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An Alternative Method for Aerosolized Prostacyclin Administration during Mechanical Ventilation Harborview Medical Center Seattle,Washington Travis J Leistiko RRT, Christopher W Schelde RRT, David R Park MD Aerosolized prostacyclin (PGI 2 ) has become an important therapy for selected patients with acute hypoxic respiratory failure Our current PGI 2 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 PGI 2 delivery method Introduction Results  An Aeroneb Pro vibrating mesh nebulizer used in the continuous mode of delivery can be an effective delivery device of aerosolized PGI 2  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 Figure: photo diagram of delivery setup BACKGROUND: Aerosolized prostacyclin (PGI 2 ) has become an important therapy for selected patients with acute respiratory failure. Our current procedure for aerosolizing PGI 2 through a ventilator circuit is to use a low- flow jet nebulizer fed varying concentrations of PGI 2 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. PGI 2 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 PGI 2 during mechanical ventilation. Characteristics of the nebulizer output capability limit the range of doses that can be delivered continuously using a single PGI 2 solution concentration. AbstractMethods and Materials 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 +5cmH 2 O and on room air then attached to a universal test lung A Novametrix CO 2 SMO 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 PGI 2 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 (PGI 2 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 InfusionAerosol producedReservoir volumeAerosol Rate PGI 2 one minute cycleafter one hourcessation 8ml/hr15 secondsVolume depleted No 16ml/hr40 secondsVolume depleted No 20ml/hr60 secondsVolume depleted No 24ml/hr60 seconds~ 1ml remaining No 32ml/hr60 seconds~ 3ml remaining Yes For further information: Please contact leistiko@u.washington.edu Figure: photo diagram of delivery setup