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Review of HumidityAerosol Therapy

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Overheating leading to patient airway burns. Inadvertent overfilling of humidifier by ... Burns to caregivers from inadvertently touching heated metal surfaces ... – PowerPoint PPT presentation

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Title: Review of HumidityAerosol Therapy


1
Review of Humidity-Aerosol Therapy
  • RsCr 224
  • Respiratory Care Theory 2

2
Definitions of Esssential Terms
  • Absolute Humidity - amount of water vapor
    actually present in the air (expressed in
    mg/liter). Sometimes called water vapor content.
  • Maximum Absolute Humidity - amount of water vapor
    that the air can hold. Sometimes called water
    vapor capacity.
  • varies directly with temperature
  • Relative Humidity - the mathematical comparison
    of the above two. Content divided by capacity

3
Essential Information for Doing Calculations of
Relative Humidity
  • The Maximum Absolute Humidity at body temperature
    is 44 mg/liter
  • This is sometimes called Body Humidity
  • Any Relative Humidity less than Body Humidity is
    called the Humidity Deficit

4
ANSI Guidelines
  • 10 mg/L for Normal patient
  • 30 mg/L for intubated patients

5
Indications for Humidifying and Warming of Gases
  • To humidify dry inspired gases
  • To overcome the humidity deficit when the upper
    airway is bypassed (trached patients or those
    with endotracheal tubes)
  • Less common indications
  • treatment of hypothermia
  • treatment of bronchospasm caused by cold air

6
Equipment Used to Humidify Gases
  • Bubble Diffusion Humidifiers

7
Factors Affecting Performance of Bubble
Humidifiers
  • Time of contact between gas the water
  • Surface area available for evaporation to occur
  • Temperature of the gas

8
How Flow Lowers Water Temp
9
Typical Wick Type Humidifier
10
Fisher-Paykel Wick Humidifier
11
Puritan-Bennett Cascade 1
12
Puritan-Bennett Cascade 2
13
Hudson-RCI Conchatherm
14
Characteristics of Heated Humidifiers
  • Water can be heated to maintain high humidity
    output
  • Temperature can be sensed downstream from the
    unit so that water temperature can be adjusted to
    maintain correct gas temperature (like thermostat
    at home)
  • Heated wires can be employed to prevent
    condensation in tubing from gas cooling

15
Why Wick Type Humdifiers Are Popular
  • Produce high vapor output even at very high gas
    flows (gt100 l/m)
  • Do not produce any water particles
  • Low risk of producing nosocomial infections
  • Have ability to utilize heated wire circuits
  • Have continuous-feed water systems

16
Hazards Problems Associated with Heated
Humidifiers
  • Overheating leading to patient airway burns
  • Inadvertent overfilling of humidifier by
    therapist
  • Increased airway resistance created by pooling of
    condensate in circuit
  • Burns to caregivers from inadvertently touching
    heated metal surfaces

17
Artificial Noses
  • Types of Heat Moisture Exchangers
  • Simple condensors
  • Hygroscopic Condenser Humidifiers (HCF)
  • Hydrophobic Condenser Humidifiers
  • Act by recycling exhaled heat moisture
  • Ideal unit should be able to produce at least
    30 mg/l - Most produce 20 - 30 mg/l

18
Problems With HMEs
  • Increase in airflow resistance (particularly when
    mucus enters unit)
  • Drying thickening of secretions can become a
    problem
  • Must be removed when administering in-line
    medication aerosol treatments
  • Lose efficiency in patients with high minute
    volumes (gt10 l/m)

19
Why HMEs Have Become Popular?
  • Significant cost savings can be realized compared
    to a standard ventilator circuit using a heated
    humidifier
  • Less therapist time needed to drain condensed
    water from circuit
  • Greater simplicity
  • However, in some cases heated-wire circuits may
    be actually cheaper than the HME

20
Bland Aerosol Therapy
  • Indications for
  • Tx of laryngotracheobronchitis (croup)
  • Tx of sub-glottic edema
  • Post-extubation edema
  • Post-operative management of upper airway
  • Presence of bypassed upper airway
  • Need for sputum induction

21
Contraindications to Bland Aerosol Therapy
  • Bronchospasm (evidence of current disease)
  • Asthma or Chronic Bronchitis patients who c/o
    SOB
  • History of airway hyperresponiveness
  • Those with a hx of asthma or other obstructive
    lung disease

22
Hazards and Complications of Bland Aerosol
  • Wheezing associated with bronchospasm
  • Infection
  • Overhydration
  • Patient discomfort
  • Caregiver exposure to contagious aerosols
  • Noise

