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aerosol
is a suspension of solid or liquid particles in gas. One of the parimary functions of the upper airway and respiratory tract is to protect the lungs from invasion by these aersols..
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Aerosol Output
Is defined as the mass of fluid or drug contined in aerosl produced by a nebulizer.
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depoisition
deposition is the settling of particles (atoms or molecules) or sediment from a solution, suspension and mixture or vapor onto a pre-existing surface.
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emitted dose
describes the mass of drug leaving the mouthpiece of a neublizer or inhaler as a aerosol.
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atomizers, nebulizers
devices that physically disperse matter into small particles and suspend them into a gas
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therapeutic index
the ratio between the dosage of a drug that causes a lethal effect and the dosage that causes a therapeutic effect.
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mass median aerodynamic diamter (MMAD)
central tendency
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volume median diamter (VMD)
laser diffraction
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geometric standard deviation (GSD)
describes the variability of particle sizes in an aerosol distrubition set at one standard eviation (SD) above or below the median (15.8% and 84.13% respectivaely)
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heterodisperse
Most aerosols found in nature and used in respiratory care are composed of particles of different sizes. The greater the GSD, the wider the range of particles sizes and the more heterodisperse the aerosol.
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monodisperse aerosols
Aerosols consisiting of particles of similiar size are referred to as monodisperse aerosols. Nebulizers that produced monodisperse aerosols are used mainly in laboratory research and in nonmedical industries.
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Inhaled mass
is the amount of drug inhaled.
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respirable mass.
THe proportion of the drug mass in partickles that are small enough (fine-partickle fraction) to reach teh lower respiratory tract is the respirable mass.
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Interial Impaction
occurs when suspended particles in motion collide with and are deposited on a surface. Because interia involves both mass and velocity, the higher the flow of a gas stream, the greater the tendency for particles to impact and be deposited in hte airways.
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Sedimentation
occurs when aerosol particles settle out of suspension and are deposited owing to gravity. The greater the mass of the particle, the faster it settles.
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Aging
The process by which an aerosol suspension cahnges overtime
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Hygroscopic water absorption
Aerosol particles can change size as a result of either evaportation or " "
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scintigraphy
drug is tagged with a radioactive substance (such as technetium) aeroslized, and inhaled
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propellant
is a material that is used to move ("propel") an object.
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Dry powder inhalers
A drypowder inhaler (DPI) is typically a breath-actuated dosing system.
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baffle
is simply a surface on which large particles impact and fall out of suspension whilie smaller particles rmeain in suspension, reducing the size of particles remaining in the aerosol.
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Residual drug volume
or dead volume, is the medication that remains in the SVN after the device runs dry.
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breath-enhanced nebulizers
entrain air through the nebulizer during inspiration
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breath-acuated neublizers
that reduce or elminate aerosol generation during the patient's expiratory phase.
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Small Volume nebulizers
have medication reservoir's less than 10ml
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