Abstract: What is described is wearable device for a user comprising: at least one motion-state sensor; at least one oximetry sensor; an alarm module configured for transmitting an emergency signal; and a device control logic comprising firmware or embedded software, wherein the motion-state sensor activates the device control logic upon sensing a no-motion or low-motion state of the user, and the oximetry sensor activates the device control logic during a low-oxygenation or low-respiration state of the user, in which the wearable device continuously monitors and detects a respiratory emergency of the user. Also described is a system comprising the wearable device to communicate an emergency alert to appropriate responders, and a method of using the wearable device for a person at risk of respiratory failure.