Med Administration in Pediatrics Flashcards
Off Label Use
- Off the label is when drugs have FDA approval but are being used for a specific age, group, or purpose in which they do not have FDA approval for
- Ex. Aspirin for prophylaxis of heart attack
- This practice is legal as the FDA cannot by law regulate how is drug is medically used
- Virtually all inhaled beta agonists and corticosteroid formulations have FDA approval for 12 year and older.
- These will be prescribed when a suitable alternative does not exist
Why do we use off label uses for Pediatric populations so much
Pediatric patient are the most common group for which off label use medications are prescribed
Due to the fact that it is so hard to get studies approved for pediatric patients
What factors will affect depoistion in in children
Smaller tracheal diameter
Shorter trachea
Higher RR
Lower MV
Lower deadspace
Lower inspiratory flow rate
DEPOSITION OF MEDICATION IN CHILDREN
A smaller fraction of the dose of aerosol medication will reach the lower airways
Decreased aerosol drug deposition to lungs due to smaller diameter of NN and pediatric lower airways.
Lower deposition may provide a comparable safety and efficacy profile to adults.
What is the acutal dose that is though to be given to neonates, ped, and adulst
~1% in Neonates and Infants
2.5% in young children
10-15% in adults
Even though smaller %, small patients may receive a higher drug/kg than adults
Aerolsolized Therapy
When less than 6 months old
The child will have a small Vt which will affect TCT and inspiratory flow
Decreased time in the airways= decreased aerosol deposition
This means they will inhale a lower % of emitted aerosol dose
What is an anatomical saftey feature in children airway
Age and size have a self limiting effect on lung dose
Produces a natural titration of dose
Aerosol doses to neonates and children and thought to be self limiting
This is due to differences between pediatric and adult airways
Dosing for Infants and NN
Generally dosing with inhaled aerosols for neonatal and pediatric patients is not based on body size and blood level
Rather it will be based on a target effect strategy with avoidance of toxicity
We give the same dose (5 puff) of Ventolin to kids that are one as we do for kids that are 3
The 3 year old will still get more medication as their airway is bigger, they have a smaller RR, etc.
DEPOSITION FACTORS
Patient
Breathing Pattern
Inspiratory Flow Rate
Tidal Volume
Cry and distress-This will seriously effect efficiency of aerosol administration
DEPOSITION FACTORS
Device
Chamber Volume
Design of inspiratory and expiratory valves if present
Amount of deadspace in mouthpiece
Electrostatic charge on plastic devices
Higher RR
Higher RR will affect sedimentation
Faster Inspiratory Flow Rate
The faster they breath in the more intertia of impactation
Breathing Pattern in Young Children
Slow, fast, holding their breath (use a spacer), crying
Look at the value on the spacer as it will open as they breath or you can look at their chest and count 5 breaths
Spacers
- The more expensive spacers will be antistatic, but when people take it home they tend to scrub it clean which can scrub off the antistatic coating
- Kid spacer is smaller than adult spacers
- What makes spacers effective
- Slow down breathing
- Children that are 2-3 is when you can start using a mouthpiece instead of a mask
Aerosol vs. MDI, MDI with Spacer vs. DPI
All are equally effective when used properly for delivering short acting B agonists
Nebs and MDI + Spacer
Nebs and MDI + Spacer are most useful in young children because they only require tidal breathing
Holds true even in acute asthma attacks
When the Child is 4 Years or Less
SVN with mask or mouthpiece if able
MDI plus Valved holding device (VHD)
For 3 years or older: mouthpiece preferable to mask if tolerated
For smaller children a smaller volume VHD is preferable, less time to empty chamber=higher delivery
When the Child is more than 4 Years
- MDI with VHD
- MDI should not be used without a VHD
- VHD also reduces oral-pharyngeal deposition
- We can recommend a DPI when the child is four
SLEEPING KIDS
~70% of children will wake up when aerosol is given during sleep
When they wake up they will become distressed and cry
Try to distract and comfort them
Age and Dose Regulating Effects
Age will have a dose regulating effect on the amount of aerosol drug reaching the lungs
Less drug will reach the lung in younger subjects, but more studies are needed
It is important to monitor the patient for adverse systemic effects
Choose appropriate device for the patient based on ability
DPI vs. MDI
DPI is more effective than MDI without a spacer. If their MDI does have a spacer then it is about equivilantto the effectiveness of DPI
Humidity
Water that exists in the form of individual molecules in the vaporous or gaseous state.
