Overview of Hemodialysis
Dialysis is a medical treatment that works similar to a kidney. It comes from the Greek language; ‘dia’ meaning ‘through’ and ‘lysis’ meaning ‘loosening or splitting’. It steps in to help when your kidneys are suddenly unable to work properly, like in an acute kidney injury, or if it’s a long-term issue, known as chronic kidney disease. This treatment helps to clean your blood by removing extra water, waste, and toxins that your kidneys would normally filter out. People may need dialysis temporarily until they can get a kidney transplant or permanently if they cannot have the procedure.
The need for dialysis is related to the number of people who experience severe kidney disease, the early detection of chronic kidney disease, and interventions to prevent it from getting worse. Regular check-ups that monitor progress can help doctors prepare for possible dialysis, reducing the number of people needing emergency intervention. It’s important that patients and their caregivers understand potential future treatments. Getting ready early helps to avoid problems. For instance, a blocked catheter or a poorly functioning access point for dialysis can lead to serious issues like infection, blood clots, bleeding, and even rapid death. People educated about dialysis are often more likely to choose home-based therapies, which can be less costly, more convenient, and improve quality of life. These programs ideally start by the time a person reaches stage 4 of chronic kidney disease.
In the year 2010, around 2.5 million people around the world were on chronic dialysis. The highest rates are seen in North America, while the most cases are reported in Taiwan and Japan. The healthcare system tracks dialysis use through registries, which help manage patient safety and care. The need for dialysis can be influenced by factors like society, culture, economy, and race. For example, African Americans see a higher rate of severe kidney disease and white populations have more chronic kidney disease. Women are more likely to have chronic disease, while men have a higher risk of severe kidney disease. Socio-economic disparities can limit healthcare access due to the impact on income or health insurance. Indigenous people in Australia, New Zealand, USA, and Canada have high rates of kidney disease, less access to transplantation, and worse outcomes. There are three main types of dialysis: Hemodialysis (HD), Peritoneal dialysis (PD), and Continuous renal replacement therapy (CRRT). The type of dialysis and how it’s administered varies across countries due to unique practices and preferences.
The doctor determines when to start dialysis based on weighing the risks of starting too early, like exposing patients to unnecessary procedures and risk of infection, against the risks of starting too late which can cause more severe problems due to uncontrolled kidney disease. Because everyone’s bodies differ, there’s no universal measurement for when dialysis should start. However, dialysis is usually considered when a specific measure of kidney function- known as eGFR – drops below 20, or if the kidney function is expected to significantly worsen within a year. Earlier start to dialysis can sometimes increase survival rates, but it may also lead to more procedures and additional healthcare costs without improving life quality. The Renal Physicians Association has developed certain criteria for identifying older dialysis patients who may have a poor prognosis.
Unfortunately, people on dialysis, especially the younger ones, have higher death rates due to issues like heart disease (40%) and infections (10%). These are mostly due to shared risk factors like chronic inflammation, significant changes in body fluid volume, an unhealthy buildup of calcium in the blood vessels, and irregularities in heart and blood vessel function during dialysis. Certain medications can help reduce the risk of cardiovascular deaths and heart-related complications among dialysis patients. High blood pressure is both a cause and consequence of kidney disease and is strongly linked with the risk of severe kidney disease. The first three months after starting dialysis can be particularly dangerous, especially for older patients. This period carries the highest death rates due to associated risks like procedures to place dialysis access and more severe health conditions that result in worsened kidney function. Therefore, effective teamwork among healthcare professionals is critical to improve outcomes for patients with severe kidney disease requiring dialysis.
Anatomy and Physiology of Hemodialysis
Dialysis is a process where unwanted substances are removed from the bloodstream. This removal process works due to a principle called concentration gradient. Simply put, the dialysis machine acts like a filter, with two ways of removing unwanted substances from the blood:
1. Diffusive clearance, which is like a gentle shuffling where smaller harmful substances are more likely to be filtered out.
