An access disconnection system includes: an arterial line； a venous line； a transmitter configured to transmit a sound wave in one of the arterial and venous lines when connected to a patient； a receiver configured to receive the sound wave from the other of the arterial and venous lines when connected to the patient； and electronic circuitry coupled to at least one of the transmitter and receiver, the circuitry configured to send a disconnection output indicative of a change in the sound waves received by the receiver from the transmitter sufficient to expect that an access disconnection of one of the arterial line and venous lines has occurred.
