Aerosol Therapy and Delivery Devices – Vocabulary Review

Indications for Aerosol Therapy

• To deliver medication (main indication): relieve bronchospasm and/or bronchoconstriction; relieve upper airway edema; anesthesia: to control pain and gagging during an endoscopic procedure; rhinitis: to relieve inflammation and vascular congestion; to promote bronchial hygiene; sputum induction; humidify dry gas.

Hazards of Aerosol Therapy

• Primary hazard: adverse reaction to medication being administered.
• Infection; airborne spread of bacteria.
• Airway reactivity/bronchospasm.
• Systemic side effects: if ext{HR} increases by 20\ \text{bpm} or more, STOP treatment immediately and notify provider.
• Excess water = over hydration; Excess sodium = hypernatremia.

Assessment of Therapy Outcomes

• Decreased work of breathing.
• Improved vital signs.
• Decreased stridor.
• Decreased dyspnea.
• Improved arterial blood gases (ABGs).
• Improved oxygen saturation.
• Adequate sputum sample outcome (if applicable).

Patient Monitoring During Therapy

• Patients must be monitored closely for adverse effects.
• Monitor: patient subjective response (pain, discomfort, dyspnea, restlessness).
• Heart rate and rhythm, blood pressure (If \Delta HR \geq 20\ \text{bpm}, stop and notify physician).
• Respiratory rate, pattern, mechanics, accessory muscle use.
• SpO₂ (pulse oximetry).
• Sputum: quantity, color, consistency, odor.
• Skin color, breath sounds.

Nebulizers: Overview

• Use a compressor to convert solutions into aerosols.
• Aerosol particles encounter a baffle; large particles impact and fall out; smaller particles remain in suspension.
• Two main types: Jet (pneumatic) and Ultrasonic.

Jet Nebulizers

• Jet nebulizers use a pressurized gas source to deliver a jet stream of air down a narrow tube through a narrow opening to a baffle.
• Also called pneumatic jet nebulizers or Small Volume Nebulizers (SVN).
• Create particle sizes within a therapeutic size range.

Types of Jet Nebulizers

• Standard jet nebulizer.
• Jet nebulizer with aerosol collection bag.
• Breath-enhanced jet nebulizer.
• Breath-actuated jet nebulizer.

Standard Jet Nebulizer

• Output to patient via 6 inch tubing.
• Uses power gas.
• Employs a reservoir with a T-piece and corrugated tubing.

Nebulizer with Aerosol Collection Bag

• Extends the standard jet nebulizer concept with a larger reservoir (bag).

Breath-Enhanced Nebulizer

• Utilizes patient inspiratory flow to entrain air through the nebulizer during inspiration.
• Increases inhaled mass by as much as 50\% over standard SVN.

Breath-Actuated Nebulizer

• Output is controlled by the breathing cycle: Inhalation triggers output; Exhalation off; Exhalation valve present; Power gas to patient.
• Can increase inhaled mass by 3-4\times over standard SVN.

Factors Affecting Penetration & Deposition

• Technical factors:
  • Manufacturer of nebulizer.
  • Flow used to power nebulizer.
  • Fill volume of nebulizer.
  • Solution characteristics (drug formulation).
  • Composition of driving gas.
  • Designs to enhance output.
  • Continuous versus breath-actuated.
• Patient factors:
  • Breathing pattern.
  • Nose versus mouth breathing.
  • Composition of inspired gas.
  • Airway obstruction.
  • Positive pressure delivery.
  • Artificial airway and mechanical ventilation.

SVN Proper Breathing Pattern

• Patients should breathe through the mouth (nose filters).
• Use a mouthpiece rather than a mask when possible to avoid facial/eye/nasal deposition.
• Breathe normally with occasional deep breaths.
• Ideally patient seated in high Fowler's position or as close as possible.
• Patient compliance is essential.

Administering an SVN

• Assemble tubing, nebulizer cup, and mouthpiece (or mask).
• Place medicine into the nebulizer cup; fill volume 3-5\,\text{mL}.
• Patient seated upright.
• Connect to power source; flow 6-10\ \text{L/min} (compressor).
• Breathe normally with occasional deep breaths until sputter or until no more aerosol is produced.
• Keep nebulizer vertical during treatment.
• Rinse nebulizer with sterile or distilled water and air dry (1–2 times per week); use vinegar solution for cleaning.

Technical Factors

• Fill volume: SVN can properly nebulize about 3-5\,\text{mL}; if medication is not at least 3-5\,\text{mL}, add normal saline to reach this volume.
• Flow: average 6-10\ \text{L/min}; increasing flow decreases particle size.
• Optimal particle size: 1-3\ \mu\text{m}} for alveoli; 2-5\ \mu\text{m} for lower airways.
• Gas density: e.g., Heliox may require flow increased by 2-3\times to produce comparable output.
• Drug formulation: some nebulizers are approved for specific formulations.

