Why should you not heat the reservoirs of a bubble humidifier used with an oronasal O2
delivery system?

What are some types of passover humidifiers?
1. Simple reservoir
2. Membrane
3. Wick

Heat and moisture exchangers (HMEs) are mainly used to do what?

For which of the following patients would you select a heated humidifier?
1. Patient receiving O2 through a bypassed upper airway
2. Patient receiving long-term mechanical ventilation
3. Patient receiving O2 through an oronasal mask

What are some potential problems with manually refilled heated humidifier reservoirs?
1. Cross contamination and infection


2. Variable compliance or delivered volume
3. Delivery of dry and/or hot gases

The relief valve on a bubble humidifier serves which of the following functions?

A design that increases surface area and enhances evaporation by incorporating an absorbent
material partially submerged in a water reservoir that is surrounded by a heating element best
describes what type of humidifier?

Which of the following are types of heat and moisture exchangers (HMEs)?
1. Simple condenser
2. Hygroscopic condenser
3. Hydrophobic condenser

A patient receiving nasal O2 at 3 L/min complains of nasal dryness and irritation. What actions would be appropriate?

Which of the following automatic feed systems are used to regulate water levels when using a
humidifier with a continuous feed system?
1. Leveling reservoirs
2. Flotation controls
3. Optical sensors

To protect against obstructed or kinked tubing, simple bubble humidifiers incorporate which
of the following?

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 heat and moisture exchanger has an efficiency rating of 80%. What does this mean?

A heated humidifier should trigger both auditory and visual alarms and interrupt power to the
heater when the delivered temperature exceeds ?

The temperature of gas delivered to a patient’s airway by a servo-controlled heated humidifier
should not vary by more than how much?

Which of the following are contraindications for heat and moisture exchangers?
1. Presence of thick, copious, or bloody secretions
2. Presence of a large leak around artificial airway
3. When a patient is suffering from hyperpyrexia
4. When a patient’s minute ventilation exceeds 10 L/min

The typical pressure pop-off incorporated into most simple bubble humidifiers releases
pressure above which of the following?

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.

An ideal heat and moisture exchanger (HME) should have an efficiency rating of at least
which of the following?

Which of the following are necessary features to look for in selecting a heated humidifier?
1. Water level readily visible
2. Over-temperature protection
3. Auditory and visual alarms
4. Minimal temperature overshoot

Which of the following are potential hazards of using heat and moisture exchangers?
1. Failure of low-pressure alarms to detect disconnection
2. Underhydration or impaction of secretions
3. Hypoventilation due to increased dead space
4. Unintended tracheal lavage from condensate

At high flow rates, what do some bubble humidifiers produce?
When checking an O2 delivery system that incorporates a bubble humidifier running at 6
L/min, you occlude the delivery tubing, and the humidifier pressure relief immediately pops
off. What does this indicate?

Which type of humidifier “traps” the patient’s body heat and expire water vapor to raise the
humidity of inspired gas?

Which of the following are features of an ideal heat and moisture exchanger (HME)?
1. High compliance
2. Minimal dead space
3. 70% or higher efficiency
4. Minimal flow resistance

Where should you place the thermistor probe for a servo-controlled heated humidifier being
used on a patient receiving mechanical ventilation?

Which of the following are potential hazards of using a heated humidifier during mechanical
ventilation?
1. Aerosolization of condensate during disconnection
2. Underhydration or impaction of secretions
3. Hypoventilation due to increased dead space
4. Unintended tracheal lavage from condensate