A dialysis machine needs access to which of the following?

A dialysis machine functions by filtering waste products and excess fluid from the blood, necessitating direct access to the bloodstream. This process is critical for individuals whose kidneys are unable to perform these functions adequately, such as in chronic kidney disease or acute kidney injury.

During dialysis, blood is drawn out of the body, processed through the dialysis machine, and then returned to the body. This requires a vascular access point which can either be a fistula, graft, or catheter inserted into large blood vessels. The other options—such as the urinary tract, small intestine, and a central artery—are not suitable for a dialysis machine because they do not provide the continuous and direct access to the blood that is essential for the filtration process. Accessing the urinary tract wouldn’t effectively filter blood, while the small intestine is involved in digestion rather than blood purification, and a central artery does not serve as a suitable access point for the exchange necessary in dialysis. Thus, the bloodstream is the correct and vital component for the function of a dialysis machine.