There was no death or device malfunction associated with the inappropriate defibrillation event.Device evaluation summary: electrode belt sn (b)(4) and monitor sn (b)(4) have not yet returned from the field.Device evaluation included review of downloaded software flag files on the day of the event.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.The software flag files revealed a shock occurred during the time in question and the response button was not depressed.Review of the ecg strip showed that at the time of the shock the patient's rhythm was atrial fibrillation with rapid ventricular response above the patient's physician prescribed treatment threshold.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 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 af with rvr.The rapid rate satisfied the rate detector of the detection algorithm.The following factors could not be ruled out as potential contributing sources (per cause and effect diagram 90e0012_a09_revfi) to the reported problem.The factors are: rate exceeds programmed threshold, ecg morphology change, patient error - did not follow training or respond to ifus, alarms, voice prompts, patient pressed response buttons earlier in detection sequence, but did not press response buttons prior to shock.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.The current commercial inappropriate defibrillation rate is consistent with the observed rate during the pivotal clinical trial (b)(4) (0.69% per patient-month with 90% confidence).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.
|