Ventilator settings are a crucial aspect of mechanical ventilation, a life-saving intervention used in critical care to support patients with respiratory failure.
These settings are meticulously adjusted by healthcare professionals to match the respiratory support to the individual needs of the patient.
Understanding the types of ventilator settings is essential for optimizing patient outcomes and ensuring the safe delivery of ventilatory support.
Mechanical ventilation made easy! Learn the basics in this simplified (free) study guide.
What are Ventilator Settings?
Ventilator settings are controls on a mechanical ventilator determining the support level delivered to a patient. They regulate ventilation and oxygenation, affecting breathing and oxygen delivery. Proper adjustment by trained professionals ensures tailored respiratory support based on the patient’s specific needs and conditions.
Types of Ventilator Settings
Ventilator settings include various parameters that healthcare professionals can adjust to meet a patient’s respiratory needs.
The primary types include:
- Tidal Volume
- Frequency (Rate)
- Flow Rate
- I:E Ratio
Note: Ventilator management is complex and requires careful monitoring and adjustments by trained healthcare professionals, such as respiratory therapists and critical care physicians. This is essential to ensure that a patient’s ventilatory needs are met while minimizing potential complications.
Watch this video or keep reading to learn more about the different types of ventilator settings.
Ventilator modes are settings that dictate how the machine assists with the patient’s breathing. Different modes provide different levels of support and control based on the patient’s respiratory condition and ability to breathe independently.
Common types include:
- Assist/control (A/C)
- Synchronous intermittent mandatory ventilation (SIMV)
- Continuous mandatory ventilation (CMV)
- Airway pressure release ventilation (APRV)
- Mandatory minute ventilation (MMV)
- Inverse ratio ventilation (IRV)
- Pressure regulated volume control (PRVC)
- Proportional assist ventilation (PAV)
- Adaptive support ventilation (ASV)
- Adaptive pressure control (APC)
- Volume-assured pressure support (VAPS)
- Neurally adjusted ventilatory assist (NAVA)
- Automatic tube compensation (ATC)
- High-frequency oscillatory ventilation (HFOV)
The two primary ventilator modes are Assist-Control (A/C) and Synchronized Intermittent Mandatory Ventilation (SIMV).
In the Assist-Control (AC) mode, the ventilator delivers a set number of breaths at a set tidal volume or pressure, but the patient can also initiate additional breaths.
In Synchronized Intermittent Mandatory Ventilation (SIMV), the ventilator provides a set number of mandatory breaths but allows spontaneous breathing in between, synchronizing with the patient’s own breathing effort.
Tidal volume refers to the amount of air that the ventilator delivers to the patient with each breath. This setting is calculated based on the patient’s ideal body weight (IBW).
Setting the correct tidal volume is important to provide adequate ventilation without causing overdistension or barotrauma to the lungs.
Therefore, healthcare providers must consider factors such as lung compliance and underlying lung pathology when setting the tidal volume.
The frequency setting determines the number of breaths the ventilator will deliver to the patient per minute. It ensures adequate ventilation and maintains the patient’s target carbon dioxide levels.
In situations where the patient cannot breathe on their own, the set rate ensures that they receive a minimum number of breaths per minute.
In other modes where the patient can initiate breaths, the ventilator still guarantees this minimum rate, providing additional support if the patient’s spontaneous breathing rate falls below the set value.
The fraction of inspired oxygen (FiO2) represents the concentration of oxygen in the air mixture that is delivered to the patient. It is expressed as a percentage, ranging from 21% (the amount of oxygen in room air) up to 100% (pure oxygen).
Adjusting the FiO2 allows healthcare providers to control the amount of oxygen a patient receives. The goal is to maintain sufficient oxygenation while minimizing the risk of oxygen toxicity, especially at higher concentrations over extended periods.
The ideal FiO2 provides adequate oxygen to meet the patient’s needs without causing harm, and it’s often adjusted based on blood oxygenation measurements and the patient’s overall clinical picture.
Flow rate refers to the speed at which the tidal volume is delivered to the patient. This setting influences the patient’s comfort and the effectiveness of ventilation.
A higher flow rate delivers the breath more quickly, which can be important if a patient has a high demand for air or in certain lung conditions where quick delivery is beneficial.
However, a flow rate that’s too high can cause discomfort and may lead to issues like air trapping, especially in patients with obstructive lung diseases.
Conversely, a flow rate that’s too low may not meet the patient’s demand for air, leading to increased work of breathing and potential respiratory distress.
