Oral Presentation Part 1

Front 1

What are the characteristics of alveolar air?

Back 1

- 100% relative humidity
- 100% body humidity
- at 37 C, alveolar gas holds approx 44mg/L of humidity
- at 37 C & 100% RH, the pressure exerted by water vapor is 47mmHg

Front 2

What is the humidity deficit?

Back 2

- the amount of humidity in alveolar gas minus the amount of humidity inspired from room air
- represents the amount of water vapor the body must add to the inspired gas to achieve saturation at body temp.

Front 3

How is humidity normally supplied to inspired gas?

Back 3

- by the nasal & oropharynx passages
- if not supplied by the nose, moisture will be taken from tracheal mucosal blanket (will dry secretions)

Front 4

What does the artificial nose do?

Back 4

- collects & uses the patient's own heat & exhaled humidity to condition the inhalation that follows

Front 5

What are the indications for humidity?

Back 5

- to prevent dry gas from drying mucosa
- to provide near body humidity when upper airway function is impaired (overcome humidity deficit)

Front 6

Where does humidity retain moisture?

Back 6

- in the respiratory tract

Front 7

What are the 3 factors that influence the efficiency of humidifiers?

Back 7

- temperature
- surface area exposure (size of bubble)
- time of contact (flow & depth of water)

Front 8

How does temp. influence the efficiency of a humidifier?

Back 8

- the greater the temp. of a gas, the more water vapor it can hold
- as gas expansion & evaporation cool water in unheated humidifiers to 10 C below ambient temp., the humidifiers become less efficient

Front 9

How does surface area affect the efficiency of a humidifier?

Back 9

- the greater the area of contact between water & gas, the more opportunity there is for evaporation to occur

Front 10

How does time of contact affect the efficiency of humidifiers?

Back 10

- the longer a gas remains in contact w/ water, the greater the opportunity for evaporation to occur

Front 11

What is the formula for relative humidity?

Back 11

RH = water vapor content/potential capacity

Front 12

What are the hazards of a humidity deficit?

Back 12

- decreased cilia activity
- decreased movement of mucus
- inflammation & necrosis of pulmonary epithelium
- bacterial culture media
- pneumonia

Front 13

What are the hazards of humidification?

Back 13

- potential electric shock
- hypothermia/hyperthermia
- thermal injury to airway
- under hydration resulting in mucus plugging
- increased WOB, hypoventilation, & alveolar gas trapping as a result of mucus plugging

Front 14

What is the difference between humidity & aerosol?

Back 14

- humidity is defined as: water in a gaseous state, water vapor, & molecular water in a gas
- aerosol is defined as water particles suspended in air or particulate water in a gas (mist/fog)

Front 15

What are the factors that influence the deposition & retention of aerosols?

Back 15

- gravity: the larger the particle, the more likely it is to deposit or "rain out"
- kinetic motion: the more particles move, the more likely they are to bump together, coalesce, & rain out
- inertial impaction: when airways narrow & alter direction, particles may continue on their same path and deposit by bumping airway walls
- ventilatory pattern

Front 16

What is the best ventilator pattern for aerosol deposition in the alveoli?

Back 16

- ideal pattern is slow, w/ deep breaths, utilizing an inspiratory hold

Front 17

What are the lung clearance methods for removal of deposited aerosol?

Back 17

- mobilization of mucus blanket
- cough
- lymphatic uptake
- phagocytes
- mechanical suctioning

Front 18

What are the indications for aerosol therapy?

Back 18

- thin secretions
- improve cough
- deliver medications
- humidification of artificial airways

Front 19

What are the hazards of aerosol therapy?

Back 19

- swelling of dried secretions (causes airway obstruction, can be fatal, patients w/ weak cough)
- can cause bronchospasm (reactive airways, asthma)
- fluid overload (edema); usually through the use of high output systems w/ infants, & CHF patients

Front 20

What is bland aerosol therapy?

Back 20

- involves the delivery of sterile water or hypotonic, isotonic, or hypertonic saline aerosols

Front 21

What are the indications for bland aerosol therapy?

Back 21

- cool mist therapy
- thin secretions
- sputum sample

Front 22

What are the characteristics of a passover humidifier?

Back 22

- gas passes across the surface of water which may be heated
- cascade humidifier w/ tower removed
- Wick or membrane

Front 23

What are the characteristics of a bubble diffuser/type humidifier?

Back 23

- gas forced through straw under water
- smaller bubbles = greater RH (more surface area for gas to come into contact w/ water)
- deeper water = greater RH
- used w/ nasal cannula & other setups to prevent dry gas from being delivered (most common in hospitals)
- usually delivers approximately 40% RH at body temp. or less

Front 24

What are the characteristics of Jet humidifiers?

Back 24

- uses Bernoulli Principle to draw gas up tube
- actually produces an aerosol that is baffled out to produce humidity
- not usually heated
- uncommon

Front 25

What are the characteristics of a heated cascade humidifier?

Back 25

- uses a grid network to spread a thin layer of water through which the gas passes before delivery to patient
- gas travels down a tower through a one-way valve & grid to produce a froth
- small bubbles increase surface area
- liquid is heated to increase potential capacity
- RH equals 100% at body temp.
- gas must be heated warm enough to be at body temp. when it reaches the patient

Front 26

What is the function of the parts of the heated cascade humidifier?

Back 26

- small port at top of tower allows patient to assist a ventilation (sensing port)
- one-way valve prevents humidity from blowing back to machine

Front 27

What are the characteristics of the Wick humidifier?

Back 27

- heater (at or near body temp.) surrounds absorbent paper which soaks up water from the bottom of humidifier
- gas passes warm wet paper and water is evaporated
- water level is maintained constant by a feed apparatus
- at body temp., can deliver 100% body RH

Front 28

What are the characteristics of a Jet nebulizer?

Back 28

- uses Bernouilli Principle: decreased pressure draws water up tube
- water sprays out, baffled into uniform size particles
- pneumatically powered
- allows high flow system to deliver precise FIO2
- can be heated

Front 29

What are the different types of Jet nebulizers?

Back 29

- Large reservoir: >250ml and allows long-term nebulization (50-75% RH)
- Standard (small): <20ml, used w/ IPPB, used primarily for short-term delivery of medications
- Mainstream: gas flows directly through nebulizing chamber
- Sidestream: aerosol is not created in main gas flow
- approx. 50% of particles in 1-5 micron size

Front 30

What are the characteristics of a Breath-actuated nebulizer (BAN)?

Back 30

- generates aerosol only during inspiration
- can increase inhaled aerosol mass 3-4x more than conventional continuous nebulization