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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.
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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, bronchodilateand 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 Hypothesis Recommended 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 diethylenetriaminepenta-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
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 DepositionUpper, Middle and Lower Recommended Experiment Control
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 Recommended – Demonstrating a large amount of aerosol depositing within the Acapella 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. BerlinskiThe 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: • You could say more data is needed to go against manufacturers recommendations • You could apply the SVN at the proximal (mouth piece) of the oscillatory PEP device when therapy time is considered a factor • 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
