Chapter 40- Aerosol Drug Therapy Flashcards
what is aersol?
a suspension of solid or liquid particles in gas
when do you use aerosol?
in clinical settings, medical aerosols are generated with atomizers, nebulizers, and inhalers
what is an atomizer
converts liquid into droplet
what is a nebulizer
the produce finer aerosol particles from liquid-based formulations over greater periods of time using compressed gas or electricity
describe an inhalers purpose
they generate aerosolized medication from liquids or dry powders for a single inhalation
what is the goal of aerosol therapy
deliver a therapeutic dose of the selected agent to the desired site of action
what are some benefits of medicated aerosol
medication aerosol provides higher therapeutic index
- higher local drug concentration in lung
- lower systemic affects
What is the aerosol output?
mass of fluid or drug
-produced by aerosol generator per actuation or unit of time
what is the determination of aerosol output?
output rate is mass of aerosol generated per unit of time
-varies depending on different nebulizers and inhalers used
how is aerosol output measured?
measured by collecting aerosol that leaves nebulizer on filters
- gravimetric analysis measures aerosol weight
- assay measures quantity of drug
what is the emitted dose?
the emitted dose describes mass of drug leaving mouthpiece
what is an important take away on aerosol output?
large amounts of particles that leave the nebulizer may never reach the lungs
Particle size:
depends on what 3 factors
- substance being nebulized
- method used to generate the aerosol
- environmental conditions
what methods are used to measure medical aerosol particle distribution?
Cascade impaction:
-MMAD-mass median aerodynamic diameter
Laser diffraction:
-VMD- volume median diameter
what are two similar between cascade and laser aerosol particle distribution
- both laser and casacade are:
- -laboratory performed tests
- measured in microns
What is medication deposition
medication deposition occurs when particles leave suspension in gas and deposit on a surface
what is an inhaled dose
small fraction of the aerosol generated and emitted from a nebulizer will be inhaled, this is known as inhaled dose
what is respirable dose
respirable dose is the fraction deposited in the lungs
what is respirable mass
respirable mass is the small amount of drug that make it to the lower respiratory tract
what % of inhaled aerosol particles will be exhaled
1-5%
what is the deposition influenced by?
- inspiratory flow rate
- flow pattern
- respiratory rate
- inhaled volume
- I:E ration
- breath holding
what are 3 key mechanism of aerosol deposition
- inertial impaction
- sedimentation
- diffusion
what is inertial impaction
occurs when an aerosol in motion collides with a surface. this is the primary deposition mechanism for larger particles
where does inertial impaction deposit
deposit primarily in nose, mouth, and pharynx
what is the particle size for inertial impaction?
particles >10
what is sedimentation deposition
occurs when aerosol particles settle out of suspension and are deposited do to gravity.
Breath holding after inhalation of an aerosol will enhance distribution across the lungs
where does sedimentation deposition deposit
deposit primarily in proximal airways (those closest to the top of the tree, such as the bronchi)
where size are sedimentation deposition
particles 1-5 microns
what is diffusion deposition
the primary deposition mechanism for small particles deep within the lung
what size particles are diffusion deposition
very small particles have very low mass and often remain in suspension and are exhaled back into the environment
where does diffusion deposition occur
deposit primarily in the peripheral airways
describe the process of inertial impaction deposition (what happens to the particles)
inertial impaction of large particles:
the masses of which tend to maintain their motion in straight lines. As airway directions changes, the large particles are deposited on nearby walls. Smaller particles are carried around corners by the airstream and fall out less readily
Putting all together:
Why is all this important?
- different medications are to be delivered to different areas and we need different nebulizers to accomplish our goal
- nebulizers are not a one size fits all
what is aerosol aging?
