Dual sequential defibrillation (DSD) systems and methods include the use of a timing device. The timing device can assist a user with DSD administration by providing notifications spaced apart by the inter-shock timing. The user can use these notifications to trigger the administration of defibrillation in a sequential manner. The timing device can also be coupled to two defibrillation devices and can output a signal to each of the defibrillation devices to cause the defibrillation device to administer a defibrillation. The output of the signals by the timing device can be spaced apart by the inter-shock timing. Additionally, the signals can be QRS-like in nature to cause the defibrillation devices to administer a defibrillation when in a sync mode.
