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Mechanical Ventilation Basics: A Complete Overview

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What is Mechanical Ventilation? What is a Ventilator? How does it work? What is the definition of Mechanical Ventilation? If you’re looking to find the answers to any of these questions, you’re in the right place.

We should have titled this article Mechanical Ventilation Made Easy because our goal is to break it down for you in a way that’s simple to learn and understand. This guide covers all the basics of Mechanical Ventilation and provides answers to all of the most common questions.

Originally, it was designed as a study guide specifically for Respiratory Therapy Students. However, we recently updated the information in a way that’s digestible for the average person. So if you found us through a Google search, this article was written for you as well. 

Mechanical Ventilation is one of the most important topics in all of medical education — especially for Respiratory Therapists and physicians.

With that being said, it’s one of the most difficult subjects to learn because of the complexity of the information. Not to worry, in this guide, we’re going to break it down for you in a way that’s much easier to understand.

So if you’re ready, let’s go ahead and dive right in.

Mechanical Ventilation

What is Mechanical Ventilation?

Mechanical Ventilation is a form of therapy that is used on patients who are unable to breathe on their own. A certain level of ventilation is required in order to maintain the proper levels of oxygen and carbon dioxide in the body. This process is referred to as Gas Exchange.

A Mechanical Ventilator is a device that is used to provide positive pressure ventilation in order to help normalize a patient’s arterial blood gas levels to maintain an adequate acid-base balance.

Mechanical Ventilation is a form of life support that is indicated in critically ill patients in the Intensive Care Unit (ICU) for short-term or long-term use. It’s often used to treat patients with cardiopulmonary disorders but is also used on postoperative patients who are recovering from anesthesia and sedation.

The ventilator can provide a full cycle of breathing during both inspiration and expiration so that the patient does not have to do any work while recovering from the underlying condition. In summary — whenever a patient is unable to ventilate or breathe on their own, this is where Mechanical Ventilation comes into play.

What is a Mechanical Ventilator?

As I mentioned, a Mechanical Ventilator is a machine that aids in a patient’s ability to ventilate. That’s where it gets its name. In other words, it helps the patient take in oxygen and remove carbon dioxide from the lungs.

While on a ventilator machine, a hollow tube, known as an endotracheal tube, connects the patient to the machine. The patient stays on the ventilator until he or she is able to achieve spontaneous breathing on their own.

It’s important to keep in mind that the use of this machine does not completely heal the condition of the patient. Rather, it helps the patient achieve stabilization while medications and other treatment modalities are used to promote healing of the underlying condition.

What are the Benefits of Mechanical Ventilation?

There are many benefits for patients who are receiving Mechanical Ventilation. These include the following:

  • It helps decrease the patient’s work of breathing which helps the respiratory muscles rest and recover. 
  • It helps the patient get adequate amounts of oxygen.
  • It provides stability and allows medications to work while the patient heals.
  • It helps the patient achieve adequate ventilation by removing carbon dioxide for effective gas exchange.

There are many benefits of Mechanical Ventilation. These are just some of the most common examples. 

What are the Risks and Complications of Mechanical Ventilation?

While Mechanical Ventilation has its benefits, it also comes with associated risks and complications as well. Some of which can actually endanger a patient’s life. The following are the most common complications of Mechanical Ventilation:

  • Barotrauma – This is a condition in which the alveoli of the lungs rupture due to overinflation from increased pressure levels. As a result, the lungs collapse which leads to very serious lung conditions that can affect breathing.
  • Volutrauma – This condition occurs when the alveoli become filled with fluid due to high tidal volumes. Tidal volume refers to the amount of air that is transported into the lungs during inhalation. Volutrauma commonly occurs in patients with Acute Respiratory Distress Syndrome (ARDS) and those who had a blood transfusion.
  • Ventilator-Associated Pneumonia (VAP) – This condition is a lung infection that develops 48 hours or more after a patient has been intubated and placed on the ventilator. Because Mechanical Ventilation involves the insertion of tubes into the airway, this increases the chances of various microorganisms entering the lungs.
  • Auto-PEEP – Auto-PEEP, or Intrinsic PEEP, is characterized by over-inflation of the lungs due to large tidal volumes, restrictive airways, or a prolonged inhalation time. If left untreated, this condition can progress to barotrauma and collapsed lungs.
  • Oxygen Toxicity – This occurs when a patient receives too much oxygen for too long of a period of time. In general, patients who receive an FiO2 > 60% for extended periods of time are at risk of oxygen toxicity.

There are other complications of Mechanical Ventilation as well. These are just some of the most common examples.

What are the Types of Mechanical Ventilation?

