Aerosol drug therapy, a cornerstone in respiratory medicine, involves the administration of medication in the form of microscopic droplets or particles suspended in a gas.
Administered to manage a range of conditions—from chronic ailments like asthma and COPD to acute settings in hospitals—this mode of therapy offers the advantage of targeted drug delivery to the lungs with minimal systemic side effects.
However, the effectiveness of aerosol drug therapy is critically dependent on various factors such as particle size, formulation, and the type of device used.
Understanding these nuances is crucial for both healthcare providers and patients to optimize therapeutic outcomes.
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What is Aerosol Drug Therapy?
Aerosol drug therapy refers to the administration of medication in the form of a mist inhaled into the lungs. In this method, drugs are dispersed into a fine spray, droplets, or particles suspended in air or another gas.
These aerosolized medications can then be inhaled directly into the respiratory system using various devices such as metered-dose inhalers (MDIs), dry powder inhalers (DPIs), or nebulizers.
It offers the benefit of targeted therapy, delivering the medication directly to the affected area—typically the bronchial tubes and lungs—thereby achieving quicker therapeutic effects while minimizing systemic side effects.
In a clinical setting, aerosol drug therapy can also be used in ventilated patients and during certain surgical procedures to deliver medications like bronchodilators or antibiotics.
Overall, aerosol drug therapy is a critical tool in the management of a range of acute and chronic respiratory conditions.
Aerosol Drug Delivery Systems
Aerosol drug delivery systems are devices used to administer medications in a form suitable for inhalation into the respiratory system.
These systems transform liquid or solid medication into an aerosol, which is a suspension of fine particles in a gas. The most commonly used aerosol drug delivery systems include:
- Metered Dose Inhaler (MDI)
- Dry Powder Inhaler (DPI)
Metered Dose Inhaler (MDI)
A metered dose inhaler (MDI) is a handheld device that delivers a specific, measured dose of medication in aerosol form. The device consists of a pressurized canister containing the medication and propellant, which is fitted into an actuator with a mouthpiece.
To administer the medication, the user must coordinate pressing down on the canister while inhaling through the mouthpiece.
MDIs are commonly used for delivering bronchodilators, corticosteroids, and combination therapies for conditions like asthma and COPD.
Spacers can be added to some MDIs to improve medication delivery, especially in children or those who find hand-breath coordination challenging.
Dry Powder Inhaler (DPI)
A dry powder inhaler (DPI) delivers medication in a powder form, negating the need for a propellant. The device holds the medication in individual doses, often in a blister pack or a capsule that is inserted into the inhaler.
To use a DPI, the patient must inhale forcefully through the mouthpiece, drawing the powdered medication into the lungs.
This technique requires a strong, quick inhalation to disperse the powder into the airways.
DPIs are often used for long-term treatment of diseases like asthma and COPD and are known for their portability and ease of use, although they may be unsuitable for patients with a weak or compromised respiratory effort.
A nebulizer is a device that converts liquid medication into a mist, enabling easy inhalation into the lungs. A typical nebulizer consists of a medication chamber, a compressor, and a mouthpiece or mask.
Unlike MDIs and DPIs, nebulizers require no special inhalation technique, making them ideal for use in infants, elderly patients, or anyone who has difficulty using handheld inhalers.
Nebulizers are commonly used in more severe cases of respiratory illness or during acute exacerbations and are often employed in clinical settings, though portable versions are available for home use.
Note: Each system has its own set of requirements for maintenance and cleaning, and not all systems are suitable for all types of medications or patients. Therefore, the choice of device can significantly impact the effectiveness of the treatment.
Types of Nebulizers
Nebulizers come in various forms, each with its own method of aerosolizing liquid medication for inhalation.
The main types of nebulizers are:
- Jet nebulizers
- Ultrasonic nebulizers
- Mesh nebulizers
Jet nebulizers use compressed air to convert liquid medication into a fine mist. This device consists of a medication cup, a compressed air machine, and a mask or mouthpiece. While effective, these nebulizers are generally larger and noisier compared to other types.
