Upon checking the log files the dispatched fse could confirm problems with the ventilator motor and replaced it, consequently.The device passed all consecutive tests and could be returned to use.Evaluation of the motor was not considered necessary since the phenomenon is known from earlier reports of the same nature.Wear-and-tear related abrasion of the collector disc may develop positions where the motor does not provide mechanic power due to contact interrupts to the carbon brushes; speed fluctuations will be the consequence.Since the motor speed is being monitored continuously, the speed fluctuations result in a deviation between measured and expected piston position.To prevent from damages the system is designed to shut down automatic ventilation and to alert the user to this condition by means of a corresponding alarm.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 11 years of use; no patient consequences have been reported.The repair exchange has 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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