Method of using a medical device

A method of using a medical apparatus, the method comprising the steps of:

• providing the medical apparatus configured to perform an initial-state function;
• the medical apparatus further configured to be modified by the addition of contents of one or more adaptor kits to perform a new medical function;
• the medical apparatus further configured to be hand-held by a person;
• and to accept and operationally integrate into the medical apparatus, the contents in a wearable automated external defibrillator adaptor kit (a wAED adaptor kit);
• the contents of the wAED adaptor kit comprising a wAED cartridge and at least one accessory;
• providing a harness and disposable electrode pads, wherein the harness is configured:
• to be secured on the person and attached to the medical apparatus;
• and
• providing the wAED adaptor kit, wherein the wAED cartridge and the harness are configured to be accepted and to be operationally integrated into the medical apparatus and further configured to enable the medical apparatus to perform a new medical function of a wearable automated external defibrillator (wAED).