They are often used in hospitals and can be less convenient for home use due to their size and need for an electrical outlet.
Ultrasonic nebulizers use high-frequency vibrations to turn liquid medication into a mist. They are quieter and faster than jet nebulizers but can be more expensive.
Ultrasonic nebulizers are typically smaller and more portable, making them convenient for travel and home use.
However, not all medications are suitable for ultrasonic nebulization, as the process can potentially alter the drug’s chemical structure.
Mesh nebulizers use a vibrating mesh or membrane with tiny holes to produce an aerosol mist. They are the newest type of nebulizer and are typically the smallest and quietest. Mesh nebulizers are battery-operated, making them highly portable.
They are efficient in drug delivery but can be more expensive than the other types of nebulizers. They’re also suitable for a wide range of medications and are often used for more specialized treatments.
Note: Each type of nebulizer has its own advantages and disadvantages, and the most suitable choice depends on a variety of factors, including the patient’s specific medical condition, age, ability to use the device, medication type, and lifestyle considerations.
Indications for Aerosol Drug Therapy
Aerosol drug therapy is indicated for a variety of conditions, primarily focusing on respiratory issues but extending to some systemic ailments as well. Here are some of the main indications:
- Asthma: One of the most common uses for aerosol drug therapy, bronchodilators and corticosteroids are often administered through inhalers to relieve symptoms like wheezing, shortness of breath, and chest tightness.
- Chronic Obstructive Pulmonary Disease (COPD): Both long-acting and short-acting bronchodilators, often combined with inhaled corticosteroids, are used to manage COPD symptoms like chronic cough, frequent respiratory infections, and difficulty breathing.
- Cystic Fibrosis: Nebulizers are frequently used to deliver medications that help to thin mucus and antibiotics to treat lung infections common in cystic fibrosis patients.
- Bronchiectasis: Nebulizers are often used to administer medications to manage chronic symptoms, including antibiotics, bronchodilators, and mucolytics.
- Pneumonia: In certain cases, especially for people who have difficulty taking medications orally or for severe infections, antibiotics may be administered through a nebulizer.
- Allergic Rhinitis and Other Allergies: Corticosteroid nasal sprays are commonly used to treat symptoms of allergic rhinitis, including congestion, sneezing, and runny nose.
- Acute Respiratory Distress Syndrome (ARDS): In a hospital setting, nebulizers may be used to administer medications like albuterol to relieve bronchospasm or other agents like surfactants in neonatal units.
- Preoperative and Postoperative Care: Aerosolized medications may be used to prepare the airways prior to surgery or to manage symptoms postoperatively.
- Ventilator Support: Patients on mechanical ventilation may receive aerosolized medications such as bronchodilators, antibiotics, or anti-inflammatory drugs through a specialized port in the ventilator circuit.
- Off-Label Uses: In some cases, aerosol drug therapy is used for off-label purposes such as administering pain medication or medication for pulmonary arterial hypertension.
Note: The specific indications for aerosol drug therapy may depend on the patient’s medical history, the severity of the condition, and other ongoing treatments.
Hazards of Aerosol Drug Therapy
While aerosol drug therapy is generally considered safe and effective for treating various respiratory conditions, there are potential hazards and side effects that healthcare providers and patients should be aware of:
- Systemic Absorption: Some inhaled medications can enter the bloodstream, leading to systemic side effects.
- Local Irritation: Medications can irritate the throat, mouth, or respiratory tract, causing coughing, sore throat, or a hoarse voice.
- Bronchospasm: Certain aerosolized medications can paradoxically induce bronchospasm, causing the airways to narrow and making breathing more difficult.
- Infection Risk: Improper cleaning of inhalers and nebulizers can lead to bacterial or fungal contamination, potentially causing respiratory infections.
- Coordination Difficulty: Failure to properly synchronize inhalation with device actuation in MDIs can result in poor drug delivery.
