Explanation: there was no death or device malfunction associated with the inappropriate defibrillation event.There is no indication that the patient sustained a serious injury.Device evaluation summary: monitor sn (b)(4) and 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.Device manufacture date: monitor - 02/09/2012; belt - 07/24/2013.The investigation into the event concludes that there was no device malfunction.A cause and effect analysis was conducted (attached) 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 improper response button use (response buttons were pressed earlier in the detection sequence but not immediately prior to treatment delivery).The ecg analysis, conducted by trained ecg technicians, identified the primary cause of the false detection was supraventricular tachycardia (svt) rate at the prescribed treatment threshold.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 an inappropriate defibrillation event consisting of one shock.A nurse had initially reported that the patient was walking to the bathroom, fell, and was treated.No injuries were reported.The patient later reported that he was walking to the kitchen, became dizzy and sat down at the time of the event.The patient's wife was reportedly trying to press the response buttons and the patient was treated.Supraventricular tachycardia at the prescribed treatment threshold contributed to the false detection.The rapid rate satisfied the rate detector of the detection algorithm.The response buttons were pressed earlier in the detection sequence but not immediately prior to treatment delivery.The response buttons functioned appropriately.Following the treatment, the patient was hospitalized.The patient remained in the hospital and continued wearing the lifevest.
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