Described herein are alarm systems for suction devices for reduced pressure therapy. Alarms systems provide alerts to the patient and/or practitioner regarding the ability of the suction device to continue to provide negative pressure to a tissue region. Alarm systems comprise a sensor mechanism, which is capable of detecting the position of a slidable seal within the suction device, and generating an alert. Certain variations of alarms systems comprise magnetic field sensitive switches and/or electric switches. Other variations of alarm systems comprise rotary encoders to detect the motion and location of constant force springs, which signal the notification mechanism to issue alerts accordingly. Described herein are alarm devices configured to retain a suction device therein and to attach the suction device to a patient. The alarm devices disclosed herein detect the depleted state of the suction device and are capable of retaining the suction device in a plurality of orientations.