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RT210 > Lesson 8: Aerosol, Humidity, CPT > Flashcards

Lesson 8: Aerosol, Humidity, CPT Flashcards

1
Q

What is humidity?

A

Humidity is water in its gaseous or molecular form.

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2
Q

What must be measured for the actual weight of water vapor in a gas to be calculated?

A

Water vapor content or absolute humidity

Explanation: this is the amount of water weight that is held in a gas and is expressed as mg/L

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3
Q

What is potential humidity and how is it determined?

A

Potential humidity is the amount of water vapor a gas can hold, and it is determined by the temperature of the gas or the capacity.

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4
Q

TABLE: 6.3 Vapor Pressure and Absolute Humidity for Air Saturated With Water Vapor

Air that is fully saturated with water vapor at 37C and a pressure of 760mmHg has a water vapor of ____mmHg, a water vapor content(absolute humidity) of ____mg/L, and a ATPS-BTPS correction factor of ____.

A

47mmHg, 44mg/L, and 1000.

Found: p.97 Ch 6

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5
Q

When a gas is not fully saturated, its water vapor content can be expressed using a measure called?

A

Relative Humidity(RH)

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6
Q

What is the RH of a gas?

A

The ratio of its actual water vapor content to its saturated capacity at a given room temperature.

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7
Q

What is the formula for RH?

A

RH(%) = Content(AH) / Capacity(PH) x 100%

AH= absolute humidity
PH= potential humidity
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8
Q

After water is converted into a vapor via evaporation, it acts as any gas. This invisible gaseous form of water is called?

A

Molecular water.

SN: Vapor is not to be confused as visible particulate water such as mist or fog. It isn’t the same thing.

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9
Q

What is the main factor affecting evaporation?

A

Temperature, no other factor Influences evaporation more

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10
Q

In what two ways does temperature affect evaporation?

A

The temperature, the capacity of air to hold water increases with it.
If water is heated, its kinetic energy is increased and more molecules are helped to escape from its surface.

SN: The temperature of a gas affects both its capacity to hold molecular water and the water vapor pressure.

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11
Q

What is humidity deficit?

A

The amount of humidity in alveolar gas minus the amount of humidity inspired.

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12
Q

Inadequate humidification can cause:

A

Decreased cilia activity and movement of mucous, inflammation and necrosis of pulmonary epithelium, retention and secretions, bacterial culture media, atelectasis, and pneumonia.

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13
Q

What are the indications for humidification?

A

To prevent dry gas from drying mucosa, and to provide near body humidity when upper airway function is impaired or bypassed.

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14
Q

Just like the nose, the mucosa lining the sinuses, trachea, and bronchi aid in ____ and ____ inspired gases.

A

heating and humidifying

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15
Q

Why is the mouth less effective at heat and moisture exchange(HME) than the nose?

A

because of the low ratio of gas volume to moist and warm surface area and the less vascular squamous epithelium lining the oropharynx and hypopharynx.

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16
Q

When someone inhales through the mouth at a normal room temperature, pharyngeal temperatures are ___ less than when the person breathes through the nose nose, with ___ less RH.

A

3C, 20%

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17
Q

What does humidity add to the respiratory tract?

A

Moisture

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18
Q

What is aerosol and does it produce?

A

A suspension of solid or liquid particles in a gas. It produces a mist or fog.

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19
Q

What is the isothermic saturation boundary?

A

This is the point at which inspired gas becomes fully saturated at 100% RH at body temperature.

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20
Q

True or False?

The heat and humidity (AH) of a medical gas should be targeted to match conditions found in normal airways at the part of the airway where the gas is being introduced.

A

True!

Rule of Thumb P. 818

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21
Q

What is the primary goal of humidification?

A

To maintain normal physiologic conditions in the lower airways.

Explanation: Proper levels of heat and humidity help to ensure normal function of the mucociliary transport system.

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22
Q

What occurs as a result of the airway being continuously exposed to cold dry air?

A

Ciliary motility is reduced, the airways become more irritable, mucus production increases, and pulmonary secretions become inspissated(thickened and dried, owing to dehydration).

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23
Q

The hazard of breathing dry gas is even more greater when the normal heat and water exchange capabilities of the upper airway are lost or bypassed. This occurs in which condtion?

A

Endotracheal intubation

Explanation: breathing dry gas through an endotracheal tube can cause damage to tracheal epithelium within minutes.

24
Q

As long as the inspired humidity of air is atleast ___% of BTPS conditions, no injury should occur in the lungs.

A

60%

25
Q

What conditions occur as a result of prolonged breathing of improperly conditioned gases through a tracheal airway?

A

Hypothermia, inspissation of airway secretions, mucociliary dysfunction, destruction of airway epithelium and ateelctasis.

26
Q

List some clinical signs and symptoms of inadequate airway humidification.

A

Atelectasis, dry nonproductive cough, increased airway resistance, increased incidence of infection, increased WOB, pt complaint of substernal pain and airway dryness, and thick, dehydrated secretions.

27
Q

ANSWER BREAK: RULE OF THUMB

A

Despite minimal levels in the standards, delivery of inspired gas to the lower airways at 30C or even 34C with 100% RH ay not be sufficient to prevent the occurrence of epithelial damage during a 6h exposure to improperly conditioned gases.

28
Q

True or False?

In prolonged breathing conditions where improperly conditioned gases exist, a delivery of inspired gas at 30C or 34C with 100% RH would be efficient in preventing epithelial damage.

A

False, p.819

29
Q

If someone is hypothermic, what common treatment is used to bring core body temperature back to normal?

