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Define humidity therapy?
Involves adding water vapor and sometimes heat to the inspired gas
What is the primary function of humidity therapy?
Heat and moisture exchange is primary function of the upper respiratory tract, mainly the nose
What is an effective humidifier/heater?
At what point is the the Isothermic Saturation Boundary located? ISB
5cm below the carina
What happens to temperature and humidity above the ISB?
Temperature and humidity decrease during inspiration and increase during exhalation
What happens below the ISB?
Temperature and humidity remain constant (BTPS)
What is the primary goal of humidification?
Maintain normal physiological conditions in lower airways (BTPS)
Define humidifier and its function?
- A device that adds molecular water to gas
- Occurs by evaporation of water from a surface
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
What are the 3 different types of humidifiers?
- Heat and Moisture Exchangers (HME)
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
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
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
The HME's DO NOT add ____ or ______ to the system
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
Heating systems are primarily used on PTs with?
Bypassed upper airways and for those on mechanical ventilation
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
What are 2 ways you can avoid refilling reservoir feed systems?
- 1. Use large reservoirs
- 2. Gravity feed systems
How many liters a day can a heated humidifier evaporate?
more then 1 L/day
What is the least amount of humidity recommended for intubated PTs?
At least 30mg/L
Some experts recommend heating the inhaled gas to maintain the airway temperature near?
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
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
Define Bland Aerosol Therapy?
Consists of liquid particles suspended in gas (oxygen or air)
What are some liquids that can be used in Bland Aerosol Therapy?
- Sterile water
- Sterile Saline (NaCI)
What is the value for hypotonic?
Less then 0.9%
What is the value for Isotonic?
What is the value for Hypertonic?
- Used for sputum induction
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
What are contraindications for bland aerosol therapy?
- History of airway hyperresponsiveness
What are some hazards and complications of bland aerosol therapy?
- Wheezing and bronchospasm
- Bronchoconstriction when artificial airway is used
- 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
What is the most common device used for bland aerosol therapy?
Large volume jet nebulizer
Unheated large volume nebulizers can produce?
Heated large volume jet nebulizers can produce?
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
What are some devices that can be used for airway appliances?
- Aerosol mask
- Face tent
- Trachestomy mask
What is used to deliver aerosol therapy to infants and children?
Mist tents and hoods
What are some problems with bland aerosol therapy?
- Cross contamination
- Enviornmental safety
- Inadequate mist production