Silver Spring Ambulance has upgraded the model of Automated External Defibrillators (AED) carried on the ambulances.  The new units will replace the Physio-Control Lifepak 500 defibrillators, which have been discontinued by the manufacturer.  The new Physio-Control Lifepak 1000 defibrillators feature a rugged construction and are programmable to match the Pennsylvania Department of Health protocol for High Performance CPR.