The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts


Ross Armstrong1, David Strong1, Ridwan Awad2, Lonny Ashworth2; 1St. Luke's Regional Medical Center, Boise, ID; 2Boise State University, Boise, ID

Background: Airway Pressure Release Ventilation (APRV) is a mode of ventilation that is used by some clinicians, in the management of patients with ARDS. By combining two different levels of CPAP, APRV allows the patient to breathe spontaneously at any point during the respiratory cycle. Frequently, during APRV the TimeLow is set to end when a percentage of the Peak-Expiratory Flow Rate (PEFR) is reached. AutoRelease is an option available on the Drager V500 that allows the clinician to set the release percentage, and then automatically switches to TimeHigh when the flowrate reaches this level. The purpose of this study is to measure the accuracy of AutoRelease percentage, while ventilating an electronic lung simulator at two different levels of resistance and compliance with three different release percentages. Method: The Hans Rudolph HR 1101 Electronic Lung Simulator was interfaced, using a size 7.5 ETT, to the Drager V500. Settings on the HR 1101 were: Resistance 10 and 20 cm H2O/L/sec, Compliance 15 and 25 mL/cm H2O, Rate 0/minute, Amplitude 0, Target Volume 3000 mL, Load Effort Default. The Drager V500 was placed in APRV at TimeHigh 5 seconds, PressureHigh 25 cm H2O, PressureLow 0 cm H2O, Tube Compensation 100%. At each compliance and resistance setting, AutoRelease was set to 25, 50 and 75%. PEFR was measured as the greatest flowrate during TimeLow. The lowest expiratory flow rate was measured by scrolling over one interval on the screen from the lowest pressure during TimeLow. The release percentage was calculated by taking the lowest expiratory flow rate and dividing it by PEFR. Results: Every measured average release percentage was lower than the release percentage set with AutoRelease, except the 25% release with a compliance of 25 ml/cm H2O and resistance of 20 cm H2O/L/sec. Conclusion: Clinicians are limited by the intervals displayed on the V500 screen when manually calculating a release percent during TimeLow. When setting TimeLow on patients with increased resistance and decreased compliance, clinicians may find AutoRelease more accurate due to limitations of cursor intervals on the V500 screen.
Sponsored Research - None