Aerosol
a suspension of particles (solid or liquid) present in gas (air):
Clinical Use of Aerosols
Humidify dry inspired gas, using water aerosol
Sputum induction & to improve mobilization and clearance of respiratory secretions using bland aerosols
Deliver aerosolized drugs (bronchodilators, anti-inflammatories and antibiotics) to respiratory tract
Medication delivery with Croup
With croup we will give something that settles in the upper airway as opposed to something that is avaliabelin the lower airway
Ultrasonic Nebulizer vs Small Volume Nebulizer
- SVN do not have a high quality control where as USN will have a higher quality control
- To get rid of residual volume in a SVN you need to top it up
- Deadvolume= residual volume
- There will be no residual volume with a USN
- USN is fading away and we are using a ultrasonic mesh instead
Hand Bulb Atomizers
Do not use baffle
Aerosol suspension designed for upper airway deposition.
nasal spray pumps (steroids) rhinitis,
high MMAD and GSD
Will give us big particles and the high the particle the high it will settle
Hand Bulb Atomizer Used for
Upper airway inflammation
Rhinitis
Local anesthesia
Particle Size and Predicted Lung Deposition
Upper Airway
Particle 5-10 micron range tend to deposit in UA and early airway generations
Ex. Medicine for Croup
Particle Size and Predicted Lung Deposition
Nose
100% deposition of particle sizes >10 microns
Particle Size and Predicted Lung Deposition
Mouth
100% deposition of particle sizes >15 microns
Particle Size and Predicted Lung Deposition
Lower Airway
Particles 1-5 micron range able to reach LRT and lung periphery
This range also called ‘respirable fraction’
Measures of Central Tendency
lMedical aerosols contain particles of many different sizes.
2 Common Ways of Measuring Central Tendency
- The average particle size is expressed in terms of a measure of central tendency.
- Mass Median Aerodynamic Diameter (MMAD)*
- Variability of particle sizes in an aerosol.
- Geometric Standard Deviation (GSD)
Mass Median Aerodynamic Diameter (MMAD)
Describes average particle diameter (µm).
50% of the particles are smaller & have less mass.
50% of the particles are larger & have greater mass.
Geometric Standard Deviation (GSD) “The Spread”
- The greater the GSD, the wider the range of particle sizes produced by a device.
- GSD < 1.22, aerosol considered monodispersed = single particle size
- GSD > 1.22, aerosol considered heterodispersed= range of particle sizes
- Most aerosols used in respiratory care
Aerosol output
Weight or mass of aerosol particles produced by nebulizer (usually per minute)
Does not indicate amount of drug reaching lungs as majority of particles leaving neb never reach lungs
Only 10-50% of administered dose actually reaches LRT, depending on device used & technique
Deposition
Particles depositing out of suspension to remain in lung
Particle Size And Lung Distribution
- Particle size is one of major factors affecting aerosol deposition in lung
- Despite knowing its size, not possible to specify exactly where particle will deposit in lung
- Particle deposition is function of several mechanisms:
- Breathing pattern
- Inspiratory flow rate
- Thus site of penetration can be predicted but not confirmed
Particles > 10 microns
Tx nasopharyngeal or oropharyngeal regions
e.g. nasal spray for rhinitis
Particles 5- 10 microns
Deposition to more central airways with significant deposition in oropharyngeal region
Particles 2- 5 microns
Deposition in LRT
More adrenergic receptors in bronchioles (compared to rest of airway) thus response with bronchodilators
Particles 0.8- 3 microns
Delivery of aerosol to lung parenchyma
Used for anti-infective drugs such as pentamidine where intra-alveolar deposition needed with minimum deposition in airways due to irritation
Mass Median Aerodynamic Diameter (MMAD)
Describes average particle diameter (µm).
50% of the particles are smaller & have less mass.
50% of the particles are larger & have greater mass.
