1.5

• Aerosolized medications


  Suspension of liquid and solid particles in air or gas generated by a device
• Sites of deposition of aerosolized medications

  • Particle size
  • Delivery device
  • Patient effort
  • Patient disease
• Mass Median Aerodynamic Diameter (MMAD)


  • Particle size above and below which 50% of mass of particles is contained
  • Major determinant of lung disposition
  • Higher MMAD indicates greater number of larger particles in aerosol
• Most devices produce multiple particle sizes
• Advantages of aerosol drug delivery

  • Immediate onset of drug action
  • Reduced side effects
  • Smaller doses of potent drugs may provide comparable therapeutic benefits
  • Can teach patients to self-administer
• Drugs administered by aerosol

  • Bronchodilators
  • Decongestants
  • Antibiotics
  • Anti-inflammatory agents
  • Mucolytics
  • Wetting agents
  • Surface-active agents
  • Anti-asthmatic agents
• Disadvantages and limitations of aerosol drug delivery

  • Inability to determine absolute amount of drug deposited in lungs
  • Efficacy dependent on patient's knowledge, coordination, and correct use of device
• Adverse effects of aerosolized drug delivery

  • Bronchospasm
  • Eye irritation
  • Eye infection
  • Increased risk of pulmonary infection from contaminated liquids
  • Occupational or bystander exposure
• Devices used in aerosolized drug delivery

  • Small-volume nebulizer (SVN)
  • Pressurized metered-dose inhaler (MDI)
  • Dry powder inhaler (DPI)
• Jet nebulizers


  • Cheapest and most common type of nebulizer
  • Gas-powered by high pressure air or oxygen through a jet
  • Solution enters stream, breaks into particles
• Ultrasonic nebulizers


  • Sound vibrations break liquid into aerosol
  • Large-volume models used for bland aerosol therapy
  • Small-volume models available for bronchodilators and antibiotics, not for medications in suspension form
• Mesh nebulizers


  • Vibrations push liquid medication through fine mesh to create aerosol
  • Battery-powered and portable
  • Deliver medication rapidly
  • Low residual volume
  • Expensive
• Circulaire II™


  • Incorporates one-way valve, distensible reservoir, and inspiratory retard in conjunction with standard SVN
  • Better aerosol deposition
  • Captures most of exhaled medication
  • Encourages more effective breathing pattern
• Figure 5.1: Nebulizer with reservoir bag to capture aerosol during the expiratory phase.
• Criteria for selecting patients for aerosol administration of drugs

  • Willingness and ability to cooperate with treatment
  • Ability to generate slow, deep breath and perform "breath-hold" at end-inspiration
  • Responsiveness of pulmonary disease to drug being used
• Comparing MDI and SVN

  • Some studies show equivalent therapeutic outcomes
  • MDI more cost-effective
  • SVN treatments may enhance drug delivery
  • Disposable SVNs may vary widely in quality of aerosol produced
• Technique for SVN treatment

  1. Assemble equipment

  2. Place medicine in nebulizer cup

  3. Connect to power source

  4. Instruct patient to breathe normally

  5. Continue breathing until sputter occurs

  6. Rinse nebulizer with sterile water; air dry
• SPAG and Aerogen
• Metered-dose inhalers


  • Frequently used by patients at home
  • Increasingly common in inpatient care
  • Proper use requires cooperative and coordinated patient
  • Proper use requires conscientious instruction and supervision
• Pressurized metered-dose inhalers


  • Now use HFA instead of CFC
  • Higher lung deposition of active drug
  • Less likely to cause bronchospasm
  • More stable medication dosage
  • Reduced medication impact
• Pressurized metered-dose inhalers contain pressurized canister with drug in powder or solution suspended in propellant
• Figure 5.2: Schematic drawing of metered-dose inhaler.
• Developments in MDI technology

  • Maxair™ Autohaler™ breath-actuated MDI assures proper inspiratory flow, removed from market in United States
  • Respimat™ soft-mist inhaler delivers metered dose of medication, spring-loaded propellant-free nebulizer
• Priming of MDIs


  1. Discharging doses to assure medication is ready for patient inhalation

  2. Many require priming if unused for specified amount of time

  3. Refer to manufacturer's information insert
• Technique for MDI treatment

  1. Remove cap and vigorously shake canister

  2. Hold inhaler with mouthpiece down

  3. Breathe out through mouth, pushing as much air from lungs as possible

  4. Push top of canister completely down at beginning of slow, deep inspiration

  5. Close mouth, inhale fully, and hold breath up to 10 seconds

  6. Exhale normally, wait 60 seconds, then repeat procedure for second inhalation if needed

  7. Replace cap on mouthpiece after use
• Spacers and holding chambers

  • Provide aerosol reservoir to improve medication delivery by pMDI
  • Hold aerosol in suspension longer
  • Effective for patients who have difficulty coordinating breaths with an MDI
  • Decrease deposition of particles in oropharynx
• Figure 5.4: Metered-dose inhaler (MDI) with spacer chamber.
• Valved-holding chamber


  • Includes one-way valve
  • Allows patient to inhale when ready and exhale without affecting aerosol
  • Helpful for patients who have difficulty coordinating pMDI and breathing patterns
  • Standard for most inpatient pMDI therapy
• Figure 5.5: Valved holding chamber.
• Dry powder aerosols


  • Inspiratory flow-driven inhalers that deliver dry powder into lungs
  • Particles <5 μm in size
  • Lactose or glucose filler acts as carrier
  • Single-dose or multiple-dose
• Examples of dry powder aerosols

  • Diskus
  • Flexhaler
  • Diskhaler
  • HandiHaler
  • Aerolizer
• Figure 5.6: Multiple-dose dry powder inhalers: (A) Diskus. (B) Flexhaler. (C) Diskhaler. Single-dose dry powder inhalers: (D) HandiHaler. (E) Aerolizer.
• Advantages and disadvantages of dry powder aerosols

  • Advantages: Better deposition of aerosol likely, no propellant gas used
  • Disadvantage: Many COPD patients cannot generate required inspiratory flow
• Technique modified for administration of corticosteroid drugs with MDI

  1. Bronchodilator should be taken first

  2. Wait 1–2 minutes after taking bronchodilator

  3. Hyperextend neck while inhaling

  4. Rinse mouth after inhaling corticosteroid
• SVN and MDI during mechanical ventilation

  • Amount of medication delivered reduced because aerosols tend to deposit in ventilator tubing and are baffled by reduced airway diameter of artificial airway
• Important considerations for SVN and MDI during mechanical ventilation

  • Drug dosage
  • Placement of devices in ventilator circuit
  • Lying in supine position
  • Using humidified air/oxygen
  • Breaths being controlled by ventilator
• SVN during mechanical ventilation

  1. Place SVN in inspiratory limb of circuit, within 12 in (30 cm) of patient Y-piece

  2. Flow through nebulizer should be 6–8 L/minute, or can use continuous gas flow

  3. Adjust dosage until therapeutic response noted
• SVN during mechanical ventilation

  • Increased risk of ventilator-associated pneumonia due to contamination
  • Thoroughly clean and disinfect nebulizer after each use
  • Rinse with sterile water and dry
  • Use single unit-dose medications if possible
• MDI during mechanical ventilation

  • Convenient and safe, but must use adapter with actuator mouthpiece
  • Types of adapters available: elbow-types, tee-types, in-line types, variety of chambers
• Key factors when using MDI during mechanical ventilation

  • Placement of MDI–adaptor system as close to airway as possible
  • Adjust dosage to achieve therapeutic results
  • 15-second pause between actuations