The invention provides an access disconnect system comprising blood tubing； a blood filter (37, 57) in fluid communication with the blood tubing； a blood processing machine (31, 51) including a blood pump (36, 56) for moving blood through the blood tubing； first and second conductive contacts (44, 46, 64, 66) located in the blood tubing on the arterial tubing side of the blood filter (37, 57), the first conductive contact (44, 64) located upstream of the blood pump (37, 57) and the second conductive contact (46, 66) located downstream of the blood pump (37, 57), the first and second conductive contacts (44, 46, 64, 66) positioned and arranged to form a conductive circuit connectable fluidly with a portion of a vascular system of a patient； a source of electric current (41, 61) connected to the first conductive contact (44, 64)； and a transmitter (73) for sending a signal indicative of an amount of current flowing through the conductive circuit when the source of electric current (41, 61) is applied.
