Transcript Storage of Medical Gases

Aerosol Therapy and Nebulizers
RET 2274
Respiratory Therapy Theory
Module 6.2
Aerosol Therapy and Nebulizers
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Aerosols
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Particulate matter suspended in a gas
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Aerosols occur in nature as pollens, spores, dust,
smoke, smog, fog, and mist
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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
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Aerosols
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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
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Aerosols
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Deposition
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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)
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Not all aerosol delivered to the lung is retained, or
deposited – a significant percentage of inhaled drug
may be exhaled
Aerosol Therapy and Nebulizers
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Aerosols
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Deposition
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Inertial Impaction – the primary deposition
mechanism for particles larger than 5 µm
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Tend to be deposited in the oropharynx and
hypopharynx
Aerosol Therapy and Nebulizers
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Aerosols
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Deposition
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Sedimentation – the primary mechanism for
deposition of particles in the 1 – 5 µm range
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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
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Aerosols
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Deposition
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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
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Particle size is not the only determinant of deposition
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Inspiratory flow rate, flow pattern, respiratory rate,
inhaled volume, I:E ration, and breath-holding all
influence deposition
Aerosol Therapy and Nebulizers
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Aerosols
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Quantification of Aerosol Delivery
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At the bedside, quantification of aerosol delivery is
based on the patient’s clinical response to the drug
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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
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Aerosols
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Hazards
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Adverse reaction to the medication being delivered
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Infection caused by contaminated solution (multidose vials), caregiver’s hands, the patient’s own
secretions
Aerosol Therapy and Nebulizers
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Aerosols
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Hazards
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Airway reactivity
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Cold and high-density aerosols can cause
bronchospasm and increased airway resistance
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Medications, e.g., acetylcysteine, antibiotics, steroids,
cromolyn sodium, ribavirin, and distilled water have
been associated with increased airway resistance and
wheezing during aerosol therapy
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Administration of bronchodilators before or with
administration of these agents may reduce the risk
of increased airway resistance
Aerosol Therapy and Nebulizers
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Aerosols
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Hazards
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Pulmonary and Systemic Effects
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Overhydration from excessive water
Hypernatremia from excess saline solution
Drug Reconcentration
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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
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Aerosols
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Delivery Systems
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MDI – Metered Dose Inhalers
DPI – Dry Powder Inhalers
Pneumatic (Jet) Nebulizers
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Ultrasonic Nebulizers
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Large volume
Small volume
Large volume
Small volume
Hand-Bulb Atomizers
Aerosol Therapy and Nebulizers
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Aerosols
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Indications – AARC Clinical Practice Guideline
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The need to deliver an aerosolized beta-adrenergic,
anticholinergic, antiinflammatory, or mucokinetic
agent to the lower airway
Aerosol Therapy and Nebulizers
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Aerosols
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Selection of Aerosol Delivery Device
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MDI – preferred method for maintenance delivery of
bronchodilators and steroids to spontaneously
breathing patient – effectiveness is highly technique
dependent
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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
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Aerosols
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Selection of Aerosol Delivery Device
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DPI – does not require hand-breath coordination, but
does require high inspiratory flows
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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
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Aerosols
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Selection of Aerosol Delivery Device
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Large volume drug nebulizers provide continuous
aerosol delivery when traditional dosing strategies
are ineffective in controlling severe bronchospasm
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Small Volume USN – used to administer
bronchodilators, antiinflammatory agents, and
antibiotics
Aerosol Therapy and Nebulizers
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Aerosols
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Patient Assessment
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Patient interview
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Respiratory history
Level of dyspnea
Observation
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Signs of increased work of breathing
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Tachypnea, accessory muscle usage
Restlessness
Diaphoresis
Tachycardia
Aerosol Therapy and Nebulizers
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Aerosols
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Patient Assessment
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Expiratory airflow measurements
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Vital signs
Auscultation of breath sounds
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FVC, FEV1, PEFR
Increase or decrease in wheezing and intensity of
sounds
Blood gas analysis
Oximetry