This is important in determining the volume, rate, and speed of ventilation, as well as the amount of oxygen that is delivered.
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.
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What are Ventilator Settings?
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.
Ventilatory support can be provided in the form of ventilation and oxygenation. Therefore, the ventilator settings will affect both the patient’s breathing and the amount of oxygen that is delivered to the lungs.
Types of Ventilator Settings
There are several types of ventilator settings that a practitioner must be familiar with, including the following:
- Tidal Volume
- Frequency (Rate)
- Flow Rate
- I:E Ratio
Each parameter can be controlled or adjusted depending on the patient’s condition and needs. This is a job duty that should only be performed by qualified physicians and respiratory therapists.
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.
There are several types of ventilator modes, including the following:
- 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)
There are pros, cons, indications, and contraindications of each ventilator mode. As a respiratory therapist, it’s a requirement to learn and develop an understanding of each mode.
When selecting a ventilator mode, you must first determine if the patient needs full or partial ventilatory support.
In general, the assist/control (A/C) mode can be used if the patient needs full ventilatory support. If they only need partial support, synchronous intermittent mandatory ventilation (SIMV) would be recommended.
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 fraction of inspired oxygen (FiO2) is the concentration of oxygen that is being inhaled by the patient.
For example, a patient with severe hypoxemia may require an FiO2 of 100% when mechanical ventilation is initiated. In this case, your goal should be to wean the FiO2 percentage down to the lowest possible level that still provides adequate oxygenation for the patient.
That is because, if a patient receives an FiO2 greater than 60% for a prolonged period of time, it increases their risk of oxygen toxicity.
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. However, 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 a decreased mean airway pressure.
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 receiving mechanical ventilation, a normal I:E ratio is set between 1:2 and 1:4. However, 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.
The sensitivity control on a ventilator is what determines how much effort (negative pressure) the patient must generate in order to trigger a breath to be delivered.
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 provided 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.
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.
There are several types of ventilator alarms, including the following:
- High Pressure
- Low Pressure
- Low Expired Volume
- High Frequency
- High PEEP
- Low PEEP
If you want to learn more about ventilator alarms, check out our full guide that goes into much more detail about each type.
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 ventilator settings.
Note: There are several popular types of mechanical ventilators that operate with slight differences regarding their modes and settings. Therefore, be sure to abide by the guidelines provided by the manufacturer of each machine.
Any operational mode will work when setting up the initial ventilator settings. Therefore, it’s important not to get too caught up in deciding on the correct mode.
However, you generally can use assist/control (A/C) if the patient needs full support or synchronous intermittent mandatory ventilation (SIMV) if they only need partial support.
The initial tidal volume setting should be set within a range of 5-10 mL/kg of the patient’s ideal body weight (IBW). Therefore, in order to calculate the initial tidal volume setting, you must know how to calculate the patient’s ideal body weight according to their height.
In general, ideal body weight can be calculated using the following formula:
IBW = 50 kg + (2 x Number of Inches over 5 feet)
For example, a patient who is 5’10” has an ideal body weight of 70 kg. Therefore, their initial tidal volume should be set within a range 350-700 mL.
The initial frequency setting should be set within a range of 10-20 breaths/min. A respiratory rate within this range helps the patient maintain acceptable ventilatory parameters.
The initial FiO2 setting should be set within a range of 30-60% unless the patient was previously receiving a higher percentage of oxygen before intubation.
In this case, you would use the FiO2 that they are already receiving.
In general, you can 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 refractory hypoxemia or severe oxygenation issues.
The initial flow setting should be set within a range of 40-60 L/min. This setting can be adjusted depending on the inspiratory demands of the patient.
The initial I:E ratio setting should be set within a range of 1:2-1:4. However, there is not a direct setting for the I:E ratio on most ventilators.
Therefore, if you need to adjust a patient’s I:E ratio, you can do so by making changes to the flow rate, inspiratory time, expiratory time, tidal volume, and frequency.
