Deck 38: Humidity and Bland Aerosol Therapy

Question 1

Which of the following inspired conditions should be maintained when delivering medical gases directly into the trachea through an endotracheal tube or a tracheotomy tube?

A) 50% relative humidity (RH) at 20° to 22° C
B) 100% RH at 37° to 42° C
C) 95% RH at 29° to 32° C
D) 100% RH at 32° to 35° C

Answer 1

D

Question 2

Gas leaving an unheated humidifier at 10° C and 100% relative humidity (absolute humidity = 9.4 mg/L) would provide what relative humidity at body temperature?

A) Approximately 100%
B) Approximately 60%
C) Approximately 40%
D) Approximately 20%

Answer 2

D
Explanation: Although the humidifier fully saturates the gas, the low operating temperature limits total water vapor capacity to approximately 9.4 mg/L water vapor, equivalent to approximately 21% of body humidity.

Question 3

Which of the following inspired conditions should be maintained when delivering medical gases to the hypopharynx, as when administering oxygen (O₂) by nasal catheter?

A) 50% relative humidity (RH) at 20° to 22° C
B) 100% RH at 20° to 22° C
C) 95% RH at 29° to 32° C
D) 100% RH at 32° to 35° C

Answer 3

C

Question 4

Indications for warming inspired gases include which of the following?
1) Treating a patient whose airways are reactive to cold
2) Providing humidification when the upper airway is bypassed
3) Treating a patient with a low body temperature (hypothermia)
4) Reducing upper airway inflammation or swelling

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 5

Which of the following inspired conditions should be maintained when delivering medical gases to the nose or mouth?

A) 50% relative humidity (RH) at 20° to 22° C
B) 100% RH at 20° to 22° C
C) 80% RH at 28° to 32° C
D) 100% RH at 32° to 35° C

Question 6

Factors affecting a humidifier's performance include which of the following?
1) Surface area
2) Temperature
3) Time of contact
4) Outlet size

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 7

Inhalation of dry gases can do which of the following?
1) Increase viscosity of secretions.
2) Impair mucociliary motility.
3) Increase airway irritability.

A)1 and 2 only
B)3 only
C)1 and 3 only
D)1, 2, and 3

Question 8

Which of the following are true about humidification and contact time?
1) The longer a gas is exposed to water, the greater is the amount of evaporation.
2) The rate of gas flow through a humidifier determines contact time.
3) Low flows decrease and high flows increase relative humidity output.
4) Bubble humidifier contact time depends on the water column depth.

A)1 and 3 only
B)1, 2, and 4 only
C)3 and 4 only
D)1, 2, 3, and 4

Question 9

The greater the temperature of the gas, the:

A) more water vapor it can hold.
B) less water vapor it can hold.
C) less efficient the humidifier is.
D) more water vapor is lost.

Question 10

What is the most important factor determining a humidifier's performance?

A) Surface area
B) Temperature
C) Time of contact
D) Gas flow

Question 11

What is the primary goal of humidity therapy?

A) Decrease airway reactivity to cold.
B) Maintain normal physiologic conditions.
C) Deliver drugs to the airway.
D) Reduce upper airway inflammation.

Question 12

What is the point in the respiratory track where inspired gas reaches body temperature, ambient pressure, saturated (BTPS) conditions?

A) Point of thermal equilibrium
B) Hygroscopic saturation boundary
C) Thermal inversion boundary
D) Isothermic saturation boundary

Question 13

Clinical indications for delivering cool humidified gas include which of the following?
1) Postextubation edema
2) Upper airway inflammation
3) Croup (laryngotracheal bronchitis)
4) Epiglottitis

A)2, 3, and 4 only
B)1, 2, and 3 only
C)1, 2, 3, and 4
D)2 and 3 only

Question 14

Which of the following factors cause the isothermic saturation boundary (ISB) to shift farther down into the airways?
1) Decreased ambient temperature
2) Increased tidal volume (V_T)
3) Endotracheal intubation

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 15

Administration of dry gases at flows exceeding 4 L/min can cause which of the following?
1) Structural damage
2) Heat loss
3) Water loss

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 16

Which of the following are clinical signs and symptoms of inadequate airway humidification?
1) Atelectasis
2) Dry cough
3) Increased airway resistance
4) Increased incidence of infection
5) Increased work of breathing

A)2, 3, and 4 only
B)1, 2, and 3 only
C)3, 4, and 5 only
D)1, 2, 3, 4, and 5

Question 17

Which of the following is false about the isothermic saturation boundary (ISB)?

