The device was checked by a dräger service engineer after the second event.The power supply was replaced as a precautionary measure; the device was tested and could be returned to use.The replaced power supply as well as the log file were evaluated by the manufacturer.The power supply was free of deviations but it could be determined that a certain flag was set in the software which indicates that the back-up battery which was connected to it at the time of event was used up.The entries in the log confirm the reported observations.During the first procedure of the day the device software registered a mains power outage and posted a corresponding alarm.The internal back-up battery was charged to 100% at the time the daily pre-use check was performed but it became depleted down to 10% residual capacity within 3 minutes.The device performed a reboot when the battery voltage dropped below the level which is required to drive the ventilator motor but could not restore operation due to insufficient energy supply.The operator used the device in manual ventilation for 13 more minutes before the workstation was power-cycled.Normal operation could be re-established again and, the surgical procedure was run for additional 33 minutes without further issues.The course of event was more or less the same during the second event - after 30 minutes into the procedure the device alarmed for "battery low" due to the fact that the residual capacity underran 10%.An automatic reboot could not restore function and the device alarmed for "vent fail".Dräger finally concludes the following: due to the fact that the replaced power supply did not exhibit any deviations, the "mains power loss" alarm during the first procedure had no device-internal root cause.An outage of the hospital's energy supply would be imaginable but more likely is an incompletely plugged power cord.This would explain why power-cycling the workstation was able to restore function; the electrical contact was obviously lost only intermittently before.During the second procedure the contact of the power cord must have been lost again and, the overaged internal battery could not ensure further operation of the device.Hence, the case was a consequence of lack of preventive maintenance (overaged battery) and unintended use error (power cord defective or loosely connected.The device clearly indicates via screen icon on which energy source it runs.A loss of mains power for whatever reason triggers a corresponding alarm and, the residual capacity is being displayed continuously with depletion alarms at 20%, 10% and 0% as required in the applicable standard.
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