Ventilators: Types and Functions
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Questions and Answers

What triggers the ventilator to supply breathable gases in CPAP spontaneous mode?

  • The ventilator is manually adjusted by the therapist.
  • The pressure drops below the sensitivity level. (correct)
  • The patient exhales forcefully.
  • The patient exceeds the set pressure level.

How does Pressure Support in spontaneous mode primarily differ from CPAP spontaneous mode?

  • It does not allow the patient to breathe independently.
  • It uses a different source of oxygen.
  • It maintains airway pressure above PEEP during inspiration. (correct)
  • It requires the patient to exhale fully before the ventilator responds.

What is assumed regarding the settings of PEEP and sensitivity levels in CPAP mode?

  • They encourage patient effort to breathe independently. (correct)
  • They are frequently adjusted during treatment.
  • They are set at the same level.
  • They remain static for the duration of treatment.

During exhalation in both CPAP and Pressure Support modes, what is the role of the ventilator?

<p>To shut off gas flow and open the exhalation valve. (B)</p> Signup and view all the answers

What is typically stored in high-pressure tanks connected to ventilators?

<p>Compressed air and oxygen. (C)</p> Signup and view all the answers

Which of the following best describes the function of blending and metering devices in ventilators?

<p>They enrich inspiratory airflow with the proper oxygen level. (A)</p> Signup and view all the answers

What component is sometimes used by ventilators in place of compressed air tanks?

<p>Air compressors. (C)</p> Signup and view all the answers

How does the introduction of microprocessors impact the control of metering devices in ventilators?

<p>They facilitate the use of electromechanical valves. (C)</p> Signup and view all the answers

Which parameter is NOT required by the therapist for mandatory breath delivery?

<p>Inspiratory pressure (D)</p> Signup and view all the answers

What does the microprocessor utilize to maintain the desired PEEP level during spontaneous breath delivery?

<p>Airway pressure sensor (B)</p> Signup and view all the answers

In mandatory volume-controlled ventilation, which parameter directly controls the exhalation flow?

<p>PEEP (C)</p> Signup and view all the answers

What happens to the exhalation valve during inhalation?

<p>It is closed to direct all delivered flows to the lungs. (D)</p> Signup and view all the answers

In pressure-controlled ventilation, what is the role of the airway pressure controller?

<p>To compute the flow to track the airway pressure trajectory. (B)</p> Signup and view all the answers

Which factor is NOT considered when computing the desired inspiratory flow trajectory in mandatory mode?

<p>Oxygen saturation (C)</p> Signup and view all the answers

What is the primary goal of the closed loop controller during pressure-controlled ventilation?

<p>To achieve the desired inspiratory pressure trajectory. (A)</p> Signup and view all the answers

Why is it often desirable to keep the patient’s lungs inflated at a pressure greater than atmospheric level at the end of expiration?

<p>To prevent lung collapse and maintain expansion. (A)</p> Signup and view all the answers

What is the primary function of a ventilator?

<p>To artificially ventilate the lungs of patients (C)</p> Signup and view all the answers

How are modern ventilators different from early manually operated ones?

<p>They utilize microprocessors and electrical valves (C)</p> Signup and view all the answers

What defines intensive care ventilators?

<p>They support patients following surgical procedures or acute disorders (C)</p> Signup and view all the answers

What principle do positive-pressure ventilators operate on?

<p>They generate pressures greater than atmospheric pressure (D)</p> Signup and view all the answers

How do negative-pressure ventilators work?

<p>By creating a negative pressure around the thoracic cage (B)</p> Signup and view all the answers

Which of the following components is NOT typically found in modern ventilators?

<p>Mechanical bellows (A)</p> Signup and view all the answers

What level of design sophistication is typically higher in ventilators used in hospitals compared to home care ventilators?

<p>Engineering design and components (C)</p> Signup and view all the answers

What outcome do designers aim for when creating mechanical ventilators?

<p>To ventilate the lungs as closely as possible to natural respiration (A)</p> Signup and view all the answers

What is the primary function of the inspiratory flow delivery system in a positive pressure ventilator?

<p>To create a positive pressure in the tubing (B)</p> Signup and view all the answers

Why have positive pressure ventilators become more popular than negative-pressure ventilators?