In general, when someone mentions Mechanical Ventilation, they are usually referring to conventional positive pressure ventilation. Here are examples of all types of Mechanical Ventilation:

  • Positive pressure ventilation
  • Negative pressure ventilation
  • Invasive mechanical ventilation
  • Noninvasive mechanical ventilation

We go into more detail about each of the types of Mechanical Ventilation throughout this article, so keep reading if you want to learn more.

Indications for Mechanical Ventilation

In general, Mechanical Ventilation is indicated whenever a patient’s spontaneous breathing is not adequate enough to sustain life. The following are examples of conditions in which ventilatory support is needed:

  1. Insufficient Oxygenation – Inadequate oxygenation, which is known as hypoxemia, can impact the functionality of tissues and vital organs in the body if left untreated. Mechanical Ventilation helps treat hypoxemia by providing a sufficient amount of oxygen into the lungs so that it can be distributed throughout the body.
  2. Insufficient Ventilation – Healthy lungs work to remove carbon dioxide from the body. Mechanical ventilatory support is indicated if the patient has inadequate ventilation by the lungs. It’s common in conditions with apnea, chronic respiratory acidosis, such as COPD, and neuromuscular disorders.
  3. Acute Lung Injury – An acute injury to the lungs that occurs from an event such as sepsis, pneumonia, aspiration, or trauma.
  4. Severe Asthma – Mechanical Ventilation may be indicated in patients who are experiencing a severe asthma attack that requires intubation.
  5. Severe Hypotension – Mechanical Ventilation may be indicated in severe episodes of low blood pressure, such as with shock, sepsis, and Congestive Heart Failure (CHF).
  6. Inability to Protect the Airway – An unconscious patient with breathing difficulties may be at an increased risk for aspiration. Aspiration occurs when the patient accidentally inhales nasal and oral secretions directly into the lungs. Establishing a patent airway and maintaining spontaneous breathing via Mechanical Ventilation can help prevent this from occurring.

There are other indications for Mechanical Ventilation as well. These are just some of the most common examples.

Contraindications for Mechanical Ventilation

A patient cannot survive unless they are receiving adequate ventilation and oxygenation. This means that there are no absolute contraindications for Mechanical Ventilation.

If a patient is in need of full ventilatory support, they are likely to need Mechanical Ventilation. There really is no way around it.

The only contraindication for Mechanical Ventilation is if the patient legally and specifically states that they do not wish to be intubated or receive life support. This is referred to as a DNI order, or Do Not Intubate. In such a case, the patient may receive Bilevel Positive Airway Pressure (BiPAP) instead as a form of Noninvasive Ventilation.

Which Medical Professionals are Trained to Operate a Mechanical Ventilator?

In general, the two types of healthcare workers who are trained to operate a ventilator are Doctors and Respiratory Therapists.

A Registered Nurse (RN) is not licensed or trained to operate a ventilator. With that said, nurses do receive basic education of the fundamentals of Mechanical Ventilation. But if a problem were to arise with a ventilator, they must call the Doctor or Respiratory Therapist for help.

Modes of Mechanical Ventilation

A ventilator mode is a way of describing how the machine assists the patient with inspiration. The characteristics of a particular mode essentially control how the ventilator functions.

Common Ventilator Modes:

  • Assist/Control (A/C)
  • Synchronous Intermittent Mandatory Ventilation (SIMV)
  • Pressure Support Ventilation (PSV)
  • Continuous Positive Airway Pressure (CPAP)
  • Volume Support (VS)
  • Control Mode Ventilation (CMV)
  • Airway Pressure Release Ventilation (APRV)
  • Mandatory Minute Ventilation (MMV)
  • Inverse Ratio Ventilation (IRV)
  • High-Frequency Oscillatory Ventilation (HFOV)

The two primary control variables are Volume Control and Pressure Control. In Volume Control, the operator has the ability to set (and control) the patient’s tidal volume.

In Pressure Control, the opposite is true. In this type of mode, the operator can set (and control) the pressure level in order to achieve a desired tidal volume.

The two primary and most common ventilator modes are Assist/Control (A/C) and Synchronous Intermittent Mandatory Ventilation (SIMV). When making a selection, you must first determine if the patient needs full ventilatory support or only partial support.

Assist/Control can be provided if the patient needs full ventilatory support. On the other hand, if the patient only needs partial support, SIMV would be recommended.

Be sure to watch the video that is attached to dive deeper into this topic. We also have a full guide on Ventilator Modes that goes into much more detail as well.

Mechanical Ventilation Settings

The settings of a mechanical ventilator are the controls that can be set or adjusted in order to determine the amount of support that is delivered to the patient.

