Respiratory Therapy Chapter 35 Quiz

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Questions and Answers

What is the primary mechanism by which large-volume jet nebulizers generate liquid particles?

Passing gas at high velocity through a small jet orifice (correct)

Heating the liquid directly prior to aerosolization

Using a piezoelectric crystal to create mechanical vibrations

Injecting liquid directly into the airflow

Which factor does NOT influence the aerosol density and total water output of ultrasonic nebulizers?

Humidity of the surrounding air (correct)

Flow settings

Signal frequency

Signal amplitude

What is the typical water output range for unheated large-volume nebulizers?

26 to 35 mg H2O/L (correct)

15 to 20 mg H2O/L

50 to 60 mg H2O/L

35 to 45 mg H2O/L

What type of airway appliance is used to minimize flow resistance in aerosol therapy?

Face tent Signup and view all the answers

Which of the following statements about heated nebulizers is accurate?

They can produce higher water output due to increased vapor capacity. Signup and view all the answers

What is the primary role of the upper airway in heat and moisture exchange?

To heat and humidify gas during inhalation and reclaim water during exhalation Signup and view all the answers

What happens to the temperature and relative humidity of inhaled gas above the isothermic saturation boundary (ISB)?

They decrease during inspiration and increase during exhalation Signup and view all the answers

Which of the following scenarios would likely cause the isothermic saturation boundary (ISB) to shift distally?

Breathing cold, dry air Signup and view all the answers

How is relative humidity expressed and calculated?

As a percentage of the amount of water vapor to the maximum it can hold at that temperature Signup and view all the answers

What is the definition of absolute humidity?

Amount of water in a specific volume of gas, expressed in mg/L Signup and view all the answers

When might humidity therapy be indicated?

When the airway is bypassed or breathing cold, dry air Signup and view all the answers

What is the body temperature pressure saturated (BTPS) condition?

Gas at 37º C and 100% relative humidity Signup and view all the answers

What is the primary function of heat-moisture exchangers (HMEs)?

Captures exhaled heat and moisture for subsequent inhalation Signup and view all the answers

Which type of HME is characterized by not adding heat or water to the system?

Heat-moisture exchangers Signup and view all the answers

Which of the following humidifiers is designed specifically for patients with minute volumes of 4-20L?

HME booster Signup and view all the answers

Which humidifier can deliver gas at 100% body humidity?

HME Signup and view all the answers

What is a characteristic of active HMEs?

They release absorbed heat and moisture into inspired gas. Signup and view all the answers

What is the potential risk when heating inhaled gas for patients with bypassed upper airways?

Risk of airway burns Signup and view all the answers

Which humidifier type adds 30-90 mL of dead space?

Passive HME Signup and view all the answers

What component is typically part of the active HME called 'Humid-Heat'?

Microprocessor Signup and view all the answers

Which condition is HME inappropriate for?

Pediatric patients and infants Signup and view all the answers

What is a common problem associated with humidification systems?

Dealing with large patient volumes Signup and view all the answers

What type of humidifier can prevent the formation of bacteria-carrying aerosols?

Wick-type humidifiers Signup and view all the answers

Which method is NOT effective in minimizing condensation in humidification systems?

Regularly changing circuit components Signup and view all the answers

Which liquid is NOT typically used in bland aerosol therapy?

Distilled vinegar Signup and view all the answers

What is the first step for respiratory therapists in ensuring proper conditioning of inspired gas?

Regularly measuring inspired FiO2 levels Signup and view all the answers

What is the purpose of a hygrometer-thermometer system in respiratory therapy?

To ensure proper humidity and temperature conditioning Signup and view all the answers

In the context of airway humidification, which statement is true?

Humidity control impacts patient comfort and health. Signup and view all the answers

Which of the following conditions could potentially arise from bacterial colonization in humidification systems?

Nosocomial infections Signup and view all the answers

Which of these is NOT a type of nebulizer used for generating bland aerosols?

High-frequency oscillatory nebulizers Signup and view all the answers

What can be done to minimize the risk of condensation in the breathing circuit?

Applying insulation to the circuit Signup and view all the answers

What is the primary benefit of using automatic systems in humidifiers?

They eliminate the need for constant manual checking and refilling. Signup and view all the answers

What is a potential risk of condensation in humidifier systems?

Occlusion of gas flow through the circuit. Signup and view all the answers

Which heating element type is commonly found in humidifiers?

Yolk or collar element. Signup and view all the answers

What minimum humidity level is recommended for intubated patients?

30 mg/L Signup and view all the answers

What should be a feature of a good humidifier to prevent cross-contamination?

A large water reservoir. Signup and view all the answers

Which system allows for refilling a humidifier without interruption?

Gravity-fed intravenous bag attachment. Signup and view all the answers

What is a disadvantage of using manual refill systems in humidifiers?

Risk of cross-contamination. Signup and view all the answers

What can be done to minimize condensation issues in humidifier circuits?

Use water traps and check humidifiers regularly. Signup and view all the answers

At what temperature is it recommended to heat inhaled gas to maintain airway temperatures?

35-37 ºC Signup and view all the answers

What is a primary function of heated humidifiers?

