T2 Flashcards
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
Simple condenser humidifier
Condenser element with high thermal conductivity
50% efficiency
Hydroscopic condenser humidifiers
Condenser element with low thermal conductivity and hygroscopic salt
70% efficiency
May retain more heat
Hydrophobic condenser humidifiers
Water repellent element
Large surface and low thermal conductivity
70% efficiency
ISO
Low compliance
Operate at 70% efficiency or better
Simple to use
Contraindications for HME use
Thick, copious , or bloody secretions
Hypothermia (32C or less)
Expired VT less than 70% of the delivered VT
HME must be removed from the patient circuit during aerosol treatments when the nebulizar is placed in the patient circuit
May be contraindicated in patients with high spontaneous minute volumes (>10L/min)
Types of heating systems
Electric
-hot plate at base
-wraparound surrounds humidifier
-yolk or collar-between reservoir and outlet
-immersion type in reservoir
-heated wire systems
Servo controlled monitors , temp near AW
New active humidification systems
Temperature to the patient should not exceed …
37 C
For bypassed AW temp must be set to …
33 C += 2
To maintain an AW temp of 35-37 C and provide a minimum of 30 mg/L of water vapor content
What type of water must be used in reservoir systems
Sterile or distilled
Hazards for heated systems
Potential for electrical shock
Hypothermia
Hyperthermia
Thermal injury to airway
Burns to patient or circuit meltdown
Under hydration and secretion impaction
Inadvertent overfilling
Bland aerosol
Large particle size than humidity
Use baffling to reproduce particle size
LVN
Piezoeléctric transducer
Crystal that makes acoustic waves within drug solution
Indications for cool bland aerosol
Upper AW edema
LTB (croup)
Subglottic edema
Post extubation edema
Post op management of upper AW
Sputum induction
Indications for heated bland aerosol
Bypassed upper AW
Management of hypothermia
Hazards of bland aerosol
Wheezing (bronchi spasms)
History of AW hypersensitivity
Nosocomical infectious
Over hydration
Patient discomfort
Caregiver infection
