The artificial kidney and urea clearance.

A theoretical efficiency has been calculated from the known urea clearance of the artificial kidney, the assumed total body water of the patient, and the initial plasma urea. The efficiency of dialysis never significantly exceeded the calculated figure. In some patients with trauma or glomerulonephritis the efficiency was very poor whereas in patients with renal failure complicating pregnancy the actual and calculated efficiencies were very close. These observations are discussed and possible reasons for the failure of dialysis to bring down the plasma urea to the expected concentration are suggested.