US Patent 7648476 Blood treatment apparatus with alarm device

A blood treatment apparatus includes a controller and a supervisor, which together monitor various sensors. The controller is equipped with a first alarm system and the supervisor is equipped with a second alarm system. To avoid competition between both alarm systems, the alarm system of the supervisor normally remains mute. A function monitoring device monitors the function of the first alarm system and signals a missing alarm to the supervisor. Only in this case will the second alarm system of the supervisor be activated.