Aerosol Output:
Aerosol output: Weight or mass of aerosol particles produced by nebulizer (usually per minute)
Does not indicate amount of drug reaching lungs as majority of particles leaving neb never reach lungs
Only 10-50% of administered dose actually reaches LRT, depending on device used & technique
Fast the flow the smaller the particales
Mechanisms of Deposition
Inertial impaction
Gravitational settling (sedimentation)
Diffusion
Recommended MMAD for Mouth
> 15 um
Recommended MMAD for Nose
10-15 um
May just say > 10 um
Recommended MMAD for Lower Airways
2-5 um
Medicated Aerosol Therapy
Delivery of aerosol particles to respiratory tract for therapeutic purposes
Desposition
Particles depositing out of supsension to remain in the lung
Particle Size And Lung Distribution
- Particle size is one of major factors affecting aerosol deposition in lung
- Despite knowing its size, not possible to specify exactly where particle will deposit in lung
- Particle deposition is function of several mechanisms:
- Breathing pattern
- Inspiratory flow rate
- Thus site of penetration can be predicted but not confirmed
Inertial Impaction
Function of particle size (mass) and velocity
Direct relationship with mass and velocity
Primary deposition mechanism for large, high mass particles (> 5 microns)
Bigger particles can’t change direction easily.
Occurs in first 10 airway generations
Inital impact of large particles whose masses tend to retain the motion in a straight line. Meaning as airway direction changes the particle are depsoitied on nearby walls. Smaller particles are carried around corners by the air flow and will fall out less readily
Sedimentation (Gravitational Settling)
- Function of particle size and time
- Occurs when aerosol particles settle out of suspension due to gravity
- Increased settling for larger particles with slower velocities
- Increased mass will lead to increased settling
- Primary mechanism for deposition of particles in 2- 5 µm range
- Occurs mostly in central airways
- As sedimentation with time, an end- inspiratory breath hold maximizes sedimentation
- e.g. a 10 sec breath-hold can aerosol deposition by ~ 10%
Diffusion- Brownian Movement
Primary mechanism for deposition of small particles < 3 microns
Mainly occurs in alveolar region where bulk gas flow ceases and aerosol particle inertia is low
Small, low mass aerosol particles are easily bounced around by collisions with carrier gas molecules
Random molecular collisions cause deposition of some particles on to surrounding surfaces
Particles < 1 micron are so stable that they may remain suspended or even exhaled
Upper and Central Airways
5-10 um
Aersol Aging
Aging: Process by which an aerosol suspension changes over time.
Therapeutic aerosols are dynamic with particles constantly growing, shrinking, coalescing or falling out of suspension
Aging of an aerosol depends on:
Ambient conditions
Composition of aerosol
Initial size of particles
Time in suspension
Effect Of Temperature And Humidity
- Aerosol particles change size as result of their hygroscopic tendency
- Rate of particle growth is inversely proportional to their size
- Smaller particles grow faster than larger particles
- Small water based particles can also shrink when exposed to relatively dry gas
- Aerosols are generated in relatively dry ambient conditions and then taken into airway where both temperature and humidity (37°C and 100% relative humidity)
Pattern Of Inhalation
- Pattern of inhalation can influence aerosol drug delivery to lungs
- It includes :
- Lung volumes at beginning and end of inspiration
- Inspiratory time and flow rates
- Mouth vs nose breathing
- Breath hold
- Optimal pattern of inhalation varies with type of aerosol generating device
Clinical Use of Aerosols
Humidify dry inspired gas, using water aerosol
Sputum induction & to improve mobilization and clearance of respiratory secretions using bland aerosols
Deliver aerosolized drugs (bronchodilators, anti-inflammatories and antibiotics) to respiratory tract
Aerosol Generators Used Clinically Include:
- Hand- bulb atomizers
- Nebulizers
- LVN
- SVN
- USN
- SPAG
- Inhalers
- MDI
- DPI
Measures of Central Tendency
- Medical aerosols contain particles of many different sizes.
- Two common ways of quantifying
- The average particle size is expressed in terms of a measure of central tendency.
- Mass Median Aerodynamic Diameter (MMAD)*
- Variability of particle sizes in an aerosol.
- Geometric Standard Deviation (GSD)
- The average particle size is expressed in terms of a measure of central tendency.