process by which aerosol suspension changes over time
how is aerosol aging dependent on
- composition of aerosol
- initial size of its particles
- particles size can change due to evaporation or hygroscopic water absorption
- time in suspension
- ambient condition
what is scintigraphy
a drug is “tagged” with a radioactive substance, aerosolized, and inhaled
how is scintigraphy measured
a scanner measure the distribution and intensity of radiation across the device and the patients head and thorax
how is scintigraphy information used for
this information is used to calculate the percentage of drug retained by the device and delivered to various areas in the patient
what does an assay (test) of the drug in a patients blood or urine over time complete
it does not estimate actual lung delivery of the drug, but it provides insight into systemic drug levels achieved after aerosol administration
what is a primary hazard of aerosol drug therapy
adverse reaction to medication
what are the secondary hazard of aerosol drug therapy
infection
airway reactivity
pulmonary and systemic effects of bland aerosols
drug concentration changes during nebulization
eye irritation
secondhand exposure to aerosol drugs (up to 70% of aerosol generated by SVN is released to the air)
Pressured metered dose inhalers (PMDI’S)
what is it
pressurized canister containing prescribed drug in volatile propellant combined with surfactant and dispersing agent
what are 3 advantages of Pressured metered dose inhalers (PMI’S)
- most commonly prescribed method of aerosol therapy
- portable, compact, and easy to use
- provides multidose convenience
what is a disadvantage of Pressured metered dose inhalers (PMI’S)
has serious limitation
-lacks counter to indicate number of doses remaining in canister
(FDA requires all new PMDI’S to have counter technology)
Pressured metered dose inhalers (PMI’S):
how do you use
- most pMDIs are “press and breathe”
- before every use inhaler must be shaken
- before initial use, inhaler must be shaken and primed 1-4 times
Pressured metered dose inhalers (PMI’S): Use
how much time between puffs
wait 30 seconds to (clinically) 1 minute between puffs
-studies shoe now that canister will return to baseline in 15 seconds. baseline is when the canister “warms” back up as the propellant has cooled it
Pressured metered dose inhalers (PMI’S):
what factors affect these
factors affecting pMDI performance and drug delivery are temperature and nozzle size and cleanliness
Pressured metered dose inhalers (PMI’S):
how does temperature effect this
this problem has been less serious with the newer HFA pMDIs
-in the 1950’s we used CFC’s (clouroflourocarbons) which are prohibited due to global warming. New tech. is HFA (Hydroflouroalkane)
Pressured metered dose inhalers (PMI’S):
how does nozzle size and cleanliness affect this
as debris builds up on nozzle or actuator orifice, emitted dose is reduced
Pressured metered dose inhalers (PMI’S):
what are aerosol delivery characteristics
- pMDI can produce particles in respirable range (MMAD 2-6 µm)
- about 80% of aerosol deposits in oropharynx
- pulmonary deposition ranges between 10% and 20% in adults and larger children
Pressured metered dose inhalers (PMI’S):
What are techniques are this device
most patient do not use proper technique
-through education of patient can take up to 30 minutes
-MDI should be actuated at beginning of inspiration with mouthpiece held 4 cm in front of open mouth
(much more coordination, better deposition)
Pressured metered dose inhalers (PMI’S):
What are concerns with open-mouth technique
- Ipratropium bromide administration along with poor coordination can result in drug being sprayed into eyes
- Anticholinergic agents have been associated with increased ocular pressure
- Steroid pMDIs can increase incidence of opportunistic oral yeast infection and dysphonia
- -Swish with water!
Pressured metered dose inhalers (PMI’S):
What do spacers do?
All spacers add distance between the pMDI and the mouth, reducing the initial forward velocity of the pMDI droplets
Pressured metered dose inhalers (PMI’S):
What are spacers?
- Simple valveless extension device that adds distance between pMDI outlet and patient’s mouth
- Reduces oropharyngeal deposition and need for hand-breath coordination
Pressured metered dose inhalers (PMI’S):
what are disadvantages of spacers
Disadvantage, bulky and typically left behind
Dry powder inhalers:
What are they?
- Breath-actuated dosing system
- Patient creates aerosol by drawing air through dose of finely milled drug powder
Dry powder inhalers:
what are the advantages
- Flow is function of ability of patient to inhale powder with sufficiently high inspiratory flow rate
- Do not use propellants and do not require hand-breath coordination needed for pMDIs
Dry powder inhalers:
how are they categorized
categorized based on design of their dose containers
Dry powder inhalers:
unit-dose DPI
Aerolizer and Handihaler dispense individual doses of drug from punctured gelatin capsules
Dry powder inhalers:
multiple-unit dose DPI
Diskhaler contains case of four or eight individual blister packets of medication on disk inserted into inhaler
Dry powder inhalers:
Multiple dose Drug Reservoir DPI
Twisthaler, Flexhaler, and Diskus are preloaded with quantity of pure drug sufficient for dispensing 120 doses of medication
Dry powder inhalers:
Advantages
- Small and portable
- Built in dose counter
- Propellant-free
- Breath-actuated
- Short preparation and administration time
- In terms of lung deposition they are as effective as MDI’s
- Particle size is 1 to 3 microns
Dry powder inhalers:
Disadvantages
Dependent on adequate inspiratory flow
Vulnerable to humidity
Not able to be used on infants/small children or anyone not able to follow instructions
Pneumatic (Jet) Nebulizers:
what are they
Most nebulizers are powered by high-pressure oxygen or air
Provided by portable compressor, compressed gas cylinder, or 50-psi wall outlet: pneumatic
Pneumatic (Jet) Nebulizers:
factors affecting this
Factors affecting nebulizer performance:
- Nebulizer design & manufacturer-Think of this like electronics, you get what you pay for!
- Flow - 6-10 lpm optimal. Higher flows shorten treatment time, but reduce efficiency
- Gas source – is it pneumatic, eclectic or can run on Heliox/gas
- Density
- Humidity and temperature
- Characteristics of drug formulation
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
how many categories
(4)
- Continuous nebulizer with simple reservoir
- Continuous nebulizer with collection reservoir bag
- Breath enhanced (BE)
- Breath actuated nebulizer (BAN)
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what is Continuous nebulizer with simple reservoir
May increase inhaled dose by 5% to 10%, or increase inhaled dose from 10% to 11% with 6-inch piece of reservoir tube
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what is Continuous nebulizer with collection reservoir bag
- Bag reservoirs hold aerosol generated during exhalation
- Allows small particles to remain in suspension for inhalation with next breath while larger particles rain out
- Attributed to 30% to 50% increase in inhaled dose
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what is Breath enhanced (BE)
Generate aerosol continuously, utilizing system of vents and one-way valves
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what is Breath actuated nebulizer (BAN)
Can increase inhaled aerosol mass by three- to fourfold over conventional continuous nebulization
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what are the techniques?
