A heat and moisture exchanger has an efficiency rating of 80. What does this mean?
a. Of the exhaled water vapor, 80 returns to the patient on inspiration.
b. The inspired temperature is 80 of the expired temperature.
c. Of the exhaled water vapor, 20 returns to the patient on inspiration.
d. The device provides 80 relative humidi-ty at body temperature.
Q. 2 An ideal heat and moisture exchanger (HME) should have an efficiency rating of at least which of the following?
a. 30
b. 50
c. 70
d. 90
Q. 3 Which type of humidifier traps the patient's body heat and expire water vapor to raise the hu-midity of inspired gas?
a. Membrane
b. Bubble
c. Heat and moisture exchanger
d. Passover
Q. 4 Which of the following are true regarding a membrane-type humidifier?
1. Water and gas are separated by a hydrophobic membrane.
2. The membrane is permeable to water vapor but not to liquid water.
3. As with other passover humidifiers, there is no bubbling action.
4. A small layer of liquid water remains on both sides of the membrane.
a. 1 and 3 only
b. 1, 2, and 3 only
c. 3 and 4 only
d. 2, 3, and 4 only
Q. 5 Advantages of passover humidifiers include which of the following?
1. They add minimal flow resistance to breathing circuits.
2. They do not require heating to maintain body temperature, ambient pressure, saturated (BTPS) conditions.
3. They do not generate any bacteria-spreading microaerosol.
4. They can maintain water vapor saturation at high flows.
a. 1 and 3 only
b. 1, 2, and 3 only
c. 2 and 4 only
d. 1, 3, and 4 only
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