A) Below the ISB, temperature and relative humidity remain constant.
B) Above the ISB, temperature and humidity increase during exhalation.
C) The ISB is normally located just below the larynx (vocal cords).
D) Above the ISB, temperature and humidity decrease during inspiration.

Question 18

Which of the following types of humidifiers are used in clinical practice?
1) Heat and moisture exchanger
2) Passover humidifier
3) Bubble humidifier

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 19

What is the simplest way to increase the humidity output of a humidifier?

A) Increase the time that the gas and the water are in contact.
B) Increase the surface area between the water and the gas.
C) Decrease the water vapor pressure of the gas.
D) Increase the temperature of either the water or the gas.

Question 20

What device adds molecular water to gas?

A) Agitator
B) Humidifier
C) Nebulizer
D) Atomizer

Question 21

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

A) Decreasing the water vapor content
B) Decreasing the relative humidity
C) Increasing the water vapor content
D) Increasing the relative humidity

Question 22

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

A) Additional heat
B) Microorganisms
C) Low pressures
D) Aerosol particles

Question 23

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

Question 24

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

A) 40 mg/L water vapor exhaled; 27 mg/L returned
B) 40 mg/L water vapor exhaled; 20 mg/L returned
C) 27 mg/L water vapor exhaled; 40 mg/L returned
D) 44 mg/L water vapor exhaled; 37 mg/L returned

Question 25

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

A) Condensate will obstruct the delivery tubing.
B) Heating will melt the reservoir or cause a fire.
C) Heating will absorb the extra water vapor.
D) Heating will cause too much aerosol impaction.

Question 26

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

A) Warm and humid gases delivered to the trachea via ventilator circuits.
B) Humidify therapeutic gases delivered at high flows to the lower airway.
C) Provide extra humidity for a patient with thick or retained secretions.
D) Warm and humid dry therapeutic gases delivered to the upper airway.

Question 27

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 humidity at body temperature.

Question 28

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

A) 5 to 10 mg/L
B) 10 to 15 mg/L
C) 15 to 20 mg/L
D) 20 to 25 mg/L

Question 29

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

A) 760 mm Hg
B) 10 cm H₂O
C) 250 kPa
D) 2 psig

Question 30

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

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 31

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

A)1 and 2 only
B)2 and 3 only
C)1, 2, and 3
D)3 only

Question 32

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

A) HEPA outlet filter
B) Pressure relief valve
C) Automatic hygrometer
D) Electronic alarm system

Question 33

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

Question 34

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?

A) Bubble
B) Wick
C) Cascade
D) Hygroscopic

Question 35

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

A) Raise the humidity of the gas to ambient levels.
B) Fully saturate the inspired gas to body temperature, ambient pressure, saturated (BTPS) conditions.
C) Cool the gas down to below room temperature.
D) Fully saturate the inspired gas to ambient temperature, ambient pressure, saturated (ATPS) conditions.

Question 36

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.

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 37

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?

A) Malfunctioning humidifier
B) Normal, leak-free system
C) Malfunctioning flowmeter
D) Leak in the delivery tubing

Question 38

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

A) 4 L/min
B) 6 L/min
C) 8 L/min
D) 10 L/min

Question 39

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

A) Mechanical ventilation
B) Oronasal O₂ delivery
C) Tracheal O₂ airway
D) Aerosol drug delivery

Question 40

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

A) Membrane
B) Bubble
C) Heat and moisture exchanger
D) Passover

Question 41

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

A) 25° C
B) 30° C
C) 35° C
D) 40° C

Question 42

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

A)2 and 4 only
B)1, 2, and 3 only
C)3 and 4 only
D)1, 2, 3, and 4

Question 43

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

A)1 and 3 only
B)1, 2, and 3 only
C)4 only
D)1, 2, and 4 only

Question 44

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

A) 2° C
B) 4° C
C) 6° C
D) 8° C

Question 45

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%

Question 46

A patient receiving ventilatory support is being provided with humidification using a heat and moisture exchanger (HME). A physician orders a bronchodilator drug administered through a metered dose inhaler (MDI) via the ventilator circuit. Which of the following must be performed to ensure delivery of the drug to the patient?

A) The inspiratory flow setting of the ventilator should be increased.
B) The HME must be removed from the circuit during MDI use.
C) The V_T setting of the ventilator should be decreased.
D) A heated humidifier should replace the HME when using the MDI.

Question 47

Which of the following statements is false of heat and moisture exchangers (HMEs)?

