The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

ACCURACY OF DELIVERED TIDAL VOLUME USING ADAPTIVE SUPPORT VENTILATION ON THE HAMILTON G5 WHEN VENTILATING AN ELECTRONIC TEST LUNG SIMULATING COPD AND ARDS

Hiroyuki Noguchi1, Lonny J. Ashworth2



Background: The Hamilton G5 has a feature referred to as Adaptive Support Ventilation (ASV). The purpose of ASV is to deliver the optimal tidal volume based upon the patient's airway resistance and compliance. As the patient's airway resistance and compliance change, the Hamilton G5 alters the level of pressure support to provide the target tidal volume at the lowest pressure possible. The purpose of this study was to compare the target tidal volume to the actual tidal volume when ventilating an electronic test lung simulating a COPD model and an ARDS model.

Methods: A Hamilton G5 was connected to an electronic lung simulator (Hans Rudolph HR 1101). HR 1101 settings: Amplitude 10, Effort Slope 5, % Inhale 20, Target Volume 3000 mL, Load Effort Normal, Rate 15/minute. Hamilton G5 settings: 100% Minute Ventilation, PEEP 5 cm H2O. To simulate a COPD model the compliance remained at 40 mL/cm H2O as the resistance was increased: 15, 20, 25 then 30 cm H2O/L/sec. To simulate an ARDS model the resistance remained at 10 cm H2O/L/sec as the compliance was decreased: 25, 20, 15 and 10 mL/cm H2O. The G5 ventilated the HR 1101 for two minutes between changing settings. At the end of the two minute period, the displayed tidal volume was recorded at the end of every minute for five minutes. The HR 1101 was then changed to the next level of resistance for COPD or to the next level of compliance for ARDS.

Results: The five recorded values for displayed tidal volume were average for each of the settings. The averaged tidal volume was subtracted from the target tidal volume; this difference was divided by the target tidal volume and expressed as a percentage. With the COPD model, as airway resistance increased the percent difference was 1.36, 1.94, 1.24 and 1.5%. With the ARDS model, as compliance decreased, the percent difference was 2.11, 3.48, 2.71 and 3.66%.

Conclusion: The Hamilton G5, during Adaptive Support Ventilation, appears to deliver a tidal volume very close to the target tidal volume when using an electronic lung simulator as airway resistance and compliance change. In addition, the delivered tidal volume was very consistent on each breath. Further studies are necessary to determine the accuracy of the delivered volume using Adaptive Support Ventilation on the Hamilton G5 when ventilating patients