An Alternative Method for Aerosolized Prostacyclin Administration during Mechanical Ventilation

1. An Aeroneb Pro vibrating mesh nebulizer used in the continuous mode of delivery can be an effective delivery device of aerosolized PGI2 • Depending on the infusion/delivery rate, the nebulizer output was more or less continuous • The nebulizer added no significant volume to the delivered tidal volumes • Whether frequent bursts of drug aerosolization should be considered a continuous aerosol should be determined due to the intermittent pauses reported in this bench study and as stated by the manufacturer • This was an independent bench study with no outside funding provided to the individuals involved Introduction • Aerosolized prostacyclin (PGI2) has become an important therapy for selected patients with acute hypoxic respiratory failure • Our current PGI2 delivery method (using a jet nebulizer fed by IV pumps that mix varying amounts of drug solution and diluent) is effective but inconvenient • The advent of a new continuous aerosolization mode of the vibrating mesh nebulizer Aeroneb Pro X (Aeroneb LTD, Galway Ireland) led us to explore whether it could be a practical and more reliable alternative to our current PGI2 delivery method Travis J Leistiko RRT , Christopher W Schelde RRT , David R Park MD Results An Alternative Method for Aerosolized Prostacyclin Administration during Mechanical Ventilation Abstract Methods and Materials 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 vibrating mesh 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: A vibrating mesh nebulizer fed 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. • A Viasys Avea (Yorba Linda, Ca) ventilator was configured as per our policy with concha type humidity and set at a frequency of 12 per minute, tidal volume 500mL,PEEP +5cmH2O and on room air then attached to a universal test lung • A Novametrix CO2SMO Plus! Monitor ( Novametrix Medical Systems, Inc Wallingford, Ct) was placed at the patient wye to monitor any variations in pressures and/or volumes showing no additional volume added to tidal volumes • A universal manometer was attached using a 3 way stop-cock adapter to monitor any internal pressure variations in the delivery device showing increased pressure buildup causing aerosol cessation at 32mL/hr infusion rate • With each PGI2 infusion rate change the nebulizers reservoir chamber was primed to the recommended 4mL volume of medication • Each infusion rate ran for 4 hours respectively and was initiated at 8mL/hr (PGI2 aerosolization equivalent to 30ng/kg/min in a 70 kg person) and increased incrementally until a continuous aerosol and volume remaining in reservoir could be achieved • We measured the proportion of time that aerosol generation was maintained, and whether or not the reservoir volume was depleted Conclusions Harborview Medical Center Seattle,Washington Figure: photo diagram of delivery setup Figure: photo diagram of delivery setup For further information: Please contact leistiko@u.washington.edu