A) Moisture output falls at high volumes and rates of breathing.
B) High inspiratory flows and high FiO₂ values can decrease HME efficiency.
C) In-use HMEs have little effect on flow resistance to breathing.
D) HMEs reduce bacterial colonization of ventilator circuits.

Question 48

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

A)2 and 3 only
B)1 and 2 only
C)1, 2, and 3
D)1 and 3 only

Question 49

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

A)1 and 3 only
B)2, and 3 only
C)3 and 4 only
D)1, 2, and 4 only

Question 50

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

A) Recommending that the flow be decreased to 2 L/min
B) Adding a humidifier to the delivery system
C) Recommending that the flow be increased to 4 L/min
D) Switching to a simple mask at 3 L/min

Question 51

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

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 52

Which of the following is false about a simple heated humidifier (one that does not incorporate a servo-control mechanism)?

A) The controller regulates the heating element's electric power.
B) The controller monitors the temperature of the heating element.
C) The controller varies current to achieve a set airway temperature.
D) The patient's airway does affect the controller.

Question 53

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

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 54

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

A)1 and 2 only
B)2 and 3 only
C)2 only
D)3 only

Question 55

When using a servo-controlled heated humidifier to deliver gas to an infant, the thermistor probe should be placed where?

A) Inside the circuit, outside the incubator, or away from the radiant warmer
B) Outside the circuit, inside the incubator, or away from the radiant warmer
C) Inside the circuit, inside the incubator, or away from the radiant warmer
D) Outside the circuit, outside the incubator, or away from the radiant warmer

Question 56

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

A) In the expiratory limb of the circuit, near but not at the "wye"
B) In the inspiratory limb of the circuit, as close to the "wye" as possible
C) In the expiratory limb of the circuit, as close to the "wye" as possible
D) In the inspiratory limb of the circuit, near but not at the "wye"

Question 57

Conditions that can cause temperature "overshoot" with servo-controlled heated humidifiers include which of the following?
1) The unit is allowed to warm up without flow.
2) Flow is decreased during normal operation.
3) The airway temperature probe becomes dislodged.
4) The unit reservoir is refilled with sterile water.

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 58

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

A)1 and 3 only
B)2, 3, and 4 only
C)2 and 4 only
D)1, 2, 3, and 4

Question 59

What should happen when the remote temperature sensor of a heated humidifier becomes disconnected or fails?
1) Power to the heater should be interrupted.
2) Auditory and visual alarms should trigger.
3) The unit's outlet valve should lock closed.

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 60

Characteristics of a servo-controlled heated humidifier include which of the following?
1) Monitors heater temperature.
2) Adjusts heater power automatically.
3) Provides automatic heater shutdown.
4) Includes temperature safety alarms.

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 61

When is a heat and moisture exchanger (HME) performing well?

A) Condensate appears in the attached flex tube.
B) No condensate is visible on the filter or insert.
C) The HME temperature is at least 40° C.
D) Condensate is visible on the filter or insert.

Question 62

Hazards and complications of bland aerosol therapy include which of the following?
1) Bronchospasm
2) Overhydration
3) Infection
4) Hemoconcentration

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 63

Which of the following are the proper temperature alarm settings for a heated humidifier used during mechanical ventilation? High Low

A) 35° C 32° C
B) 37° C 30° C
C) 39° C 33° C
D) 35° C 30° C

Question 64

In checking a servo-controlled heated-wire humidifier system, you notice that a few drops of condensate tend to form but only near the patient's airway. Based on this observation, what can you conclude?

A) The gas at the airway is fully saturated.
B) The temperature setting of the heater is too high.
C) The airway temperature exceeds the dew point.
D) The temperature setting of the heater is too low.

Question 65

Which of the following is false about heated humidifier condensate?

A) It can block or obstruct the delivery circuit.
B) It must be treated as contaminated waste.
C) It requires that circuits be drained frequently.
D) It poses minimal infection risk.

Question 66

For which of the following patients might you recommend administration of a hypertonic saline aerosol?
1) Acquired immune deficiency syndrome (AIDS) patient with severe pneumonia symptoms
2) Patient with a bypassed upper airway
3) Patient suspected of having tuberculosis

A)1, 2, and 3
B)2 and 3 only
C)1 and 2 only
D)1 and 3 only

Question 67

Which of the following are acceptable means to help minimize the problems caused by condensation in heated humidifier circuits?
1) Installing water traps in the circuit
2) Using a heated-wire circuit
3) Setting heater temperature to 25° to 28° C

A)1, 2, and 3
B)2 and 3 only
C)1 and 2 only
D)1 and 3 only

Question 68

During routine use on an intubated patient, a heated humidifier should deliver inspired gas at which of the following?

