Both are semi-automatic HeartSine AEDs that share the same 2.4-lb form factor, IP56 ruggedness rating, 4-year Pad-Pak cartridge, SCOPE biphasic waveform, and 8-year warranty. The single functional difference is CPR Rate Advisor: the 450P includes it, the 350P does not. The 450P uses ICG (impedance cardiogram) signal through the defibrillator electrodes to measure the actual rate of CPR compressions being delivered, then coaches the rescuer with real-time audio and visual feedback ("push faster," "push slower," "good speed"). The 350P provides voice prompts and a CPR metronome only, with no real-time rate measurement. The 450P typically costs $200 to $300 more than the 350P. Choose the 450P for untrained rescuer programs where compression rate quality matters; choose the 350P for trained responder programs or tighter budgets.
