1. Aerosol Therapy and Nebulizers
RET 2274
Respiratory Therapy Theory
Module 6.2

2. Aerosol Therapy and Nebulizers
Aerosols
Particulate matter suspended in a gas
Aerosols occur in nature as pollens, spores, dust, smoke, smog, fog, and mist
In the clinical setting, medical aerosols are generated with atomizers, nebulizers, and inhalers – physical devices that disperse matter into small particles and suspend them into a gas

3. Aerosol Therapy and Nebulizers
Aerosols
Medical aerosols are intended to deliver a therapeutic dose of the selected agent to the desired sit of action, e.g., bronchioles

4. Aerosol Therapy and Nebulizers
Aerosols
Deposition
Only a portion of the aerosol generated from a nebulizer (emitted dose) man be inhaled (inhaled dose) – a smaller fraction of fine particles may be deposited in the lung (respirable dose)
Not all aerosol delivered to the lung is retained, or deposited – a significant percentage of inhaled drug may be exhaled

5. Aerosol Therapy and Nebulizers
Aerosols
Deposition
Inertial Impaction – the primary deposition mechanism for particles larger than 5 µm
Tend to be deposited in the oropharynx and hypopharynx

6. Aerosol Therapy and Nebulizers
Aerosols
Deposition
Sedimentation – the primary mechanism for deposition of particles in the 1 – 5 µm range
The greater the mass of a particle, the faster it settles
Tend to be deposited in the central airways
Breath holding after inhalation of an aerosol increases enhances sedimentation

7. Aerosol Therapy and Nebulizers
Aerosols
Deposition
Brownian Diffusion – is the primary mechanism for deposition of small particles <3 µm – bulk gas flow ceases and aerosol particles reach the alveoli by diffusion
Particle size is not the only determinant of deposition
Inspiratory flow rate, flow pattern, respiratory rate, inhaled volume, I:E ration, and breath-holding all influence deposition

8. Aerosol Therapy and Nebulizers
Aerosols
Quantification of Aerosol Delivery
At the bedside, quantification of aerosol delivery is based on the patient’s clinical response to the drug
Pulmonary function; peak flow, forced expiratory volumes or flow
Physical changes; reduced wheezing, shortness of breath, or retractions
Side effects; tremors, tachycardia

9. Aerosol Therapy and Nebulizers
Aerosols
Hazards
Adverse reaction to the medication being delivered
Infection caused by contaminated solution (multi-dose vials), caregiver’s hands, the patient’s own secretions

10. Aerosol Therapy and Nebulizers
Aerosols
Hazards
Airway reactivity
Cold and high-density aerosols can cause bronchospasm and increased airway resistance
Medications, e.g., acetylcysteine, antibiotics, steroids, cromolyn sodium, ribavirin, and distilled water have been associated with increased airway resistance and wheezing during aerosol therapy
Administration of bronchodilators before or with administration of these agents may reduce the risk of increased airway resistance

11. Aerosol Therapy and Nebulizers
Aerosols
Hazards
Pulmonary and Systemic Effects
Overhydration from excessive water
Hypernatremia from excess saline solution
Drug Reconcentration
During evaporation, heating, baffling, and recycling of drug solutions undergoing jet or ultrasonic nebulization, solute concentrations may increase – exposing patients to increasingly higher concentrations of drug therapy. Increase in concentration usually time dependent, the greatest effect occurring when medications are nebulized over extended periods, as in continuous aerosol drug delivery

12. Aerosol Therapy and Nebulizers
Aerosols
Delivery Systems
MDI – Metered Dose Inhalers
DPI – Dry Powder Inhalers
Pneumatic (Jet) Nebulizers
Large volume
Small volume
Ultrasonic Nebulizers
Hand-Bulb Atomizers

13. Aerosol Therapy and Nebulizers
Aerosols
Indications – AARC Clinical Practice Guideline
The need to deliver an aerosolized beta-adrenergic, anticholinergic, antiinflammatory, or mucokinetic agent to the lower airway

14. Aerosol Therapy and Nebulizers
Aerosols
Selection of Aerosol Delivery Device
MDI – preferred method for maintenance delivery of bronchodilators and steroids to spontaneously breathing patient – effectiveness is highly technique dependent
Accessory devices; e.g., spacer and holding chambers are used with MDI to reduce oropharyngeal deposition of drug and overcome problems with poor hand-breath coordinaiton

15. Aerosol Therapy and Nebulizers
Aerosols
Selection of Aerosol Delivery Device
DPI – does not require hand-breath coordination, but does require high inspiratory flows
Most patients in stable condition prefer DPI delivery systems
SVN – less technique and device dependent and are the most useful in acute care

16. Aerosol Therapy and Nebulizers
Aerosols
Selection of Aerosol Delivery Device
Large volume drug nebulizers provide continuous aerosol delivery when traditional dosing strategies are ineffective in controlling severe bronchospasm
Small Volume USN – used to administer bronchodilators, antiinflammatory agents, and antibiotics

17. Aerosol Therapy and Nebulizers
Aerosols
Patient Assessment
Patient interview
Respiratory history
Level of dyspnea
Observation
Signs of increased work of breathing
Tachypnea, accessory muscle usage
Restlessness
Diaphoresis
Tachycardia

18. Aerosol Therapy and Nebulizers
Aerosols
Patient Assessment
Expiratory airflow measurements
FVC, FEV1, PEFR
Vital signs
Auscultation of breath sounds
Increase or decrease in wheezing and intensity of sounds
Blood gas analysis
Oximetry