<p>They are more efficient at treating a variety of breathing disorders (D)</p> Signup and view all the answers

What characterizes volume-controlled ventilation in mandatory ventilation mode?

<p>It delivers a specified tidal volume to the patient (B)</p> Signup and view all the answers

Which of the following statements about pressure-controlled ventilation is correct?

<p>It raises airway pressure to a predetermined level (C)</p> Signup and view all the answers

Mandatory ventilation completely takes over which aspect of a patient's respiration?

<p>Ventilating the lung (A)</p> Signup and view all the answers

What causes the flow of atmospheric air into the lungs during inspiration?

<p>Pressure gradient between the atmosphere and the lungs (B)</p> Signup and view all the answers

Which patient population can benefit from positive pressure ventilators?

<p>Patients of any age, from neonates to adults (C)</p> Signup and view all the answers

Which phase of respiration is characterized by a sub-atmospheric pressure level?

<p>Inspiration (C)</p> Signup and view all the answers

What happens during the exhalation phase in a positive pressure ventilator?

<p>The exhalation control system opens a valve to the atmosphere (D)</p> Signup and view all the answers

What is a primary drawback of the traditional negative-pressure ventilator design?

<p>It causes a venous blood pool in the abdomen. (C)</p> Signup and view all the answers

What is a key characteristic of spontaneous ventilation modes like CPAP?

<p>It allows for continuous airway pressure during spontaneous breaths (D)</p> Signup and view all the answers

What improvement was made to recent designs of negative-pressure ventilators?

<p>They restricted negative pressure application to the chest walls. (B)</p> Signup and view all the answers

What is a common issue associated with negative-pressure ventilators during patient care?

<p>They interfere with synchronization with the patient's efforts. (A)</p> Signup and view all the answers

How do positive-pressure ventilators generate inspiratory flow?

<p>By applying positive pressure to the airways (B)</p> Signup and view all the answers

What is a disadvantage of the design of negative-pressure ventilators in terms of patient monitoring?

<p>They reduce optimal visibility of the patient. (B)</p> Signup and view all the answers

Why are negative-pressure ventilators considered bulky?

<p>They need to encompass a larger portion of the body. (C)</p> Signup and view all the answers

What factors must a ventilator operating in mandatory mode control?

<p>Tidal volume, respiration rate, inspiratory flow pattern, and oxygen concentration (D)</p> Signup and view all the answers

During controlled mandatory ventilation, what does the tidal volume delivered by the ventilator depend on?

<p>Area under the flow waveform (B)</p> Signup and view all the answers

How does the pressure waveform differ during volume controlled ventilation among patients?

<p>It varies according to patient respiratory mechanics (D)</p> Signup and view all the answers

What is the role of positive end expiratory pressure (PEEP) in ventilation?

<p>To prevent the alveoli from collapsing during expiration (D)</p> Signup and view all the answers

In mandatory pressure-controlled ventilation, how is the airway pressure maintained?

<p>Independently of patient airway compliance and resistance (D)</p> Signup and view all the answers

What happens to the airway pressure at the end of exhalation in volume controlled ventilation?

<p>It may not end at atmospheric pressure (C)</p> Signup and view all the answers

What is the primary characteristic of controlled mandatory ventilation (CMV)?

<p>It allows complete control over the breathing cycle (A)</p> Signup and view all the answers

Which statement is true regarding the inspiratory flow waveform in controlled mandatory ventilation?

<p>A half sinewave is often selected as the waveform shape (A)</p> Signup and view all the answers

Flashcards

Ventilator (respirator)

A medical device that artificially ventilates the lungs of patients who can't breathe naturally.

Intensive care ventilator

Sophisticated ventilators used in hospitals for patients post-surgery or with acute respiratory problems.

Home ventilator

Less complex ventilators used to treat chronic respiratory conditions at home.

Negative-pressure ventilator

An older type of ventilator that uses negative pressure to inflate the lungs.

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Positive-pressure ventilator

Modern ventilators that use positive pressure to inflate the lungs.

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Manually operated ventilator

Early ventilators using bellows to inflate lungs, requiring manual operation.

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Acute respiratory problems

Sudden, severe breathing difficulties.

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Chronic respiratory conditions

Long-term respiratory illnesses.

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Patient Circuit

The system of tubes connecting a positive pressure ventilator to the patient's airway, delivering air and allowing for exhalation.