To provide optimal humidity levels in inspired gas. Signup and view all the answers

Study Notes

Chapter 35: Humidity and Bland Aerosol Therapy

Learning Objectives:
- Describe airway heat and moisture exchange.
- Identify the effects of dry gases on the respiratory tract.
- Determine when to humidify and warm inspired gas.
- Explain how various types of humidifiers work.
- Describe methods to improve humidifier performance.
- Outline the selection and safe use of humidifier heating and feed systems.
- Identify indications, contraindications, and hazards of humidification during mechanical ventilation.
- Describe monitoring techniques for patients receiving humidity therapy.
- Explain how to identify and resolve common problems with humidification systems.
- State when to apply bland aerosol therapy.
- Explain how large-volume aerosol generators function.
- Identify delivery systems used for bland aerosol therapy.
- Describe identifying and resolving common problems with aerosol delivery systems.
- Describe sputum induction techniques.
- Explain how to select appropriate therapies to condition a patient's inspired gas.

Humidity Therapy

Physiological Control of Heat & Moisture Exchange:
- The upper airway (primarily the nose) warms and humidifies inspired gases.
- The nose also cools and reclaims water from exhaled gases.
- Body temperature–pressure–saturated (BTPS) conditions are optimal;
  - Body temperature at 37° C;
  - Barometric pressure;
  - Saturated with water vapor (100% relative humidity at 37° C).
- Isothermic saturation boundary (ISB):
  - Above ISB, temperature and relative humidity decrease during inspiration and increase during exhalation.
  - Below ISB, temperature and relative humidity remain constant.
  - ISB shifts distally when breathing cold, dry air or via an artificial airway.
- Humidity deficit:
  - Inspired air that is not fully saturated at body temperature.
  - The body's own humidification system corrects the deficit.
  - Humidity deficit = 44 mg/L – absolute humidity.
- Relative Humidity: Ratio of water in a given volume of gas to the maximum amount the gas can hold at that temperature (%).
- Absolute Humidity: Amount of water in a given volume of gas (mg/L).

Humidification Levels

At least 30 mg/L humidity is recommended for intubated patients.
Humidifiers should provide optimal humidity levels in inspired gas.
Heat inhaled gas to maintain airway temperatures near 35-37° C.

Equipment (Humidifiers)

Humidifier: Device that adds water to gas by evaporation from a surface.
- Physical principles:
  - Temperature: Higher temperature gases hold more water.
  - Surface area: Greater surface area increases evaporation rate.
  - Contact time: Longer contact time increases evaporation.
  - Thermal mass: Larger water quantity increases humidifier's heat capacity.
Types of Humidifiers:
- Bubble: Breaks gas into small bubbles for gas-water interaction, can produce aerosols at high flow rates, poses risk of infection.
- Passover: Gas passes over a water surface (Reservoir/Wick/Membrane). Usually unheated. Advantage is it maintains saturation at high flow rates and has minimal flow resistance.
- Heat-moisture exchangers (HMEs): Passive humidifiers, often described as "artificial noses." Do not add heat or water to the system; they capture and reuse exhaled heat and moisture.

Heating Systems

Heat improves water output in bubble and passover humidifiers.
Primarily used in patients with bypassed airways or those on mechanical ventilation.
Heating inhaled gas can pose risks such as airway burns.

Reservoir and Feed Systems

Heated humidifiers can evaporate over 1 L of water per day.
Gravity feed systems and large water reservoirs are used to refilling devices.
Manual Systems: Large reservoirs filled manually.

Setting Humidification Levels

Problem Solving & Troubleshooting (Humidity Systems)

Condensation:
- Risks to patients and caregivers.
- Wastes significant water.
- May block gas flow.
- Potential for aspiration.
Cross-contamination:
- Water in the circuit can be a source of bacterial colonization, so minimizing condensation is crucial to reduce infection risk. Wick-or membrane type passover humidifiers prevent bacteria-carrying aerosols.
- Proper gas conditioning:
  - Respiratory therapists regularly track FiO2 and check pressure, volume, and flow.
  - Hygrometer/thermometer systems assess inspired gas humidity.
Bland Aerosol Therapy: Includes liquid particles suspended in gas. Devices include large-volume jet nebulizers and ultrasonic nebulizers. Variety of liquids like sterile saline, hypotonic, isotonic, and hypertonic solution can be used.
Large-Volume Jet Nebulizers: Most common devices, pneumatically powered and connected to flowmeters. Unheated units typically produce 26-35 mg H2O/L, heated ones, 35-55 mg H2O/L, largely because larger water capacity is increased. The variable air-entrainment port allows for air mixing and adjustments of flow rates and FiO2 levels.
Ultrasonic Nebulizers: Use piezoelectric crystals that convert radio waves into vibrations to create aerosols. Particle size inversely correlates with signal frequency. Amplitude directly impacts aerosol volume. Flow and amplitude settings influence aerosol density and total water output.
Airway Appliances: Used with large-bore tubing to limit flow resistance and prevent condensate buildup. Includes aerosol masks, face tents, T-tubes, and tracheostomy masks.
Enclosures (mist tents and hoods): Deliver aerosolized particles to infants and children but can present problems like heat retention and CO2 buildup, issues handled via manufacturer-specific methods.
Sputum Induction: Cost-effective, safe method to diagnose pulmonary conditions (TB, Pneumocystis, pneumonia, lung cancer). Uses high-density hypertonic saline aerosol (3-10%) for effective mucociliary clearance.
Choosing the Correct Therapy: The treatment is selected based on proper patient assessment, including underlying conditions (hypothermia, dry air, thick lung secretions, etc.). The assessment should indicate the need for humidification.

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Description

Test your knowledge on humidity and bland aerosol therapy with this quiz. Covering essential concepts such as airway heat and moisture exchange, and the operation of humidifiers and aerosol systems, this quiz will reinforce your understanding of respiratory care principles. Perfect for students and practitioners in the field of respiratory therapy.