- Drug Deposition: Inefficient drug delivery can result in medication depositing in the mouth or throat instead of reaching the lungs, reducing effectiveness.
- Tachyphylaxis: Repeated use of certain medications, like short-acting bronchodilators, can lead to reduced effectiveness over time.
- Oropharyngeal Candidiasis: Inhaled corticosteroids can increase the risk of developing oral thrush.
- Environmental Impact: Some propellants used in MDIs are greenhouse gases, contributing to environmental pollution.
- Cost: Some aerosol drug delivery systems like mesh nebulizers or certain inhalers can be expensive, posing a financial burden.
- Drug Interactions: Aerosolized medications can interact with other drugs, leading to increased side effects or reduced effectiveness.
- Unsuitable for Acute Severe Asthma: Nebulizers often require more time to deliver medication and may not be suitable for emergency treatment of severe asthma attacks.
- Wastage: Some of the drug dosage may be lost during administration, particularly with nebulizers, reducing the efficiency of the treatment.
- Variable Dosage: Factors like breathing technique, device type, and patient age can influence the actual dose received, complicating treatment management.
- Psychological Dependence: Over-reliance on reliever inhalers, particularly in asthma, can lead to inappropriate management of the condition.
Note: Understanding these hazards is essential for both healthcare providers and patients to maximize the benefits of aerosol drug therapy while minimizing risks.
Aerosol Drug Therapy Practice Questions
1. What does the aerosol particle size depend on?
It depends on the substance being nebulized, the method used to generate the aerosol, and the environmental conditions surrounding the particle.
2. How are medical aerosols generated in the clinical setting?
They are generated with devices that physically disperse matter into small particles and suspend them in gas.
3. How does a large-volume ultrasonic nebulizer work?
It incorporates air blowers to carry mist to the patient for the delivery of bland aerosol therapy or sputum induction.
4. How do ultrasonic nebulizers work?
They use a piezoelectric crystal to convert electrical energy into high-frequency vibrations to produce aerosols. The aerosol output is directly affected by the amplitude setting.
5. How do you prime an MDI?
To prime an MDI, you should shake the device and release one or more sprays into the room air if the device is new or hasn’t been used in a while.
6. How is aerosol output measured?
By collecting aerosol that leaves a nebulizer and on a special filter
7. How are DPIs categorized?
They are categorized by the design of their dose containers.
8. How often do you assess a patient on continuous nebulization?
Assess them every 30 minutes for the first 2 hours, then hourly after that for adverse drug responses
9. What affects MDI performance and drug delivery?
Low temperatures can decrease the output of a CFC MDI, and if debris build up on the nozzle or actuator orifice, it reduces the emitted dose.
10. What are three examples of aerosol devices?
Atomizers, nebulizers, and inhalers
11. What factor is most crucial in developing an effective program of aerosol drug self-administration in an adult patient requiring maintenance bronchodilator therapy?
Good patient education
12. What are the beneficial characteristics of using an MDI?
They are portable, compact, and easy to use.
13. What are heterodispersed aerosols?
Aerosols with particles of different sizes
14. What are the key mechanisms of aerosol deposition?
Inertial impaction, gravimetric sedimentation, and Brownian diffusion
15. What are the medication delivery issues for infants and children?
They have smaller airway diameters, faster breathing rates, lower minute volumes, and their nose breathing filters out large particles.
16. What are monodispersed aerosols?
Aerosols with particles of the same sizes
17. What are small-volume ultrasonic nebulizers used for?
They are used for the delivery of aerosolized medications (i.e., bronchodilators, antibiotics, and anti-inflammatory agents).
