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Define humidity therapy?
Involves adding water vapor and sometimes heat to the inspired gas
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What is the primary function of humidity therapy?
Heat and moisture exchange is primary function of the upper respiratory tract, mainly the nose
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What is an effective humidifier/heater?
the nose
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At what point is the the Isothermic Saturation Boundary located? ISB
5cm below the carina
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What happens to temperature and humidity above the ISB?
Temperature and humidity decrease during inspiration and increase during exhalation
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What happens below the ISB?
Temperature and humidity remain constant (BTPS)
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What is the primary goal of humidification?
Maintain normal physiological conditions in lower airways (BTPS)
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Define humidifier and its function?
- A device that adds molecular water to gas
- Occurs by evaporation of water from a surface
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What are the 3 physical principles governing humidifier function?
- Temperature - the higher the temp of gas, the more water it can hold (increased capacity)
- Surface Area - Affects the rate of evaporation. The greater the area of contract between water and gas, the more oppurtunity there is for evaporation
- Contact Time - Evaporation increases as the contact time increases
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What are the 3 different types of humidifiers?
- Bubble
- Passover
- Heat and Moisture Exchangers (HME)
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What is the max flow on the bubble humidifier and what is it usually used with?
- Max flow is 10 LPM, after that flow will change temp of water and mess up gas
- Usually used with nasal cannula
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What are the 3 different types of Passover humidifiers?
- Reservoir type - Used with mechanical ventilation, BiPAP
- Wick type - Cylinder of absorbent material is placed upright with the gravity dependent end in the water reservoir surrounded by a heating element. Water is drawn up by capillary action and saturates the wick
- Membrane type - Seperates water from the gas stream by means of hydrophobic membrane causing water vapor molecules to pass through the membrane but the liquid water cannot
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When should you NOT use an Heat and Moisture Exchanger?
DO NOT use if your PT has increased secretions, has a fever or is dehydrated
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The HME's DO NOT add ____ or ______ to the system
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What are some contraindications of HME's?
- For PTs with thick, copious, or bloody secretions
- For PTs with an expired tidal volume < 70% of the delivered tidal volume (eg. those with large bronchopleural fistulas or incompetent or absent endotracheal tube cuffs
- For PTs whose body temperature is <32'C
- For PTs with high spontaneous minute volumes (>10L/min)
- An HME must be removed from the PT circuit during in-line aerosol drug treatments
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Heating systems are primarily used on PTs with?
Bypassed upper airways and for those on mechanical ventilation
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When using a heating system, where should you place the temperature probe?
- On the inspiratory limb of the circuit
- DO NOT place the temp. probe in an isolette or radiant warmer. The probe will be warmed and shut down the humidifier
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What are 2 ways you can avoid refilling reservoir feed systems?
- 1. Use large reservoirs
- 2. Gravity feed systems
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How many liters a day can a heated humidifier evaporate?
more then 1 L/day
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What is the least amount of humidity recommended for intubated PTs?
At least 30mg/L
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Some experts recommend heating the inhaled gas to maintain the airway temperature near?
35-37'C
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What are some disadvanatages about condensation with a humidifier?
- Poses risk to PTs and caregivers
- Wastes alot of water
- Can occlude gas flow through a circuit
- Can be aspirated
- Problem can be minimized with a use of water traps and heated circuits
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What are some ways to avoid cross contamination?
- Water in the circuit can be a source of bacterial colonization
- Minimizing condensation is helpful to reduce risk of colonization
- Frequently changing circuit is not needed to reduce nosocmial infection
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Define Bland Aerosol Therapy?
Consists of liquid particles suspended in gas (oxygen or air)
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What are some liquids that can be used in Bland Aerosol Therapy?
- Sterile water
- Sterile Saline (NaCI)
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What is the value for hypotonic?
Less then 0.9%
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What is the value for Isotonic?
0.9%
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What is the value for Hypertonic?
- 3%-10%
- Used for sputum induction
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What are some indications of bland aerosol therapy?
- The presence of an upper airway edmea - cool, bland aerosol
- Laryngotracheobronchitis LTB
- Subglottic edema
- Postextubation edema
- Postoperative management of the upper airway
- The presence of a bypassed upper airway
- The need for sputum specimens or mobilization of secretions
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What are contraindications for bland aerosol therapy?
- Bronchoconstriction
- History of airway hyperresponsiveness
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What are some hazards and complications of bland aerosol therapy?
- Wheezing and bronchospasm
- Bronchoconstriction when artificial airway is used
- Infection
- Overhydration
- PT discomfort
- Caregiver exposure to airborne contagions produced during the coughing or sputum induction
- Edema of the airway wall
- Edema associated with decreased compliance and gas exchange and with increased airway resistance
- Sputum induction by hypertonic saline inhalation can cause bronchoconstriction in PTs with COPD, asthma, CF, or other pulmonary diseases
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What is the most common device used for bland aerosol therapy?
Large volume jet nebulizer
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Unheated large volume nebulizers can produce?
26-35mgH20/L
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Heated large volume jet nebulizers can produce?
35-55mgH20/L
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How does a ultrasonic nebulizer work?
- An electrically powered device that uses a piezoelectric crystal to generate aerosol
- The crystal transducter converts radio waves into high-frequency mechanical vobrations that produce the aerosol
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What are some devices that can be used for airway appliances?
- Aerosol mask
- Face tent
- T-Tube
- Trachestomy mask
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What is used to deliver aerosol therapy to infants and children?
Mist tents and hoods
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What are some problems with bland aerosol therapy?
- Cross contamination
- Enviornmental safety
- Inadequate mist production
- Overhydration
- Bronchospasm
- Noise
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