The initial sensitivity setting should be set within a range of -1 and -2 cmH2O. This setting can be adjusted depending on how much help a patient needs to trigger a breath from the ventilator.
The initial PEEP setting should be set within a range of 4-6 cmH2O. A patient with oxygenation issues may require higher levels of PEEP.
Therefore, this setting can be adjusted depending on the needs of the patient.
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 (RN), however, do receive some limited training on how to interpret some of the basic ventilator settings.
However, 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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Ventilator Settings Practice Questions:
1. What is the definition of ventilator settings?
Ventilator settings refer to 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.
2. In a patient with chest trauma, what should the flow setting be, and what would you do to minimize the chance of barotrauma?
The flow should be set above 60 L/min, and this patient needs lower tidal volumes and a higher respiratory rate in order to minimize the chances of barotrauma.
3. What ventilator setting makes it easier for a patient to initiate a breath?
4. What flow pattern is used in the pressure-controlled mode, and what type of patients typically like this pattern?
The descending flow pattern is typically used, and COPD patients usually tolerate this pattern well.
5. What should be adjusted in a patient that has a set tidal volume of 600 mL but is actually receiving 850 mL?
In this case, you would need to decrease the pressure setting because the patient’s actual tidal volume is 250 mL above the desired tidal volume.
6. What are the normal ventilator settings for a postoperative adult patient?
Mode: SIMV; Tidal volume: 5-10 mL/kg; Rate: 10-12 beats/min; Inspiratory time: 1 second; Flow: 40-60 L/min; PEEP: 5; FiO2: start at 100% and titrate to keep their saturation > 90%
7. What ventilator mode is appropriate for a patient with a closed head injury?
8. What ventilator mode is appropriate for a new patient who was admitted for COPD?
9. What is the normal range for trigger sensitivity?
The normal range is -1 to -2 cmH2O.
10. What type of ventilation would we use for normal lungs when other systems are shutting down?
11. When would you not want to use volume ventilation in a patient with a CHF exacerbation?
You would not want to use volume ventilation if the patient’s PIP is high. Also, you would want to consider using NIV first unless it is contraindicated.
12. Which ventilator alarm would likely sound if there is a leak in the circuit?
13. What is trigger sensitivity?
It is the setting that determines how easy it if for the patient to initiate a breath.
14. What is the normal high minute ventilation alarm?
It should be set 10 L/min above the patient’s resting minute ventilation.
15. Which type of ventilator mode is best for a patient with ARDS?
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16. Which ventilator mode is best for a patient with a closed head injury but no lung injuries?
17. What type of flow pattern occurs when using a volume-controlled mode?
18. What inspiratory time would you use for a patient with a CHF exacerbation?
You would want to use an inspiratory time of 1 to 1.5 seconds.
19. A patient was found unconscious, but you do not have any other information about the patient. What initial ventilator settings would you select?
Mode: volume-controlled; Tidal volume: 5-10 mL/kg; Respiratory rate: 10-20 breaths/min, Inspiratory time: 1 second; PEEP: 5 cmH2O; and FiO2: 100%
20. What are the causes of a high-pressure ventilator alarm?
Coughing, kinking in the circuit or tube, secretions, decreased compliance, increased Raw, and mucous plugging
21. What is the normal flow setting for a postoperative hip surgery patient?
22. An adult male patient presents to the ER after a motor vehicle accident. He has an increased ICP and needs to be placed on the ventilator. Which mode would you select?
23. What is the purpose of permissive hypercapnia?
It is used to decrease the PIP, which decreases the risk of barotrauma.
24. What is the term for when a COPD patient needs to be mechanically ventilated while they also have acute respiratory failure?
Acute-on-chronic respiratory failure
25. What mode is best for a patient with chest trauma from a motor vehicle accident?
26. What is the recommended initial ventilator setting for FiO2?
The initial setting for FiO2 should be set within a range of 30-60% unless the patient was previously receiving a higher percentage before intubation. In this case, you would use the FiO2 they were already receiving.
