Pre-shock communication window to synchronize coordinated therapy

A first defibrillator comprising:

• a measurement circuit configured to detect an electrocardiogram (ECG) of a subject;
• a treatment circuit configured to output a primary electrical shock to the subject and to output a secondary electrical shock to the subject;
• an input device configured to receive an input signal from a rescuer;
• and
• a processor configured to:
• determine, by analyzing the ECG, that the subject has refibrillated after administration of the primary electrical shock;
• in response to determining that the subject has refibrillated after administration of the primary electrical shock, switch an operating mode of the first defibrillator from a single-shock mode to a multi-shock mode;
• in response to switching the operating mode of the first defibrillator from the single-shock mode to the multi-shock mode:
• during a predetermined delay period after the input device has received the input signal from the rescuer, output, to a second defibrillator, an instruction to administer a third electrical shock to the subject, the third electrical shock being temporally overlapping with the secondary electrical shock;
• and
• in response to expiration of the predetermined delay period after the input device has received the input signal from the rescuer, cause the treatment circuit to output the secondary electrical shock to the subject.