An apparatus and techniques for determining whether a medical electrode, such as a defibrillation electrode coupled to an automated external defibrillator, is in a condition for replacement. The determination can be made as a function of one or more data. In one exemplary embodiment, the determination is a function of one or more measurements of an impedance of a hydrogel bridge in a test module. In another exemplary embodiment, the determination is a function of one or more environmental condition data from one or more environmental sensors.