- Quantifying = Measuring=mathamatical value which helps us to compare things
GSD the range seen
Disadvantages of Aerosol Drug Therapy
There are a number of variables that can affect dose of aerosol drug delivered to the airways
Difficulties in dose estimation and dose reproducibility
lack of technical information on aerosol producing devices
Inconsistency on devices use and on patient and health care provider comprehension
Advantages of Aerosolized Medications
Onset is rapid as drug is delivered to the intended target area (respiratory tract)
Aerosol doses smaller than those for systemic treatment
Systemic side effects fewer and less severe than with oral or parenteral therapy. Parenteral: taken into the body in a way other than through the alimentary tract or digestive system (IV, IM)
Inhaled drug therapy painless and relatively convenient
Effective Aerosol Therapy
Delivers adequate amount of drug to site of action
Minimal waste
Low cost
Why do we care about particles sizes in aerosols?
We know size influences deposition. So if we want to target a specific part of the respiratory tract, we design an aerosol of appropriate size.
Recommended MMAD for Parenchyma (alveolar Region)
0.8-3 um
Hazards Of Aerosol Therapy
- Primary hazard:
- Adverse reaction to drug being administered
- Other hazards include:
- Infection
- Aerosol generators can cause nosocomial infections by spreading bacteria by airborne route
- Common sources of infection include:
- Contaminated solutions (multiple drug dose vials)
- Inadequate hand washing between patients
- Contaminated respiratory equipment (homecare)
- Infection
The particle size of aerosolized drug released controlled by:
- Vapor pressure of propellant blend
- Increased vapor pressure will decrease particle size
- Diameter of actuator opening
- Decreased actuator opening Decreased particle size
Types of Nebulizer
SVN
USN
SPAG
Operate on different physical principles to generate aerosol from solution
Baffle
by which solution is shattered into suspension of liquid particles in carrier gas
Most Nebulizers Contain
lReservoir chamber
lBaffle or a similar mechanism
Small Volume Nebulizer
Hand held nebulizer
<10 ml volume
Clinical use for over 100 years
Small reservoir, gas powered (pneumatic) aerosol generators
High pressure gas source (air or O2)
50 psi wall outlet
Air compressor
Compressed gas cylinder
SVN Equipment Design
- Utilize jet shearing princiaple for creating aerosol from drug solution
- Powered by high pressure stream of gas directed through a restricted orficie
- Gas strem leaving jet passes htrough the opening of capillary tube immersed in drug solution
- Produces low lateral pressure at its outlet due to high jet veolocity
- Draws liquid up capillary tube and into jet stream where it is sheared into droplets producing a heterodisperseaerosol
- This aerosol is also directed against one or more well designed baffles which reduces MMAD & GSD to within a target range
- Droplets that impact on baffle return to reservoir to be nebulized again
How much to put into a SVN & where to set the flow meter?
Residual or ‘dead’ volume
Ideal filling volume
Length of Tx time
Continuous vs intermittent nebulization
Gas source & flow rate
Physical nature of solution to be nebulized
Temperature and Humidity
Residual Dead Volume and Jet Nebulizers
Jet nebulizers do not aerosolize below minimum volume called ‘dead’ volume
Dead volume is amount of drug solution remaining in reservoir when device begins to ‘sputter’ and aerosolization ceases
~ 0.5 to 1.0 ml but varies with different devices (always read the device manufacturers specifications)
Ideal Filling Volume
At any given flow rate an increase in volume will result in an increase in time of effective nebulization
A volume between 3-5 ml (or as per manufecters recommendations) of solutions is recommended
Treatment Time
Increase volume will also decrease concentration of drug remaining in residual volume thus increase drug dose to patient
increase volume will lengethn treatment time- too long may affect patient compliance (convience)
Intermittent Nebulization
Accomplished by patient controlled finger port that directs gas to neb on inspiration only
Wastes less aerosol but increases treatment time
Technique requires good hand- breath coordination
Effect of Gas Source and Flow Rate
- Gas pressure and flow rate affect to variables
- Size of particle produced
- output (affecting length of treatment time)
- Increase flow rate or gas pressure
- decreased particle size and shift MMAD lower
- Increased flow rate or gas pressure
- increased output thus shorten time of treatment
- At a flow rate of 6 lpm, volume 3 ml, treatment will last 10 min
- At a flow rate of 8 lpm, volume 5 ml, treatment will last 10 min
- Thus adequate flow rate for SVN is 6-8 lpm depending on volume
Gas Density
Affects both aerosol production and deposition
