Type of reportable event: there was no death or device malfunction associated with the inappropriate defibrillation event.Device evaluation summary: monitor sn (b)(4) and electrode belt sn (b)(4) were returned and evaluated at the distributor, in accordance with procedures recommended by zoll manufacturing corporation.The evaluation included review of downloaded software flag files on the day of the event and incoming functional testing.The review of the software flags consisted of an analysis of the downloaded data to identify any fault flags or unusual patterns of software flags.The software flag files did not suggest a device malfunction that would contribute to the inappropriate treatment.During the incoming functional testing, a 1hz simulated normal sinus rhythm signal was applied to the ecg electrodes, followed by a 5hz simulated treatable arrhythmia signal which verified proper performance of the detection algorithm.During the transition to the 5hz signal, the device was confirmed to properly enter into a treatment sequence which includes a verification of the tactile vibration alarm, audio messaging, and siren alarms, as well as a test of the pulse delivery circuitry.The pulse delivery circuitry test verified proper charging of the high voltage capacitors and proper delivery of five full energy 150j biphasic pulses.The functional testing confirmed proper response button functionality, ecg acquisition, detection algorithm performance, and pulse delivery functionality.The investigation into the event concludes that there was no device malfunction.A cause and effect analysis was conducted using all of the available information which includes the incident report, device evaluation, software flag files, and ecg strips.The primary cause of the inappropriate shock was lack of response button use prior to shock delivery.The response buttons were pressed after the third treatment was delivered.The response buttons functioned appropriately.The ecg analysis, conducted by trained ecg technicians, identified the primary cause of the false detection was non-sustained ventricular tachycardia (nsvt).The rapid rate satisfied the rate detector of the detection algorithm.Inappropriate defibrillations are an anticipated risk associated with the use of the lifevest.Patients are instructed through alarms, voice messages, ifu, and training to press the response buttons to prevent an inappropriate defibrillation.(b)(4).A summary of the safety and effectiveness data (ssed), including the inappropriate defibrillation safety objective supporting fda's approval of the lifevest, can be found at http://www.Accessdata.Fda.Gov/cdrh_docs/pdf/p010030b.Pdf.The lifevest detection algorithm complies with iec 60601-2-4 performance requirements for sensitivity and specificity.
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A us distributor contacted zoll to report that a patient experienced one inappropriate shock followed by three appropriate shocks.It was reported that the patient became dizzy while walking at work before passing out.Non-sustained ventricular tachycardia (nsvt) contributed to the false detection.The rapid rate satisfied the rate detector of the detection algorithm.The patient received the first treatment while in nsvt at 180 bpm.The post-shock rhythm was sinus tachycardia at 120 bpm with nsvt at 180 bpm.The patient then received an appropriate treatment while in ventricular fibrillation (vf).The post-shock rhythm was an idioventricular rhythm/sinus bradycardia at 40 bpm with motion artifact.The patient then received a second appropriate treatment during ventricular tachycardia (vt) at 270 bpm with motion artifact.The post- shock rhythm was idioventricular tachycardia at 40 bpm with pvcs transitioning to sinus bradycardia at 30 bpm.The patient received the final appropriate treatment while their rhythm was vt at 280 bpm with motion artifact.The post-shock rhythm was sinus bradycardia at 30 bpm with motion artifact.The response buttons were pressed after the third treatment was delivered, but not immediately prior to the delivery of the fourth treatment.The response buttons functioned appropriately.The patient reportedly fell and hit his head, however no injuries were reported.The patient reportedly regained consciousness after the treatments.The patient was taken to the hospital after the event and continues wearing the lifevest.There was no death or device malfunction associated with the inappropriate defibrillation event.
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