Dräger evaluated the log file and could determine that a specific error code was logged frequently for the date of event.This error code indicates that the auxiliary vacuum pressure went out of range.The auxiliary vacuum pressure is needed to operate the valves which control the ventilation cycles and to keep the ventilator diaphragm in place during piston movement to avoid wrinkling.If the necessary vacuum pressure can't be built-up anymore this may lead to significant impairments in ventilation and/or severe damages to the ventilator unit.Consequently, the system reacts with a shutdown of automatic ventilation and generation of a corresponding alarm.The triggering conditions for the loss of vacuum pressure can be multiple; especially when reflecting that the involved device is almost 15 years old.The inlet dust filter for the pump may be occluded which inhibits pump operation, an issue with the pump itself would be imaginable as well as leakages in the control tubes used for valve actuation.Dräger contacted the user facility to obtain further information.It was reported that the hospital's biomed has checked the device and was unable to duplicate the error condition.This leads to the conclusion that the triggering condition for the loss of vacuum was of temporary nature only like e.G.A detached control tube at the apl bypass valve.A further differentiation is not possible without examination of the device which is inhibited due to the isolated location of the unit.Dräger recommended the precautionary replacement of certain parts with potential causal connection to the reported issue to avoid recurrence.Finally, it can be concluded that the device has responded as designed upon an error condition with unknown origin - automatic ventilation was shut-down for safety reasons and, the user was alerted to this condition by means of the appropriate alarm.Manual ventilation with the built-in breathing bag remains possible then.
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