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Ventilator Settings Explained

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Ventilator Settings are the inputs on the machine that determine how much support is provided for the patient. If you’re here to learn about the basic and initial ventilator settings explained in a way that’s easy to understand, you’re in the right place. 

Ventilator Settings 

What are Ventilator Settings?

To give a brief definition, ventilator settings are the controls on a mechanical ventilator 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. The good news is, that is exactly what we’re going to cover in this article. 

Examples of the Basic Ventilator Settings:

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

Keep reading if you want to learn more about each of the basic ventilator settings. Below, we’re going to provide a detailed overview of each.

Basic Ventilator Settings Explained:

In this section, we’re going to break down each ventilator setting, one by one. Each setting can be controlled or adjusted depending on the patient’s condition and needs.

Ventilator Mode

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

Common Modes of Mechanical Ventilation include:

  • 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)

When selecting a ventilator mode, you must first determine if the patient needs full or partial ventilatory support. Assist/Control (A/C) can be provided if the patient needs full ventilatory support. If they only need partial support, Synchronous Intermittent Mandatory Ventilation (SIMV) would be recommend.

We have a full guide that covers all the Ventilator Modes in more detail, so be sure to check that out if you want to learn more.

Tidal Volume

Tidal Volume refers to the volume of air that is inhaled and exhaled from the lungs during normal breathing. The tidal volume setting on the ventilator determines how much air is delivered to the lungs by the machine.

Frequency (Respiratory Rate)

The respiratory rate, also referred to as the breathing rate, is simply the rate at which breathing occurs. It typically refers to the number of breaths that are taken per minute and the normal range is 10-20 breaths/minute.

The frequency setting on the ventilator determines how many breaths are delivered to the patient by the machine.

Fraction of Inspired Oxygen (FiO2)

The FiO2, or fraction of inspired oxygen, is the concentration of oxygen that is being inhaled by the patient.

For patient with severe hypoxemia, an FiO2 of 100% may be required when mechanical ventilation is initiated. But your goal should be to wean the FiO2 down to the lowest possible level that provides adequate oxygenation. If a patient receives an FiO2 > 60% for a prolonged period of time, it increases their chances of oxygen toxicity.

Flow Rate

The inspiratory flow rate is a rate that controls how fast a tidal volume is delivered by the ventilator. The setting can be adjusted depending on the patient’s inspiratory 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. This is necessary when obstructive diseases are 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.

Inspiratory-to-Expiratory Ratio (I:E Ratio)

The I:E ratio refers to a ratio of the inspiratory portion compared to the expiratory portion of the breathing cycle.

For patients on the ventilator, the normal I:E ratio is between 1:2 and 1:4. A larger I:E ratio may be delivered if a patient is in need of a longer expiratory time due to the possibility of air trapping.

The I:E ratio can be adjusted by making changes to the flow rate, inspiratory time, expiratory time, tidal volume, and frequency settings. 

Trigger Sensitivity

The sensitivity control is what determines how much effort (negative pressure) the patient must generate in order to trigger a breath from the machine.

The normal sensitivity setting should be set between -1 and -2 cmH2O. If the sensitivity is set too high, it will cause the ventilator to initiate auto-triggering and increase the total frequency of breaths. If it’s set too low, the patient could have a difficult time initiating a breath.

Positive End Expiratory Pressure (PEEP)

PEEP is a positive pressure that is delivered during the expiratory phase of the breathing cycle in order to prevent the closure of alveoli and allow increased time for oxygen exchange to occur.

It’s typically indicated in patients with refractory hypoxemia and those who have not responded well to a high FiO2.

Ventilator Alarms

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

Common Ventilator Alarms Include:

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

If you want to learn more, be sure the check out our full guide on Ventilator Alarms.

Initial Ventilator Settings

Once it has been determined that mechanical ventilation is indicated for a patient who needs help with oxygenation and/or ventilation, then you must know how to properly input the initial settings.

Each mechanical ventilator machine is different, so be sure to abide by the guidelines provided by the manufacturer. However, here are some general guidelines that you can use when determining the initial ventilator settings.

  • Mode – Any operational mode will work when setting up the initial ventilator settings! Don’t get too caught up on deciding on the right mode, especially for the TMC Exam. With that said, just as a reminder, you can select A/C in the patient needs full support or SIMV if they only need partial support.
  • Tidal Volume – The initial tidal volume setting should be 5 – 10 mL/kg of the patient’s ideal body weight (IBW).
  • Frequency – The initial frequency setting should be 10 – 20 breaths/min.
  • FiO2 – The initial FiO2 setting should be 30 – 60% unless the patient was previously receiving an higher percentage of oxygen before intubation. Then you would use that previous FiO2. Strive to provide the lowest concentration of oxygen that’s possible to maintain a normal PaO2. An FiO2 up to 100% as an initial setting is appropriate for patients with severe oxygenation issues.
  • Flow Rate – The initial flow setting should be 40 – 60 L/min.
  • I:E Ratio – The initial I:E ratio setting should be 1:2 – 1:4.
  • Sensitivity – The initial sensitivity setting should be between -1 and -2 cmH2O. 
  • PEEP – The initial PEEP setting should be 4 – 6 cmH2O

How to Read Ventilator Settings?

Being able to read and understand the settings on a ventilator is a highly valuable skill set that is usually only performed by doctors and Respiratory Therapists.

Registered Nurses, however, do receive some limited trained on reviewing the basic ventilator settings. But their license does not allow them to adjust or make changes to the settings. Again, this is something that must be performed by the Respiratory Therapist or physician.

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