Humidity And Aerosol Flashcards
What is humidity
Water in the gaseous state
What is the maximum amount of water vapor present in a gas
44 mg/L absolute humidity
47 mmHg partial pressure
Humidity therapy
Actual weight of water vapor contained in a given volume of gas is expressed in
Mg/L or g/cu.m.
At body temperature, what is our absolute humidity
44 mg/L
Absolute humidity =
RH X capacity (must be given : except know at 37 degrees Celsius absolute humidity is 44 mg/L)
How is. RH (relative humidity) expressed and obtained
Expressed as a percentage, obtained with a hygrometer
Formula for RH
Absolute humidity/ capacity
Partial pressure of water vapor at 37 degrees C is
47 mmHg (torr)
What is humidity deficit
The physiological term that refers to the difference between the inspired gas’s water content and the water content of a gas at body temperature and pressure.
Formula for humidity deficit
Body humidity (44mg/L) - actual (absolute humidity)
Causes of humidity deficit
Retention of secretions (increased Raw)
Airway mucus plugging
Obstruction of the airway
Infection
What do less that body humidity secretions tend to do
Dry, making them thicker and more difficult to mobilize
Humidity therapy primary indication
To humidify dry inspired gases
To overcome the humidity deficit when the upper airway is bypassed
Factors influencing humidity therapy
Temperature
Surface area
Contact time
How often should heated humidifiers be replaced
Every 24 hours
How much humidity are heated humidifiers capable of delivering
100 % body humidity
Are nosocomial infections caused by humidifiers
No, because molecular water is too small to carry bacteria
Bubble humidifier pop offs at
2 psi, 40 lpm
How much humidity can a bubble humidifier deliver
35-40% body humidity
What happens if humidifier is ran dry
The thermostat automatically shuts off
Heat and moisture exchanger
Under ideal conditions, the HME can produce 70-90% body humidity
What should you do if patients secretions begin to thicken while using the HME
The HME should be changed to a heated humidifier
Contraindications of heat and moisture exchanger
Thick copious / bloody secretions
Increased Raw
Low exhaled Vt
Body temp < 32 degrees C
High minute volume
During in line medicated nebulizer treatments
Troubleshooting humidity therapy
If secretions are becoming thicker and harder to suction you should
Add heater
Replace humidifier (especially HME ) with conventional heated humidifier.
How often should the humidifier be changed
Every 24 hours
Indications for aerosol therapy
Upper airway edema
Deliver medications
Post extubation edema
Post op management of upper airway
Bypassed upper airway
Sputum induction
Contraindications of aerosol therapy
Bronchoconstriction
History of airway hyperresponsiveness
Hazards of aerosol therapy
Wheezing or bronchospasms
Bronchoconstriction when artificial airway used
Infection
Overhydration
Patient discomfort
Swelling of dried retained secretions
Exposure to airborne pathogens
Aerosol face mask delivers
21-100% o2 with flow rates of 8-15 lpm
Face tent delivers
21-40% with flow rates of 8-15 lpm
Tracheostomy collar delivers
35-60% O2 with flowrate of 8-115 lpm
Mist should be visible at all times. Even during inspiration to ensure adequate flowrates
T-pieces (Briggs adaptors) deliver
21-40% O2 with flowrates at 8-15lpm
A 50 - ml reservoir (6 in.) should always be attached to the distal end of the T-piece, otherwise FiO2 will be reduced
Mist should be visible at all times
Tents deliver
21-50% o2 with flowrates of 8-15 lpm
Large volume nebulizers working principle
Bernoulli (uses capillary tube (Venturi, Pitot))
Large volume nebulizer aerosol size
Nebulizers produce about 50% of their particles in the 0.5 to 3 ug size range
Small volume nebulizer ideal breathing pattern
Tidal breathing through mouth with occasional slow, deep inspirations through the mouth. Breath hold (5-10 seconds) slow passive expiration
How long should you shake MDI for
5-10 seconds then discharge one dose if inhaler hasn’t been used in over 24 hours
How do you inhale MDI.
Begin to breathe in slowly through open mouth while actuating inhaler. Inspiration should take three to four seconds
Ultrasonic nebulizer signal frequency determines
The particle size
What does the signal amplitude determine on an ultrasonic nebulizer (USN)
Amount of mist
Couplant usually contains tap water
90% of the aerosol particles produced fall within the 0.5 to 3.0 ug range.
Aerosol therapy trouble shooting
If an aerosol producing device (nebulizer) is producing very little mist what should you do
Check the nebulizer jet for clogs
Check the capillary tube and/or the filter on the capillary tube for clogs
How often should heated nebulizers be replaced and why
Every 12-24 hours because they are. The greatest source of delivery of contaminated moisture to the patients.
Pseudomonas species are the most common contaminant
Aerosol therapy trouble shooting
Keeping water drained out of the aerosol tubing will prevent
Increasing the delivered FiO2
Decreased the total gas flow to the patient
Decrease aerosol output
Never drain accumulated water in the aerosol tubing back into nebulizer.
