Dialysis is a medical procedure that artificially filters waste products, excess fluids, and balances electrolytes in the blood, functions normally performed by the kidneys. When kidneys lose this ability, waste materials can build up to dangerous levels, leading to severe health complications. Intermittent dialysis is a widely used form of this life-sustaining treatment, designed to manage kidney failure by regularly cleansing the blood outside the body. It offers a structured approach to renal replacement therapy, supporting individuals whose kidneys can no longer adequately remove toxins.
Understanding Intermittent Dialysis
Intermittent dialysis, also known as intermittent hemodialysis (IHD), purifies the blood by removing waste products, excess fluid, and restoring electrolyte balance. This is necessary when kidneys can no longer effectively filter, a condition known as kidney failure. Kidney failure can manifest as either acute kidney injury (AKI), a sudden and sometimes temporary loss of kidney function, or end-stage renal disease (ESRD), a permanent and severe decline in kidney function.
Unlike continuous forms of dialysis, intermittent dialysis is performed in distinct sessions, lasting a few hours each, several times a week. This intermittent nature means waste products and fluids are removed rapidly during treatment, followed by intervals where the body’s natural processes are unsupported. The goal is to prevent the accumulation of toxins like urea and creatinine, manage fluid overload, and maintain healthy levels of electrolytes such as potassium and sodium.
The Dialysis Process
The intermittent dialysis procedure involves several steps, beginning with establishing vascular access to the patient’s bloodstream. This access allows blood to be safely drawn from the body, filtered by the dialysis machine, and then returned. The most common types of vascular access include an arteriovenous (AV) fistula, an AV graft, or a central venous catheter. An AV fistula, created by connecting an artery and a vein, is preferred for durability and lower infection risk, though it requires months to mature.
Once vascular access is established, two needles are inserted into the access site, connecting the patient’s bloodstream to the dialysis machine. One tube draws blood, which flows into the dialyzer, often called an “artificial kidney.” Inside the dialyzer, thousands of hollow fibers with semi-permeable membranes separate the blood from a cleansing fluid called dialysate.
The dialysate is a solution with an electrolyte composition similar to healthy blood, but without waste products. As blood flows through the dialyzer’s fibers, waste products like urea and creatinine, along with excess fluid, move across the semi-permeable membrane into the dialysate through processes like diffusion and ultrafiltration. Diffusion occurs as substances move from an area of higher concentration (the blood) to lower concentration (the dialysate), while ultrafiltration removes excess water by creating pressure differences. A blood pump ensures the patient’s blood circulates through the dialyzer at a controlled rate (200-400 mL/min), while fresh dialysate continuously flows around the fibers (500-800 mL/min). The cleansed blood is then returned to the patient’s body through the second tube connected to the access site. A typical intermittent hemodialysis session lasts 3 to 5 hours and is performed three times per week.
When Intermittent Dialysis is Used
Intermittent dialysis is a standard treatment for both acute kidney injury (AKI) and chronic kidney disease (CKD), particularly end-stage renal disease (ESRD). In AKI, where kidney function declines suddenly, intermittent dialysis can be used temporarily to support the body while the kidneys recover. This is common in intensive care unit (ICU) settings, where rapid removal of toxins and fluid may be necessary.
For individuals with chronic kidney disease, intermittent dialysis provides long-term, regular treatment to manage the ongoing loss of kidney function. Patients with ESRD receive treatments three times per week, a schedule providing adequate clearance without additional benefits from more frequent sessions. Physicians consider several factors when deciding if intermittent dialysis is the appropriate modality. These include patient stability, as rapid fluid and solute shifts during sessions can cause blood pressure fluctuations. The need for quick removal of excess fluid or severe electrolyte imbalances also favors intermittent dialysis due to its efficiency in a shorter timeframe.
Living with Intermittent Dialysis
Individuals undergoing intermittent dialysis need to make lifestyle adjustments to support their treatment and health. Dietary considerations are significant, often involving fluid intake restrictions to prevent fluid overload between sessions. Patients also need to monitor potassium and phosphorus consumption, as these electrolytes can accumulate when kidneys are not functioning properly.
Adherence to the prescribed treatment schedule is important for maintaining health and preventing complications. Missing sessions or altering the duration without medical guidance can lead to dangerous buildups of waste products and fluids. Patients may experience short-term sensations after dialysis, such as fatigue or muscle cramps, as the body adjusts to rapid fluid and electrolyte shifts. Regular medical follow-ups are necessary to monitor kidney function, assess the effectiveness of dialysis, and manage any potential complications or side effects.