The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts


Brent Kenney1, David Wheeler2; 1Respiratory Care Service, Mercy St. John's Health System, Springfield, MO; 2Cardiothoracic Anesthesia, Cleveland Clinic, Cleveland, OH

BACKGROUND: The Drager VN500 is a dedicated Neonatal and Pediatric ventilator that entered service in the Level 3 NICU in last November. The ventilator mode used in the NICU with the VN500 was PC-SIMV, and the software version was 2.10. Immediately upon connection to a patient the therapist in attendance noted a consistent alarm pattern. Upon assessment it was noted that the alarm indicated a PEEP high condition. METHODS: The patient-ventilator system was assessed and evaluated for obstruction of the endotracheal tube, expiratory valve or ventilator tubing. There was no identifiable source of obstruction identified. There was no identifiable cause for excessive PEEP and the ventilators were secured for evaluation in a controlled environment. RESULTS: Three newly acquired VN500 ventilator platforms were evaluated in the laboratory environment using the Michigan Instruments 5601i Adult/Infant test lung utilizing ventilator parameters commonly employed in our the Neonatal environment. Test lung settings were Compliance 0.003 L/cmH2O, Resistor Rp50, Infant Lung. VN500 settings were: Mode - PC-SIMV, Pinsp - 20cmH2O, PEEP 5 cmH2O, Frequency - 50/minute, and Inspiratory Time - 0.35 seconds. The data acquired from the Michigan Instruments5601i Adult/Infant test lung validated the hypothesis that during routine FIO2 adjustment the VN500 automatically adjusts the bias flow to expedite the FIO2 change. This rapid alteration of bias flow actuated the PEEP high alarm. The PEEP high alarm is triggered when the baseline PEEP exceeds 4 cmH2O greater than clinician set PEEP. The high auto-PEEP condition is created by the ventilators controlling algorithms furtive changes in bias flow. In addition to the excessive auto-PEEP increase during the FiO2 adjustment there is a baseline PEEP decrease following the FIO2 change. Graphic analysis demonstrates both the increase in PEEP created by the excessive flow increase and the excessive delay in the realization of the baseline, clinician set, PEEP. CONCLUSIONS: The VN500 and the initial software (2.10) created excessive and potentially dangerous levels of Auto-PEEP as well as a momentary loss of clinician set PEEP in our NICU. This iatrogenicaly created level of Auto-PEEP and co-attendant loss of baseline PEEP may be harmful in the context of an NICU. The final resolution is not in place 6 months after discovery and notification of the manufacturer.
Sponsored Research - None
Michigan Instruments 5601i Test Lung Data
Ventilation by Drager VN500 Neonatal/Pediatric Ventilator