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Exhalation Control System

A component of a positive pressure ventilator that controls the release of exhaled air from the patient's lungs to the atmosphere.

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Mandatory Ventilation

A ventilator mode where the machine completely controls breathing, delivering breaths at set intervals and volumes.

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Volume-controlled Ventilation

A mandatory ventilation mode where the ventilator delivers a specific volume of air to the lungs with each breath.

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Pressure-controlled Ventilation

A mandatory ventilation mode where the ventilator raises the pressure in the airways to a specific level during each breath.

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Continuous Positive Airway Pressure (CPAP)

A spontaneous ventilation mode where a constant positive pressure is delivered to the airways, helping to keep them open.

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Pressure Support Ventilation

A spontaneous ventilation mode where the machine provides extra pressure to the airways during each inhalation to help the patient breathe.

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Pressure Gradient

The difference in pressure between two areas, such as the atmosphere and the lungs, that causes air to move from high pressure to low pressure.

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Inspiration (Inhalation)

The process of breathing air into the lungs, achieved by creating a lower pressure inside the lungs than in the surrounding atmosphere.

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Expiration (Exhalation)

The process of breathing air out of the lungs, achieved by increasing the pressure inside the lungs to exceed the atmospheric pressure.

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Thoracic Muscles

Muscles surrounding the chest cavity that help with breathing by expanding and contracting.

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Why Negative-Pressure Ventilators are Less Ideal

They are bulky, noisy, difficult to synchronize with the patient's breathing, and can create a blood pool in the abdomen.

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What Makes Positive-Pressure Ventilators More Effective

They are less bulky, easier to synchronize with the patient's breathing, and generate the inspiratory flow by applying positive pressure to the airways.

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Controlled Mandatory Ventilation (CMV)

A ventilator mode where the machine controls all aspects of breathing, including tidal volume, respiration rate, inspiratory flow pattern, and oxygen concentration.

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Tidal Volume

The amount of air inhaled or exhaled in one breath during CMV.

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Respiration Rate

The number of breaths per minute during CMV.

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Inspiratory Flow Pattern

The shape of the flow of air into the lungs during CMV.

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Oxygen Concentration

The percentage of oxygen in the air delivered to the lungs during CMV.

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Positive End Expiratory Pressure (PEEP)

Pressure maintained in the lungs at the end of exhalation during CMV, preventing the alveoli from collapsing.

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Mandatory Pressure-Controlled Ventilation

A ventilator mode where the machine sets and maintains a specific airway pressure during inspiration, regardless of patient lung compliance.

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Airway Pressure

The pressure inside the airway during CMV, set and maintained by the ventilator.

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CPAP (Continuous Positive Airway Pressure)

A spontaneous ventilation mode where a constant positive pressure is delivered to the airways, helping to keep them open.

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How does CPAP work?

When a patient attempts to breathe, the pressure drops below the sensitivity level, and the ventilator responds by providing breathable gases to raise the pressure back to the PEEP level.

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What is the difference between CPAP and Pressure Support?

CPAP delivers constant pressure, while Pressure Support provides extra pressure only during inspiration.

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How is a normal breath delivered in Pressure Support Mode?

When the patient's airway pressure falls below the set sensitivity, the ventilator kicks in to raise the airway pressure to the pressure support level set by the therapist.

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What happens during exhalation in Pressure Support Mode?

The ventilator stops the airflow when the patient starts to exhale, and controls the exhalation valve to maintain the set PEEP level.

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What is the primary role of the blending and metering device in a ventilator?

To enrich the inspiratory airflow with the correct oxygen level and to deliver a tidal volume according to the therapist's specifications.

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Closed Feedback Loop

A system where the output of a process is measured and fed back to control the input, ensuring the desired outcome is maintained.

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Why are electromechanical valves becoming popular in ventilators?

Their use is becoming popular due to the introduction of microprocessors controlling metering devices.

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Spontaneous Ventilation

A ventilator mode where the patient initiates breaths, and the machine assists with pressure or volume support.

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PEEP (Positive End-Expiratory Pressure)

A pressure maintained in the airways at the end of exhalation, preventing lung collapse and improving oxygenation.

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Peak Flow

The maximum flow rate of air delivered during inspiration.

