The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

COMPARISON OF NEGATIVE INSPIRATORY FORCE MEASUREMENTS USING THE DRAGER XL VENTILATOR, THE VENTRAK 1550 MONITOR, AND THE MAGNAHELIC PRESSURE GAUGE

Mark Siobal1, Julin Tang1, Hannah Ong2



Background: The Drager XL Ventilator (Drager Medical, Telford, PA) is equipped with an automated negative inspiratory force (NIF) maneuver. In clinical practice differences between the ventilator and hand held pressure manometer measurements of NIF have been noted. We compared simultaneous NIF measurements through the Drager XL Ventilator with the Magnahelic Pressure Gauge (Dwyer Instrusments, Michigan City, IN) and the Ventrak 1550 Monitor (Novametrix, Wallingford, CT) during a lung model simulation of spontaneuos breathing efforts.

Methods: A dual chamber Michigan Instruments Test Lung (Grand Rapids, MI) with the two chambers locked together was ventilated on one side (muscle chamber) by a Versamed iVent Ventilator (VersaMed, Pearl River, NY) set in the pressure control mode at a frequency of 10 breaths per minute. The duration (DUR) and intensity (INT) of the force applied to the muscle chamber was set at combinations of 0.5 and 1.0 second and 15 and 30 cm H20. A Drager XL Ventilator with PEEP and Pressure Support set to zero, with a Ventrak 1550 flow/pressure sensor and a Magnahelic Pressure Gauage placed between the ventilator circuit and the other chamber of the test lung (lung chamber) was used to simultaneouly measure NIF. During each DUR and INT setting the Drager Ventilator automated NIF maneuver was performed and compared to the negative pressure recorded by the Ventrak Monitor and the Magnahelic Pressure Gauge (Test 1). The Drager Ventilator circuit was then disconnected and an occlusion test was performed with just the Ventrak Monitor and Magnahelic Pressure Gauge (Test 2). Test 1 and Test 2 were repeated with 5 Magnahelic Pressure Gauges at each DUR and INT combinations.

Results: Two of the 5 Magnahelic pressure guages were found to need calibration because of NIF measurements significantly higher or lower than both the Drager Ventilator and the Ventrak Monitor. The NIF measurements by the Drager XL Ventilator (V) did not differ from the measurements by the Ventrak Monitor (VT) or the three remaining Magnahelic Pressure Guages (M) during either test.

Conclusion: NIF measurements using the Drager XL Ventilator automated maneuver agrees with measurements from the Ventrak Monitor and calibrated Magnahelic Pressure Gauges during simulated spontaneous breathing efforts.