HUMIDIFIERS

1
HUMIDIFIERS
2
Passover/Blow-by

• Depends on evaporation to supply humidity to air
  directed across its surface
• Efficiency can be increased by heating either the
  H2O or the air
• Used in - isolettes - incubators -
  hot pot on Emerson ventilator
• Chief hazard is reservoir can be source of
  infection

3
Bubble-diffusion Humidifier

• Dry gas is forced down a diffuser tube and
  released as bubbles under the surface of H2O
• Bubbles of O2 ascend to the surface, acquiring
  humidity and pop at the surface, releasing water
  vapor into the gas-filled area above the waters
  surface
• Effectiveness is determined by - number
  size of bubbles - time
• - temp. - length temp. of tube

4
HEATED HUMIDIFIERS Wick Humidifiers

• Originally developed for vaporization of
  anesthesia gases
• Dry gas is exposed to a cloth or sponge submerged
  in H2O, where evaporation takes place
• Effectiveness is determined by the temp. of the
  water , temp. press. of the gas, the humidity
  deficit of the gas
• Pot. hazard is water-bred microbes

5
Cascade Humidifier

• Based on the cascading principle,where H2O falls
  or pours across a surface
• Uses an advanced bubble-type humidifier principle
• Examples include - Bennett Cascade -
  Bennett Cascade II - Bourns

6
Condensing Humidifiers

• Called HCH (hygroscopic condenser humidifier) or
  HME (heat moisture exchanger)
• Utilizes a patients exhaled gas to warm and
  humidify each subsequent inspiration
• Uses principle that exhaled gas is approx. 90-95
  sat. with water vapor at approx. 1-2C lower than
  body temp.

7
Condensing Hum. (contd)

• When gas is exhaled through the HME core it
  contacts H2O-seeking material, its dewpoint is
  reached and H2O condenses onto the surface. Dry
  gas passes through and is humidified
• Should have output of 22-28 mg H2O/L
• Inhaled gas can be humidified from 50-65 of body
  humidity