Intermittent hemodialysis (IHD) is a medical procedure that filters a person’s blood when their kidneys can no longer perform this important function. It is a life-sustaining treatment for individuals with kidney failure. This process circulates blood outside the body through a specialized machine to remove waste products, excess fluids, and balance electrolytes.
Understanding the Need for Hemodialysis
Healthy kidneys play several roles in the body, filtering waste products, balancing fluid and electrolyte levels, and producing hormones that regulate blood pressure and red blood cell production. When kidneys fail, often due to conditions like end-stage renal disease (ESRD) or acute kidney injury (AKI), these functions cease. This leads to an accumulation of toxins, such as urea and creatinine, and excess fluid in the bloodstream.
The buildup of waste and fluid can cause severe symptoms, including swelling, nausea, and fatigue, and can lead to coma or death if untreated. Dialysis, including intermittent hemodialysis, becomes necessary to prevent these complications by artificially performing the kidneys’ filtering and balancing tasks. Individuals who have lost a significant portion of their kidney function, 85 to 90 percent, become candidates for dialysis.
The Hemodialysis Procedure
Intermittent hemodialysis diverts the patient’s blood through an external circuit for purification. The system’s core is the dialysis machine, which includes a dialyzer, often called an artificial kidney. This dialyzer contains thousands of tiny, semi-permeable fibers. A specially formulated cleansing fluid, known as dialysate, flows on one side of these fibers.
To begin, blood is drawn from the patient’s body through a vascular access point created surgically, such as an arteriovenous (AV) fistula, an AV graft, or a catheter. This blood then travels through tubing into the dialyzer. Inside the dialyzer, waste products like urea, creatinine, and excess electrolytes move from the blood into the dialysate across the semi-permeable membrane through a process called diffusion.
Simultaneously, excess fluid is removed from the blood through ultrafiltration, driven by pressure differences across the dialyzer membrane. This process restores the patient’s fluid balance. The “cleaned” blood is then returned to the patient’s body through a separate line in the vascular access. The dialysate fluid, now containing the removed waste, is discarded.
Treatment Frequency and Environment
Intermittent hemodialysis treatments are scheduled three times per week, with each session lasting three to five hours. The exact duration and frequency adjust based on individual medical needs, remaining kidney function, and fluid and waste accumulation between sessions. This regular schedule helps manage waste products and maintain appropriate fluid levels.
Patients receive intermittent hemodialysis in a dedicated dialysis center or hospital, where medical staff closely monitor them. Before each session, the patient undergoes routine checks, including weight, blood pressure, and temperature, to assess fluid status and overall condition. During treatment, patients are seated comfortably, and staff continuously monitor blood pressure, blood flow rates, and machine parameters to ensure the procedure runs smoothly. While not painful, some patients may experience temporary side effects like nausea, dizziness, or muscle cramps due to rapid fluid shifts.
Distinguishing Intermittent Hemodialysis
Intermittent hemodialysis (IHD) is distinguished from other kidney replacement therapies, such as continuous renal replacement therapy (CRRT) and peritoneal dialysis (PD), by its scheduled, distinct sessions. Unlike CRRT, which provides continuous, slow removal of waste and fluid over 24 hours or more for critically ill patients, IHD rapidly clears solutes and excess fluid over a shorter period. This rapid clearance makes IHD efficient for removing large amounts of waste quickly.
Peritoneal dialysis, another alternative, uses the abdominal lining (peritoneum) as a natural filter, involving the introduction and drainage of dialysate solution directly into the abdominal cavity, often performed daily at home. In contrast, IHD requires external blood circulation through a machine. The choice of IHD over other modalities depends on the patient’s stability, the urgency of waste removal, and logistical factors like access to a dialysis center or the ability to perform home treatments. IHD remains a common and effective treatment for acute kidney injury and chronic kidney disease.