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: Variable pressure support (VariablePS) is a new option available on the Drager V500. VariablePS varies the pressure support at a fixed percentage determined by the clinician, allowing a spontaneously breathing patient the ability to retain a normal, spontaneous tidal breathing pattern, which is highly variable with differing volumes, flows, and inspiratory times. An increasing amount of literature is supporting modes of ventilation, both assisted and mandatory, that allows for variability of the normal breathing pattern.1 The purpose of this study is to determine the variability of the Peak Inspiratory Pressures (PIP) and associated inhaled tidal volumes. 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 12 cm H2O/L/sec, Compliance 30 mL/cm H2O, Rate 15/minute, Amplitude 5, Load Effort Normal. The Drager V500 was placed in PCV-PS with VariablePS active, PEEP of 5 cm H2O, Tube Compensation off, Slope 0.20 seconds, Inspiratory Flow Termination 25%, Pressure Support of 10, 15 and 20 cm H2O, Variances of 30% and 60%. At each pressure support setting with 30% and 60% variances, PIP and Inhaled Tidal Volume (Vti) were measured on the V500 for each breath. Data were measured on each breath for a total of 450 breaths. Results: The pressure support means were within 1 cm H2O of the set PIP (PEEP + pressure support). Volumes were highly variable depending on the amount of pressure support set and the percentage of variation applied to the pressure support. When set at 30% Variance, PIP was as low as 20% and has high as 40%. When set at 60% Variance, PIP was as low as 50% and as high as 60%. Conclusion: VariablePS provided a varying level of pressure support at each percent setting. Results demonstrated a variable tidal breathing pattern on a spontaneous breathing test lung. When using VariablePS, clinicians need to consider the PIP's and volumes that could be generated when a greater variability percentage is set using PCV-PS with VariablePS.
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