Decrease density of carrier gas (heliox)-> Decrease aerosol impaction and thus better deposition in lungs
With heliox, output is much less than with air or O2 requiring in flow to produce comparable weight of aerosol per minute
Thus even though heliox increased amount of aerosol in lungs, it requires very high flows
Temperature and Humidity
Affect particle size and conc. of drug remaining in neb
Evaporation of water ®¯temp. of aerosol below ambient ®solution viscosity thus ¯neb output
Loss of water by evaporation ®¯particle size and solute concentration
Aerosol particles entrained into warm saturated gas stream, can grow in size depending on solution’s tonicity
When Aerosol Particles Enter the Respiratory Tract
Aerosol from isotonic solntend to maintain their size
Aerosol from hypertonic solntend to in size
Aerosol from hypotonic solntend to shrink & evaporate
Type Of Solution
Viscosity and density of medication formulation effects both its output and particle size
Performance of SVN is tested for different drug solutions
Cannot be assumed to produce adequate particle sizes for all solutions
Bronchodilator solutions generally meet above described specifications, thus are usually administered with these devices
However with certain solutions, volumes and flow rates suggested earlier may need to be modified such as:
- Pentamidine
- Antibiotics that have different characteristics and viscosity
- Gentamicin requires 10- 12 lpm to produce adequately small aerosol particles
Advantages Of SVN
Less technique and device dependent
Minimal coordination
Effective with low insp flows and volumes which improve deposition
Useful in very young, very old, pts in severe distress, debilitated patients
No breath hold is required, although it can’t hurt
Patients in severe distress may have high inspiratory flows…we like the fact we can use a “hands free mask” & just continuously administer medication, eventually some medication reaches our intended target site
Disadvanatges Of SVN
Treatment time can get long
Contamination
Wet cold spray with mask delivery
External power source-electrical power, or compressed gas
Commonly Use Nebulizer Solutions
- Salbutamol sulphate (Ventolin)
- lpratropium bromide (Atrovent)
- Combivent
- Budesonide (Pulmicort)
Salbutamol sulphate (Ventolin)
- Reliever; bronchodilator; short acting beta agonist (SABA)
- Single or Unit Dose Nebules
- 2.5 mg in 2.5 ml
- 5 mg in 2.5 ml
- Multi-dose vial
- 5 mg per ml
lpratropium bromide
lpratropium bromide (Atrovent)
Reliever*; bronchodilator; short acting anticholinergic (SAAC)
- Single dose or unit nebules
- 125 mcg/ml
- 250 mcg/ml
- Multi-dose vial
- 250 mcg/ml
Combivent
Combines salbutamol sulphate with ipratropium bromide (ventolinwith atrovent)
Reliever; bronchodilator; SABA with SAAC
SABA vs. SAAC
SABAs work to relieve bronchospasm in the small airways
SAACs work to prevent bronchospasm in the larger airways (bronchi)
Budesonide
Budesonide (Pulmicort)
Controller; Anti- inflammatory; steroid
Single or Unit dose vials
- 0.125 mg/ ml in 2 ml
- 0.25 mg/ ml in 2 ml
- 0.5 mg/ ml in 2 ml
Geometric Standard Deviation (GSD) “The Spread”
The greater the GSD, the wider the range of particle sizes produced by a device.
GSD < 1.22, aerosol considered monodispersed = single particle size
GSD > 1.22, aerosol considered heterodispersed = range of particle sizes
Most aerosols used in respiratory care
What will enhance particle deposition by inertial impaction
Turbulent Flow
Convoluted passages
Bifurcation of the airways
Inspirtory flows of > 30 lpm
Ultrasonic Nebulizers (USN)
- Electrically powered
- Can deliver high output and high aerosol densities
- Operate on piezoelectric principle
- Uses piezoelectric crystal to create aerosol
- Crystal transducer converts electrical signal into high frequency acoustic vibrations
- Vibrations create oscillation waves
- Oscillation waves form droplets which break free as fine aerosol particles
- Not routinely used in hospitals for aerosolization of medications
Advantages of USM
Small size
Rapid nebulization with shorter treatment time
smaller filling volume
portability (batteries)
As dead space is minimal we can use a small volume of solution and shorter treatment time-Can also be used for undilated bronchodilators
Dsiadvantages of USM
Expensive
Fragility-Lack of durability
Infection control
Small Particle Aerosol Generator (SPAG)
Large reservoir, pneumatically powered nebulizer
Can hold 300 ml of soln for long periods of nebulization
Operates on jet shearing principle with baffle, also has drying chamber to further reduce particle size to ~1.3 µm MMD
Solns in SPAG reservoir replaced 24 hours
Residual solution discarded before adding new solution
Nebulizer connected to hood or ventilator for administration to patient
Small Particle Aerosol Generator (SPAG) and Ribavarin
Used for administering ribavirin (antiviral agent) in the treatment of RSV
There are other ways to treat RSV in infants that may be used.