Support can be provided in the form of ventilation and oxygenation. You must develop an understanding of how each setting can be adjusted in order to provide more or less of each type of support for the patient.

Examples of the Basic Ventilator Settings:

  • Mode
  • Tidal Volume
  • Frequency (Rate)
  • FiO2
  • Flow Rate
  • I:E Ratio
  • Sensitivity
  • PEEP
  • Alarms

We have a full guide that dives deeper into all of the basic Ventilator Settings, so definitely check that out if you want to learn more. 

What is Flow in Mechanical Ventilation?

The flow setting in Mechanical Ventilation is also known as the Inspiratory Flow Rate. It’s the rate that controls how fast a tidal volume is delivered by the machine. It’s a setting on the ventilator that can be adjusted depending on the patient’s inspiratory needs and demands.

The normal inspiratory flow rate should be set at around 60 L/min. With that said, most ventilators can deliver up to 120 L/min if a patient needs a prolonged expiratory time which is necessary when an obstructive disease is present.

If the flow rate is set too low, it could result in patient-ventilator dyssynchrony and an increased work of breathing. If the flow rate is set too high, it could result in decreased mean airway pressures.

Ventilator Alarms and What They Mean

A Ventilator Alarm is a safety mechanism on the machine that uses set parameters to provide alerts whenever there is a potential problem related to the patient-ventilator interaction.

The alarms can be visual, audible, or both, depending on the ventilator setting and the patient’s condition.

Common Ventilator Alarms:

  • High Pressure
  • Low Pressure
  • High Volume
  • Low Volume
  • High Frequency
  • Apnea
  • High PEEP
  • Low PEEP

There are Input Power Alarms that refer to the loss of the electrical and/or pneumatic source that powers the machine. There are also Output Alarms that refer to the pressure, volume, flow, and time. These are typically what’s common when referring to Ventilator Alarms.

Drugs for Mechanical Ventilation

When a patient is receiving Mechanical Ventilation, there are certain drugs and medications that may be required in order to provide comfort and facilitate ventilation and airway management.

The two primary reasons that medications are given: Sedation and to provide patient comfort while on the machine.

Types of Medications for Mechanical Ventilation:

  • Sedatives – they affect the brain in a way that helps the patient relax which reduces stress, anxiety, and agitation.
  • Analgesics – they provide relief from pain.
  • Paralytics – they are used to assist with intubation and surgery and to relieve laryngeal spasm.

Some patients may be able to tolerate Mechanical Ventilation without drug therapy. However, medications are often required in order to minimize stress and anxiety.

Be sure to read our full guide on Mechanical Ventilation Drugs if you want to learn more about each of these medications and their uses.

What Artificial Airway Types are Used for Mechanical Ventilation?

An Artificial Airway is important because it establishes a connection between the patient and the ventilator. Without a patent airway, it will be impossible for the patient to receive the positive pressure that is delivered by the machine.

There are two primary artificial airway types that are used in Mechanical Ventilation.

Primary Artificial Airway Types for Mechanical Ventilation:

  1. Endotracheal Tube (ET Tube) – an artificial airway that is inserted into the trachea through the mouth or nose as a means to establish a connection for mechanical ventilatory support. It is the most common airway type that is used for short-term Mechanical Ventilation (2 weeks or less).
  2. Tracheostomy Tube (Trach) – an artificial airway that is placed directly into the trachea through a surgical opening in the throat. It’s used for long-term Mechanical Ventilation (Longer than 2 weeks).

In the medical field, whenever someone mentions an artificial airway, they are usually referring to one of these two types.

However, there are some other types of special airways worth mentioning that are also used in Mechanical Ventilation.

Special Airways for Mechanical Ventilation:

  • Oropharyngeal airway
  • Nasopharyngeal airway
  • Laryngeal Mask Airway (LMA)
  • King Laryngeal Tube
  • Esophageal Obturator Airway
  • Esophageal Gastric Tube Airway
  • Esophageal-Tracheal Combitube
  • Double-Lumen Endobronchial Tube

If you want to learn more and dive deeper into this topic, be sure to check out our full guide on Airway Management.

Common Methods for Airway Insertion

In order to perform successful and effective Mechanical Ventilation, a patent airway must be established with an artificial airway. The following methods can be used:

  • Endotracheal intubation
  • Nasotracheal intubation
  • Tracheostomy
  • Cricothyrotomy

Again, be sure to check out our full guide on Airway Management to learn more.

Ventilator Graphics and Waveform Analysis

Ventilator Graphics refer to the waveforms that are displayed on the screen of a Mechanical Ventilator that provide real-time data and measurements of a patient’s interaction with the machine.

