T2 Flashcards
(39 cards)
Capillary action
Liquid in a small tube moves upward against gravity (jet neb)
Recommended heat and humidity levels
Nose/mouth
Temp. 20-22
Relative humidity -50
Absolute humidity -10
Recommended heat & humidity levels
Hypopharynx
Temp - 29-32
Relative humidity- 95
Absolute humidity- 28-34
Recommend heat & humidity levels
Trachea
Temp 32-35
Relative humidity - 100
Absolute humidity- 36-40
Humidity
Molecular water, invisible moisture, water in a gaseous state, quality of wetness in the air
Absolute humidity
Amount of the water in a given volume of gas
Relative humidity • capacity = AH
Relative humidity
Ratio between amount of water in a given volume of gas and the amount it can hold (%)
Actual humidity/ capacity • 100 = RH
Body humidity
Absolute humidity at body temp (%)
Absolute humidity/ capacity • 100 = BH
Humidity deficit
Inspired gas that is not fully saturated the body creates a deficit (mg/L and %)
Humidity deficit (mg/L) = capacity - absolute
Humidity deficit (%) = deficit in mg/L / capacity • 100
Why deliver humidity at body temp?
If adequate humidification is not provided , patients airways will dry out . Secretions become thick, tenacious and inspissated. RAW increases and secretions are harder to mobilize
Indications for humidification and warming of inspired gases
Primary :
—Humidification of dry medical gases
—Overcome humidity deficit created by bypassed UAW
Indications for humidification and delivery of cool aerosol
To treat UAW inflammation from
- laryngotrachealbronchitis LTB (croup)
- Epiglottis
- Post - extubation edema
Sputum induction
Effects / Hazards of lack of humidity and heat
- hypothermia
- inspissated secretions
- impaired mucociliary function
- destruction of AW epithelium
- mucus plugs & atelectasis
Evaporation
Liquid water turning into a water vapor and increasing the RH % of that gas.
Occurs in non-heated and heated humidifiers
Condensation
When a gas that is 100% saturated (100% RH) is cooled, it’s capacity decreases and water vapor turns back into liquid
Occurs in ventilator and aerosol tubing as source gas moves towards patient
S&S of inadequate humidification
Atelectasis
Dry, nonproductive cough
Increased airway resistance
Increased incidents of infection
Increased work of breathing
Substernal pain
Thick, dehydrated secretions
Goal of humidification
Provide 100% humidity for patients with bypassed UAW
minimize or eliminate a humidity deficit while breathing dry medical gas
Humidifier
Adds molecular water to gas
Nebulizar
Small water particles (aerosol) dispersed into gas for evaporation
Aerosol
Suspended particle of substance in a gas
Principles governing humidification
Temperature
Surface area
Contact time
Thermal Mass
Bubble humidifier
Most common
15 to 20 mg/L absolute humidity
Pressure Pop-off (2 psig)
Pass - Over humidifier
Reservoir: directs directs gas over surface of water
Wick: Absorbent material to increase the surface area for dry gas to interface with heated water.
Membrane: separates gas by placement of hydrophobic membrane. Water vapor passes thru easily while liquid water & pathogens cannot.
Advantages — maintain saturation of gas at high flow rates , add small amount of resistance to circuit, decrease risk of infection
Passive humidifiers - heat & moisture exchanger - HME ( aka artificial nose )
Provides 30 mg/L water vapor 70% efficient
3types : simple condenser, hygroscopic & hydroscopic