Ribavarin with a type of interferon is also used to treat Hep C
Types of Inhalers
Metered Dose Inhalers (MDIs)
- Puffers
Dry Powdered Inhalers (DPI)
- Turbuhaler
- Diskus
- Handihaler
Metered Dose Inhalers
Small pressurized canisters
Multiple doses of accurately metered drug
Many different drugs & come in different doses
3- 6 µm MMAD
Initial velocity and dispersion of aerosol ~ 80% of dose leaving actuator to impact and deposit in oropharynx
Pulmonary deposition ranges 10- 20%
Technical Design of Metered Dose Inhalers
Metered Valve Function
When inverted and placed in actuator, suspension will fill the metering valve chamber
When canister is depressed into actuator, drug- propellant mixture in metering valve is released under pressure
- Liquid propellant is ejected from pressurized valve rapidly expanding and vaporizes (ambient pressure)
- shatters liquid stream into an aerosol
- Upon release, metering valve refills with drug- propellant mixture from canister ® ready for next discharge
- Metering valve volume: 30 to 100 µL
- ~60- 80 % by weight consists of propellant
- ~ 1% active drug
Metered Dose Inhaler-Propellant
Drug mixed/suspended in with propellant
Dispersing agents or surfactants added to prevent coalescence of drug particles
Propellants: Chloro-fluoro carbons (CFCs) have been replaced with hydrofluoro alkanes (HFAs)
Propellants maintain steady vapor pressure as canister used / exhausted
Pressure in canister is specific to medication formulation
Factors Affecting MDI Performance
- Increase or decrease of drug concentration in first discharge, or if standing unused
- Drug suspension can separate from propellant when stored unused (creaming)
- MDI canister needs to be shaken before first actuation & if not used for period of time
- Rapid actuations can lead to turbulence and coalescence of particles
- Actuations – at least 30 seconds apart
- Loss of propellant from metering valve
- Little or no drug discharged on actuation
- Can be felt and heard by user
- Usually takes days and weeks to occur
- Regular use of MDI prevents this!
Advantages of MDI
Portable and Compact
Efficient Drug Delivery
Shorter treatment time
Disadvantages of MDI
Complex hand- breathing coordination required (if no holding chamber used)
Canister depletion difficult to determine accurately
Possible reactions to propellant
High oropharyngeal impaction and loss if holding chamber not used
Foreign body aspiration of coins and debris from mouth piece
Sensitive to extremem temps
MDI Contents
The MDI is empty is on shaking
- it seems light
- There is no movement of particles
- Recently there will be a counter which indicates 0 doses left
You can hold the canister next to your ear and shake it several times. If it has medicine, you’ll hear and feel the liquid contents swishing back and forth.
Another method is to keep track of the number of puffs you take in a notebook. You could also plan how long it will last based on the prescribed puffs per day: for example, using 2 puffs, 2 times a day. Calculate how many days this will last.
