I keep getting asked this question - what is good dialysis? What needs to be done to get good quality, optimal dialysis that enables someone to lead a normal life on dialysis? Why do some people do so well on dialysis and live almost normal lives while others simply cannot cope with the burden and end up sick and lacking enegy?
Good dialysis comes from multiple factors. Some are in the control of the patient while other factors are in the control of the clinical team that comprises of the nephrologist and the dialysis centre staff in the case of hemodialysis and the nephrologist and Clinical Coordinator in the case of Peritoneal Dialysis.
I am describing these factors below.
Factors in control of the patient:
1. Get optimal frequency and duration. Try to get as many dialysis hours per week as your time and money permit. Healthy kidneys work 24 hours a day, seven days a week. Since dialysis is replacing kidney function, we need to get as close to that as possible to lead a healthy, active life. Try to avoid the two day gap between dialysis sessions. Get every other day dialysis (Mon, Wed, Fri, Sun, Tue, Thu, Sat...) if your centre has that option. Otherwise try to get four sessions a week which is even better.
2. Try to get Hemodialfiltration (HDF). Several studies have shown that HDF provides much better outcomes than conventional HD. The clearance in HDF is by means of convection and not diffusion like in HD. Convective clearance is much better than diffusion. Patients also generally report a lower recovery time after a session with HDF than with HD.
3. Try to get an AV Fistula (AVF) as your dialysis access. A good access is very important for good dialysis. If you do not have a good access, blood cannot be drawn and cleaned by the dialyser efficiently. AVFs are known to be the best hemodialysis access among all types. So try to have an AVF as your dialysis access and take good care of it by keeping the area clean, watching out for signs of infection like redness, tenderness and itching. Let your doctor know as soon as you see any such signs. Do not lift heavy things with the hand on which your AVF is. Never allow Blood Pressure cuffs to be tied on the AVF hand. Do not take injections on that hand. No blood samples should be drawn from that hand (unless it is from the dialysis needle inserted for dialysis).
4. Ensure that you don’t need to remove too much fluid during a session. The human body is limited in the amount of fluid that can be removed during a dialysis session. This is due to the constraint of the dialysis system having access only to the blood of the body to remove blood whereas excess fluid is present in not only the blood, but also inside the cells of the body and even the space between the cells. When fluid is removed from the blood, the excess fluid present within and outside the cells rushes into the blood but this refilling can happen at a low rate. Removing fluid at high rates causes a phenomenon called ‘organ stunning’ which harms various organs. Typically anything more than 10 ml/kg of body weight/hour can be harmful for the heart. So if your weight is around 70 kg and you are doing a four hour dialysis session, your UF target should not be more than 2.8 litres. So drink less than that between two sessions.
Factors in control of others:
1. Set the Blood Flow Rate (Qb) and Dialysate Flow Rate (Qd) optimally. These two parameters are perhaps the ones with the most impact on the amount of cleaning of toxins that happens during a dialysis session. Qb, usually mesasured in ml/minute is the rate at which blood is pumped out from the body, passed through the dialyser (artificial kidney) and then pumped back into the body. Qd, also measured in ml/minute is the rate at which dialysate (the solution formed by mixing purified water and the concentrate solutions (called Part A and Part B) in a fixed proportion which flows within the dialyser around the hollow fibres) is passed through the dialyser. You can read more about this here.
Too low Qb and Qd means not enough cleaning is happening. These cannot be set as high as you feel like however. High Qb and Qd are harmful for the access and the heart. So optimal numbers must be set based on the individual characteristics of each patient. However, a Qb of anything lower than 250 ml/min or higher than 400 ml/min needs to be done only due to some strong reasons.
Typically Qd is set to a value near twice of Qb. Some HD machines do not allow every single possible value for Qd and have only a small number of options. Setting the Qd to the closest of two times Qb is usually done.
2. Proper reprocessing, if dialyser is being reused. Several centres use reprocessed dialyzers and reprocessing dialyzers has been established to be a safe and effective way to reduce costs. It must be ensured that proper protocols are followed while reprocessing dialyzers. The main thing to ensure is that the pores in the hollow fibres within the dialyzer are cleared for the next use and the dialyzer has been properly disinfected. Automated reprocessing is generally preferred to manual methods. Automated machines have a test called the Fibre Bundle Volume test which states how effective the dialyzer is likely to be compared to the first use. Centres follow standards of between 70% to 80% of the original efficiency. It is best to discard dialyzers that fall below this threshold.
