Why is blood contamination a problem with high-flux dialysis?

Blood contamination is a significant concern in high-flux dialysis due to the nature of the membranes used in the process. High-flux membranes are designed to allow the passage of larger solutes, which can include certain proteins and other particles ranging from 2000 to 10,000 daltons in size. This attribute is essential for facilitating the clearance of larger toxins that may accumulate in patients with kidney failure.

The problem arises when these membranes are not selectively permeable enough to prevent potentially harmful particles from entering the blood. If a dialysate solution becomes contaminated or if blood and dialysate flow is not adequately managed, there is a risk that harmful particles could pass through the membranes into the bloodstream. This can lead to serious complications, including infections or inflammatory reactions.

The other options provided do raise relevant issues but do not directly relate to the core mechanism behind blood contamination in high-flux dialysis. The membranes' ability to allow larger particles to traverse them is the crucial factor that defines the risk of blood contamination in this dialysis process.