Aerosol Drug Therapy Flashcards
What is an Aerosol?
suspension of solid or liquid particles in gas generated with devises that physically disperse matter into small particles and suspend them into gas
What is the goal of Aerosol therapy?
Deliver a therapeutic dose of the selected pharmacological agent to the desire site of action
Particle sizes
measured by particle suspension in a lab
Heterodisperse
Aerosols with different particle sizes (most common)
Monodisperse
Aerosols with particles of similar size
Particle size depends on…
substance, method used to generate, environment
Inhaled Mass
Only fraction of emitted aerosols will be inhaled
Respirable Mass
Only fraction of inhaled is deposited into the lungs
MMAD
mass median aerodynamic diameter which is a method to measure aerosols
What influences particle mass
inspiratory flow rate, flow pattern, respiratory rate, inhaled volume, I:E ratio, breath-holding
Types of aerosols
atomizes, nebulizers, inhalers
Adding medication to aerosols
provides higher therapeutic index
Types of deposition
inertial impaction, sedimentation, brownian diffusion
Inertial Impaction
particle size >5 - impacts upper airway; nose, larynx, and trachea - mainly oropharynx
Sedementation
particle size 1-5 - central airways (2-5 lower airways) (1-3 parenchyma, alveolar region)
Breath Holding
after inhalation of aerosol increases sedimentation and distribution across lungs
Brownian
particle size <3 - parenchyma (respiratory region)
particle size between 0.5 and 1
very low mass and can be exhaled back out
particle sizes <0.5
greater lung retention rate
Hazard of aerosol therapy
adverse reaction to medication, airway reactivity leading to bronchospasm
Types of aerosol therapy
MDI, DPI, pneumatic nebulizers, large volume nebulizers
MDI (pressurized Metered Dose Inhaler)
portable, compact, easy to use, most commonly prescribed, rescue inhaler, drug = HFA (hydrofluoroalkane)
Priming
shaking device and releasing one or more sprays into air when pMDI is new or hasn’t been used in awhile
pMDI particle size
2-6 (about 80% deposits in oropharynx and 10-20% is deposited pulmonary)
Open-mouth concerns
steroid in pMDI can increase the risk of thrush and difficulty speaking (dysphonia) (EDUCATE PATIENT TO RINSE MOUTH)
Spacer and Holding chambers
must be used with MDI
spacer
extension to device that is valveless and adds distance between pMDI and patients mouth, this reduces oropharynx deposition and need for hand breath deposition
Holding chamber
extension to MDI that has valves to prevent aerosol in chamber from being cleared on exhalation, higher respirable drug dosage into the lungs with less oropharyngeal deposition. better than the spacer for for hand breath cordination
DPI ( Dry Powder Inhalers )
a breath-actuated dosing system that an aerosol is created when the patient draws air through dose of finely milled drug powder
DPI flow
dispersion depends on creation of turbulent flow in inhaler, flow should be at least 40-60 L/Min. Low inspiratory flow decreased dose to lungs and increases particle size
who shouldn’t use DPI
no infants, small children, those who cannot follow instructions, and patients with severe airway obstruction
pneumatic jet nebulizers
powered by high-pressure oxygen on air by a portable compressor, compressed gas cylinder, 50 psi wall outlet
nebulizer performance depends on
baffles, flow, and gas source
baffles
surface in which particles impact and fall out of suspension and smaller particles stay in suspension
small-volume nebulizers
slow inspiratory flow optimizes SVN, delivery method is by mask and mouthpiece, 10mL of meds, 7-10 minute treatments
large-volume nebulizers
useful for severe bronchospam, 30mL of meds, treatment lasts up to 2 hours
types of large-volume nebulizers
small particle aerosol generator (SPAG), vibrating mesh nebulizers, smart nebulizers, Akita (activaero)
issues with administering aerosol to infants and children
smaller airway diameter, breathing rate is faster, nose breathing (filters out large particles), lower minute volumes, patient cooperation, NEVER give to crying children.
Blow-By technique
when patient cannot tolerate mask treatment, the treatment is given toward a patients nose / mouth several inches away
Assessing a patient receiving aerosol treatment
patient interview, observation, measure vital signs, asuculation (before/after), ABG, oximetry
Aerosol treatment to mechanical ventilated patients
measure changes in peak/ plateau pressure; a drop in peak pressure and if PEEP decreases means treatment is working
nasal oxygen
flows >30 L/Min have higher deposition
