Hemodialysis (HD). A Life-saving Treatment

Dialysis is a procedure that can remove waste products, other undesired substances, and excessive fluid when kidney function is no longer effective. There are two main forms of dialysis: hemodialysis (HD) and peritoneal dialysis (PD).

HD is a life-saving treatment for patients with end-stage kidney disease (ESKD). It uses an artificial kidney that contains thousands of hollow fibers which provide a tremendous surface area for the dialysis process.

How does HD work

Hemodialysis uses an artificial membrane that can perform many kidney filtering and blood cleansing functions. The membrane is manufactured in the form of hollow fibers through which blood flows from one end to the other and is returned to the patient. Only a small percent of the patient’s total blood volume is in the circuit at any given time.

In the space between the hollow fibers flows a water-like solution called the dialysate. As blood passes through the fibers, waste products move from the blood into the dialysate. While normal kidneys function 24/7 to maintain body composition, HD is a much more aggressive treatment since it is only done over 3-4 hours, usually several times a week.

HD requires blood to flow through the artificial kidney rapidly. To meet this requirement it is usually necessary to have a minor surgical procedure in order to create an arterial-venous fistula or graft, both of which provide a direct connection between an artery and a vein. These are collectively referred to as vascular access. Thus, HD is a circuit through which blood flows continuously through the artificial kidney. The continuous flow of dialysate through the artificial kidney helps to remove waste products and restore normal mineral and fluid balance. The blood is then returned to the patient.

Of possibly substantial importance, an exciting development on the horizon is an implantable dialysis device. This device will essentially do the work of HD but do so continuously in a manner much like the kidney. Laboratory trials look promising, but the device is likely several years away for humans.

What are the common complications of hemodialysis?

Bacterial infections of vascular access require prompt treatment or the access can become unusable. Removal of vascular access may be necessary to prevent the infection from spreading into the blood and other organs.

In addition to infections, vascular access injuries or scarring may result in insufficient blood flow into the dialysis circuit, severely limiting dialysis efficiency.

The need for removal of a large volume of fluid from the patient in one session can cause low blood pressure (hypotension), leading to weakness, dizziness, nausea, and headache. Those with chronic heart disease are particularly at risk.

Rapid changes of mineral balance in the body (especially sodium) can result in confusion and seizures.

Other problems include side effects of the medications used during dialysis, bleeding from the access, muscle cramps, malnutrition, diabetes, and maintaining medication levels.

Creating and maintaining functional vascular access in diabetics may be challenging because of diabetes-associated underlying damage to blood vessels.

Living with hemodialysis

With ESKD, you and your family are often faced with significant adjustments to schedules, transportation, and home support.

• You will receive ESKD nutritional guidance (a special diet) that is similar to your diet in mid to late Stage IV chronic kidney disease. With dialysis, compliance with these dietary guidelines becomes essential, helping to maintain health while reducing the intensity or amount of HD required.
• You also may need to periodically receive injectable medications.
• The frequency and time required for HD can be burdensome for individuals who cannot easily get to the dialysis center or must travel long distances. For those who work, arrangements for the time away may become necessary.
• Daily or nightly home HD also can provide effective treatment of ESKD. This is another option for certain patients. For home HD, both the patient and a partner receive considerable dialysis training to conduct dialysis safely and successfully. Advantages of home HD include better control of blood pressure, improved neurological function, fewer required medications, diminished need for aggressive fluid and mineral corrections, and a better overall quality of life. The availability of this form of treatment has expanded considerably.
• An exciting development on the horizon is an implantable dialysis device that can do the work of HD, but continuously in a manner much like the kidney. Laboratory trials look promising but the device is most likely several years away for humans.