2. Convective clearance, where a water-based force pushes unwanted substances through the filter.
The cleansing or filtering fluid used in the machine is called dialysate. It’s kind of like laundry detergent for your blood, except it is made of ultra-pure water mixed with salts and sugar. When in contact with the patient’s blood, harmful waste products in the blood are drawn out into the dialysate, while the salts and sugar remain behind. The dialysate constantly needs refreshing to ensure the harmful substances don’t return to the blood.
The efficiency of dialysis depends on the difference in waste concentration between the blood and dialysate, the type of filter used, and the size of the waste molecules. The process tries to avoid reaching a point where the blood and dialysate have the same amount of waste, as that would mean waste removal has stopped. To achieve this, the philosophy of ‘countercurrent’ flow is adopted, meaning fresh dialysate is constantly used and dirty blood is continuously replaced with cleaned blood.
Medical professionals also use a measure called Kt/V to check how effective a dialysis session was. This measure results from a study conducted in 1985, which found that a score of less than 0.8 meant that the patient might not be doing well. On the other hand, a score of more than 1.0 was linked to good outcomes for patients. The Kt/V measure calculates the amount of blood cleaned of a waste product known as urea during a dialysis session and compares it to the amount of urea in the body. If you get a score of 1.0, it implies all the urea has been cleared from your blood.
Dialysis could be a periodic treatment or a continuous one. For patients who have an unstable heart condition or are retaining too much fluid in the body, continuous treatment within their blood vessels is preferable.
Why do People Need Hemodialysis
Starting hemodialysis treatment becomes necessary if a person has a serious illness that is associated with:
* Acute kidney injury
* Uremic encephalopathy, a type of brain disorder caused by kidney failure
* Inflammation of the heart lining, known as pericarditis
* Life-threatening high potassium levels, known as hyperkalemia
* Acidosis that doesn’t respond to treatment, which means the body has too much acid
* Excess body fluids causing complications in different organs (like pulmonary edema, which is fluid accumulation in the lungs)
* Failure to grow properly or malnutrition
* Nerve damage in the hands and feet, known as peripheral neuropathy
* Stomach problems that can’t be controlled
* People who don’t show symptoms but have a Glomerular Filtration Rate (GFR, a measure of kidney function) between 5 to 9 mL/min/1.73 m²[1]
* Any intake of harmful substances
These conditions interfere with the body’s control of cytokines (molecules that modulate the immune response), leading to issues like blood vessel dilatation, weakening of the heart’s function, and a weakened immune system. These problems may cause damage to the organs, instability in blood pressure and heart rate, or delays in kidney recovery. Hemodialysis, a type of Renal Replacement Therapy (RRT), improves the removal of cytokines from the body, particularly in conditions like sepsis. But there’s also potential harm that might arise from complications related to the catheter (tube used in the treatment), imbalances in body salts, and low blood pressure during hemodialysis.
The National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI) developed guidelines to provide guidance on how to appropriately perform hemodialysis. The guidelines suggest that when patients reach the fourth stage of Chronic Kidney Disease (CKD, when the GFR falls to 30 mL/min/1.73 m^2), they should be informed about kidney failure and the available treatment options, including kidney transplantation, home or in-centre hemodialysis, PD, and non-invasive treatment. Informing family members and caregivers is also recommended. The decision to start maintenance dialysis should consider the signs and symptoms of renal failure (such as itching, acid-base or electrolyte imbalances, inflammation of serous membranes), problems with fluid or blood pressure regulation, and a progressive decline in nutritional status despite diet adjustments or impaired cognition. The decision to start dialysis should consider these factors rather than just the level of kidney function in an individual who has no symptoms.
Some heart conditions may require dialysis. These include heart rhythm problems due to imbalances in body salts, uremic pericarditis, and fluid overload due to severe congestive heart failure that occurs when kidney function is subpar. Following structural abnormalities in the heart, salt imbalances (calcium, magnesium, and potassium) are the most common causes of heart rhythm problems. Metabolic acidosis (buildup of too much acid in your body) and decreased kidney excretion in patients with chronic kidney disease or renal failure can lead to issues with potassium. Improper use of certain blood pressure medications in heart patients, such as ACE inhibitors, angiotensin-receptor blockers, and aldosterone antagonists can also cause problems. In patients with renal failure, high levels of urea can also cause uremic pericarditis. Patients with CKD and heart failure can experience fluid retention, which worsens the heart failure and leads to a lung condition known as pulmonary edema.