Formulations and Approved Nebulizers

• Bronchodilators: No specific nebulizer listed.
• Budesonide (Pulmicort Respules): Do not use with ultrasonic nebulizers.
• Tobramycin (TOBI): Pari LC.
• Dornase alfa (Pulmozyme): Hudson T Up-draft II, Marquest Acorn II, Pari LC, Durable Sidestream, Pari Baby.
• Pentamidine (NebuPent): Marquest Respirgard II.
• Ribavirin (Virazole): Small Particle Aerosol Generator (SPAG).

Dead Volume / Residual Drug Volume

• Dead volume ≈ 0.5-1\,\text{mL}; remaining solution trapped inside neb is not inhaled.
• After sputtering, tap to drop medication back into cup (only a couple of times; beyond that is unproductive).
• Dump dead volume after each treatment.
• Saline nebulizes faster than medication; leaving dead volume for next treatment may result in a higher dose than intended.
• Ensure SVN is vertical; tilting affects aerosol output.

Cleaning the SVN

• Disassemble nebulizer and wash in warm soapy tap water.
• Soak cup and mouthpiece for 1 hour in a solution of 1 part 5% distilled white vinegar and 3 parts hot water (acetic acid ~1.25%).
• Rinse with sterile or distilled water and air dry.
• Store nebulizer in a Ziploc bag.
• Clean the compressor surface with a damp cloth or sponge; an alcohol or disinfectant wipe can be used.
• Never immerse the compressor in water.
• Hospital protocol: SVN may be changed out every few days per facility policy.

Large Volume Nebulizer (LVN)

• Used to deliver bland aerosols to the upper airway.
• For thick secretions, heating element may be added.
• Incorporate air entrainment device for a specific FiO₂ (21–100%).
• As FiO₂ is decreased, air entrainment is increased, decreasing mist density.

Troubleshooting LVN

• Not misting enough: check for clogged capillary tube.
• Insufficient flow or water level.
• Aerosols in short puffs indicate condensation in tubing; use condensation collection bag (do not drain back into nebulizer container).

Ultrasonic Nebulizers

• Principle: electrical energy converts to mechanical (vibrational) energy via piezoelectric crystal to produce aerosol.
• Among nebulizers, highest output range for aqueous solutions without heating.
• Clean with vinegar solution.
• Can nebulize bronchodilators.
• Recommended for patients with thick tenacious secretions (CF).

Ultrasonic Nebulizer Anatomy (Concept)

• Drug solution -> Power transmitter -> Aerosol -> Patient; acoustic waves via piezoelectric transducer.

Portable USN Nebulizer

• Portable nebulizer device with power select control.

Gas Injection Nebulizer (GIN)

• Provides high-output aerosol therapy with a wide range of inspired oxygen concentrations.
• Not an air-entrainment device; closed system requiring two gas flows.
• Second gas is injected via attached titration tube to achieve any FiO_2 at any flow.
• For FiO_2 from 21-50\%: connect to air flowmeter and titrate oxygen.
• For FiO_2 from 50-100\%: connect to O₂ flowmeter and titrate air.
• Delivers both low and high FiO₂ aerosol therapy with flow rates meeting or exceeding patient inspiratory demand.
• AKA: Misty Ox Nebulizer.

Misty Ox GIN

• Shown as Misty Ox GIN device in labeling; ON / STY CA (device labeling image).

SPAG (Small Particle Aerosol Generator)

• Delivers Ribavirin (Virazole) for treating RSV infections.
• Not to be used with any other substance.

Delivery Devices

• Aerosol Mask.
• Face Tent.
• T-piece adaptor.
• Trach collar or mask.

Aerosol Mask

• Uses: LVN for humidification; SVN-delivered medication.

Face Tent

• Used for patients with facial trauma.

T-piece Adaptor

• Attaches to oral or nasal endotracheal tube to deliver aerosol.
• Can be used for weaning from mechanical ventilation.
• Also called Briggs adaptor.

Trach Collar / Mask

• Fits over tracheostomy tube with elastic band to secure around neck.
• Patient movement will not pull on tracheostomy tube.

Inhalers: MDIs, DPIs, Respimat

• MDI: Metered Dose Inhaler.
• DPI: Dry Powder Inhaler.
• Respimat: Soft Mist Inhaler (SMI).

