A Wireless Monitoring Apparatus is used in conjunction with an automated external defibrillator (AED) system for patient rescue in mass-casualty incidents. The rescuer applies the device on each patient. The wireless monitoring apparatus automatically analyzes the patient's heart rhythm and communicates with the AED system. The AED system is therefore is able to display information with regard to each patient, notifies the rescuer on actions to take and can deliver defibrillation therapy if needed.