The inspiratory-to-expiratory ratio determines the duration of inhalation compared to exhalation. Normally, the duration of exhalation is longer than inhalation, with a typical I:E ratio around 1:2.
However, in mechanical ventilation, this can be adjusted.
For instance, in conditions like acute respiratory distress syndrome (ARDS), a longer inspiratory time (i.e., an increased I:E ratio) can be beneficial for oxygenation.
In obstructive lung diseases like chronic obstructive pulmonary disease (COPD), longer exhalation times are often needed to prevent air trapping and to allow complete exhalation, requiring a lower I:E ratio.
Sensitivity refers to the responsiveness of the ventilator to the patient’s spontaneous breathing efforts. It determines how much effort the patient must exert to trigger the ventilator to deliver a breath.
This setting is important for ensuring patient comfort and synchrony with the ventilator. If the sensitivity is set too low, the patient may struggle to initiate a breath, leading to increased work of breathing.
On the other hand, if the sensitivity is set too high, the ventilator may deliver breaths even when the patient is not attempting to breathe, which can lead to hyperventilation or patient-ventilator dyssynchrony.
Positive end-expiratory pressure (PEEP) is a setting that maintains a certain amount of pressure in the lungs at the end of expiration.
This positive pressure helps to keep the alveoli open, improving oxygenation and gas exchange by preventing alveolar collapse (i.e., atelectasis).
PEEP is particularly beneficial in treating patients with conditions that cause oxygenation issues or refractory hypoxemia.
However, setting PEEP too high can lead to overdistension of the lungs, increased intrathoracic pressure, and potential impairment of cardiac function, so it must be carefully balanced against the patient’s clinical status.
Ventilator alarms are critical safety features designed to alert healthcare providers to changes in ventilation or the patient’s condition, or to issues with the ventilator itself.
These alarms can be set based on various parameters like high or low pressure, volume, or rate.
For instance, a high-pressure alarm may indicate a blockage or kink in the ventilator tubing, patient coughing, or a change in lung compliance, while a low-pressure alarm might suggest a disconnection or leak in the ventilator circuit.
Alarms for low exhaled volume can indicate a significant leak or that the patient has become disconnected from the ventilator.
Therefore, properly set ventilator alarms are essential for ensuring patient safety. They allow prompt intervention to resolve any issues and ensure the patient is receiving the appropriate ventilatory support.
Initial Ventilator Settings
Setting up initial ventilator settings is a critical task that requires careful consideration of the patient’s specific respiratory needs and underlying condition.
These settings are often based on standard guidelines and then fine-tuned based on patient response and arterial blood gas (ABG) analyses.
The key initial ventilator settings typically include:
- Mode: The choice of mode may depend on the patient’s condition and the goals of ventilation. Common initial modes include Assist/Control (A/C) for full support or Synchronized Intermittent Mandatory Ventilation (SIMV) for partial support.
- Tidal Volume (VT): For adults, an initial tidal volume of 6-8 mL/kg of ideal body weight is recommended.
- Frequency: An initial respiratory rate of 10-20 breaths per minute is typical, but this should be adjusted based on the patient’s acid-base status to maintain appropriate carbon dioxide elimination.
- FiO2: Start with an initial FiO2 within a range of 30-60% or matching the pre-intubation oxygenation level if higher. An FiO2 of 100% oxygen is often used in emergency situations, but the goal is to aim for the lowest FiO2 that maintains a satisfactory arterial oxygen saturation (SpO2) or PaO2.
- Flow Rate: Initial settings typically range from 40 to 60 L/min. The flow rate should be adjusted based on the patient’s comfort and the desired inspiratory time.
- I:E Ratio: The initial I:E ratio is often set between 1:2 and 1:4, but this may be adjusted based on the patient’s disease state and response to ventilation.
- Sensitivity: Set the sensitivity between -1 and -2 cmH2O so the patient can comfortably trigger the ventilator with minimal effort.
- PEEP: Initial PEEP may be set around 5 cmH2O to prevent alveolar collapse at end-expiration. In patients with ARDS or significant oxygenation issues, higher levels of PEEP may be beneficial.
- Alarms: To ensure patient safety, set alarms appropriately for high and low limits for parameters such as tidal volume, respiratory rate, minute ventilation, and pressure.
Remember: These initial settings are just a starting point. Ventilator settings should be continuously assessed and adjusted based on the patient’s clinical status, blood gas results, and overall response to ventilation. Close monitoring is essential to ensure optimal ventilation and to minimize complications.
How to Calculate the Initial Tidal Volume Setting
The initial tidal volume setting for mechanical ventilation is typically set based on the patient’s ideal body weight (IBW) to minimize the risk of lung injury. The recommended range is usually 6-8 mL/kg of IBW.
