Injectable physiological monitoring system

An injectable device for use in subcutaneous physiological monitoring of a patient, the injectable device comprising:

• a hermetically sealed body;
• a plurality of sensors that provide an indication of at least one physiological event of a patient, wherein the plurality of sensors includes an accelerometer located within the body that generates an activity signal in response to at least one of a activity or a position of the patient and at least two electrodes spaced along the hermetically sealed body of the injectable device and in contact with tissue of the patient for monitoring a physiological signal associated with the patient;
• and
• a monitoring unit located within the body and coupled to the accelerometer and the at least two electrodes, wherein the at least two electrodes are utilized to measure an impedance signal related, wherein the monitoring unit utilizes the measured impedance to determine a hydration of surrounding tissue of the patient and wherein the monitoring unit is further configured to, based at least in part on the determined hydration and the activity level of the patient, detect an impending cardiac decompensation of the patient.