The device was subject to an on-site check by the dispatched dräger service engineer who confirmed the reported ventilator failure upon log file review.The error condition could be traced back to the ventilator motor.The ventilator motor assembly was replaced, consequently.The device passed all consecutive tests and was returned to use.Evaluation of earlier reported similar events revealed that wear-and-tear related abrasion of the collector disc had resulted in development of positions where the motor does not provide mechanic power due to contact interrupts to the carbon brushes; speed fluctuations will be the consequence.The speed fluctuations result in a deviation between measured and expected piston position.The piston hub defines the applied tidal volume and thus, to prevent from potentially hazardous output and/or from damages to the ventilator unit, the system is designed to shut down automatic ventilation and to alert the user to this condition by means of a corresponding alarm.As confirmed for the particular case, manual ventilation and the monitoring functions remain available to the full extent.Dräger finally concludes that the device behaved as specified upon the malfunction of a single component after 15 years of use; no patient consequences have been reported.The repair exchange had fully solved the device problem.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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