight. 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, often without help. This frees patients from the routine of having to go to a dialysis clinic on a fixed schedule multiple times per week. Peritoneal dialysis can be performed with little to no specialized equipment (other than bags of fresh dialysate).

STARTING INDICATIONSThe decision to initiate dialysis or hemofiltration in patients withrenal failuredepends on several factors. These can be divided into acute or chronic indications.Acute indications for dialysis:Indications for dialysis in the patient withacute kidney injuryare summarized with the vowel acronym of "AEIOU".Acidemiafrommetabolic acidosisin situations in which correction with sodium bicarbonate is impractical or may result in fluid overload.Electrolyteabnormality, such as severehyperkalemia, especially when combined with AKI.Intoxication, that is, acute poisoning with a dialyzable substance. These substances can be represented by the mnemonic SLIME:salicylic acid,lithium,isopropanol, Magnesium-containing laxatives, andethylene glycol.Overloadof fluid not expected to respond to treatment with diuretics.Uremiacomplications, such aspericarditis,encephalopathy, orgastrointestinal bleeding.Chronic indications for dialysis:Symptomatic renal failureLowglomerular filtration rate(GFR) (RRToften recommended to commence at a GFR of less than 10-15 mls/min/1.73m2). In diabetics, dialysis is started earlier.Difficulty in medically controlling fluid overload, serum potassium, and/or serum phosphorus when the GFR is very low COST AND EXPENDITURE

PERITONEAL DIALYSIS-

This involves the cost of the PD bags of fluid. The fluid is available in different concentrations. The rate of the fluid does not depend on the concentration. The rate depends only on the volume. Most people on CAPD use the 2 liter bags while those on CCPD use 5 liter bags.

CAPDThere are different companies offering PD treatmentin India like Baxter, Gambro etc.Cost of one 2 liter bag: Rs. 170

Total cost of bags assuming 4 exchangesper day, 7 days a week: Rs. 21,000

CCPDCost of one 5 liter bag: Rs. 416Total cost of bags assuming 2 bags used per night, 7 nights a week: Rs. 25,000Cost of renting homeChoice machine: Rs. 10,000 per month.

HEMODIALYSIS-Cost of dialysis with new kit: Rs. 2,000 to 3,000Cost of dialysis with reuse: Rs. 1,250 to Rs. 2,300Assuming one does thrice a week session and uses a new kit every 2 weeks:

Total minimum cost: Rs. 17,000

INTRODUCTIONDialysis in chemistry, separation of suspended colloidal particles from dissolved ions or molecules of small dimension by means of their unequal rates of diffusion through pores of semi-permeable membrane. Dialysis also called hemodialysis, renal dialysis or kidney dialysis in medicine, the process of removing blood from patients whose kidney functioning is faulty, purifying that blood by dialysis and returning it to the patients bloodstream. The artificial kidney or hemodialysis is a machine that provides a means for removing certain undesirable substances from blood or adding needed components to it. Another function of natural kidney, secretion of hormones that influences blood pressure cannot be duplicated. Modern dialyzers rely on physiochemical principles Dialysis and ultra filtration.In dialysis two liquids separated by a porous membrane exchange those components that exist as particles small enough to diffuse through pores. When blood is brought into contact with one side of such membrane dissolve substances pass through into a sterile solution placed on other side of membrane .To prevent or limit the loss of diffusible substances required by the body, such as sugars, amino acids and necessary amount of salts. Those compounds are added to the sterile solution; thus their diffusion from blood is offset by equal movement in opposite direction. The lack of diffusible material in blood can be corrected by incorporating them in the solution from which they enter the circulation.Although, water passes easily through the membrane, it is not removed by dialysis because its concentration in blood is lower than in solution. Indeed, water tends to pass from solution into blood. The dilution of blood that would result from this process is presented by ultra filtration by which some of the water , along with some dissolved material is forced through the membrane by maintain the blood at higher pressure than solution.

HISTORY

The process of Dialysis was first employed in 1861 by British chemist Thomas Graham.Dialysis which was first used to treat human patients in 1945 replaces or supplements the action of kidney in a person suffering from acute or chronic renal failure or from poisoning by diffusible substances, such as Aspirin, Bromides or Barbiturates. Dr.Willem Kolff, a Dutch physician, constructed the first working dialyzer in 1943 during theNazi occupation of the Netherlands.Due to the scarcity of available resources, Kolff had to improvise and build the initial machine usingsausage casings,beverage cans, awashing machine, and various other items that were available at the time. Over the following two years,[1943-1945] Kolff used his machine to treat 16 patients suffering fromacute kidney failure, but the results were unsuccessful. Then, in 1945, a 67-year-old comatose woman regained consciousness following 11 hours of hemodialysis with the dialyzer, and lived for another seven years before dying from an unrelated condition. She was the first-ever patient successfully treated with dialysis.The membrane first used in dialysis were obtained from animals or prepared from collodion, cellophane has been found to be more suitable and tubes or sheet of it are used in many dialyzers. In late 1960s hollow filaments of cellulosic or synthetic materials were introduced for dialysis; bundles of such filaments provide a large membrane surface in a small volume, a combination advantageous in devising compact dialyzers. DIET FOLLOWED DURING DIALYSIS

The hemodialysis diet is tailored to patients who are instage 5 of chronic kidney disease (CKD), also known asend stage renal disease (ESRD). These patients have very little or nokidney functionand must undergo dialysisto clean their blood of waste and excess fluids.Hemodialysis is one type of dialysis. The procedure is done several times a week, usually for 3 to 4 hours at a time. The hemodialysis diet is designed to reduce the amount of fluid and waste that builds up between hemodialysis treatments so that you can feel your best.

In addition to enjoying a variety of nutritious foods, the hemodialysis diet will introduce a higher amount ofproteininto your eating plan. The exact amount will be determined by yourdietitian. You will be encouraged to get proteinfrom high quality sources such as lean, meat, poultry, fish and egg whites. These high protein foodsprovide all the essential amino acids your body needsThe hemodialysis diet will restrict foods that contain high amounts ofsodium,phosphorus andpotassium. Your dietitian will provide you with a diet guide and food lists that indicate which foods are allowed and which ones you should avoid or limit. You will also limit your fluid intake.

Potassiumbuilds up in the blood between dialysis treatments. The amount of potassiumthat accumulatesis determined by the amounts and types of foods eaten, as well as how much kidney function remains. Too much potassium is very dangerous. It can cause muscle weakness and make your heart stop beating. Potassium is easily removed by dialysis. Certain fruits, vegetables, dairy products and other foods that are very high in potassium will need to be restricted on your hemodialysis diet.

Phosphorusis difficult for hemodialysis to filter from the blood. This mineral can build to high levels in the bloodstream and cause complications to your health, such asweak bones,heart problems, joint pain, or skin ulcers. By limiting foods that contain phosphorus, you lessen the risk of developing other health problems. Sodiumcauses your body to hold onto more fluid and raises your blood pressure. You may feel uncomfortable and short of breath if you consume too much sodium and fluid. When excessfluid is removed during dialysis, you can get muscle cramps and feel dizzy and weak during or after treatment. Eating less sodium and drinking less fluid can help you feel comfortable before and after your dialysis sessions.

Fluid intake is not limited to what you can drink; fluid is also hidden in some foods you eat. Being aware of the fluid in foodssuch as gelatin, ice, sherbet, watermelon, sauces, gravies and other high liquid foods is important.