A system for managing care of a person receiving emergency cardiac assistance is disclosed that includes one or more capacitors for delivering a defibrillating shock to a patient; one or more electronic ports for receiving signals from sensors for obtaining indications of an electrocardiogram (ECG) for the patient; a patient treatment module executable on one or more computer processors to provide a determination of a likelihood of success from delivering a future defibrillating shock to the person with the one or more capacitors, using (a) information about a prior defibrillating shock, and (b) a value that is a function of current ECG signals from the patient.