The investigation was performed based on the available information and analysis of the electronic log file.A sporadic malfunction of a cpu board, which controls the device-internal communication between user interface and vgc (ventilation and gas controller), was identified to be root cause of the reported failure.This internal communication failure leads to a shutdown of the ventilator and gas mixer simultaneously.In this situation, the device automatically switches to monitoring mode while alarming the user to this condition by means of a corresponding alarm.Manual ventilation with emergency oxygen dosage remains possible including the application of anesthetic gas as well.The monitoring functionality remains unaffected.The procedure how to establish the emergency gas supply is described in the instructions for use.Dräger finally concludes, that the device has reacted according to its safety concept and has performed an emergency shutdown of the affected components accompanied by the respective alarms.After the shutdown the user rebooted the device, performed a successful power-on self-test and continued the ventilation using volume mode without further issues.Similar cases are known ¿ however, the exact failure mechanism could not be determined during in-depth analysis.It was only possible to narrow down the root cause to the respective pcb, which was already replaced as a precautionary measure.The fact that the identical type of board is used in the workstation twice and does not exhibit malfunctions in the second application periphery makes a general design issue rather unlikely.A reasonable explanation would be electrostatic discharge of the user during interaction with the device or any other kind of electromagnetic disturbance that exceeds the immunity barriers of the device.The apollo was developed in compliance to the requirements of iec 60601-1-2.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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