The device was checked by dräger in follow-up of the event, the reported observation however could not be duplicated.Based on an initial log file check, a certain pcb was replaced as a precautionary measure.The unit was returned to use after having passed all tests against specifications.Log file analysis was provided by the manufacturer and revealed the following: the device performed the automatic power-on self-test (post) in the morning of the doe whereby the calibration of all pressure sensors failed.This led to a non-functional state of the device; the user power-cycled the workstation and cancelled the next instance of the post.A procedure was started using man/spont with switchover to volume mode one minute later.The device detected that the pressure monitoring of the ventilator unit was inoperable, forced an autonomous shut-down of automatic ventilation and posted the corresponding vent fail alarm.The user placed the device into standby shortly afterwards.Afterwards, the device was restarted again and, the user was requested by screen prompt to remove the breathing system from the device to allow a calibration of the pressure sensors.This was done successfully; the unit was subject to several repeated posts which were all passed.The replaced pcb has the pressure measurement onboard.It was returned to manufacturer for evaluation and installed into the periphery of a lab device.It did however not exhibit any deviation during a long-term test run.All in all, the root cause for the failure of the pressure monitoring during the course of event could not be found.Dräger finally concludes that the device responded as designed upon a deviation detected during pre-use check ¿ the workstation entered a non-functional state.It was the decision of the user to restart the device and to put it into operation without repeating the post.
|