Scintigraphic Assessment of Radio-Aerosol
Pulmonary Deposition With the Acapella
Positive Expiratory Pressure Device and
Various Nebulizer Configurations
Brian K. Walsh, RRT-NPS, RRT-ACCS, RPFT, FAARC
Boston Children’s Hospital and
Harvard Medical School
Background
• There are several components to optimal delivery
of medications to the pulmonary system
– Breathing patterns – including muscle weakness
– Diameter of the airway – mucus, inflammation,
bronchospasm or maybe a combination
• Inhaled medications can promote hydration,
reduce viscosity, bronchodilate and aide in
mucociliary clearance
– Has become an acceptable adjunct
Background
• Bronchial hygiene therapy involves
noninvasive and invasive techniques to assist
with mobilization and clearance.
• Two modalities are:
– Positive expiratory pressure (PEP)
– High frequency oscillatory PEP
• PEP – to stabilize the airways, preventing
collapse and possibly improving collateral
ventilation
Moving Stenosis and Collateral
Ventilation
Walsh, Resp Care, 2011; 56;9
McCool, Chest 2006;129;250
Oscillatory PEP
• May have the added benefit of dislodging
thick secretions and decrease mucus
viscoelasticity
• Acapella high-frequency oscillatory PEP
produces oscillations during EXHALATION by
the use of a magnetic valve that creates
intermittently occlusions.
– 5 pressure settings at approximately 13 Hz
– Not position dependent / two flow range devices
Research Question
• Proximal placement of nebulizer would be
superior to manufacture recommended
(distal) and equal to nebulizer alone
Recommended
Hypothesis
Control
Conflicts of interest are properly disclosed on page 329.
Methods
• Randomized crossover clinical trial
• Approved by research committee
• Subjects
– Non-smoking, healthy males, no lung disease, 18-30
years with normal spirometry
• Procedure
– SVN run at 7 L/min with 3.6um +/- 2.2um MMAD
with 4 mL of saline and technetium-99m-labeled
diethylene triamine penta-acetic acid (25mCi) and
nebulized over 9 mins
– Randomized to 3 different configurations
Procedure Continued
• Via mouth piece with subjects seated upright
• Breathing patterns were standardized with
deep breaths and inspiratory pauses
• Immediately after administration scintigraphy
was performed
• Lung images were divided into regions of
interest
Lung Regions of Interest
Scintigraphy
Most commonly used
for the diagnosis of
pulmonary embolism
via
ventilation/perfusion
scan. Less commonly
used to evaluation
lung transplants and
right to left shunts.
Results
•
•
•
•
•
Enrolled 14 males, but only 10 completed
Mean age was 24.4 (2.2)
BMI 22.6 (2.6)
Spirometry normal
Deposition was similar in the right and left
lungs
• There was less total deposition in
configuration A than B or C
Lung Deposition Total Lung
Recommended
Experiment
Control
Lung Deposition
Upper, Middle and Lower
Recommended
Experiment
Control
Lung Deposition
Central, Intermediate and Peripheral
Discussion
• Despite the Acapella appearing to be a nice
reservoir the distal placement likely creates
impaction of larger particles
• Internal mechanisms within the Acapella
create turbulent or transitional flow that
increase the deposition of larger particles in
the device
• Some evidence that MMAD is reduced due to
a filtering effect
Discussion
A.Recommended – Demonstrating a
large amount of aerosol
depositing within the Acapella
A.Proximal placement (Experiment)
– Demonstrating a large amount
of aerosol within the mouth piece
and valve
Discussion
• PEP in general may play a role in aerosol
delivery
– Some findings supportive
– Some findings within SD
– Some findings consistent with prolonged
expiratory phases that may allow lower inspired
drug delivery compared to normal breathing with
periodic inspiratory holds
• Maybe they should have used a breath actuated
nebulizer??
Discussion
• Lung deposition was not statically different
however trends were noticed
– Normal distribution of ventilation were consistent
with results.
• Limitation
– These were normal subjects who do not exhibit
the same breathing or flow pattern
– They didn’t describe or measure minute
ventilation during the administration
Editorial by Dr. Berlinski
The Order of the Factors Affects a Product
• Combining therapies is attractive
– Is marketed to reduces time
– Yet, can increase cost or reduce effectiveness by
reducing aerosol delivery by 70%
• Limitations discussed regarding normal
subjects, however concluded that it would
likely be the same in lung diseased patients
• Order of therapies may matter
– Some have recommended a certain order of
therapies in the past
Conclusions
• Placing the nebulizer distal to the oscillatory PEP
device decreased intrapulmonary deposition,
compared to proximal placement, and compared
to nebulizer alone.
• Three possible take home messages:
1. You could say more data is needed to go against
manufacturers recommendations
2. You could apply the SVN at the proximal (mouth piece)
of the oscillatory PEP device when therapy time is
considered a factor
3. You could # 2 to all patients who require the
combination of therapies
What you cannot conclude…
• The experimental placement and combined
therapy is superior to SVN alone
• BAN would be better
Review and Comments