A) Temperature of 33 ± 2° C, with a minimum of 30 mg/L of water vapor
B) Temperature of 37 ± 2° C, with a minimum of 44 mg/L of water vapor
C) Temperature of 20 ± 2° C, with a minimum of 10 mg/L of water vapor
D) Temperature of 30 ± 2° C, with a minimum of 24 mg/L of water vapor

Question 69

When using nebulizers, where should you place them to minimize risk of contamination?

A) In the inspiratory limb only, at a high point in the circuit
B) In both the expiratory and inspiratory limbs, at high points in the circuit
C) In the expiratory limb only, at a low point in the circuit
D) In both the expiratory and inspiratory limbs, at low points in the circuit

Question 70

A patient has been supported by a mechanical ventilator using a heat and moisture exchanger for the last 3 days. Suctioning reveals an increase in the amount and tenacity of secretions. Which of the following actions is indicated?

A) Increase the hygroscopic condenser humidifier temperature.
B) Reassess the patient's secretions over the next 24 to 48 hr.
C) Replace the hygroscopic condenser humidifier with a new one.
D) Switch the patient to a large-volume heated humidifier.

Question 71

Which of the following barrier precautions should be used when heated humidifier circuits are changed or removed?
1) Wearing gloves
2) Wearing goggles
3) 5-min hand scrub

A)1 and 2 only
B)2 and 3 only
C)1 and 3 only
D)1, 2, and 3

Question 72

For which of the following patients would you recommend bland aerosol therapy administration?
1) Patient with a history of airway hyperresponsiveness
2) Patient with a bypassed upper airway
3) Patient with active bronchoconstriction

A)1, 2, and 3
B)2 only
C)1 and 2 only
D)1 and 3 only

Question 73

The amount of condensation occurring in a heated, humidified gas delivery system depends on which of the following?
1) Length, diameter, and mass of the circuit
2) Temperature differential along the circuit
3) Ambient temperature
4) Rate of gas flow through the circuit

A)2 and 4 only
B)1, 2, and 3 only
C)3 and 4 only
D)1, 2, 3, and 4

Question 74

When using water traps to help minimize the problems caused by condensation in a heated-humidifier ventilator circuit, where would you place the traps?

A) In the expiratory limb only, at a high point in the circuit.
B) In both the expiratory and inspiratory limbs, at high points in the circuit.
C) In the expiratory limb only, at a low point in the circuit.
D) In both the expiratory and inspiratory limbs, at low points in the circuit.

Question 75

How often should heat and moisture exchangers be inspected and replaced?

A) At least every shift
B) When contaminated by secretions
C) At least every day
D) When condensate is visible

Question 76

When checking a patient attached to a servo-controlled heated-wire humidifier breathing circuit, you notice no visible condensate anywhere in the tubing. Based on this observation, you can conclude that the relative humidity of the delivered gas is which of the following?

A) Less than 25%
B) 25% to 90%
C) 90% to 100%
D) Less than 100%

Question 77

For which of the following patients might you recommend bland aerosol therapy administration?
1) Patient with upper airway edema
2) Patient with a bypassed upper airway
3) Patient who must provide a sputum specimen

A)1, 2, and 3
B)2 and 3 only
C)1 and 2 only
D)1 and 3 only

Question 78

Which of the following reduce the risk of nosocomial infection when using heated humidification systems?
1) Use of wick or membrane humidifiers
2) Use of heated-wire delivery circuits
3) High humidifier reservoir temperatures
4) Frequent changing of delivery circuits

A)1 and 3 only
B)1, 2, and 3 only
C)3 and 4 only
D)2, 3, and 4 only

Question 79

Which of the following are true when heated-wire circuits are used with heated humidifiers except:

A) the humidifier operates at a higher temperature.
B) there is less condensate and a reduced need for drainage.
C) cost savings (less water and staff time) are realized.
D) there is less infection risk for both patient and caregivers.

Question 80

What is the most reliable indicator that the gas delivered by a servo-controlled heated-wire humidifier system is fully saturated at the airway?

A) Observing no visible condensate anywhere in the delivery tubing
B) Confirming an airway temperature between 32° and 35° C
C) Observing a few drops of condensate at or near the patient's airway
D) Observing condensate over the full length of the delivery tubing