PERSEUS A500

Description of Event or Problem

THE DRAEGER A500, WHEN IN A FLOW-TRIGGERED MODE, OCCASIONALLY WILL DELIVER A RAPIDLY OSCILLATING PRESSURE, AT A NON-PHYSIOLOGICALLY RAPID FREQUENCY, RESULTING IN LITTLE OR NO EFFECTIVE GENERATION OF TIDAL VOLUME. THIS RESULTS IN A SITUATION IN WHICH THE PATIENT IS NOT BEING VENTILATED. WHEN THIS OCCURS, THE MACHINE GIVES NO WARNING THAT IT IS UNABLE TO DELIVER AN APPROPRIATE VENTILATORY PATTERN. FOR PATIENT FLOW TRIGGER DETECTION, THE SOFTWARE ALGORITHM OF THE PERSEUS A500 UTILIZES AN EXPIRATORY PROTECTION TIME OF 150 MS. EXPIRATORY PROTECTION TIME DENOTES THE TIME FRAME FROM THE BEGINNING (AT THE START) OF THE EXPIRATORY PHASE WHERE TRIGGER EVENTS ARE IGNORED. DEPENDING ON VARIOUS PATIENT CONDITIONS, THIS EXPIRATORY PROTECTION TIME IS TOO SHORT, RESULTING IN THE OBSERVED CONDITION. INCREASING THE EXPIRATORY PROTECTION TIME RESOLVES THE POTENTIAL FOR THE ISSUE TO OCCUR. THE EXPIRATORY PROTECTION TIME IS NOT A USER SETTABLE PARAMETER AND NEEDS TO BE CHANGED WITHIN THE SOFTWARE OF THE PERSEUS A500. A SOFTWARE REVISION IS IN THE PROCESS OF BEING DEVELOPED.