Lecture 2 Flashcards
(34 cards)
1
Q
3 Main Uses of aerosol Therapy
A
1Humidification of dry inspired gases, using bland aerosols
2. Improved mobilization and clearance of respiratory secretions, including sputum induction, using bland aerosols of water and hypertonic or hypotonic saline
3. Delivery of aerosolized drugs to the respiratory tract
2
Q
- Suspension of liquid or solid particles between
____ and ____ micrometers ( um) in diameter in a
carrier gas. - For pulmonary diagnostic and therapeutic applications, the particle size range of interest is ___ to ____ um.
A
- 0.001 and 100 micrometers
- 1 to 10 um.
3
Q
- Describing the tendency of aerosol particles to
remain in suspension.
A
Stability
4
Q
- Referring to the depth within the lung
reached by particles.
A
Penetration
5
Q
- Describing the process by which particles
deposit out of suspension to remain in the lung.
A
Deposition
6
Q
- Aerosol-generating devices for orally inhaled drugs have typically had an efficiency of ___ to ___%, from a device usually reaches the lower respiratory tract, regardless of the device type.
- Newer aerosol-generating devices are proving exceptions to this lack of efficiency, with ____ to ____%or more of the dose reaching the lungs
A
- 10 to 15%
- 30% to 50%
7
Q
- inhalant devices such as metered dose inhalers (MDIs), small volume nebulizers (SVNs), and dry powder inhalers (DPIs) include a range of sizes (________) rather than a single size (monodisperse).
A
polydisperse or heterodisperse
8
Q
- Most frequently occuring particle size in the
distribution.
A
Count mode
9
Q
- Particle size above and below which 50% of the particles are found (i.e., the size that evenly divides the number of particles in the distribution).
A
Count median diameter (CMD)
10
Q
- Particle size above and below which 50% of the mass of the particles are found (i.e., the size that evenly divides the mass of the particles in the distribution).
A
Mass median diameter (MMD) or mass median aerodynamic diameter (MMAD)
11
Q
- Measure of the dispersion of a distribution (i.e., the scattering of values from the average), calculated as the ratio of particle size below which 84% of the particles occur to the particle size below which 50% occur, in a log-normal distribution. This ratio determines how spread out the particles are in relationship to their size.
A
Geometric standard deviation (GSD)
12
Q
MMD or MMAD indicates where the mass of drug is centered in a distribution of particle sizes. Aerosol particles are three-dimensional and have volume.
Formula:
A
V = (4/3) pier3
V volume; r radius
13
Q
- As a result, the bulk of drug mass is centered in the ________ sizes.
- Because it is the ________ entering the lung on which the therapeutic effect is based, it is necessary to know where the mass is centered in a range of particle sizes to know whether that distribution will be efficient for penetration into the respiratory tract and delivery of an adequate dose
A
- larger particle
- mass of the drug
14
Q
-
A
- Cascade Impaction
- Laser Scattering
15
Q
- what is the ideal size for the lower respiratory tract (last 5-6 generation) and what is the particle size for better penetration?
- Particle size for the upper airways (First 6 generations.)
- Particle size for the nose
- Particle size for the mouth
- may be useful for treating the upper airway (naso
pharynx and oropharynx).
A
- 1 to 5um and 1 to 3 um
- 5 to 10 um
- > 10um
- > 15um
- > 5
16
Q
- The labels respirable fraction and respirable dose previously were used to refer to the percentage or fraction of aerosol drug mass in a particle size range with a high probability of penetrating into the lower respiratory tract.
A
Fine Particle Fraction (1-3um)
17
Q
- are useful to treat the nasopharyngeal and oro
pharyngeal regions.
An example is a nasal spray for perennial rhinitis, such as a corticosteroid.
A
Particles > 10um
18
Q
- may shift deposition to the more central airways, although significant oropharyngeal deposition is expected.
An example is a nasal spray, but there is no one standard device that creates this specific particle size.
A
Particles 5-10um
19
Q
- deposition shifts from the oropharynx and large airways to the overall lower respiratory tract (large
airways to periphery). This size range is considered useful for the bronchoactive aerosols currently in use.
For example, -adrenergic receptors have been identified throughout the airway but with greater density in bronchioles.
A
Particles 2-5um
20
Q
- increased delivery of an aerosol to the lung parenchyma, including the terminal airways and alveolar region, can be achieved with particles
less than 3 m.
A
Particle 0.8 to 3.0um
21
Q
Three physical mechanisms usually are considered for aerosol particle deposition in the human lung:
A
- Inertial impaction
- Gravitational settling (sedimentation)
- Diffusion (brownian motion).
22
Q
INERTIAL IMPACTION (occurs in the 1st 10 airway generation)
- what tract where particle velocity is highest, airflow tends to be turbulent, and total cross- sectional area of the airway is smallest.
A
upper airway and early bronchial generations
23
Q
- is a function of particle size and time. Settling is
greater for larger particles with slow velocities, under the influence of gravity.
The probability of deposition by sedimentation is highest in the last five or six airway generations.
For a 5-m-diameter particle, the settling rate is
reported to be 0.7 mm/sec.
A
Gravitational Settling
24
Q
- affects particles less than 1 m and is a function of
time and random molecular motion.
A
Diffusion (brownian motion)
25
Effect of Temperature and Humidity
- aerosol is generated under relatively __________ conditions and then taken into the airway, where temperature and humidity rapidly increase to saturation at 37°C.
- aerosol drugs are not only heterodisperse in size but are also ___________ (i.e., readily absorbing moisture).
- dry ambient
- hygroscopic
26
- encompasses various devices that operate on different physical principles to generate an aero
sol from a drug solution. The SVN is a type of aerosol
generator that converts liquid drug solutions or suspensions into aerosol.
- often used with infants or with patients in acute respiratory distress, slow breathing and an inspiratory pause may not be feasible or obtainable.
- One of the main advantages of SVNs is that dose
delivery occurs over _____________ breaths, rather than in one or two inhalations.
- Nebulizer
- Jet nebulizer
- 60 to 90 breaths
27
- are small-reservoir, gas-powered (pneumatic) aerosol generators, also referred to as handheld nebulizers or as updraft nebulizers or unit-dose nebulizers.
Jet (pneumatic) nebulizers
28
- use a plate or mesh with multiple apertures (small holes) to move the liquid formulations through a fine mesh to generate aerosol. These nebulizers have no internal baffling mechanism and create aerosol by way of the aperture plate or the ultrasonic horn.
Mesh nebulizers.
29
- are electrically powered devices operating on the piezoelectric principle and capable of high output.
Ultrasonic nebulizers
30
- this device is a large reservoir nebulizer, capable of holding 300mL of solution for long periods of nebulization,
Operates on a jet shearing principle
This device was used during the clinical trials of the aerosolized antiviral drug ribavirin (Virazole) and is marketed.
Small Particle Aerosol Generator (SPAG)
31
- this device is small reservoir, gas powdered (pneumatic) aerosol generators, also referred to as handheld nebulizer (HHNs) or as updraft nebulizer or unit dose nebulizer (UDNs)
Small volume nebulizer
32
- this nebulizer does not aerosolize below a minimal volume, termed the dead volume, which is the amount of drug solution remaining in the reservoir when the device begin to sputter, and aerosolization ceases.
- 0.5 to 1.0mL volumer order
Gas Powdered Nebulizer
33
34