27. Which ventilator alarm cannot be silenced?
The low-source gas alarm
28. What is permissive hypercapnia?
It refers to the process of allowing the PaCO2 to rise slightly by providing small tidal volumes at a faster respiratory rate. This decreases the risk of barotrauma.
29. Which alarm cannot be silenced?
The high-pressure alarm.
30. A child arrives in ER with an acute asthma attack and needs to be mechanically ventilated. Which type of ventilation would you recommend?
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31. If a patient is in a volume-controlled mode and the high-pressure alarm is sounding, what is most likely the problem?
The patient’s lung compliance has decreased, which is causing an increase in PIP.
32. Why do we allow larger tidal volumes in patients with neuromuscular diseases?
Because it allows the patient to meet their “air hunger” needs
33. What types of patients can benefit from permissive hypercapnia?
Patients with ARDS
34. If the flow setting is increased on a mechanical ventilator, what setting may also need to be adjusted?
You may need to change the trigger from flow to pressure.
35. What are the two methods for the trigger setting?
Flow and pressure
36. Which flow patterns are the most common on a ventilator?
Square, which is often seen in volume-controlled modes; and Descending, which is often seen in pressure-controlled modes
37. Which type of ventilation should be used on a patient with an acute lung injury?
38. What type of ventilation would you recommend for an adult patient with ARDS?
39. What happens to a mechanically delivered breath if the high-pressure alarm is reached?
The alarm will sound, and the breath will be terminated.
40. Which alarm settings can be triggered by a leak?
The low pressure, low tidal volume, and low minute ventilation alarms
41. If a patient has a tidal volume of 4-8 mL/kg and a respiratory rate of 15-25 breaths/min, what disease process is likely?
They patient likely has ARDS because a smaller tidal volume and faster respiratory rate will decrease the risk of barotrauma and minimize the patient’s PIP.
42. What are the various factors used to trigger ventilator breaths?
Pressure, flow, time, and manual
43. What is the mean airway pressure?
The pressure maintained in the airways throughout an entire respiratory cycle
44. Which blood gas value is the primary indicator of adequate ventilation?
45. What are the various ways you can adjust the I:E ratio on a volume-cycled ventilator?
By adjusting the flow, inspiratory time, tidal volume, or respiratory rate
46. What FiO2 limit is considered dangerous and can lead to oxygen toxicity?
An FiO2 greater than 60%
47. What settings on a ventilator are used to adjust the PaO2?
FiO2 and PEEP
48. How does PEEP increase blood oxygenation?
It increases alveoli recruitment by allowing positive pressure at the end of expiration before inhalation, which restores the functional residual capacity.
49. How can the inspiratory time improve blood oxygenation?
It allows for a longer inhalation time, which provides a longer contact time for diffusion to take place.
50. What is the appropriate action for any ventilator problem that is not immediately identified and corrected?
Remove the patient from the ventilator and begin manual ventilation with a bag-valve-mask.
51. What ventilator changes could be made to correct respiratory acidosis?
You can increase the tidal volume or respiratory rate in order to blow off more CO2. In this case, you should adjust the tidal volume first, but if the tidal volume is already in the ideal range, then you can adjust the respiratory rate.
52. What ventilator changes can be made to correct respiratory alkalosis?
Decrease the tidal volume or respiratory rate
53. What ventilator changes can be made to correct a high PaO2?
Decrease the FiO2 or PEEP
54. What is the goal for PaCO2 and pH in a COPD patient with chronic hypercapnia who is receiving mechanical ventilation?
The goal is to get them to their baseline because their PaCO2 and pH are usually always acidic.
55. What is the normal tidal volume range?
The normal range is 5-10 mL/kg of the patient’s ideal body weight.
56. What is the most common setting for the initiation of apnea ventilation?
57. What techniques can be used to monitor the possible cardiac effects of positive pressure ventilation?
Arterial-line, continuous blood pressure monitor, and Swan-Ganz catheter
58. What is an advantage of pressure-controlled ventilation over volume-controlled ventilation?
It has a lower risk of barotrauma.