When a Person Should Avoid Hemodialysis
Some people can’t undergo a treatment called hemodialysis, which is a procedure that cleans the blood when the kidneys can’t function properly. The main reason someone can’t have this treatment is if the veins in their body are hard to reach, which is necessary for the treatment. Other reasons that might prevent someone from having hemodialysis include:
* Difficulty reaching the veins
* A fear of needles
* Heart failure
* A blood condition that affects the blood’s ability to clot
For patients with extensive vein disease, modern techniques are used to enhance the process of reaching the veins. People who are afraid of needles may be able to overcome this fear with the help of certain numbing medicine and support from nurses. However, for those with a severe clotting problem, the balance of anticoagulants (decoagulants) becomes complicated.
Patients can refuse the dialysis treatment, and doctors must respect this wish. Despite this, doctors must make sure they have addressed all aspects that can be improved or changed, such as any unfounded fears about dialysis or if a mental health condition might be affecting the patient’s decision-making. Consultation with a mental health professional might be requested in such cases. For those with multiple health conditions, the treatment approach might be shifted to comfort care, which includes all suitable treatments except for dialysis.
For patients who feel their life quality would be negatively affected by the discomfort of hemodialysis, alternatives such as medication and diet management can be used to alleviate the symptoms of the end stage of kidney disease. This might include pain management with pain relievers and use of certain medications for severe itching and sleep problems. The aim is to provide comfort and prevent suffering, especially in scenarios where additional time gained from dialysis would be mostly spent having or recovering from the treatment sessions.
Equipment used for Hemodialysis
Hemodialysis (HD) is a process performed by an apparatus, involving two main parts: the blood circuit and the dialysis solution circuit. This equipment removes waste and excess fluids from your blood because your kidneys are no longer able to do so themselves.
The blood circuit and the dialysis solution circuit are connected by a special filter, known as a dialyzer. It has small openings that allow waste and fluid to pass through but prevent larger, necessary blood components from being removed. Semi-permeable membranes, which are thin barriers that allow some substances to pass through while stopping others, separate the blood from the dialysis solution. These membranes can be made from various materials, including specially treated cellulose or manufactured materials like polysulfone, designed to work effectively and not trigger an immune response.
The dialysis machine monitors the entire process. It warms the dialysis solution, regulates concentration of its components, and checks if blood leaks into the dialysis fluid, stopping the process if it happens. It also controls the amount of fluids removed from your body during the treatment. After the blood is cleaned, it is returned back into your body. If there’s a risk of the bloodline separating, alarms and sensors will be engaged to stop the procedure and ensure patient safety.
Launching the process involves important steps like preparation of dialysis solution, which must have the right temperature and concentration of dissolved substances. Receiving too much or too little of this solution could lead to imbalance in the body and result in complications. In addition to ensuring that the solution is within the right temperature range, the system also monitors the concentration of the dialysis fluid throughout the process, which is very important for patient safety.
Furthermore, depending on a patient’s individual needs, bicarbonate concentrate used in the dialysis solution can be altered to ensure proper acid-base balance in the body. The machine also uses a method called ‘dry weight’ probing to see how effective the treatment is. If the machine finds that fluid is leaving a patient’s body too quickly during the dialysis, causing potential harm, it can adjust the rate to protect the patient’s health. Ultimately, the goal is to get the right balance of salt and water during dialysis and between treatments.
The dialysis process is continuously adjusted and monitored to maintain the stability of the patient’s body as much as possible. The next generation in treatment includes wearables and implantable artificial kidneys. These newer technologies use an innovative system that can continuously clean the dialysate so it can be reused. The results of this advancement mean a potentially smaller device with reduced operation costs. Such advancements might bring us closer to the era of self-care treatment for kidney failure.
Who is needed to perform Hemodialysis?