A

Heating and humidifying the inspired gas.

Exp: Warmed, humidified gases are used to prevent or treat many abnormal conditions.

30
Q

What is a humidifier, how does it function?

A

A humidifier is a device that adds molecular water to gas.

This process occurs by evaporation of water from a surface to a gas that is not 100% saturated with water vapor.

31
Q

What four variables or principles affect the performance of a humidifer?

A

Temperature, surface area, time of contact, and thermal mass.

32
Q

What is the effect of temperature, surface area, contact time, and thermal mass on the performance of humidifier function?

A

Temperature: the higher the temperature of a gas, the more water vapor it can hold(increased capacity), and vice versa.
Surface area: the greater the surface area of contact between water and gas, the more opportunity for evaporation to occur.
Contact time: the longer a gas remains in contact with water, the greater the opportunity for evaporation to occur.
Thermal mass: the greater the mass of water or the core element of a humidifier, the greater its capacity to hold and transfer heat.

33
Q

List the types of humidifiers and determine whether they are active or passive.

A

Active humidifiers: bubble humidifiers, pass-over humidifiers, nebulizers of bland aerosols, and vaporizers, jet humidifier

Passive humidifiers: heat and moisture exchangers(HME).

34
Q

What organization establishes specifications covering the design and performance requirements for medical humidifiers?

A

The American Society for Testing and Materials(ASTM).

35
Q

When using a bubble humidifier and an obstruction is present what warning is given to prevent bursting of the humidifier bottle?

A

A pressure relief valve or pop-off lets out an audible and a visible alarm and will resume normal position when pressures return to normal.

36
Q

The pop-off is commonly a gravity- or spring loaded valve that releases pressures greater than ____psi.

A

2

37
Q

How is a pop-off used to determine if an O2 delivery system has any leaks? What response determines that it is leak-free or that it has a leak?

A

It is determined by obstructing delivery tubing at or near the patient interface. If the pop-off sounds the system is leak free, if the pop-off does not sound then a leak may be present or a faulty pop-off valve was used.

38
Q

What is a passover humidifier and what are the three common types?

A

Pass-over humidifiers direct gas over a surface containing water.

The three types are: simple reservoir, wick type, and membrane type

39
Q

If a humidifier puts out a R.H. of 100% at any given temperature, and then of a gas increases, the RH will ____.

A

Decrease

Example: If at 30C a cascade puts out 100% RH, and then the temperature increases to 37C, less than 100% RH is delivered to the patient.

40
Q

If the temperature of a gas, that has a RH of 100% decreases, the RH will ____ ___ ____, but the potential and actual humidity will ___ which will result in rain out and a ____ in delivered humidity.

A

Stay the same, decrease, decrease

Explanation: a humidifier puts out a gas that is 37C and has. RH of 100%. The gas is delivered to the patient through large bore tubing. As the gas travels through the tubing it is cooled because the average room temperature is 24C.

41
Q

What are some common ways to increase the surface area ratio of humidifers?

A

Generate a water droplet aerosol, expose gas to a saturated wick, and employ a bubble or diffusion head

42
Q

Aerosol suspension produced by USN have what MMADS?

A

2 to 6 um

43
Q

How often should HMEs be inspected and replaced?

A

Every 8 hours or when contaminated by secretions.

44
Q

What are some potential problems with manually refilled heated humidifier reservoirs?

A

Cross contamination and infection, variable compliance or delivered volume, and delivery of dry and/or hot gases

45
Q

Heat and moisture exchangers are mainly used to do what?

A

Warm and humidify gases delivered to the trachea via ventilator circuits.

46
Q

What factors affect pulmonary deposition of an aerosol?

A

size and nature of the particles, shape and motion of the particles, and physical characteristics of the airways

47
Q

If tolerated, a specified postural drainage position should be maintained for at-least how long?

A

3-15 mins

48
Q

Indications that a pt is having problems with retained secretions?

A

Lack of sputum production, labored breathing, development of a fever, and increased crackles and rhonchi.

49
Q

What are the indications for aerosol therapy?

A

To thin secretions.
To improve cough.
To deliver medications.
Humidification of artificial airways.

50
Q

What are the hazards of aerosol therapy?

A

Swelling of dried secretions, causes bronchospasm, particularly in asthmatic pts and those with reactive airways, fluid overload, and nosocomial infections.

51
Q

A. Humidifiers

List the factors that influence R.H.:

A
  1. surface area exposure(the size of the bubble).
  2. time of contact (flow and depth of water)
  3. Temperature
52
Q

What is a passover humidifier and its function? What two types exist?

A

With a passover humidifier gas passes across the surface of water. Water evaporates into the gas, increasing the humidity of the gas. Water in this system can also be heated.

The two types are a wick and a membrane passover humidifier

53
Q

What is the function of a bubble diffuser or bubble type humidifier? How does it affect R.H.?

A

With a bubble humidifier gas is forced through straw under water.
The smaller the bubbles, the greater the R.H.(more surface area for gas to come into contact with water), the deeper the water, the greater the R.H., and the greater the temperature, the greater the R.H.

54
Q

What is the most common low flow system that is used with a bubble humidifier?

A

It is commonly used with a nasal cannula to prevent dry gas from being delivered

55
Q

What humidifier uses the Bernoulli principle to draw gas up tube?

A

Jet humidifier

56
Q

List the types of nebulizers.

A

Jet nebulizer, small volume, mainstream nebulizer, and babbington nebulizer(hydrosphere)

RT210 (4 decks)

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