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The log file of the affected device was provided and analysed for the investigation.Based on the log file analysis, the reported event could be confirmed: on the 27th of december 2023 at 01:59 system time, the device performed an unexpected, synchronized restart of the ventilator and the display unit.The root cause was determined to be an access problem in the software task processing.The safety concept of the device provides that the software monitors the function of the device with regard to correct operation.If a deviation is detected during operation of the ventilator, the safety software triggers a synchronized restart of the ventilator and the display unit to bring the system into a specified state.During the restart sequence, ventilation is temporarily interrupted, and the safety valve is opened to ambient, allowing the patient to breathe spontaneously.The restart is indicated by an activated auxiliary acoustic alarm.A single ventilator restart sequence lasts up to 8 seconds until the device automatically resumes ventilation with the last settings.The display unit restart sequence can take up to a maximum of 1 minute.In the meantime, the user can observe the ventilation already resumed and safety-relevant parameters such as fio2 concentration, minute volume and airway pressure on the oled display of the ventilator.Finally, the alarm message "ventilation unit restarted" with accompanying acoustic alarm is displayed on the display and the additional acoustic alarm goes off automatically.In the present case, the ventilator has reacted as specified to the detected deviation and resumed ventilation with the last settings after the restart.The number of similar cases, related to the same root cause, is within the expected range of the respective risk assessment and thus accepted.
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