A dialysis care team is a group of skilled medical professionals who work together to provide patients with comprehensive care as they adjust to life dependent on dialysis. Dialysis is a treatment that does the job of the kidneys when they’re not able to. This team is led by a doctor who specializes in kidney-related conditions, also known as a nephrologist. They help patients understand the progression of their kidney disease and how best to slow down the loss of kidney function. A nephrologist also encourages patients to be active in making choices about their treatments.
Supporting the nephrologist, there are other trained providers like nurses and assistant providers who work together to look after kidney patients in clinics and during dialysis treatments. A nurse who specializes in nephrology specifically on dialysis patients, making sure they are receiving the right medications and that their dialysis treatment is properly administered. They also guide patients and their caregivers on how to conduct dialysis at home. Another specialist called a renal dietitian helps prepare meals that suit the specific dietary needs of each patient, and they focus on things like ensuring the effectiveness of dialysis, managing bone health, and controlling anemia.
Other professionals are involved, such as the nephrology social workers who support patients and their families in coping with kidney disease. They can suggest lifestyle changes, provide emotional support, and connect patients with services that can help improve their quality of life.
On the treatment side, patient care technicians perform the dialysis procedure, keeping a close eye on patients throughout the process. Meanwhile, biomedical technicians take care of the dialysis machines and maintain water quality at the dialysis center.
One key aspect of dialysis treatment is creating and maintaining access for the dialysis machine to clean the patient’s blood. This is done by a vascular access surgeon. Imaging, done by a radiologist, helps in planning this access surgery. Sometimes, catheters need to be placed or other treatments need to be done by an interventional radiologist. An access coordinator keeps track of the patient’s access history, ensures the correct treatment was carried out, and keeps records up to date.
Billing personnel are available to answer any questions about insurance coverage, billings, or payments related to the treatment.
The National Kidney Foundation also provides valuable support. They fund research for managing kidney disease, educate the community about kidney diseases and treatment options, and offer supportive programs and services to kidney disease patients.
But, it’s important to note that the most important members of the dialysis care team are the patients and their families or caregivers. They are at the center of all decisions and plans regarding the treatment.
Preparing for Hemodialysis
Preparing for in-home dialysis treatments contributes to a quarter of admissions to the hospital for those with chronic kidney disease. The best method for this procedure is the distal AV fistula. However, if a patient doesn’t have any viable superficial veins left for dialysis, synthetic grafts and tunneled central venous catheters can serve as alternatives. Only those patients who have exhausted all other options are advised to opt for a permanent catheter.
Before setting up a home hemodialysis system, legal restrictions regarding the home’s use for this medical purpose have to be assessed. It’s important to ensure that the home has a sturdy structure that isn’t plagued by issues like dampness, mold, or high pollution levels. The home should have stable electricity and abundant water supply. Arrangements also need to be made for purifying the water needed for dialysis and disposing of waste.
Community house hemodialysis offers a home-like setting for patients to have their treatments. Each patient is given their own space with all the necessary dialysis equipment. They are then responsible for carrying out their own dialysis. If a patient needs dialysis five or more times a week, having a dedicated dialysis machine at the community location is ideal. However, those who only need to have dialysis every other day can share a machine. The home HD program takes care of the maintenance of the infrastructure and equipment.
The timing and location of dialysis treatments depend on a patient’s preference and the mobility of the dialysis machine. If a patient chooses to perform their dialysis at night, they are restricted to their bedrooms. Similarly, a person who fears accidentally dislodging their dialysis needle would likely prefer to perform their dialysis treatments during the day. The responsibility of conducting dialysis at home is split between the patient and the home HD program. Both parties – as well as any caregiving providers – need to clearly understand their roles. These roles should be documented in a contract or in-unit policy. It should also be clarified who is responsible for installing and maintaining the dialysis equipment.
How is Hemodialysis performed
In the US, about 430,000 people are reliant on hemodialysis, a treatment for kidney failure that helps clear out waste and excess fluid from your blood. There are multiple ways to connect patients to the hemodialysis machine: through a catheter, through a surgical connection between an artery and vein known as an arteriovenous fistula, or through a similar connection made with synthetic materials called arteriovenous grafts.