MDIs and Examples

• Atrovent HFA (ipratropium bromide HFA) – Inhalation aerosol (anticholinergic/B2-agonist combination with Combivent).
• Combivent – ipratropium bromide and albuterol sulfate (anticholinergic/B2-agonist combination).
• Spiriva HandiHaler – tiotropium bromide inhalation powder (anticholinergic).
• Albuterol (Proventil) HFA – albuterol sulfate inhalation aerosol (B2-agonist).
• Aerobid – flunisolide (corticosteroid) inhaler system.
• Foradil Aerolizer – formoterol fumarate inhalation powder (long-acting B2-agonist).
• Xopenex HFA – levalbuterol tartrate inhalation aerosol (B2-agonist).
• Corticosteroids: Fluticasone propionate (Flovent) HFA; Budesonide (Pulmicort Turbuhaler).
• Advair Diskus – fluticasone propionate 250 mcg + salmeterol 50 mcg (corticosteroid/B2-agonist combination).
• Intal – cromolyn sodium inhalation aerosol.
• Tilade – nedocromil sodium inhalation aerosol.

MDI: Description & Components

• A small portable device designed to provide a precise dose of medication in a fine mist directly into the airways.
• Each activation dispenses about 100-200\ \mu g of medication.
• Only about 10-20\% of the dose is deposited into the lungs.
• Propellants used to provide the spray.

MDI: Components

• Drug/Propellant mixture.
• Propellant = 80\% of contents.
• Canister; metering valve; mouthpiece/actuator (boot) critical for particle size and plume geometry.
• Important: do not mismatch actuator boots of different HFAs or use a generic actuator.

Propellants

• Two main propellants: CFCs (chlorofluorocarbons) and HFAs (hydrofluoroalkanes).
• CFCs have detrimental effects on the ozone layer and are no longer used.
• HFAs have replaced CFCs and offer advantages.

Administration of MDI

• Shake inhaler and remove cap.
• Prime before initial use to ensure correct dose.
• Exhale completely.
• Hold inhaler 1–2 inches in front of mouth.
• Start breathing slowly through mouth and press down on the inhaler once.
• Continue breathing in slowly, taking a deep breath.
• Hold breath and count to 10. Exhale normally.
• If more than one puff is ordered, repeat steps 3–8.
• If quick-relief medicine, wait 1 minute between puffs; otherwise, follow manufacturer directions.
• If corticosteroid, rinse mouth after use.

Spacers / Valved Holding Chambers

• Used with MDIs to increase deposition and improve delivery.
• Reduces oropharyngeal deposition.
• Reduces need for coordination.
• Several designs by various manufacturers (examples: AeroChamber, Zana/VORTEX, etc.).
• Spacer = simple valve-less extension requiring some hand-breath coordination; Valved holding chambers vent exhaled gas, allowing aerosol to remain for inhalation on next breath, protecting patients from poor coordination.

How Does a Spacer Work?

• Inhaler adaptor; flow signal whistle (on some models).
• Inhaler body; valve; mouthpiece; cap.

Valved Holding Chambers / Spacers: Advantages & Disadvantages

• Advantages:
  • Reduced oropharyngeal drug impaction.
  • Simplifies coordination.
  • Allows use of MDI during acute airflow obstruction with dyspnea.
• Disadvantages:
  • Large and cumbersome compared with MDI alone.
  • Additional expense.
  • Some assembly may be needed.
  • Possible contamination with inadequate cleaning.

MDI with Valved Holding Chamber: Administration

• Warm MDI in hand.
• Assemble and prime if necessary.
• With normal breathing, actuate MDI once and have patient breathe through the device for 3-7\ \text{breaths} (adults: 3; children: 7).
• Allow 30–60 seconds between actuations.

Dry Powder Inhalers (DPIs)

• DPIs are breath-actuated.
• Create an aerosol when the patient’s inspiratory effort draws air through the device.
• No hand-breath coordination is required.
• Excessive inspiratory flow can increase oropharyngeal deposition.

DPI: Advantages & Disadvantages

• Advantages:
  • Small and portable.
  • Built-in dose counter.
  • Propellant-free.
  • Breath-actuated.
  • Short preparation and administration time.
• Disadvantages:
  • Highly dependent on patient’s inspiratory flow.
  • Patients may be less aware of delivered dose.
  • Relatively high oropharyngeal deposition can occur.
  • Humidity sensitivity and exhaled humidity in mouthpiece can affect performance.

DPI Dosing: Two Types

• Unit Dose: load a single dose prior to each use (capsule or blister pack).
  • Examples: Aerolizer; HandiHaler — unit dosing.
• Multi-dose: entire month’s prescription in one reservoir.
  • Examples: Diskus; Turbuhaler; Twisthaler.

DPIs: Common Devices

• Aerolizer (unit dosing; capsule form).
• HandiHaler (unit dosing; capsule form).
• Diskus (unit-dosing; blister strip form).
• Turbuhaler (multi-dosing).
• Twisthaler (multi-dosing).
• Diskus example values: 250/30; Advair 50/…