Question 1

Increasing the flow through an unheated bubble humidifier has which of the following effects?

Accepted Answer

As gas flow increases, these devices become less efficient as the reservoir cools and contact time is reduced.

Question 2

At high flow rates, what do some bubble humidifiers produce?

Accepted Answer

At high flow rates, bubble humidifiers can produce aerosols.

Question 3

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.

Accepted Answer

Passover humidifiers have several advantages as compared to other types of humidifiers. These include adding minimal flow resistance to breathing circuits, not requiring heating to maintain BTPS conditions, and not generating any bacteria-spreading microaerosol. Additionally, they can maintain water vapor saturation even at high flows. Therefore, options 1, 3, and 4 are correct, making choice (D) the best answer. Option 2, which states that passover humidifiers do not require heating to maintain body temperature, is incorrect, as this is not one of the advantages of these humidifiers.

Question 4

Which of the following best describes the performance of a typical hygroscopic condenser HME?

Accepted Answer

These devices typically achieve approximately 70% efficiency (40 mg/L exhaled, 27 mg/L returned).

Question 5

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

Accepted Answer

Heating the reservoirs of these units can increase humidity content but is not recommended because the resulting condensate tends to obstruct the small-bore delivery tubing to which they connect.

Question 6

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

Accepted Answer

Traditionally, HME use has been limited to providing humidification to patients receiving invasive ventilatory support via endotracheal or tracheostomy tubes.

Question 7

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

Accepted Answer

These devices typically achieve approximately 70% efficiency (40 mg/L exhaled, 27 mg/L returned).

Question 8

What is the typical water vapor output of an unheated bubble humidifier?

Accepted Answer

The answer of What is the typical water vapor output...

Question 9

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

Accepted Answer

Typically, the pop-off is either a gravity or spring-loaded valve that releases pressures above 2 psig.

Question 10

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

Accepted Answer

Passover humidifiers can include simple reservoir types, membrane types, and wick types, all of which are designed to add moisture to the air in different ways.

Question 11

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

Accepted Answer

1, 2, and 3 are all types of heat and moisture exchangers (HMEs), each utilizing different mechanisms to conserve or add moisture and heat to the respiratory gases.

Question 12

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

Accepted Answer

Bubble humidifiers incorporate a simple pressure-relief valve or pop-off.

Question 13

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.

Accepted Answer

1) Water and gas are separated by a hydrophobic membrane - True, this is the basic principle of a membrane-type humidifier.
2) The membrane is permeable to water vapor but not to liquid water - True, this is what allows the water to pass through as water vapor and humidify the gas without creating any droplets.
3) As with other passover humidifiers, there is no bubbling action - True, as there is no bubbling action in this humidifier.
4) A small layer of liquid water remains on both sides of the membrane - False, there is no liquid water left behind, as the water vapor is what passes through the membrane.

Question 14

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?

Accepted Answer

Typically a wick is placed upright with the gravity-dependent end in a heated water reservoir.

Question 15

What is the goal of using an unheated bubble humidifier with oronasal O₂ delivery systems?

Accepted Answer

Unheated bubble humidifiers are commonly used with oronasal O₂ delivery systems (see Chapter 41) the goal is to raise the water vapor content of the gas to ambient levels.

Question 16

The relief valve on a bubble humidifier serves which of the following functions?
1) It indicates when flow has been interrupted.
2) It protects the device from pressure damage.
3) It warns you when the water level is low.

Accepted Answer

The relief valve on a bubble humidifier serves to indicate when flow has been interrupted and to protect the device from pressure damage. It does not warn when the water level is low.

Question 17

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?

Accepted Answer

If the system is obstructed at or near the patient interface and the pop-off sounds, the system is leak free.

Question 18

Unheated bubble humidifiers are of limited effectiveness at flows above which of the following?

Accepted Answer

Unheated bubble humidifiers are of limited effectiveness at flow rates higher than 10 L/min.

Question 19

Simple unheated bubble humidifiers are commonly used to humidify gases with what type of systems?

Accepted Answer

Unheated bubble humidifiers are commonly used with oronasal O₂ delivery systems (see Chapter 41) to raise the water vapor content of the gas to ambient levels.

Question 20

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

Accepted Answer

Like the nose, a heat and moisture exchanger captures exhaled heat and moisture and uses it to heat and humidify the next inspiration.

Quiz 38: Humidity and Bland Aerosol Therapy

Increasing the flow through an unheated bubble humidifier has which of the following effects?

At high flow rates, what do some bubble humidifiers produce?

Which of the following best describes the performance of a typical hygroscopic condenser HME?

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

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

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

What is the typical water vapor output of an unheated bubble humidifier?

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

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

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

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

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?

What is the goal of using an unheated bubble humidifier with oronasal O₂ delivery systems?

The relief valve on a bubble humidifier serves which of the following functions? 1) It indicates when flow has been interrupted. 2) It protects the device from pressure damage. 3) It warns you when the water level is low.

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?

Unheated bubble humidifiers are of limited effectiveness at flows above which of the following?

Simple unheated bubble humidifiers are commonly used to humidify gases with what type of systems?

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

Quiz 38: Humidity and Bland Aerosol Therapy

Increasing the flow through an unheated bubble humidifier has which of the following effects?

At high flow rates, what do some bubble humidifiers produce?

Which of the following best describes the performance of a typical hygroscopic condenser HME?

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

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

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

What is the typical water vapor output of an unheated bubble humidifier?

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

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

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

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

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?

What is the goal of using an unheated bubble humidifier with oronasal O2 delivery systems?

The relief valve on a bubble humidifier serves which of the following functions? 1) It indicates when flow has been interrupted. 2) It protects the device from pressure damage. 3) It warns you when the water level is low.

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?

Unheated bubble humidifiers are of limited effectiveness at flows above which of the following?

Simple unheated bubble humidifiers are commonly used to humidify gases with what type of systems?

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

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

What is the goal of using an unheated bubble humidifier with oronasal O₂ delivery systems?

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?