A needle is used to get into your blood circulation. The “fistula first” initiative recommends creating an arteriovenous fistula for most patients because it’s reliable for access. However, many patients have an arteriovenous graft where artificial material is used to connect an artery and vein. During dialysis, your blood is pumped through a filter, or dialyzer, at a speed between 300 and 500 milliliters per minute. At the same time, a cleaning fluid called dialysate flows in the opposite direction at a speed of 500 to 800 ml/min. The lower pressure on the dialysate side is what makes it possible to remove the right amount of fluid.
The success of hemodialysis is measured by how much blood urea nitrogen – a waste product in your blood – is reduced each time. Ideally, this should be 65 to 70 percent. The amount of dialysis should be adjusted for each person based on their need for fluid removal, management of high potassium and phosphate levels, acid levels and blood pressure control
There are different ways to conduct dialysis with varying pros and cons. Daily (six-times-a-week) dialysis helps with managing high blood pressure and phosphate levels and reduces heart mass, leading to better physical health as reported by patients. However, it also sees an increase in death rate and hospitalization for heart failure. Dialysis at home can be done 3 to 6 nights per week for 6-8 hours each according to the individual’s lifestyle choice. But this method can lead to blood access complications, caregiver burden, and rapid loss in kidney function.
In women with end-stage kidney disease who are pregnant, long, frequent hemodialysis sessions are recommended, whether at home or in-center. In cases where the kidneys are nearly or completely failed, three dialysis sessions per week are advised, each lasting at least three hours. Additional or longer sessions may be needed for those with substantial weight gain, poorly controlled blood pressure, poor metabolic control, or difficulty in achieving dry weight, which is the body weight without any excess fluid buildup. The best rate of fluid removal for each session should balance maintaining normal body fluid levels, clearing waste products and managing blood pressure with minimal changes to heart function and minimal symptoms during dialysis.
It’s important to note that patients on dialysis often experience a diminished quality of life, with increased risks for illness and death. Quality of life can be of two categories – physical and mental. Physically, patients might have impaired mobility and limitations, affecting their sleep and fatigue levels. Mentally, patients might experience depression and anxiety. However, intensive hemodialysis can improve both physical and mental aspects of quality of life and can also significantly reduce recovery time post-dialysis.
When patients need to travel, they can arrange for dialysis at local dialysis centers 6 to 8 weeks in advance to ensure availability. The patient’s usual dialysis center must send over medical history, bloodwork and treatment records, medication lists, insurance information, and any special needs to the center they will be visiting.
Possible Complications of Hemodialysis
When undergoing hemodialysis, a procedure used for kidney failure, some complications can occur.
One is intradialytic hypotension, essentially a drop in blood pressure during the procedure. This could cause symptoms like dizziness, lightheadedness, or feeling nauseous. The role of your doctor or nurse will be to make you comfortable, usually by shifting your position so your head is lower than your feet, and giving you a small volume of fluid (100 mL) through the blood way. This is meant to bring the blood pressure back to a normal level.
Another potential issue is muscle cramps, the cause of which isn’t really known. Factors like low blood pressure, dehydration, or certain types of dialysis solution could lead to these cramps. Your doctor might treat these by giving you a saline solution and suggesting stretching exercises for relief.
Then there are more serious complications that might require immediate attention:
Dialysis disequilibrium syndrome: This could occur during or right after a person’s first treatment. Symptoms may include restlessness, confusion, headaches, muscle twitching, and even coma. This happens when varying urea concentrations in your brain and blood cause fluid to move into your brain, thereby increasing the pressure inside your skull. If dialysis happens too quickly, it could lead to seizures and brain swelling. Measures to counteract this could include adding different compounds to your blood to keep concentrations balanced.
