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Aerosol Therapy and Nebulizers
RET 2274
Respiratory Therapy Theory
Module 6.2
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
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
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
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
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
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
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
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
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
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
Aerosol Therapy and Nebulizers
Aerosols Delivery Systems
MDI – Metered Dose Inhalers DPI – Dry Powder Inhalers Pneumatic (Jet) Nebulizers
Large volume Small volume
Ultrasonic Nebulizers Large volume Small volume
Hand-Bulb Atomizers
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
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
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
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
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
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
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