59. What is a pressure trigger?
It occurs when the patient generates an inspiratory effort that drops the pressure in the system, which triggers the machine into inspiration.
60. What is a time trigger?
It occurs when the machine begins inspiration at a predetermined time.
61. What is a flow trigger?
It occurs when the patient generates an inspiratory effort that changes the flow in the system, which triggers the machine into inspiration.
62. What is an advantage of a flow vs pressure trigger?
Flow is more sensitive to the patient’s effort
63. What is a pressure limit?
It sets a maximum inspiratory pressure that can be delivered to the patient in order to stop inspiration and begin expiration.
64. What is a pressure-limiting relief valve?
It is essentially a high-pressure alarm. It releases any pressure in the system by venting any volume that is remaining. In other words, it allows the volume to escape.
65. How does PEEP work?
It works by increasing the functional residual capacity. On expiration, pressure is held at an elevated baseline above the atmospheric pressure.
66. What is CPAP in mechanical ventilation?
When used on the ventilator, CPAP is essentially the same thing as PEEP. In this mode, the patient must be breathing spontaneously.
67. How does PEEP contribute to removing CO2?
It doesn’t. PEEP only affects oxygenation, not ventilation.
68. What are patient-triggered modes?
They are modes where the patient determines their own respiratory rate, inspiratory flow rate, and volume of breaths.
69. What basic parameters must be set on a ventilator?
Volume, frequency, mode, and the initial FiO2
70. What does the flow rate setting determine?
It determines how fast a tidal volume is delivered by the ventilator.
What are the Normal Ventilator Settings?
There is no set of normal ventilator settings because every patient is different and will require a unique combination of settings depending on their condition.
However, there are some guidelines and initial ranges that we can use when setting up a new patient on the mechanical ventilator.
What are the Most Common Ventilator Settings?
The most common ventilator settings are tidal volume, frequency, and FiO2. However, the respiratory therapist must also be familiar with the mode, flow rate, I:E ratio, sensitivity, PEEP, and alarm settings.
What are the Most Important Ventilator Settings?
The most important ventilator settings are those that provide the patient with adequate oxygenation and ventilation.
The respiratory therapist must closely monitor the patient’s oxygen saturation and ventilator parameters in order to ensure that the ventilator settings are appropriate.
What Dangers are Involved with Ventilator Settings?
The dangers of ventilator settings arise when the settings are not appropriate for the patient’s condition. This can lead to hypoxia, hyperventilation, and barotrauma.
Therefore, it is important to set appropriate initial ventilator settings and make adjustments as needed.
What Do the Numbers on a Ventilator Machine Mean?
The numbers on a ventilator machine represent the various settings that can be adjusted. For example, the display screen of a ventilator will show values for the tidal volume, respiratory rate, FiO2, flow rate, I:E ratio, sensitivity, and PEEP settings.
If a patient has inadequate values, it could trigger a ventilator alarm to alert healthcare professionals of an underlying problem. Then the settings should be adjusted depending on the patient’s needs.
Understanding each of the different ventilator settings is critical when it comes to delivering adequate support to the patient. The settings must be appropriate for the patient’s condition in order to avoid any potential dangers.
This includes the parameters that can affect their overall ventilation and oxygenation. As a respiratory therapist, you’re in charge of monitoring the patient to ensure that their settings are appropriate.
As their condition changes, it’s your responsibility to make adjustments to the ventilator settings as needed. Thanks for reading!
John Landry, BS, RRT
John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.
- Chang, David. Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
- Rrt, Cairo J. PhD. Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 6th ed., Mosby, 2015.
- Faarc, Kacmarek Robert PhD Rrt, et al. Egan’s Fundamentals of Respiratory Care. 11th ed., Mosby, 2016.
- Md, Hagberg Carin. Benumof and Hagberg’s Airway Management. 3rd ed., Saunders, 2012.