During hemo-dialysis about 500 ml (range 50-800 ml) of dialysate flows through the dialyer (The plastic casing that contains dialysis membrane and which partitions blood on one side and dialysate on the other).
Water treatment is an essential requisite for safe dialysis.
In a 4 to 5 hrs session about 120 to 150 liters of water thus comes into contact with blood.
A very small impurity in this water thus can get magnified and produce serious consequences in the renal failure patient.
If dialysis water is unfit, it results in recurrent fever, poor health and nutrition of patient, electrolyte abnormalities etc. High aluminium levels can produce brain disorder called dementia and aluminium related bone disease. High chlorine levels can cause severe reactions.
Water treatment is done for ensuring safe dialysis water.
If ground or municipal supply provides hard water it is softened by machine.
Particulate matter is removed by filters consisting of pebbles, sand and other materials first so that large particles are removed, small particles than are removed by microfilters which can remove 5-micron size particles.
Chlorine is removed by adsorption on to carbon particles. It should be present in water before it is treated but removed during water treatment.
Excessive salts are measured as TDS (total dissolved solids) expressed as parts per million or ppm in short.Both cations and anions measured and TDS is equal to about 100 X total ions expressed as milliequivalents. It is usually 0.5 to 1 times the conductivity value.
Bacteria and their products produce harmful substances. These need to be removed and water prevented from letting them grow again by regular maintenance of the pipes and drainage system.
To produce water of sufficiently good quality, various criteria have been laid by different countries. AAMI dialysis criteria is one such criteria. In these acceptable levels of various chemicals and other impurities are mentioned.
Good quality dialysis water reduces morbidity, mortality, and complications in dialysis. It results in better overall health and quality of life for the patient.