23
Types of Nebulizers Used for Bland Aerosol Therapy
  • Large Volume Jet Nebulizers
  • Ultrasonic Nebulizers

24
Schematic of Large Volume Jet Nebulizer
25
Schematic of Ultrasonic Nebulizer (USN)
26
Solutions Used for Bland Aerosol Therapy
  • Water - most irritating cheapest to use
  • Normal Saline (0.9 NaCl) - least irritating
    salt crystals can condense on water intake
    causing no aerosol to be produced
  • Hypertonic Saline - 5 or 10 - used only for
    sputum indutions

27
Delivery of Inhaled Medications
  • Delivery systems
  • MDIs
  • DPIs
  • Small volume jet nebulizers
  • aka HHNs SVNs wet nebs med nebs neb meds
    acrons
  • USNs
  • Specialized aerosol systems

28
Definitions
  • Aerosol
  • Penetration
  • Deposition
  • Stability
  • Retention
  • Clearance

29
Factors for Penetration and Deposition
  • Size of particle decides how far before
    depositing into the respiratory tract

30
Indications for aerosols
  • Deliver medications
  • Humidify gases
  • Mobilize secretions

31
Hazards
  • Overhumidification
  • Bronchospasm
  • Infection

32
Examples of MDIs
33
Characteristics of MDIs
  • Exact same dose each actuation
  • High initial aerosol velocity
  • Currently uses chloroflourocarbon (CFC)
    propellant. Hydroflouroalkanes (HFA) will
    replace CFCs pending final approval.
  • Without using a spacer - up to 80 of aerosol
    lands in the oropharynx or mouth
  • 10 - 20 reaches small airways
  • administration is very technique dependent

34
MDI Accessory Devices
  • Holding chambers or spacers
  • Improve ease of administration
  • Decrease oral-pharyngeal deposition
  • Improve distribution of the mist
  • Flow-triggered MDIs
  • Currently only Maxair (pirbuterol) is available

35
Optimal Technique for Using MDI
  • Shake MDI first (warm if cold)
  • Actuate into chamber
  • Inhale slowly deeply
  • Maintain a 10 second breath hold
  • Allow 30 seconds between actuation

36
Disadvantages of MDIs
  • Coordination can be a problem
  • Requires use of additional spacer
  • High oral-pharyngeal deposition
  • Easy for patients to overuse
  • Some medications can be quite expensive
  • Some patients can run out without realizing

37
Characteristics of DPIs
  • Always are breath actuated since no propellant is
    used
  • Easier to self-administer - no spacer needed
  • Not very many drugs are available in this form
  • At least as good as MDI in terms of deposition
    and drug response
  • Cant be used with young children in ventilator
    circuits

38
Brand Names
  • Rotahaler Albuterol
  • Spinhaler Intal
  • Turbuhaler Terbutaline
  • Advair Flovent and Salmeterol

39
Optimal Technique for Using DPI
  • Patient must use high inspiratory flows
  • Best not used if patient is having severe SOB
  • Breath holding is not critical
  • Medication should be stored in a low humidity
    environment

40
Disadvantages of DPIs
  • Some patients cant generate high inspiratory
    flows needed
  • Assembly of unit can be difficult for some
  • Difficult to give high doses
  • Some pharyngeal deposition is unavoidable
  • Not that many medications available in this form
    (currently)

41
Small Volume Nebulizers
  • Generally hold 2 - 6 ml of solution
  • Can be filled using unit-dose preparations or
    multi-dose vials
  • Generally require 4-8 l/m of flow to actuate
  • Can be driven with either oxygen or air
  • When using oxygen - FIO2 can be 40 - 90 !!
  • Should be used instead of MDI or DPI if patient
    is tachypneic

42
Disadvantages of SVNs
  • Too complex for some patients to use
  • Requires assembly periodic cleaning
  • Not easily portable like the MDI or DPI
  • Not all medications are available
  • No steroids currently available for SNV
    administration

43
Specialized Medication Nebulizers
  • Respigard II - filters exhaled gas - delivers
    very small particles (1-2 microns)
  • Circulair - Uses a reservoir bag to conserve
    medication - enhances aerosol delivery
  • Continuous HEART Nebulizers - used for
    continuous drug administration (1-3 hours)
  • SPAG unit- used for administration of ribavirin

44
Small Volume Ultrasonic Nebulizers
  • Produce very dense mists at very high outputs
  • Compact units portable easy to use
  • Used for delivery of undiluted medications
    (bronchodilators antibiotics)
  • Some units can be powered by cigarette lighter
    adapter present in a car

45
Problems with USNs
  • Expensive to purchase
  • Prone to breakdown
  • Not all mediations are available in multi-dose or
    unit dose forms
  • Medication must be manually added to unit prior
    to use

46
The End
  • Thats all folks
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