Hemodialysis is a procedure that patients who have limited or virtually non-existent kidney function undergo to remove both waste products and extra fluid from their bloodstream. Blood from an artery of a hemodialysis patient is diverted into an artificial kidney where the blood enters numerous tiny fibers. An aqueous salt solution called dialysis fluid flows around these fibers. Waste products, most notably urea, and excess fluid within the blood pass through the fibers and into the dialysis fluid. The purified blood returns to the bloodstream through a vein. Consider the schematic of an artificial kidney below. After a certain amount of time in dialysis treatment, the flow rates and concentrations are as follows.
Input: 350.0 mL/min Blood from an artery 1.730 mg Urea/mL and 560.0 mL/min Dialysis fluid
Output: 347.0 mL/min Blood to a vein 1.581 mg Urea/mL
What is the rate of urea removal from the blood stream?
If the flow rate of dialysis fluid leaving the artificial kidney is approximately the same as the flow rate of dialysis fluid into the artificial kidney, what is the concentration of urea in the waste dialysis fluid?
People with kidney failure may also experience fluid buildup if their kidneys are no longer capable of producing enough urine. Thus, because it lessens water retention, the fluid removal aspect of kidney dialysis is also important. However, if fluid is removed too quickly, the patient may experience dangerous drops in blood pressure. For an average-sized patient, a removal of 350 mL/hour is considered safe. In the dialysis example given above, how much fluid is removed from the blood in mL/hour?
If the fluid removal rate is constant over the course of dialysis, what is the total volume of fluid removed from the blood stream during a 3.65 hour dialysis treatment?