If a physician or Respiratory Therapist is skilled at reading and understanding ventilator graphics, they can easily make the proper adjustment in order to provide the best care possible for the patient.

Examples of Ventilator Graphics and Waveforms

  • Flow-volume loop
  • Pressure-volume loop
  • Constant flow waveform
  • Descending ramp flow waveform
  • Volume-controlled ventilation waveform
  • Pressure-controlled ventilation waveform

If you want to learn more about this topic, be sure to check out our full guide on Ventilator Graphics and Waveforms.

What is Noninvasive Mechanical Ventilation?

Noninvasive ventilation (NIV) involves the administration of ventilatory support without using any type of invasive artificial airway. Instead, NIV uses a mask that tightly seals to the face in order to provide ventilatory support.

Indications for Noninvasive Ventilation:

  • Acute respiratory failure
  • Congestive Heart Failure (CHF)
  • Pulmonary Edema
  • Severe Dyspnea
  • A Do Not Resuscitate (DNI) order is in effect

Noninvasive ventilation is often used in order to avoid the complications that are associated with invasive Mechanical Ventilation.

What is Bilevel Mechanical Ventilation?

Bilevel Positive Airway Pressure (BiPAP) is a form of noninvasive ventilation that distributes two levels of pressure in order to provide ventilatory support for the patient. It’s one of the two forms of noninvasive ventilation, CPAP being the other.

Be sure to check out our full guide on Noninvasive Ventilation if you want to learn more about BiPAP and CPAP. 

What is Ventilator-Associated Pneumonia?

Ventilator-Associated Pneumonia (VAP) is a lung infection that develops 48 hours or more after a patient has been intubated and placed on the ventilator.

The main causes of VAP are the formation of microorganisms within the ET tube and aspiration of mucus or secretions. Because the ET tube is considered as a foreign body, it interferes with the normal protective upper airway reflexes, specifically coughing. This, in turn, results in rapid colonization of aerobic gram-negative bacteria.

Once the secretions are contaminated, they slowly gain access to the lower airway through a fold in the wall of the cuff, resulting in infection. Therefore, the longer the duration of mechanical ventilation, the greater the risk of developing VAP.

If you want to learn more, be sure to check out our full guide on Ventilator-Associated Pneumonia for all the causes and prevention strategies that are used.

What is Neonatal Mechanical Ventilation?

Neonatal Mechanical Ventilation refers to the act of providing ventilatory support for a baby or newborn infant. Many of the concepts are similar to providing Mechanical Ventilation in adults but there are some key differences when it comes to technique, equipment, and ventilator settings.

If you want to learn more and dive deeper into Neonatal Mechanical Ventilation, be sure to read through our full guide on this topic.

How Long is a Patient Connected to a Ventilator?

The answer to this question depends on the condition of each individual patient. As I mentioned earlier, the primary use of a Mechanical Ventilator is to keep the patient stable long enough to heal.

In general, as soon as a patient is able to breathe on their own, they should undergo spontaneous breathing trials (SBTs) for weaning and extubation.

Weaning from Mechanical Ventilation

Weaning is the process of withdrawing a patient from the ventilator once they are able to breathe spontaneously on their own. Extubation refers to the removal of the endotracheal tube.

This process can occur abruptly or it may need to occur gradually over multiple days. In general, the longer a patient has been on the ventilator, the longer the weaning process will take.

What is a Spontaneous Breathing Trial?

A Spontaneous Breathing Trial (SBT) is a technique used on patients who are receiving mechanical ventilatory support in order to test their readiness for weaning. After an SBT has been performed and a patient meets certain criteria, this means that they passed the trial and can be extubated and removed from the ventilator.

If the weaning criteria were not met during the trial, the patient must be placed back on full ventilatory support. Only one Spontaneous Breathing Trial should be performed every 24 hours in order to give the patient adequate time to rest.

If you want to learn more about extubation and Weaning from Mechanical Ventilation, be sure to check out our full guide on the topic. 

Final Thoughts

So there you have it. That wraps up our ultimate guide on Mechanical Ventilation and I hope that you now have a better understanding of this topic. Again, this is definitely one of the most difficult subjects for Respiratory Therapy students to learn. But, in my opinion, it’s also the most important.

Because, depending on where you work, RT’s must provide care for patients who are on a ventilator on a daily basis. So if you fail to develop an understanding of the concepts of Mechanical Ventilation, how are you supposed to adequately take care of your patients?

Again, hopefully this guide along with the other resources on our website can help make the learning process easier for you. Thank you so much for reading and as always, breathe easy my friend. 

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