2007 OPEN FORUM Abstracts
BREATH ANALYSIS OF ADAPTIVE SUPPORT VENTILATION AND PROPORTIONAL ASSIST VENTILATION
S. Richey1, D. Grooms2
Table 1: A Comparison Between ASV & PAV
Background: Adaptive Support Ventilation (ASV,Hamilton Medical) and Proportional Assist Ventilation (PAV,Tyco Healthcare) are two modalities that assess patient work of breathing and incorporate this data into their algorithms to titrate the compensation pressure and additionally frequency in ASV. The purpose of this study was to explore the differences between the two modalities in a simulated spontaneous breathing model applying various work loads throughout constant minute ventilation.
Methods: The two ventilators under investigation were alternatively connected to a simulated spontaneous breathing model consisting of a dual chamber, Double TTL test lung (Michigan Instruments). One test lung (driving model) was powered by a Galileo Ventilator (Hamilton Medical) to generate spontaneous breathing of a second test lung (spontaneous model). The Volume Control-CMV mode was used for the driving ventilator with the following settings: Vt = 530, Frequency = 14 (minute ventilation= 7.42), I-time = 1.0 seconds, PEEP= +5, Peak flow = 51 lpm delivered with a sinusoidal waveform pattern, which created a peak inspiratory flow at the proximal end of the E.T.T. of 18 lpm on the spontaneous model. Flow measurement was verified utilizing a âBicoreâ monitoring device (Bicore Monitoring Systems). ASV settings: Ideal Body Weight= 73kg, Minute Volume %= 100, pramp=25ms, ETS=25%, Trigger= 2 cmH2O, PEEP=0. PAV settings: 80% compensation, PEEP=0, Trigger= 2 cmH2O. Test conditions consisted of: 1. static compliance of 50 ml/cmH20, with added resistance of 6 & 9 cmH2O/L/sec 2. static resistance of 4 cmH2O/L/sec, with compliance changes of 70,50, & 30 ml/cmH20. Breath Analysis consisted of capturing time and pressure data from the proximal end of the E.T.T. by utilizing the Galileoâs Auxiliary pressure port and Data Logger software (Hamilton Medical). The âArea Under the Curveâ was calculated for each breath using the âlinear trapezoidal ruleâ & the paired two sample t test was used to evaluate differences between the modalities using spreadsheet software (Excel, Microsoft). A p value less than 0.05 was considered statistically significant.
Results: There were considerable differences with all measured respiratory data when comparing ASV to PAV in every test scenario (table 1).
Conclusion: There are many differences between the two modalities in regards to breath delivery, and compensation pressure. Conversely, both modes ventilated with safe tidal volumes and PIP.
|Minute Ventilation (p=0.03)||7.44 lpm||8.54 lpm|
|Tidal Volume (p=0.01)||491.20 ml||610.60 ml|
|Frequency Total (p=0.03)||15 bpm||14 bpm|
|Frequency Spontaneous (p=0.01)||3 bpm||14 bpm|
|Inspiratory Time (p=0.01)||1.73 seconds||1.00 seconds|
|Area Under the Curve (p=0.01)||232.93 cmH2O||186.20
|Peak Pressure (p=0.01)||12.14 cmH2O||15.98 cmH2O|
All measured values are displayed as "means". Area Under the Curve was used to calculate total pressure compensation.