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Hemodialysis 101-The Basics

Updated on July 8, 2014
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Dominique earned an MBA at Keller Graduate School of Management and is now creating a new blog site to offer insight into embracing ifel

Hemodialysis Basics

When kidney function drops below 15%, the kidneys are no longer capable of filtering the blood properly in order to remove toxins or excess fluid so it can be excreted as urine. Because of this, toxins build up in the body as well as excess fluid. Through hemodialysis, blood is removed from the body, and filtered through an artificial kidney, or dialyzer. The filtered blood is then returned to the body. During dialysis, about two cups, or a pint, of blood are outside of the body at any given time. An access needs to be created (typically in the arm) in order for dialysis to be performed. With this access, the blood is removed from the body with the use of one needle (the arterial, or red) and returned through a second needle (the venous, or blue). There are three different kinds of accesses that can be created for use during hemodialysis:

  1. Arterio-venous (AV) graft

  2. AV fistula

  3. Catheter

The AV fistula is the most recommended type of access within the dialysis community. However, doctors/nephrologists will make the determination as to which access is best on by patient basis.

At the Dialysis Center

A patient who goes to a clinic or facility for a hemodialysis treatment will check his or her weight upon arrival as well as having blood pressure and temperature checked prior to beginning treatment. Any weight gained between treatments will indicate how much excess fluid needs to be removed during the patient's treatment. A dry weight will be established by the doctors and will be used as a "target weight." After this information has been recorded by a dialysis technician or nurse, the patient is then put on the machine. This simply means he or she is connected to the machine to receive treatment. If the patient has a fistula or a graft, two needles will be stuck into the access. One will take the blood out of the body and into the arterial line, then to the dialyzer, and then returned to the patient through the venous lines. If the person has a catheter (a temporary access) he or she will have two tubes connected to two separate ports that will perform the same functions as the separate needle sites. Once the patient is put on the machine, it is programmed with the information collected earlier and then the treatment begins. No blood actually touches the machine itself; instead it acts as a sort of pump, while also keeping careful track of such things as the patient's blood pressure, dialysis solution temperature, blood flow rate (BFR), and ultrafiltration (the amount of fluid being removed from the pa the patient's blood). The machine mixes the dialysis solution (called dialysate) which then goes through the artificial kidney (dialyzer) and helps pull toxins, excess fluld, and potassium from the blood. The dialysis machine also has a pump mechanism which creates a pumping action on the blood lines, carrying blood away from the body and then back to the body after passing it through the dialyzer. There are also safety features on machine that will alarm if it detects anything dangerous that may be happening such as:

  • An air bubble detector that signals if air gets into the blood lines during treatment

  • if pressure builds up in the blood lines (arterial or venous)

  • if conductivity, which is the concentration of dissolved chemicals in the solution, gets out of range

  • blood leak detector which monitors for blood leaking into the dialysate from the artificial kidney

  • if the dialysate flow drops

  • If the patient's blood pressure drops or elevates during the treatment


Dialysis...It's a Lifestyle--Dialysis Blog


Length of Hemodialysis Treatments

Blood needs to be filtered thru the artificial kidney for several hours, depending on the patient's needs for adequate blood cleansing and removal of excess fluid. In general, treatments are done three times a week for 3-5 hours each treatment. The average treatment lasts four hours, but can vary depending on what the nephrologist determines will offer adequate treatment. This will be determined by blood work values that are drawn on a monthly basis to check clearances (adequacy of the treatment). There are alternative hemodialysis treatments available such as home or nocturnal hemodialysis. Nocturnal dialysis is usually done overnight for eight hours while the patient is sleeping at home or in a center. Home hemodialysis is done more frequently and for shorter treatment times than in-center treatments.

Hemodialysis Factoids

  • In conjunction with hemodialysis treatments, dietary and fluid restrictions must be followed pretty strictly and there are medications that will likely be needed to take the place of other kidney functions like those that regulate blood pressure and one for the prevention of anemia (low blood count) called EPO

  • In-center hemodialysis affords the patient with the benefit of having his or her treatment performed my medical professionals; they will also be there to monitor the patient's progress during the treatment

  • It is an effective life-sustaining treatment for a person with end stage renal disease (ESRD) also called chronic kidney failure (CKF)

  • Patients tend to feel wiped out after hemodialysis treatments

  • The dietary restrictions limit foods that are high in sodium, calcium, phosphorus, and fluid intake is typically limited to one liter (1000cc, or approximately 34ozs.) per day

  • The patient can spend his or her time on the machine sleeping, listening to music, reading, watching TV, chatting with neighboring patients and staff members, or other quiet activities

  • Nocturnal dialysis can give a patient the feeling of "normalcy" since the treatment takes place during non-productive, sleeping hours whether in the clinic or at home

  • Advanced notice and arrangements will have to be made for a patient to travel out of town, but it is a possibility for hemodialysis patients to travel

  • Monthly labs will be drawn to keep track of the patients' clearances, or adequacy of dialysis as well as to check other vital levels related to kidney function (i.e. phosphorus and calcium levels, blood count, potassium levels, parathyroid hormone, etc.)


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