Dialyzer reactions: These are termed as Type A and B reactions. Type A reactions are severe allergic reactions that can cause symptoms like shortness of breath, itching, sneezing, watery eyes, stomach cramps, and diarrhea, usually within the first half an hour of dialysis. This is typically due to an allergic reaction to the sterilising agent used for the dialysis machines. Your doctor will treat these reactions with antihistamines, steroids, and adrenaline. Type B reactions cause chest or back pain and are due to activation of immune system components. Trying a different dialysis membrane might prevent these.
Hemolysis: This refers to destruction of red blood cells and is a medical emergency during dialysis. Signs include a red or pink color in the tubes and a sharp drop in red blood cell count. Doctors will run blood tests and watch over you for delayed symptoms.
Air embolism: A very serious but rare complication occur when air gets into the bloodstream, and can be fatal. This might occur when foam is observed in the blood line of the machine. The countermeasure would be to place you on your left side, administer oxygen, and remove air from the heart where possible.
Less serious complications can include nausea and vomiting, headache, back pain, and itching, which are usually linked to low blood pressure or an early sign of the disequilibrium syndrome mentioned earlier. These can be treated with medications and changes in dialysis membranes.
An ongoing challenge of hemodialysis is maintaining the vascular access site, the area where the dialysis machine is connected to the body. Problems here can lower the quality of life of dialysis patients. Measures to prevent this include avoiding trauma to the arm, rotating needle insertion sites and checking for signs of infection.
Lastly, electrolyte imbalances can also occur during dialysis, causing problems such as high or low levels of potassium, magnesium, sodium, or calcium. Sudden cardiac deaths, often caused by dangerous heart rhythms, are more likely to occur around the time of starting dialysis. It’s crucial to monitor electrolyte levels and provide appropriate guidance for avoiding food or drink that sensitises to these risks.
What Else Should I Know About Hemodialysis?
People with chronic kidney disease (a longstanding disease that gradually damages the kidneys) often need a procedure called dialysis, which is like a machine washing of the blood. When the kidneys aren’t working well, harmful substances, like ADMA, indoxyl sulfate, and p-cresol, can build up in the blood. These can damage the blood vessels and may lead to heart disease. Additionally, the failing kidneys produce less of a substance called renalase, which helps regulate blood pressure and protects against heart disease. Dialysis patients also often have chronic inflammation, a long-term condition where the body is trying to protect itself but ends up causing damage. Tests for inflammation can predict how serious the kidney disease is.
Dialysis patients often have hard, stiff arteries and high blood pressure only during dialysis. This is more common in patients with long-term fluid overload. Lowering the amount of sodium in the dialysis fluid and prescribing certain blood pressure medicines can help.
Heart disease and kidney disease are linked, and patients with a history of both have a higher risk of serious illness and death. As kidney function decreases and protein is lost in the urine (a sign of kidney damage), the risk of heart disease and death increases. Therefore, it’s important to identify and manage risk factors for heart disease in patients with mild kidney disease to prevent death from heart disease before they need a kidney replacement.
Heart problems in patients with chronic kidney disease can include stiff and calcified (hardened) blood vessels and an enlarged heart. Diseases like heart failure and fluid overload can look similar, so other diseases need to be ruled out. Measuring the pressure in the heart can help tell whether fluid overload is due to heart problems or other issues. Dialysis can be critical for treating serious heart problems in patients with both heart and kidney disease.
High levels of a substance called FGF-23, along with high levels of calcium and phosphorus in the blood and irregularities in the parathyroid glands (small glands in the neck that control calcium balance), can increase the risk of death. For patients on dialysis, these mineral imbalances can cause hardening of the blood vessels and the heart valves, leading to serious health problems and death. Dialysis sessions can also cause abnormal heart rhythms and, along with other conditions like diabetes, increase the risk of clogged arteries in the legs (peripheral arterial disease) and stroke.
A study from France found that the risk of spreading the COVID-19 virus during a type of dialysis called continuous renal replacement therapy is minimal. Although the patients’ blood contained the SARS-CoV-2 virus (which causes COVID-19), the dialysis fluid did not. Therefore, using a filter to remove viruses during dialysis doesn’t seem necessary. Instead, healthcare workers should focus on preventing the spread of the virus during procedures.
