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Aerosol
An aerosol is suspension of liquid or solid particles in a gas.
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Aerosol output
Defined as the mass or fluid or drug contained in aerosol produced by nebulizer.
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Output rate
Is the mass of aerosol generated per unit of time. Varies by diff neb and inhalers.
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Emitted dose
Described the mass of drug leaving the mouthpiece as a aerosol.
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Respirable dose
Fraction of inhaled dose deposited in the lungs.
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What do most nebs in RC produce? what aerosol?
Bland Aerosol.
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Different kind of deposition?
- 1. Interial impaction
- 2. sedementation
- 3. diffusion
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Interial Impaction
Occurs when aerosol in motion collides with a surface (greater than 5-10 um) (oro/hypopharynx)
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Sedementation
Occurs when aerosol particles settle out (1-5 um) of suspension and are depsoited due to gravity. Small particles represent primary for deposition. Increases w/ breath holding. The greater the mass of particle, the faster it will settle.
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Diffusion.
Very small particles (.5-1 um) Stay suspended in lungs and exhaled back into the environment.
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Factors that will affect Deposition
- 1. Depends on particle size
- 2. Instrument.
- 3. Where you want it to go.
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MMAd (Massmedian aerosol dynamic diamater) 1-2 microns, 2-5 microns, and 5-10 microns?
- 1-2 microns - Lung parendyma = deep lung tissue
- 2-5 microns - central lower airway (broncodilators, steroids)
- 5-10 microns - oro/hypopharynx (upper airway) (condition CROUP)
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Why we encourage patient to do breath hold? what are we achieving?
Sedementation increases with breath holding, deposits due to gravity. Higher chance?
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Primary hazard of aerosol drug therapy?
Is the adverse reaction to the medication.
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Actual systems we use in the hospital. (Three common drug aerosol delivery systems.)
- 1. Breath actuated MDI
- 2. spacers and holding chambers.
- 3. Drug powder inhalers
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Breath actuated MDI
triggers actuation (to put into motion, activate) when patinet inhales, useful when patient coordinate inhalation w/ actuation.
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spacers and chambers
designed to reduce oropharyngeal deposition, needs hand -breath coordination.
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Dry powder inhalaer
A breath actuated dosing system.
Patient creates aerosol by sucking air through a dose of finley milled drug powder. "Thrush" a yeast infection on tongue, starts cracking happens when you don't rense.
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Large volume vs continious neb. Most common hazard? has to do w/ a drug?
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