18. What are the hazards of aerosol drug therapy?
Infection, airway reactivity, pulmonary and systemic effects of bland aerosols, drug concentration changes during nebulization, and eye irritation
19. What is therapeutic aerosol deposition influenced by?
Inspiratory flow rate, flow pattern, respiratory rate, inhaled volume, I:E ratio, and breath-holding
20. What are two methods used to measure medical aerosol particle distribution?
(1) Cascade impaction and (2) Laser diffraction
21. What contributes to the aging of aerosols?
The composition of the aerosol, initial size of the particles, time in suspension, and ambient condition
22. What does gravimetric analysis measure?
23. What happens to the temperature of a solution placed in an ultrasonic nebulizer?
The temperature of the solution increases.
24. What is a dry powder inhaler (DPI)?
It is a breath-actuated dosing system by which a patient creates an aerosol by drawing air through a dose of finely milled drug powder. The dispersion of powder into respirable particles depends on the creation of turbulent flow in the inhaler.
25. What is an aerosol-emitted dose?
The mass (amount) of the drug leaving the mouthpiece as an aerosol
26. What is aerosol output?
The mass (amount) of fluid or drug contained in an aerosol
27. What is aerosol output rate?
The mass (amount) of aerosol generated per unit of time
28. What is aerosol aging?
The process by which aerosol suspension changes over time
29. What is a metered-dose inhaler (MDI)?
A pressurized canister containing a prescribed drug in a volatile propellant combined with surfactant and a dispersing agent
30. What is an aerosol?
A suspension of solid or liquid particles in air or gas
31. What is a positive response indicated by continuous nebulization?
An increase in peak flow greater than 10% with a goal of at least 50%
32. What is a disadvantage of an MDI?
80% of the aerosol hits the back of the throat, depositing the medication in the oropharynx
33. What is an ultrasonic nebulizer capable of?
They produce higher aerosol outputs and densities than conventional jet nebulizers.
34. What is Brownian diffusion?
The primary deposition mechanism for very small particles that can travel deep within the lungs
35. What is gravimetric sedimentation?
When aerosol particles settle out of suspension and are deposited due to the pull of gravity
36. What is inertial impaction?
When aerosols in motion collide with and are deposited onto a surface
37. What is the blow-by technique?
A delivery technique where the aerosol is directed from the nebulizer to the patient’s nose and mouth from a distance of several inches from the face
38. What is the fundamental principle of aerosol deposition?
Only a fraction of the emitted aerosol will be inhaled, and only a fraction of what is inhaled will make it to the lungs
39. What is the most commonly prescribed method of aerosol therapy?
40. What is the primary hazard of aerosol drug therapy?
An adverse reaction to the medication
41. What is the relationship between GSD and the range of particle sizes?
The greater the GSD, the wider the range of particle sizes and; therefore, a more dispersed aerosol
42. What is the difference between a spacer and a holding chamber?
A spacer is valve-less and just adds distance from the point of discharge to the mouth. A holding chamber has valves for holding the medication.
43. Where should the aerosol generator be placed with IPPV?
It should be placed in the circuit close to the patient’s airway.
44. Why would you prime an MDI?
To mix the drug and propellant and to ensure that an adequate dose is provided.
45. Why would you use continuous nebulization?
For the treatment of refractory bronchospasm
46. What are the two most common laboratory methods used to measure medical aerosol particle size distribution?
Cascade impaction and laser diffraction
47. What are the three categories of DPIs?
(1) Unit-dose, (2) Multiple unit-dose, and (3) Multiple-dose drug reservoir
48. What is aerosol drug administration?
The process of administering an aerosol medication to a patient’s lungs.
49. What are the different types of aerosols?
Pollen, spores, dust, smoke, fog, and mist
50. Aerosol particles can change size as a result of what?
Evaporation or hygroscopic water absorption
51. What is aerosol aging?
The process by which an aerosol suspension changes over time
52. What is the aim of medical aerosol therapy?
To deliver a therapeutic dose of the selected agent to the desired site of action
53. What is the SPAG?
The SPAG was manufactured specifically for the administration of ribavirin (Virazole) to infants with a respiratory syncytial virus (RSV) infection. It incorporates a drying chamber with its own flow control to produce stable aerosols.
