Humidification Therapy on ventilated patients

Humidification therapy

1. Humidification
Therapy

2. HUMIDIFICATION THERAPY
Humidification therapy involves adding
water vapor and heat to the inspired gas.
Humidity
The presence of moisture in its molecular
form in a gas or gas mixture

3. Absolute humidity: The actual weight of
water in a volume of gas or gas mixture
expressed as mg/L.
Relative humidity: The absolute humidity of a
volume of gas expressed as a percentage
of the water vapor capacity of the gas.
% RH = Absolute humidity/Saturated
capacity x 100

4. Body humidity
The absolute humidity in a volume of gas
saturated at body temperature of 37 °C;
equivalent to 43.8 mg/L
% BH = (absolute humidity/43.8 mg/L) x 100.

5. Humidity deficit
▪Inspired air that is not fully saturated at
body temperature
▪Deficit is corrected by body’s own
humidification system
▪Humidity deficit = 44 mg/L –absolute
humidity

6. Physiologic control of heat &
moisture exchange
In a healthy person, 75% of respiratory gas
conditioning takes place in the upper respiratory
tract (nasopharynx)
The remaining 25% are taken over by the trachea.
The upper respiratory tract warms, humidifies and
cleanses 1,000 to 21,000 litres of respiratory gas daily,
depending on body size and physical capability.

7. Isothermic saturation
boundary (ISB)
Crucial for the proper functioning of the lower
airways and the alveoli that inspired gases are fully
saturated with water vapor and warmed to body
temperature upon reaching the carina. This point in
the upper airways is called the ISB.
At this boundary, the inspired gas should have 100%
relative humidity and a temperature of 98.6 °F
(37°C)

8. Normally 5 cms above the carina
Above the ISB, temperature and humidity
decrease during inspirationand increases
during exhalation
Below the ISB, temperature and relative
humidity remains constant

11. Indications of
humidification therapy
Primary
1.Humidifying dry medical gases
2.Overcoming the humidity deficit created
when the upper airway is bypassed
Secondary
1.Managing hypothermia
2.Treating bronchospasm caused by cold air

12. Clinical Signs and Symptoms of Inadequate Airway
Humidification
• Atelectasis
• Dry, non productive cough
• Increased airway resistance
• Increased incidence of infection
• Increased work of breathing
• Patient complaint of substernal pain and airway
dryness
• Thick, dehydrated secretions

13. Humidifiers
Humidifier is a device that adds molecular
water to gas, occurring by evaporation of
water from a surface

14. Physical principles governing
humidifier function
Temperature
Surface area
Time of contact
■Thermal mass

15. Types of Active Humidifiers
Bubble humidifier
Pass over humidifier
Nebulizers of bland aerosols.
Vaporizers.

17. Bubble humidifiers
Breaks an under water gas stream to small bubbles
Can provide absolute humidity of 15-20 mg/L
Become inefficient when oxygen flow increase
above 10 L/min
These devices incorporates a pressure releasing
valve to prevent bursting of humidifier bottle (P
above 2 psig)

18. Pass over humidifier
•Directs gas over a water surface
•3 types
1.Simple reservoir
2.Wick type
3.Membrane type

19. Simple Reservoir
Direct gas over the surface of a volume of water
The surface of gas-fluid interface is limited
Used in room temperature fluid with NIV (CPAP or
BIPAP)

20. Wick type humidifier
Wick-Cylinder of absorbent material placed upright
in the water reservoir and surrounded by a heating
element
Continually draws water up from the reservoir and
keeps the wick saturated; As dry gas enters the
chamber it flows around the wick quickly picking up
heat and moisture and leaving the chamber fully
saturated
Water drawn up by capillary action and wick kept
fully saturated with water vapour
No bubbling occurs

22. Membrane type humidifier
A hydrophobic membrane separates water
from the gas stream by means of
hydrophobic membrane.
Water vapourmolecules pass through the
membrane but liquid water cannot.
Bubbling does not occur

24. Heat and moisture exchangers
•“Artificial Nose”
Captures exhaled heat and moisture and adds to the
inhaled dry cold gas
Do not add extra moisture hence a passive humidifier
70% humidity.
Traditionally HME use is limited to mechanically
ventilated patients or long term spontaneously breathing
patients on tracheostomy tubes.

26. HMEs
Advantages
▪Inexpensive
▪Easy to use
▪Small and lightweight
▪Disposable
▪Do not require water,
temperature monitor, alarms
▪No burns, no danger of over
hydrations and electric shock.
Disadvantages
▪Less effective than active
humidifiers
▪Can deliver only limited
humidity
▪Increased in dead space
▪Increased tidal volume
and work of breathing
▪Need to change every
24hrs

27. Thank U