- Slow inspiratory flow optimizes SVN aerosol deposition
- Selection of delivery method (mask or mouthpiece) is based on patient ability, preference, and comfort
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what are the infection control issues
Nebulizers should be cleaned and disinfected, or rinsed with sterile water, and air dried between uses
Pneumatic (Jet) Nebulizers:
Small-volume nebulizers (SVN)
what are the advantages
- Many drugs available for aerosolization
- Aersolize drug mixtures
- Pt. not able to follow commands
- No coordination needed
Large Volume Jet Nebulizers:
what are they
Large volume jet nebulizers are also used to deliver aerosolized drugs to the lung
-Particularly useful when traditional dosing strategies are ineffective in the management of severe bronchospasm
Large Volume Jet Nebulizers:
affect on the heart
The high-output extended aerosol respiratory therapy nebulizers
Large Volume Jet Nebulizers:
what is a Small particle aerosol generator (SPAG)
The regulator is connected to two flowmeters that separately control flow to the nebulizer and flow through the drying chamber
Large Volume Jet Nebulizers:
what flow should a Small particle aerosol generator (SPAG) be at?
Nebulizer flow should be maintained at approximately 7L/min with total flow from both flowmeters not less than 15L/min
Large Volume Jet Nebulizers
Smart nebulizers:
I-neb (Phillips respironics)
what are I-neb?
- Breath-actuated passive vibrating mesh nebulizer
- Has adaptive aerosol delivery that monitors pressure changes and inspiratory time for patient’s first three consecutive breaths
Large Volume Jet Nebulizers
Smart nebulizers:
I-neb (Phillips respironics)
what are I-neb drug aerosolized?
- Drug is aerosolized over 50% of inspiratory maneuver during fourth and subsequent breaths
- Has been released for delivery of prostacyclin
what are some delivery issues for special medication
Infants and children: Smaller airway diameter than adults Breathing rate is faster Nose breathing filters out large particles Lower minute volumes
how are infants and children’s cooperation disadvantaged in special medication?
Patient cooperation and ability varies with age and developmental ability
- Aerosols should never be administered to crying child
- Crying reduces lower airway deposition of aerosol medication
what is a blow-by technique for special medication
Blow-by technique
Used if patient cannot tolerate mask treatment
Practitioner directs aerosol from nebulizer toward patient’s nose and mouth distance of several inches from face
Highly ineffective
how do you select a special aerosol drug delivery system
Must be prescribed for the appropriate patients and are used properly
what is the role of the RT for a bronchodilator therapy protocol
Assess patient response:
- Ongoing patient assessment is key to -effective bronchodilator therapy protocol
- Peak flow measurement can provide trends if same device is used from one treatment to next
how would RT assess patient response in bronchodilator therapy protocol
Components of patient assessment Patient interviewing Observation Measurement of vital signs Auscultation Blood gas analysis Oximetry Conduct dose-response titration to determine best dosage for patients with moderate obstruction
what is the most important part of the role of RT during bronchodilator therapy protocol
patient education
what are some special aerosol therapy for treatment of pulmonary arterial hypertension
- Iloprost
- Treprostinil
what are some special considerations for therapy for pulmonary arterial hypertension
- Administered with specific nebulizers in discrete doses, that are repeated throughout the day
- Other formulations
What is off-label use
Clinicians may explore and consider nonstandard methods (doses, frequency, and devices) for administration of approved inhaled drugs to patients in acute care environment
what are should be avoided with off-label use
- Use of drugs that have not been approved for inhalation, ranging from heparin to certain antibiotics
- Should be avoided when approved and viable alternative exists
what is the most important consideration of off-label use
Off-label administration should always be backed by appropriate departmental or institutional policies and procedures
who is Continuous nebulization for refractory bronchospasm used for
CBT with nebulized albuterol doses ranging from 5-20 mg/hour have proved to be safe for adult and pediatric patients with severe asthma
what are two keys points of Continuous nebulization for refractory bronchospasm
- Patient carefully assessed every 30 minutes for first 2 hours; then hourly
Patient must be observed for adverse drug responses - Positive response indicated by increase in PEFR of at least 10% after first hour of therapy. Goal is at least 50% of predicted value
how do we control environmental contamination (3)
- Use of one-way valves and filters can help
- Negative-pressure rooms and treatment booths are useful strategies
- Personal protective equipment is recommended when caring for patient with disease that can be spread by airborne route
how does nebulized drugs contaminated the environment
- Nebulized drugs may enter room directly from nebulizer or during patient exhalation
- Continuous pneumatic nebulizers produce greatest amount of second-hand aerosol
what medication is associated with contamination environment
Pentamidine and ribavirin were associated with health risks to caregivers