54. What is the baffle?
A surface on which large particles impact and fall out of suspension, whereas smaller particles remain in suspension, reducing the size of particles remaining in the aerosol
55. Before the initial use and after storage, what should happen to every MDI device?
Each MDI should be primed by shaking and actuating the device to the atmosphere one to four times. Without the priming, the initial dose actuated from a new pMDI canister contains less active substances.
56. What is a breath-actuated nebulizer?
An aerosol device that is responsive to the patient’s inspiratory effort and reduces or eliminates aerosol generation during exhalation; they can generate aerosol only during inspiration, which eliminates the waste of aerosol during exhalation and increases the delivered dose
57. What is a breath-actuated pressurized metered-dose inhaler?
A variation of a pMDI that incorporates a trigger that is activated during inhalation, which reduces the need for the patient or caregiver to coordinate the actuation with inhalation
58. What is a breath-enhanced nebulizer?
A nebulizer that entrains room air in direct relationship to the inspiratory flow of the patient; they generate aerosols continuously using a system of vents and one-way valves to minimize aerosol waste
59. Breath holding after inhalation of an aerosol does what?
It increases the residence time for the particles in the lungs and enhances distribution and sedimentation.
60. When assessing a patient’s response to bronchodilator therapy, you notice a decrease in wheezing accompanied by an overall decrease in breath sounds. What’s most likely the cause of this?
Increasing airway obstruction
61. What are cascade impactors?
They are designed to collect aerosols of different size ranges on a series of stages or plates.
62. The CDC recommends that nebulizers should be what?
They should be cleaned, disinfected, rinsed with sterile water, and air-dried between uses.
63. What are chlorofluorocarbons (CFCs)?
They are gaseous chemical compounds that were originally used to power metered-dose inhalers but have been phased out of use.
64. How often should you clean holding chambers and spacers?
They should be cleaned monthly or as recommended by the manufacturer.
65. Which part of the lung is preferred for the deposition of beta-adrenergic bronchodilators?
The lower airways
66. Cold air and high-density aerosols can cause what?
Reactive bronchospasm and increased airway resistance
67. What are the concerns of patients using disposable nebulizers at home?
There may be degradation of the performance over multiple uses.
68. What is continuous drug delivery?
When nebulization occurs over an extended period of time
69. How does an atomizer differ from an SVN?
Atomizers do not have baffles
70. What is the inspiratory flow requirement when using a DPI?
71. DPIs should not be used for what?
They should not be used for the management of acute bronchospasm.
72. When should an MDI be activated for a ventilator patient?
You should coordinate the actuation of the MDI with the beginning of the ventilator inspiration.
73. Drugs for nebulization that escape from the nebulizer into the atmosphere, or are exhaled by the patient, can be inhaled by who?
They can be inhaled by the caregiver or anyone in the vicinity of the treatment.
74. When used in conjunction with high-frequency oscillatory ventilation, the administration of albuterol sulfate by a vibrating mesh nebulizer placed between the ventilator circuit and the patient airway has been reported to do what?
It has been reported to deliver greater than 10% of the dose to both infants and adults.
75. When using a 50-psi flowmeter to drive an SVN, you would normally set the flow at what?
76. Exhalation into the device before inspiration can result in what?
It can result in a loss of drug delivery to the lungs.
77. Eye irritation is caused by what?
It is caused by aerosol therapy that is administered via a face mask, which leaks from the mask during delivery.
78. Poor patient response to bronchodilator therapy often occurs because of what?
An inadequate amount of the drug reaches the airway
79. What is a potential problem with continuous bronchodilator therapy?
An increased drug concentration can be adversely given
80. What is priming?
A technique that involves shaking the device and releasing one or more sprays into the air when a pMDI is new or has not been used in a while
81. What is a propellant?
The component of an MDI that propels or provides thrust
82. A reservoir on the expiratory limb of the nebulizer does what?
It conserves drug aerosols
83. What is residual drug volume?
It is the dead volume of medication that remains in the SVN after the device stops generating aerosol and “runs dry.”
