Dialysis

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Dialysis:

Dialysis is a method of removingtoxic substances (impurities or wastes) from the blood when the kidneys areunable to do so. Dialysis is most frequently used for patients who have kidney failure, but may also be used toquickly remove drugs or poisons in acute situations. This technique can be lifesaving in people with acute or chronic kidney failure.

Methodsof dialysis:

Dialysis can be performed usingseveral different methods.

PERITONEAL DIALYSIS:

Peritoneal dialysis works byusing the body's peritoneal membrane, which is inside the abdomen, as asemi-permeable membrane. Special solutions that help remove toxins are infusedin, remain in the abdomen for a time, and then are drained out. This form ofdialysis can be performed at home, but must be done every day.

HEMODIALYSIS:

Hemodialysis works by circulatingthe blood through special filters outside the body. The blood flows across asemi-permeable membrane (the dialyzer or filter), along with solutions thathelp remove toxins.

Hemodialysis requires a bloodflow of 400-500 milliliters per minute (ml/min). A normal IV tube in an arm orleg will not support that volume of blood flow, so dialysis uses specialways of accessing the blood in the blood vessels.

The access can be temporary orpermanent. Temporary access takes the form of dialysis catheters. These arelarge-size catheters (hollow medical tubing) placed in large veins thatcan support acceptable blood flows. Most catheters are used in emergencysituations, for short periods of time. However, catheters called tunneled catheterscan be used for prolonged periods of time, often weeks to months.

Permanent access is created bysurgically joining an artery to a vein. This allows the vein to receive bloodat high pressure, leading to thickening of the vein's wall. Now this "arterializedvein" can sustain repeated puncture and also provides excellent blood flowrates. The connection between an artery and a vein can be made using bloodvessels (an arteriovenous fistula, or AVF) or a synthetic bridge (arteriovenousgraft, or AVG).

The AVF is more desirable,because rates of infection are very low and it is quite durable. It may takemany months for the AVF to mature, so careful planning is required.

The AVG can be accessed a fewweeks after creation. It provides good flows but has a high complication rate.It should be attempted only if the AVF is not feasible.

Blood is diverted from the accesspoint in the patient's body to a dialysis machine. Here, the blood flowscounter-current to a special solution called the dialysate. The chemicalimbalances and impurities of the blood are corrected and the blood is thenreturned to the body. Typically, most patients undergo hemodialysis for threesessions every week. Each session lasts 3-4 hours

How to Prepare for theTest?

It is important to adhere to thediet and medicines prescribed by the dialysis staff and your nephrologist.

Just before your health careprovider begins the hemodialysis procedure, the following assessments will bemade:

* Blood pressure
* Temperature
* Heart rate
* Breathing rate
* Weight
* Chest assessment
* Examination of venous access

Why the Test is Performed?

This procedure removescontaminants from the blood that could, and eventually would, result in deathif the kidney is not functioning.

The kidneys function as filters forthe blood, removing products of amino acid breakdown. More than that, theyserve to reclaim and regulate body water, maintain electrolytebalance, and ensure that the blood pH remains between 7.35 and 7.45. Withoutthe function of the kidney, life is not possible.

Dialysis serves to replace someof the functions of the kidney. Since dialysis is not a constant ongoingprocess, it cannot serve as a constant monitor as do normal functioningkidneys, but it can eliminate waste products and restore electrolyte and pHlevels on an as-needed basis.