Patent ID: 8903498

Claim:
An external medical device, comprising: a housing; a user interface in connection with the housing; and a processor within the housing configured to: cause the user interface to issue a first prompt instructing a user to cause chest compressions to be delivered to a patient during a cardiopulmonary resuscitation (CPR) period, the delivered chest compressions having a chest compression frequency f; receive an input signal for the patient receiving the chest compressions; select a comb filter mechanism; apply the comb filter mechanism to the input signal to at least substantially remove chest compression artifacts from the input signal, wherein the chest compression artifacts correspond to the chest compressions being delivered to the patient, and wherein the comb filter mechanism substantially rejects content in the frequency f plus content in at least one more frequency that is a higher harmonic to the frequency f but substantially passes frequencies between the frequency f and the higher harmonic; and determine a recommendation based at least in part on a result of the application of the comb filter mechanism to the input signal and at least one other parameter, the recommendation being selected from a group consisting of the following: shock, no-shock, and indeterminate.