84. What is the respirable mass?
The proportion of an aerosolized drug to reach the lower respiratory tract
85. What is the risk for caregivers and bystanders when administering aerosol drug therapy?
They are at risk of hazards from exposure to secondhand aerosol drugs.
86. What is sedimentation?
It occurs when aerosol particles settle out of suspension and are deposited due to gravity.
87. What is the most commonly used device for medical aerosol therapy?
Small-volume nebulizer (SVN)
88. A small-volume ultrasonic nebulizer can be used to administer what?
Bronchodilators, anti-inflammatory agents, and antibiotics
89. What is a spacer?
A simple valve-less extension device that adds distance between the MDI outlet and the patient’s mouth; this distance allows the aerosol plume to expand and the propellants to evaporate before the medication reaches the oropharynx
90. What are spacers and valved holding chambers designed to do?
They are designed to reduce both oropharyngeal deposition and the need for hand-breath coordination.
91. Is the mouthpiece better than the mask for delivering aerosol drugs?
As long as the patient is mouth breathing, there is little difference in clinical response between therapy given by mouthpiece and therapy given by mask.
92. What are the three categories of nebulizers?
(1) Pneumatic jet nebulizers, (2) Ultrasonic nebulizers, and (3) Vibrating mesh nebulizers
93. What is the recommended timing interval when using an inhaler?
Manufacturers recommended waiting 30-60 seconds between actuations.
94. In order to avoid an oral yeast infection, the patient should do what after inhaling a corticosteroid drug?
Rinse their mouth
95. What problems are associated with using a SPAG to deliver ribavirin?
(1) Caregiver exposure, and (2) Drug precipitation can jam the breathing valves or occlude the ventilator circuit
96. A typical SVN is powered by what?
It is powered by a high-pressure stream of gas that is directed through a restricted orifice.
97. What is a unit-dose DPI?
A type of DPI that dispenses individual doses of the drug from punctured gelatin capsules
98. Ultrasonic nebulizers use a piezoelectric crystal to do what?
To generate aerosol
99. What is volume mean diameter (VMD)?
The median diameter of an aerosol particle measured in units of volume
100. Baffling systems decrease what?
They decrease both the MMAD (size) and GSD (range of sizes) of the generated aerosol.
101. When ribavirin and pentamidine are administered, where should the treatment be provided?
They must be administered in a private room that is equipped for negative pressure ventilation with adequate air exchange.
102. Without a dose counter, there is no viable method to determine what?
To determine how much drug is remaining in the MDI
103. What are some advantages of using an MDI?
They are inexpensive, light, compact, and resistant to moisture. They also provide quick delivery and consistent doses. They are available with most anti-asthmatic drugs.
104. What are some disadvantages of using an MDI?
Some patients have difficulty with the coordination of activation and inspiration, and it can be time-consuming to teach. There is also the cold-freon effect, which is the inability to continue to breathe when the propellant is released into the mouth.
105. What patients cannot use a DPI?
Children under the age of 5 and patients unable to generate a sufficient inspiratory flow.
106. What are some of the advantages of using a spacer?
There is no need for hand-breath coordination, it increases drug deposition in the lungs, it reduces drug deposition in the mouth, it can be used in children with a face mask, and it decreases the incidence of oral thrush
107. What are the characteristics of a jet nebulizer?
It cools during operation, provides a small aerosol particle size, and is less expensive than the alternatives.
108. How effective is the “blow-by” technique in infants?
It is not very effective
109. How should drug dosages be adjusted when they’re being administered via SVN to patients receiving mechanical ventilation?
Administer 2 to 5 times the normal dose
110. What is the optimal flow rate when using an SVN?
6 to 8 L/min
111. What are the characteristics of ultrasound nebulizers?
They heat up during operation, produce larger aerosol particles, are more expensive, and create less noise than the alternatives.
