An access disconnection method includes supporting a transmitter including a wireless communication apparatus, a receiver, a portion of an arterial line, a portion of a venous line and electronic circuitry by a member separate from a blood treatment machine. The method further includes operably communicating the electronic circuitry with the transmitter and the receiver, enabling transmission of a wave from the transmitter in one of the arterial and venous lines, enabling receipt of the wave by the receiver in the other of the arterial and venous lines, and enabling a disconnection output to be sent to the blood treatment machine via the electronic circuitry. The disconnection output is indicative of a change in the wave received by the receiver from the transmitter sufficient to expect that an access site disconnection of one of the arterial and venous lines has occurred.