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Airway Pressure Controller

A component of the ventilator that regulates the pressure delivered to the airways during inspiration.

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Inspiratory-Expiratory Ratio

The ratio of the duration of inspiration to the duration of expiration in a breath.

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Study Notes

Ventilators

  • Ventilators, also called respirators, artificially ventilate the lungs of patients unable to breathe naturally.
  • Early ventilators used bellows, manually operated.
  • Modern respirators have sophisticated components, such as microprocessors, valves, and transducers.
  • Two main types of ventilators exist: intensive care, for short-term acute respiratory problems or assistance after surgery, and less complex, used for chronic respiratory problems at home.
  • Negative-pressure ventilators create negative pressure to mimic natural breathing. This was the initial approach.
  • Positive-pressure ventilators use pressure above atmospheric levels to ventilate the lungs. These are more common now.

Introduction

  • They are broadly classified into negative-pressure and positive-pressure types.
  • Positive pressure ventilators are more common and versatile.
  • They are used for acute and chronic respiratory conditions.

Ventilation Modes

  • Ventilation modes depend on patient conditions.
  • Mandatory Ventilation:
    • Controlled mandatory ventilation (CMV): The respirator completely controls the ventilation.
      • Volume-controlled ventilation: Delivers a specific volume in each breath.
      • Pressure-controlled ventilation: Raises airway pressure to a predetermined level during inspiration.
  • Spontaneous Ventilation:
    • Continuous Positive Airway Pressure (CPAP): Maintains positive pressure in the airway. A variation of this mode is used for those who can breathe but require additional support. The sensitivity level should be lower than the PEEP.
    • Pressure Support: The respirator maintains pressure above PEEP during inspiration.

Breathe Delivery Control

  • The valves, for both air and oxygen, are within closed feedback loops.
  • The microprocessor controls these valves.
  • These loops utilize the sensors for the air and oxygen flow level for mandatory breathing to the lungs.
  • During exhalation, the valves are actuated to reach the desired PEEP level.
  • The system is geared for flexibility to control necessary parameters like respiration rate and tidal volume, and others related to the type of mandatory breath.

Mandatory Volume Controlled Inspiratory Flow Delivery

  • The valves open to deliver blended gasses.
  • The therapist controls all parameters for the mandatory breaths. These parameters include the respiratory rate, flow waveform, tidal volume, oxygen concentration, peak flow, and PEEP.
  • The microprocessor calculates the respiratory flow trajectory.

Pressure Controlled Inspiratory Flow Delivery

  • The ventilator controls airway pressure, rather than volume, to ensure uniformity for patients.
  • The controller measures the patient's breath's inspiratory pressure, respiration rate, pressure trajectory, which acts as the reference for the controller to act according to these specifications.

Expiratory Pressure Control in Mandatory Mode

  • When exhalation starts, the flow terminals; pressure is regulated.
  • The controller closes the exhalation valve when pressure reaches a set PEEP level, keeping the lungs inflated.

Spontaneous Breath Delivery Control

  • The controller takes inputs such as PEEP, pressure support level, and sensitivity to compute desired pressure. The control loops then operate valves to deliver the total flow.

Defining Terms

  • Continuous Positive Airway Pressure (CPAP): Maintains constant pressure in the patient's airway, typically near or below PEEP.
  • Mandatory Mode: The respirator controls all breathing parameters.
  • Patient circuit: Connects the patient to the ventilator.
  • Positive End Expiratory Pressure (PEEP): A selected pressure maintained at exhalation.
  • Pressure Controlled Ventilation: Maintains the airway pressure, during inspiration, independent of patient resistance.
  • Pressure support: Type of spontaneous ventilation that the ventilator adds pressure to the airway above PEEP, to support the patient.
  • Spontaneous mode: The patient initiates breaths with support from the respirator.
  • Volume-controlled ventilation: Volume of each breath is preset by the therapist.

Summary

  • This information focuses on mechanical ventilators, which are broadly divided into negative-pressure and positive-pressure types.
  • Positive-pressure ventilators deliver targeted breathing parameters.

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This quiz covers the essential aspects of ventilators, including their types, historical development, and modern applications in healthcare. Learn about the differences between negative-pressure and positive-pressure ventilators and their role in managing respiratory conditions. Test your knowledge on ventilation modes and their significance.

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