Accurately determining the patient’s IBW is crucial for this calculation, and it’s commonly estimated using the following formula:
IBW (kg) = 50 + (2 x Number of Inches over 5 feet)
For example, calculate the IBW for a patient who is 5’10” by filling in the formula.
IBW = 50 + (2 x 10)
IBW = 70 kg
Now, apply the range for the initial tidal volume (6-8 mL/kg of IBW):
- Lower end: 6 mL/kg × 70 kg = 420 mL.
- Upper end: 8 mL/kg × 70 kg = 560 mL
Hence, for this patient, the initial tidal volume should be set between 420 and 560 mL.
Remember: This is an initial estimate, and the actual setting may need to be adjusted based on the patient’s lung mechanics, gas exchange, and overall response to mechanical ventilation. Regular monitoring and adjustments are essential for optimal patient care.
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 a 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: 6-8 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 you use for normal lungs when other systems are shutting down?
11. When would you not want to use volume-controlled ventilation in a patient with a CHF exacerbation?
You would not want to use volume-controlled 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 is for a 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?
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 might indicate that the patient needs suctioning?
The high-pressure alarm.
30. A child arrives in the ER with an acute asthma attack and needs to be mechanically ventilated. Which type of ventilation would you recommend?
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 on a mechanical ventilator is increased, 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?
The 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?
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 to blow off more CO2. In this case, you should adjust the tidal volume first, but if it is already in the ideal range, 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 6-8 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 that 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.
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 in which the patient determines his or her own respiratory rate, inspiratory flow rate, and breath volume.
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.
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FAQs About Ventilator Settings
What are the Normal Ventilator Settings?
Normal ventilator settings for adults typically include a tidal volume of 6-8 mL/kg of predicted body weight, a respiratory rate of 12-20 breaths per minute, FiO2 adjusted to maintain SpO2 of 92-98%, and PEEP set at 5-10 cm H2O.
These settings support natural breathing patterns and are adjusted based on the patient’s specific needs and response.
What are the Most Common Ventilator Settings?
Common ventilator settings involve the mode of ventilation (e.g., Assist-Control or SIMV), tidal volume (6-8 mL/kg), respiratory rate (12-20 breaths/min), FiO2 to achieve optimal oxygenation, and PEEP (5-10 cm H2O) to prevent alveolar collapse.
These foundational settings are tailored to the patient’s condition.
What are the Most Important Ventilator Settings?
The key ventilator settings are tidal volume, FiO2, PEEP, and the ventilation mode.
Tidal volume ensures adequate ventilation, FiO2 is vital for oxygenation, PEEP keeps alveoli open, and the ventilation mode coordinates the machine’s support with patient efforts.
These parameters are crucial for effective and safe respiratory support.
What Dangers are Involved With Ventilator Settings?
The dangers involved with ventilator settings primarily stem from inappropriate adjustments that can lead to ventilator-induced lung injury (VILI), oxygen toxicity, and hemodynamic instability.
Excessive tidal volumes can cause barotrauma or volutrauma, while high levels of FiO2 over prolonged periods can lead to oxygen toxicity, affecting the lungs and other organs.
Incorrectly set PEEP can either lead to alveolar collapse (if too low) or overdistension and impaired venous return (if too high), affecting oxygenation and circulation.
Note: It’s crucial to tailor ventilator settings to the individual’s needs and closely monitor their response to minimize these risks.
What Do the Numbers on a Ventilator Machine Mean?
The numbers on a ventilator machine represent key parameters of respiratory support being provided to the patient.
These typically include tidal volume (the amount of air delivered to the lungs with each breath, in mL), respiratory rate (breaths per minute), FiO2 (the percentage of oxygen in the inspired air), and PEEP (positive end-expiratory pressure in cm H2O).
Other numbers may indicate the patient’s current respiratory rate, the volume of air expired, and various pressures within the ventilator circuit.
Note: Understanding these numbers is essential for managing and adjusting the ventilator to ensure optimal support for the patient’s respiratory needs.
The management of ventilator settings is fundamental in the treatment of patients requiring mechanical ventilation.
Each setting plays a specific role in tailoring the ventilatory support to the patient’s current respiratory status and needs.
Therefore, healthcare professionals must possess a deep understanding of these settings to provide optimal care, minimize potential complications, and navigate the challenges presented in critical care environments.
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.
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- 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.
- Mora Carpio AL, Mora JI. Ventilator Management. [Updated 2023 Mar 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.