112. What aerosol output is an ultrasonic nebulizer capable of delivering?
0.2 to 1.0 mL/min
113. What are the hazards of aerosol therapy?
Bronchospasm, over-hydration, overheating of inspired gases, delivery of contaminated aerosol, and tubing condensation draining into the airway
114. Why is particle size important in aerosol therapy?
The ability of aerosols to travel through the air, enter the airways, and deposit in the lungs is largely based on particle size.
115. What devices generate therapeutic aerosols?
Atomizers and nebulizers
116. The mass of aerosol particles produced by a nebulizer in a given unit of time best describes which quality of an aerosol?
117. What is a common method to measure aerosol particle size?
118. What is used to identify the particle diameter, which corresponds to the most typical settling behavior of an aerosol?
Mean mass aerodynamic diameter (MMAD)
119. What is the primary mechanism for the deposition of large particles in the respiratory tract?
120. What will increase aerosol deposition by inertial impaction?
Variable or irregular passages and turbulent gas flow
121. Where do most aerosol particles in the 5-10 μm range deposit?
122. Where do most aerosol particles in the 1-5 μm range deposit?
123. What term describes the primary mechanism for the deposition of small particles?
124. Where do most aerosol particles that are less than 3 μm deposit?
125. How can you monitor a patient for the possibility of reactive bronchospasm during aerosol drug therapy?
Measure pre and post-peak flow and the %forced expiratory volume in 1 second; auscultate for adventitious breath sounds; observe the patient’s response; and communicate with the patient during therapy
126. What is the preferred method of delivering a bronchodilator to spontaneously breathing patients who are intubated and receiving mechanical ventilation?
Metered-dose inhaler (MDI)
127. When fired inside the mouth, what percentage of the drug dose delivered by an MDI deposits in the oropharynx?
128. Before inspiration and actuation of an MDI, the patient should exhale to which of the following?
Functional residual capacity
129. To ensure delivery of proper drug dosage with an MDI, which of the following must be done first?
The canister should be warmed to hand or body temperature, and the canister should be vigorously shaken.
130. What type of patients are most likely to have difficulty using an MDI inhaler?
Those who are in acute distress, infants and young children, and elderly patients
131. What is a potential limitation of flow-triggered MDI devices?
The high flows necessary for actuation
132. Which type of patient would you recommend against using a flow-triggered MDI as the sole bronchodilator delivery system?
A patient that is likely to develop acute severe bronchospasm
133. The key difference between an MDI holding chamber and a spacer is that the holding chamber incorporates what?
A one-way inspiratory valve
134. What device would you select to deliver an aerosolized bronchodilator to a young child?
MDI with a holding chamber and mask
135. The proper use of a dry powder inhaler requires that the patient is able to do what?
Generate inspiratory flows of 60 L/min or higher
136. What device depends on the patient’s inspiratory effort to dispense a dose?
Dry powder inhaler (DPI)
137. For what patient groups is the DPI for bronchodilator administration NOT recommended?
Infants and children under 5 and patients with an acute episode of bronchospasm
138. Exhalation into which device can result in a loss of drug delivery?
Dry powder inhaler (DPI)
139. SVN output drops after lowering the patient’s bed while giving a treatment, but there is 3 mL of solution still left in the reservoir. How can you correct this problem?
Reposition the patient so that the SVN is more upright
140. What should you do to minimize a patient’s infection risk between drug treatments with an SVN?
Rinse the SVN with sterile water and air-dry
141. The physician has ordered ribavirin (Virazole) to be administered by aerosol to an infant with bronchiolitis. Which device would you use for delivery?
Small particle aerosol generator (SPAG)
142. What problems are associated with the delivery of virazole using a SPAG?
Caregiver exposure and drug precipitation in the ventilator circuit
143. For the maintenance administration of bronchodilators to adult patients with adequate inspiratory flows, which aerosol devices would you recommend?
