The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

BENCH STUDY OF HELIOX TANK DURATION WHEN USING THE LTV 1200 VENTILATOR

Joel M. Brown, Gary Dombroski, John S. Emberger, Victoria Weaver, Rozelle Clark; Christiana Care Health System, Newark, DE

Background: In the event of severe respiratory distress, due to obstructive airway pathology, heliox can be used to reduce the patients overall work of breathing. A RCP most often delivers heliox via a NRB mask, but also has been asked to deliver this gas mixture via mechanical ventilation both invasive and non-invasive. Over the past 4 years we have used Pulmonetics turbine driven ventilator LTV 1200 (LTV) as both a transport and critical care ventilator. In this study we wanted to determine if the LTV could accurately deliver heliox throughout the duration of the heliox tank. The tank used in the study was an “H” sized heliox 70/30 mixture. Method: This bench study was performed using a Michigan Instruments Inc. Dual adult test lung with the lung compliance set at 50 ml/cm H20 and a 5 cm H20/L/sec fixed airway resistor in line. The Novametrix NICO Cardiopulmonary Management System was used to obtain Exhaled Vt and PIP data at the test lung. The NICO was set to monitor heliox 70/30. We obtained a calculated Exhaled VT and Insp flow by multiplying the data found on the LTV patient monitoring screen by the heliox density factor of 1.6. An “H” sized heliox tank 70/30 was supplied to the LTV1200 ventilator via high pressure oxygen inlet. A total of 3 trials were performed using a new ventilator circuit for each one. The following ventilator settings were used for each trial: Volume Assist Control, RR=12, Vt=500mL It= 1.0second, PEEP=5cmH20. Results: The actual exhaled Vt from the LTV was 486mL +/- 20.0. The calculated Vt from the LTV was 777 +/- 32mL while the Vt on the NICO was 750 +/- 40.0mL. The LTV PIP was 21.01 +/- 1.13cmH2O and the NICO PIP was 21.05 +/-1.04cmH20. The “Low O2 Pressure” alarm, which is triggered when gas inlet pressure is less then 35 PSI, was activated at the end of each trial. The Vt on the NICO dropped shortly after the low gas pressure alarm activated. With a tank pressure of 1650 PSI the average tank duration was 3 hours 36 minutes +/- 25 minutes. The tank pressure decreased at a predictable rate (see graph for more information). Conclusion: The LTV 1200 accurately delivered the calculated Vt to the patients through all 3 trials. The PIP remained consistent for all 3 trials. The LTV appropriately alarmed when the tank pressure was below 50 PSI. The heliox was depleted from the tank at a predictable rate. Sponsored Research - None