The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Travis Leistiko1, Chris Schelde1

Background: Aerosolized prostacyclin (PGI2) has become an important therapy for selected patients with acute respiratory failure. Our current procedure for aerosolizing PGI2 through a ventilator circuit is to use a low-flow jet nebulizer fed varying concentrations of PGI2 by an IV pump. Variations in liquid volume within these nebulizers are common and are thought to be due to either condensation from the circuit, which could compromise the drug concentration, or the inability of these nebulizers to maintain the desired output. We sought an alternative and more reliable delivery method.

Methods: A Viasys Avea ventilator was configured with a standard circuit and humidifier attached to a universal test lung. An ultrasonic nebulizer (Aeroneb Pro-X) was placed proximal to the wye. PGI2 solution (0.03 mg/mL) was delivered to the nebulizer by an IV pump at varying infusion rates to achieve a dose equivalent to 10- 30 ng/kg/min (assuming a 70kg patient). The nebulizer was used in the continuous delivery mode. A 3-way stopcock and manometer was included between the IV pump and nebulizer reservoir chamber allowing us to monitor internal pressure variations.

Results: At the lowest infusion rate of 8 mL/hr (corresponding to 10 ng/kg/min), the drop of solution pumped into the nebulizer produced an aerosol that lasted approximately 15 seconds each minute. An infusion rate of 16 mL/hr (20 mg/kg/min) produced an aerosol lasting 40 seconds each minute. At 24 mL/hr (30 ng/kg/min) aerosol generation was continuous. Increasing the infusion rate to 32 mL/hr (40 ng/kg/min) resulted in continuous aerosol production and an adequate volume maintained in the reservoir chamber. The lowest possible infusion rate necessary to maintain a continuous aerosol was 20 mL/hr. At infusion rates greater than 32 mL/hr, the nebulizer ceased output due to elevated chamber pressure.

Conclusion: An ultrasonic nebulizer feed by an IV pump can provide titratable delivery of aerosolized PGI2 during mechanical ventilation. Characteristics of the nebulizer output capability limit the range of doses that can be delivered continuously using a single PGI2 solution concentration.