DPI and MDI with a holding chamber
144. What aerosol drug delivery systems would you not recommend for a toddler or small child?
MDI and SVN
145. What is the best way to confirm that a patient can properly self-manage a newly prescribed form of aerosol drug therapy?
Have the patient provide a return demonstration
FAQs About Aerosol Drug Therapy
What is Aerosol Output?
Aerosol output is a term that refers to the total mass or weight of the particles that are produced by an aerosol generator for dispersion. In general, the aerosol output will vary greatly depending on the drug delivery system that is used.
It is measured by collecting an aerosol particle on a filter once it is dispersed and analyzing the weight or quantity.
If you measure the weight, this is referred to as the gravimetric analysis, which is typically less reliable because of the weight changes that occur due to evaporation. Analyzing the quantity is a more reliable way of measuring aerosol output.
What is Aerosol Deposition?
Aerosol deposition is the process by which aerosol particles are removed from the air and settle onto surfaces. This can occur through several different mechanisms, including gravity, inertial impaction, and diffusion.
During aerosol therapy, a large portion of aerosol particles never make it to the lungs due to deposition in the back of the throat or in the larger airways.
This could be due to the aerosol particle size or the patient’s breathing pattern. As a practitioner, understanding how to control these variables is important for improving the overall delivery of aerosol therapy to your patients.
What is an Atomizer?
An atomizer is a device that is used to generate an aerosol. It typically consists of a cup or reservoir for the liquid medication, a power source, and a nozzle.
The most common type of atomizer is the piezoelectric crystal atomizer, which uses a piezoelectric crystal to generate vibrations that create an aerosol.
What is a Baffle on a Nebulizer?
A baffle is a device that is used to direct the airflow in a nebulizer. It is typically placed between the compressor and nozzle to help control the direction of the airflow.
They play a key role in the ability of a nebulizer to generate aerosol particles.
What is a Breath-Actuated Nebulizer?
A breath-actuated nebulizer is a type of nebulizer that produces aerosols during inspiration when negative pressure is generated by the patient. This is important because it prevents medication doses from being wasted.
When a patient takes a breath in, negative pressure is created, which activates the device so that medication is drawn into a reservoir and aerosols can be generated.
What is a Breath-Enhanced Nebulizer?
A breath-enhanced nebulizer is a type of nebulizer that generates continuous aerosols, which help increase the amount that is inhaled. They use a system of one-way valves and vents to limit the amount of medication that is wasted.
When a patient takes a breath in, there is an inspiratory vent that allows air to move into the nebulization chamber where aerosols are generated.
Then, as the patient exhales, the inspiratory vent closes so that the drug aerosols can only exist through a one-way valve that is located near the mouthpiece of the device.
What is Brownian Diffusion?
Brownian diffusion is the random motion of particles that are suspended in a fluid. This motion is caused by the collisions of the particles with the molecules of the fluid.
The spread of aerosol particles in the air is due to Brownian diffusion. The size and shape of the particles will affect the rate of diffusion.
What is an Emitted Dose?
The emitted dose is the amount of drug that is emitted from an aerosol generator. It is typically expressed in milligrams or micrograms.
Some aerosol delivery devices are able to generate higher doses than others.
What is a Propellant in an Inhaler?
A propellant is a gas that is used to expel medication from an inhaler device. The most common propellants are chlorofluorocarbons (CFCs), which have been phased out due to their negative impact on the environment.
Hydrofluoroalkanes (HFAs) are the most common type of propellant used in inhalers today. They are less harmful to the environment than CFCs but can still contribute to greenhouse gas emissions.
Aerosol drug therapy is an indispensable tool in the treatment of respiratory conditions. Its targeted approach allows for effective management with reduced systemic impact.
However, the success of this therapy is contingent upon a comprehensive understanding of its different parameters like aerosol mechanics, pharmacokinetics, and device types.
As ongoing research brings forth new formulations and technologies, clinicians and patients must stay updated to make the most of this localized treatment option, thereby improving both the quality of care and patient outcomes.
John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.
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