What does the term "ultrafiltration" mean in hemodialysis?

Ultrafiltration in hemodialysis specifically refers to the process of removing excess fluid from the blood. This occurs during dialysis when a pressure gradient is created across the dialysis membrane, allowing water to move out of the blood into the dialysate solution. This helps to manage the patient’s fluid balance, especially in individuals with kidney failure, where the kidneys are unable to adequately remove excess fluid.

Maintaining the right fluid balance is crucial for patient health, as excess fluid can lead to complications such as hypertension and fluid overload, which can strain the heart and lungs. The process of ultrafiltration is distinct from simply removing waste products or adding electrolytes, which are different aspects of hemodialysis that target toxin clearance and electrolyte balance, respectively. Additionally, while filtering blood under high pressure is part of the overall hemodialysis process, it does not accurately describe ultrafiltration alone, which focuses specifically on fluid removal.