Defibrillator with protocol for selectively interrupting cpr

A defibrillator for detecting a shockable heart rhythm during CPR comprising:

• a high voltage delivery circuit for delivering electrotherapy;
• an ECG front end circuit coupled to a source of ECG signals;
• a controller communicatively coupled to the ECG front end circuit, comprising
• a CPR analyzer for identifying periods of no CPR activity,
• a treatment decision processor responsive to the ECG signals which acts to estimate the likelihood of a shockable rhythm existent during a CPR period and which determines whether CPR should be interrupted prior to the end of the CPR period to deliver electrotherapy, wherein the treatment decision processor uses ECG signals obtained only during the periods of no CPR activity as identified by the CPR analyzer, and further wherein the treatment decision processor determination is based on ECG signals accumulated over two periods of no CPR activity as identified by the CPR analyzer separated by a period of CPR activity as identified by the CPR analyzer;
• and
• a user interface, responsive to the controller determination, which provides an output instruction to stop CPR and a subsequent output instruction to deliver electrotherapy through the high voltage circuit.