Embodiments of the invention include systems, protective casings for smartphones, and associated methods to enhance use of an automated external defibrillator (AED) device before arrival of emergency medical personnel. A system can include a smartphone and a protective casing abuttingly contacting one or more side portions of the smartphone and retaining the smartphone positioned therein. The smartphone can include a defibrillation control module to control defibrillation of a victim of sudden cardiac arrest. The protective casing can include sensors, capacitors, and extendable electrode pads. The protective casing further can include a check module to determine whether the victim's heart rhythm requires an electrical shock to reestablish a normal heart rhythm, a space module to measure presence and amount of preselected materials relatively near the system, and a shock module to activate the one or more capacitors and generate an electrical current to deliver an electrical shock to the victim's chest.