Ventilator Settings Explained: Overview of Basic and Initial Settings

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. 

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:

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

Our complete guide on Ventilator Alarms is coming soon. Be sure to join our email list to be notified when it’s available.

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?

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.

If you want to develop a better understanding of how to read ventilator settings, you can use the practice questions below.

Ventilator Settings Practice Questions:

1. What is the definition of ventilator settings?
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. If you have a patient with chest trauma, what would you want the set flow to be above and what would you do to minimize the chances of barotrauma?
The flow should be set above 60 LPM. This patient needs lower 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?
Sensitivity

4. What flow pattern is used in pressure-controlled mode and what type of patients typically like this pattern?
Descending; and COPD patients.

5. If you have a patient with a set tidal volume of 600 mL but they are getting 850 mL, what would you adjust and why?
In this case, you would need to decrease the pressure setting because the normal tidal volume is 250 mL above the set tidal volume.

6. What would be the normal ventilator settings for an adult postoperative patient?
Mode: SIMV, Tidal volume: 5-10 mL/kg, Rate: 10-12 bpm, i-Time: 1 second, Flow: 40-60 LPM, PEEP: 5, FiO2: start at 100% and titrate to keep their saturation > 90%.

7. If you have a patient with a closed head injury, what mode would you choose for this patient?
Volume-controlled ventilation. Don’t use PEEP if a patient has increased intracranial pressure.

8. You have a patient who was admitted for COPD exacerbation. Which ventilator mode would you choose?
Pressure control

9. What is the normal range for trigger sensitivity?
The normal range is -1 to -2 cm H2O.

10. What type of ventilation would we use for normal lungs when other systems are shutting down?
Volume ventilation

11. For a patient with a CHF exacerbation, when would you NOT want to use volume ventilation?
You would not want to use volume ventilation if the PIP is high. Also, you would want to consider using NIV first unless it is contraindicated.

12. If there is a leak in the patient circuit, which alarm would likely sound?
The Low-pressure alarm.

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 would you use for an ARDS patient?
Pressure Controlled Ventilation

16. Which type of ventilator mode would you use for a closed head injury patient if there are no lung injuries?
Volume Controlled Ventilation

17. What type of flow pattern would you see when using a volume-controlled mode?
Square

18. What I-time would you use for a patient with a CHF exacerbation?
You would want to use an I-time of 1 to 1.5 seconds. The reason we want a longer I-time is to use the pressure as a way to decrease the edema associated with their CHF exacerbation.

19. You have a patient who was found unconscious and you do not have any other information about the patient. What would the initial ventilator settings need to be?
Mode: Volume-controlled, Tidal volume: 5-10 mL/kg, Respiratory Rate: 10-20 bpm, I-time: 1 second, PEEP: 5 cmH2O, and FiO2: 100%.

20. Your patient’s high-pressure ventilator alarm is sounding. What are the specific causes of this alarm?
Coughing, kinking in the circuit or ET tube, secretions, decreased compliance, increased Raw, and mucous plugging.

21. What would the normal flow setting be for a postoperative hip surgery patient?
40 – 60 L/min

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 type of mode would you select for this patient?
Volume-controlled ventilation

23. What is the purpose of permissive hypercapnia?
It is used to decrease the PIP and the likelihood 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 should you set for a patient that has chest damage from a motor vehicle accident?
Pressure-controlled mode.

26. What are the levels of alarms during mechanical ventilation?
Level 1: Immediately life-threatening (includes the failure of electrical power, exhalation valve, or timing). There can be excessive or no gas delivery to the patient. The remaining 2 levels are potentially life-threatening and non-life threatening.

27. What alarm cannot be silenced if gas is critical to the ventilator operation?
The low-source gas alarm

28. What is permissive hypercapnia?
The process of allowing the PaCO2 to rise slightly in order to give small tidal volumes and a higher respiratory rate which can decrease the chances 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 select?
Pressure-controlled ventilation

31. If a patient is in a volume-controlled mode and the high-pressure alarm is going off, what is likely the problem?
The patient’s lung compliance has decreased which is causing an increase in PIP.

32. Why do we allow for larger tidal volumes for patients with neuromuscular diseases?
It allows for the patient to meet their “air hunger” needs.