Spacers and Holding Chambers
Simple extension devices that puts distance between MDI and patient’s mouth
MDI accessory devices designed to decreaseinitial velocity of particles released from MDI before reaching oropharynx
Decrease oropharyngeal deposition
Can reduce bad taste of meds and eliminate cold propellant effect
Allow for vaporization of propellants and decrease particle size by evaporation thus better deposition in LRT and lung
Reservoir Device
Also known as extension device
is the global term for spacers and holding chamber
It will slow down and decrease the size of the particles
The longer the device the slower and smaller the particle will become
Spacer
Simple extension device
Extend aerosol spray away from the mouth
Holding Chamber
A spacer device with the addition of one way valves
Contain and hold aerosol until inspiration occurs
Reservoir Designs
Size
Shape
Volume
Presence of a one way valve
Inspirtory flow indicators
Advantage of Reservoir Devices
Decrease oropharyngeal drug loss
Sligt seperation of MDI actuation and inhalation
Disadvantage of Reservoir Devices
Some brands are large and cumbersome
Assembly required
Possible source of bacterial contamination with inadequate cleaning
Dry Powder Inhalers (DPI)
Unit doses of drug in powder form
Breath actuated and dispense drug during inspirtion
Flow from user creates an aerosol micro fine solid particles of drug as it is inhaled through the mouth piece
Are as effective as MDIs for deposition and drug response
Common DPI Designs
Diskus
Turbuhaler
HandiHaler
Diskus
Pre loaded doses
Each dose contained in a foil blister which is advanced and opened as the inhaler is used
Turbuhaler
Powder preparation reloaded in the device-Opened by rotating grip or thumb wheel
High number of doses (60-200)
May have a counter incorporated which will give a warning when there are ~ 20 doses left
Effective flow rate ~40 lpm (30-60 lpm)
Desiccating agent present
HandiHaler
Contains a single dose powder preparation of drug in gelatin capsule
Capsule inserted into the device and punctured to release powder prior to inhalation
Carrier subsatnce (glucose or lactose) improves flow properties of powder suitable volume to unit dose
Advanatges of DPI
Small and portable
Short preparation and administration time
less hand- breathing coordination
No propellants (thus environmentally friendly)
No ‘cold freon effect’ causing bronchoconstriction or inhibiting full inspiration
Count of remaining drug doses relatively easy
No extension device needed
Disadvantages of DPI
Patients not as aware of dose inhaled thus may distrust delivery
Possible reaction to glucose or lactose carrier substance
High inspiratory flow rates needed
Most of carrier impacts in oropharynx & can cause irritation
Important Points to Remeber in Regards to DPI
High Inspirtory Flows are the most critical factor in DPIs-Inspirtory flow of >30-60 lpm are needed
Should not be used with patient that are unable to generate a high inspiratory flow (small children, acute bronchospasm, etc)
Exhalation into the device may result in a loss of drug
High humididty can affect DPI drug avalibility-Hygroscopic partical will clump together when exposed to high humididty thus increasing particle size
Factors Associated With Reduced Aerosol Drug Deposition In The LungCriteria For Choosing An Aerosol Delivery Device
Mechanical ventilation
Artificial airways
Reduced airway size (infants and children)
Severe airway obstruction
Poor patient compliance and Technique
Limitation of specific delivery device
Criteria For Choosing An Aerosol Delivery Device
- Avalibility of drug formula
- Desires site of deposition
- Patient
- age
- Acuity of problem
- Alertness
- Ability to follow instruction
- Preference
When to Use a Small Volume Neb
-
Emergency
- Unable to follow instruction/disoriented
- Tachypneic (>25 bpm)
- Unstable respirtory pattern
- Poor inspirtory capcity
- Incapability of breath hold
- Patient preference/home use
- Formulation of drug
When to Use of MDI
Able to follow instruction and demonstrate correct use
Adequate inspirtory capcity
Capable of breath hold
stable respirtory pattern
drug is avalible in MDI form
When to Use a Reservoir Device
With all MDI aerosol
Especially in patient that have poor hand breathing coordination
Enhanced MDI use and reduced oropharyngeal losss
When to Use a DPI
Drug available in DPI form
Poor MDI coordination
Sensitive to propellants
Capable of generating high inspiratory flow rates (> 30-60 lpm) depending on drug
Need accurate dose count monitoring
Strive for consistency with devices.
What Happends when we add Normal Saline into a SVN
Adding diluent (normal saline) does not alter amount (dose) of drug present in neb;
Conc. of solution is less but not amount of drug
What are the medication delivery issues for infants and children?
They have smaller airway diameters, faster breathing rates, nose breathing filters out large particles, lower minute volumes, and spontaneous patient cooperation can be an issue.
What is the blow-by technique?
It is used if the patient cannot tolerate mask treatment. The aerosol is directed from the nebulizer towards the patients nose and mouth from a distance of several inches from the face.