3. Proper quality of purified water. The quality of water used for dialysis is a very important factor in the quality of dialysis. Centres have a Reverse Osmosis-based water purification plant. This plant usually has various types of filters that remove different kinds of impurities from the raw water that is available in that area. The last stage usually is a special membrane that is the most important stage. Proper maintenance procedures for this water treatment plant are critical to maintain the quality of the water produced by the plant.
4. Using appropriate dialyzers. Though this factor is not completely in control of the dialysis team, it is an important factor in dictating the quality of dialysis. There are a large number of dialyzers available these days and generally, the larger the surface area of the dialyzer, the better the quality. The surface area is expressed in square meters. The sizes available these days are 1.1 sq. m., 1.3 sq. m., 1.8 sq. m., 2.1 sq. m., etc. People who are bigger built benefit from dialyzers of higher surface area. Another factor to consider while picking a dialyzer is whether it is low flux, middle flux or high flux. High flux dialyzers typically remove ‘middle molecules’ like Beta-2-microglobulin and Homocysteine. These cause different problems over a long period of time if not removed effectively. The higher the surface area of the dialyzers, the more expensive it is. Also high flux dialysers are more expensive than middle flux dialyzers which are more expensive than low flux dialyzers.
Factors in control of the patient:
1. Getting optimal number of exchanges and dwell times. With PD, the number of exchanges and the dwell time is one of the most important factors that dictates the effectiveness of dialysis. This is different for different individuals. A test called the Peritoneal Equilibration Test gives an indication of the characteristics of the peritoneal membrane of the patient which helps the doctor determine how many exchanges and how long the dwell should be. Once the prescription is made, it is completely up to the patient to adhere to that prescription. Adherence to this prescription is critical to ensure that the removal of toxins and fluid is effective. Patients must never skip an exchange and stick to the dwell time prescribed by the nephrologist.
2. Maintaining sterile techniques during exchanges and exit site dressing. PD makes the patient susceptible to bacterial infections. While contracting a bacterial infection does not impact the quality of the dialysis directly, these infections are often difficult to treat and can sometimes cause problems in the ability to do an exchange itself. That is why, it is very important to maintain sterile techniques while performing exchanges and exit site dressings. Repeated infections can sometimes cause loss of the ability to do PD as well. The patient must be watchful of any signs of infection like redness, tenderness and itching around the exit site and cloudy drain bags (like cotton wool in the bag after the drain) or pain while draining, fever etc. The nephrologist must be alerted immediately.
3. Eat a lot of protein. Protein loss is munch greater on PD than on HD. It is important for a good quality of life to eat good quality of protein of different types from a wide variety of sources. The recommended intake is 1.2 grams of protein per kg body weigh per day. For a 70 kg person, this means about 85 g of protein per day.
Factors in control of others:
1. Ensuring that the PET test is done and acted upon periodically. The PET test is typically done after the patient settles down on PD. Again, this could vary based on patient factors. But the PET test classifies the patient based on on how quickly the peritoneal membrane transports solutes. This dictates how long the dwell (time for which fluid is allowed to reside in the peritoneal cavity) should be. Draining the fluid from the cavity too quickly results in sub-optimal removal of toxins and unnecessarily having to do more exchanges for the same clearance. Letting the fluid dwell for too long results in transport of solutes back into the blood from the fluid. Both are not desirable. If the optimal dwell time is short, then a PD cycler may be advised which allows the patient to do several exchanges at night while asleep and connected to a machine which does the exchanges. A requirement of long dwell times means manual exchanges during the day is more practical.
2. Try to limit number of high concentration fluid bags used. High concentration fluid bags are necessitated to remove more fluid. However, high concentration fluid bags wear down the peritoneal membrane and reduce its life-span. So doctors must prescribe high concentration bags only as needed.
3. Treating infections promptly. Like discussed earlier, infections are the biggest problem in PD and whenever there are any signs of infection, prompt action must be taken to identify the organism and suitably treat it.
Good dialysis comes from a co-ordinated effort by both the patient and the clinical team that is responsible for the treatment. It is most important for both to first-of-all believe that it is possible to live a good life despite being on dialysis. Then both must act to address the aspects in their control. If this is done, most people can lead long, productive lives on dialysis. I have omitted things like work, exercise, anemia etc. because the focus of this post is mainly the quality of the actual dialysis itself. Please let me know if I have missed anything that contributes to good dialysis and I will include it.
For more information about the basic concepts of dialysis click here.
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