33. What types of patients can benefit from permissive hypercapnia?
ARDS patients. It uses a high respiratory rate and a low tidal volume to prevent a high PIP (barotrauma).

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 of setting a trigger?
Flow and Pressure.

36. Which flow patterns are the most common on a ventilator?
Square – often seen in volume controlled modes. Descending – often seen in pressure controlled modes.

37. Which type of ventilation should be used for a patient with an acute lung injury?
Pressure-controlled ventilation

38. For an adult patient with ARDS who weighs 70 kg, which type of ventilation would you select and what tidal volume would you aim for?
You should select pressure-controlled ventilation and tidal volume should be set at 280-560 mL. Patients with ARDS require a smaller tidal volume than normal.

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 your patient has a tidal volume of 4-8 mL/kg and a respiratory rate of 15-25 bpm, what disease process does this patient likely have?
They likely have ARDS. A smaller tidal volume and higher respiratory rate will decrease the chances of barotrauma and minimize the PIP.

42. What are the various factors used to trigger ventilator breaths?
Pressure and Flow (from the patient), Timed (from the ventilator), or Manual (from the operator)

43. What is the mean airway pressure?
It is the pressure maintained in the airways throughout an entire respiratory cycle.

44. Which blood gas value is the primary indicator of adequate ventilation?
PaCO2

45. What are the various ways you can adjust the I:E ratio on a volume-cycled ventilator?
By adjusting the flow, I-time, tidal volume, or the respiratory rate.

46. What FiO2 limit is considered dangerous in regards to possible oxygen toxicity?
Greater than 60%.

47. What settings on a ventilator are used to increase or decrease the PaO2?
FiO2 and PEEP

48. How does PEEP increase the 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 manually ventilating the patient with a bag-valve mask.

51. What ventilator changes could be made to correct respiratory acidosis?
Increase the tidal volume or respiratory rate in order to blow off more CO2. Adjust the tidal volume first, but if the tidal volume is already in the ideal range, then adjust the respiratory rate.

52. What ventilator changes could be made to correct a respiratory alkalosis?
Decrease the tidal volume or respiratory rate.

53. What changes could be made to correct a high PaO2?
Decrease the FiO2 or PEEP.

54. What is the goal for the PaCO2 and pH when mechanically ventilating a COPD patient with chronic hypercapnia?
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 ideal body weight.

56. What is the most common setting for the initiation of apnea ventilation?
The most common settings is 20 seconds.

57. What techniques can be used to monitor the possible cardiac effects of positive pressure ventilation?
An arterial-line, continuous blood pressure monitor, and a Swan-Ganz catheter.

58. What is an advantage of pressure control ventilation over volume control ventilation?
It helps to prevent barotrauma.

59. What is the pressure trigger?
The patient generates an inspiratory effort that drops the pressure in the system, therefore, triggering the machine into inspiration.

60. What is a time trigger?
The machine begins inspiration as a result of a predetermined time.

61. What is a flow trigger?
The patient generates an inspiratory effort that changes the flow in the system, therefore, triggering 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. Basically, it stops inspiration.

64. What is the pressure-limiting relief valve?
It is basically the 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, the pressure is held at an elevated baseline above the atmospheric pressure.

66. What is CPAP in mechanical ventilation?
When used on a ventilator, CPAP is essentially the same thing as PEEP except that the patient must be taking spontaneous breaths.

67. How does PEEP contribute in 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 respiratory rate, inspiratory flow rate, and volume of breaths.

69. What basic parameters must be set on a ventilator?
Volume, rate, mode, and the initial FiO2.

70. What should be the initial ventilator setting for FiO2?
The initial FiO2 should be 30 – 60% unless the patient was previously receiving an higher percentage of oxygen before intubation. Then you would use that previous FiO2.

Final Thoughts

And if you need more help, be sure to download a copy of the free eBook using the link below. Thank you so much for reading and as always, breathe easy my friend.

Recommended Reading

Mechanical Ventilation Final Exam (Study Guide)

Initiation of Mechanical Ventilation (Practice Questions)

Ventilator Modes Practice Questions for Respiratory Therapy Students

Ventilator Waveforms and Graphics (Practice Questions)

Weaning from Mechanical Ventilation (Practice Questions)