Question | Answer |
What is Humidity Therapy? | The addition of molecular water vapor to a gas delivered to the airway. |
What are results of a dry airway? | Increased mucus production.
Thickened Secretions.
Decreased Cilia funtion
Increased airway irritability |
What patient population are most susceptible to a dry airway? | Patients with bypassed airways |
What are the normal functions of the upper airway? | Filter
Heat
Humidity |
Where does inspired air achieve BTPS conditions? | At the Carina |
Which part of the upper airway heats and humidifies on inspiration? | The nose, it's more efficient than the mouth. |
What happens to inspired gas on expiration? | It cools and transfers heat to the cool trachea.
It condenses and returns to the airway. |
What is relative humidity? | The ratio comparing absolute humidity to its saturated capacity at a given temperature. |
How is relative humidity expressed? | As a percentage |
Absolute humiditity is? | The actual water vapor present |
What is saturated capacity? | The maximum amount of vapor a gas can hold. |
What is the saturated capacity of body temperature? | 43.8 mg/L |
How do you calculate relative humidity? | Absolute humidity divided by saturated capacity X 100 |
What is the humidity deficit? | the amount of water vapor that the body must add to inspired gas to achieve 100% relative humidity at body temperature. |
How do you calculate the humidity deficit? | capacity at body temperature- absolute humidity |
What is body humidity? | The ratio comparing absolute humidity to the saturated capacity at body temperature? |
How do you calculate body humidity? | absolute humidity/saturated capacity X body temp |
What is the goal of humidity therapy? | To maintain normal physilogic conditions in the airway. |
What are indications for humidity therapy. | Humidity dry medical gases
Overcome the humidity deficit when upper airway is bypassed.
Managing hypothermia
treat bronchospasm caused by cold air. |
What is humidifier? | A device that adds molecular water vapor to a gas |
Facts about humidifiers. | Should provide at least 60% relative humidity at BTPS.
Some humidifiers can be heated.
Intubated patients need 30 mg/L of water vapor |
What are the 3 variables that govern humidifier function? | Temperature
surface area
time of contact |
Temperature | The greater the temperature the greater the water output |
Surface area | The greater the surface area, the greater the evaporation, the greater the vapor output |
Time of contact | The greater the contact time, the greater the evaporation, the greater the water vapor output |
What are the types of humidifier systems? | Room
Bubble
Passover
Heat Moisture Exchanger (HME) |
Bubble Humidifier | Pneumatically powered (powered by gas)
Not heated
Inneficient
Absolute humidity approximately 15-20 mg/L |
What is the bubble humidifier used with? | Simple oxygen delivery devices. (i.e. cannula) |
What safety feature does the bubble humidifier have? | A pop off safety valve for pressure relief (Audible, pops off at 2 PSIG) |
How is a passover humidifier powered? | It can be pneumatically and electrically powered. |
What are the three tips of passover humidifiers? | Simple resivoir passover
Wick
Membrane |
What are some facts about the passover humidifier? | It is heated
very efficient (30+ mg/L)
Used with mechanical ventilators |
Simple resivoir passover humidifier | Directs gas over surface of water and picks up vapor. (CPAP/Heated or non heated)
It can maintain saturated gas at high flow rates. It's functional at high flow rates due to low resistance to airflow. |
Wick passover humidifier | It's heated an very efficient
Passes over heater/saturated wick. It does not bubble. |
Membrane passover humidifier | Separates water from the gas stream by means of a hydrophobic membrane. It is heated and only allows water vapor to come through but blocks liquid water. |
What do active humidifiers use? | Electric heat |
What do passive humidifiers use? | The body heats it with exhaled gas. |
What is an example of a passive humidifier? | Heat moisture exchanger (HME)
AKA artificial nose |
How is the HME powered? | Passive/patient powered |
How does the HME work? | It captures exhaled heat and water vapor and uses it to heat and humidify the next breath. |
What is the efficiency rating? | Approximately 70% |
How is the Heat Moisture exchanger used? | With artificial airways/mechanical ventilators |
What are the contraindications to an HME? | Presence of copious, thick, or bloody secretions; leak around ETT;hypothermia; and a high minute ventilation |
How often must HME's be changed? | Every 24 hours or prn |
What are the hazards of an HME? | Underhydration, Secretion buildup in HME, Increased WOB, mucous plugging, increased deadspace, and hypothermia |
What is a special consideration of the Heat Moisture Exchanger? | It must be removed for administration or aerosol drugs. |
What are indications for heating systems? | Bypassed airway, hypothermia, airway sensitive to cold air |
What are contraindications to heating systems? | Airway inflammation |
What are some types of heating elements? | Hot plates, wrap around heaters, yolk or collar heating elements, immersion heaters |
What are some hazards to heating systems? | Overheating the airway or humidifier system. |
What should always be monitored with the heating systems? | The water level and the temperature |
What are two hazards of humidity therapy? | Condensation
Infection Risk/Cross contamination |
Condensation | Disrupts or occludes the gas flow.
It can be aspirated.
Is an infection risk. |
Infection risk/cross contamination | monitor handling of devices
use disposible equipment
use automatic feed reservoirs
Avoid contamination with the floor and trash can.
Change circuit as required/needed |
What are some ways to ensure adequate gas conditions? | Use hygrometer to monitor humidity levels.
Monitor temperature.
Monitor water levels. |
What are aerosols? | |
What are some examples of aerosols? | Liquid, smoke, dust, fog, pollen |
Bland aerosol therapy is | a form of humidity therapy where solutions are aerosolized.
(saline, sterile H20) |
What is a device that creates an aerosol? | A nebulizer |
What are indications for bland aerosol therapy? | bypassed airway
treatment of upper airway inflammation
sputum induction |
What are the two types of nebulizers? | large volume jet nebulizer
ultrasonic nebulizer |
How is the large volume jet nebulizer powered? | Pneumatically |
Some facts about the jet volume nebulizer | It can be heated and is very efficient
It usually runs continuously |
What is a large volume jet nebulizer used with? | Aerosol mask, face tent, trach collar, Briggs adaptor, oxygen tents and oxygen hoods |
What must you use to power this? | An adequate flow rate. |
What does the large volume jet nebulizer contain? | A baffle to break up H20 particles and an Fi02 control |
How is the ultrasonic nebulizer powered? | With electricity |
What are some facts about the ultrasonic nebulizer? | It is not heated
It should only be used intermittently
It is used with the same devices as large volume jet nebulizer. It can also be used as a room humidifier |
What are some risks to the ultrasonic nebulizer? | overhydration and bronchospasm |
How does the ultrasonic nebulizer work? | It uses a piezoelectric crystal to convert electrical energy into sound waves. |
How is particle size controlled? | It is controlled by frequency for uniform particle size but the output is controlled by the therapist. |
The ultrasonic nebulizer only provides? | Room air |
What are some hazards of bland aerosol therapy? | Infection risk/cross contamination
Environmental issues (TB)
Swelling secretions (overhydration)
Bronchospasm
Overhydration
Noise
Condensation
Overheating when using a heater |
What is the goal of aerosol drug therapy? | To deliver a therapeutic dose of a selected agent to the desired site of action |
What are the benefits of aerosol drug therapy? | Targets the site of action
High therapeutic index (very effective/fewer systemic side effects) |
List some categories of aerosol drugs. | Bronchodilators
Steroids
Mucolytics
Antibiotics |