Transcript 2008 Open Forum Poster

An Alternative Method for Aerosolized Prostacyclin Administration during Mechanical Ventilation
Travis J Leistiko RRT , Christopher W Schelde RRT , David R Park MD
Harborview Medical Center Seattle,Washington
Abstract
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 lowflow 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.
Introduction
• Aerosolized prostacyclin (PGI2) has become an important therapy
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Methods 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 +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
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
Results
Infusion
Aerosol produced
Reservoir volume
Aerosol
Rate PGI2
one minute cycle
after one hour
8ml/hr
15 seconds
Volume depleted
cessation
No
16ml/hr
20ml/hr
40 seconds
60 seconds
Volume depleted
Volume depleted
24ml/hr
60 seconds
~ 1ml remaining
32ml/hr
60 seconds
~ 3ml remaining
No
No
No
Yes
Conclusions
 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
Figure: photo diagram of delivery setup
•Figure: photo diagram of delivery setup
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