Plateau pressure is the amount of pressure needed to keep the lungs inflated in the absence of airflow. It can be measured during mechanical ventilation by applying an inspiratory hold or occluding the exhalation port at end-inspiration for 0.5–2.0 seconds.
This article will provide an overview of plateau pressure, its importance, and how it should be monitored in patients receiving mechanical ventilation.
What is Plateau Pressure?
Plateau pressure is the pressure in the lungs during mechanical ventilation that can be measured by performing an inspiratory pause at the end of inspiration.
It is also known as the peak alveolar pressure and is the best bedside clinical reflection of transpulmonary pressure.
An accurate plateau pressure cannot be measured while a patient is breathing. Therefore, sedation may be required to obtain a plateau pressure measurement if the patient has an active respiratory drive.
That is because it can temporarily suppress the patient’s drive to breathe so that the plateau pressure can be obtained during a pause at end-inspiration.
Why is Plateau Pressure Important?
Plateau pressure is important because it can help to determine the amount of pressure needed to keep the lungs inflated in the absence of airflow.
It serves as an excellent bedside assessment of the ventilation pressure level that could potentially be dangerous to the patient’s lungs. Too much pressure can lead to barotrauma and overdistention.
Limiting the plateau pressure reduces the risk of ventilator-induced lung injuries. Therefore, lower plateau pressures usually result in better patient outcomes.
Plateau Pressure Normal Value
The normal value for plateau pressure is less than or equal to 30 cmH2O. However, the normal range for plateau pressure is 25–30 cmH2O.
If the plateau pressure exceeds 30 cmH2O, it increases the risk of barotrauma and ventilator-induced lung injuries.
What Causes an Increased Plateau Pressure?
Increased plateau pressure can result from conditions that cause lung stiffness and decreased lung compliance. Some examples include pulmonary fibrosis and acute respiratory distress syndrome (ARDS).
Pulmonary fibrosis is a condition characterized by the scarring of lung tissue, which makes it difficult for the lungs to expand.
ARDS is a serious lung condition characterized by fluid in the alveoli. It results in refractory hypoxemia, decreased lung compliance, and severe oxygen insufficiency.
How to Measure Plateau Pressure on the Ventilator
In order to measure plateau pressure, the practitioner who is operating the mechanical ventilator must use the “inspiratory pause” control after a breath has been delivered but before exhalation.
This inspiratory hold should last briefly, usually in the range of 0.5–2.0 seconds. This allows enough time for the measurement to be obtained.
The ventilator uses a manometer to measure the plateau pressure. Then the reading is displayed on the screen where it can be interpreted by respiratory therapists and other medical professionals.
How to Calculate Plateau Pressure
Plateau pressure can be measured by performing an inspiratory hold on a mechanical ventilator. However, it can also be calculated with the following formula:
Plateau pressure = (tidal volume / static compliance) + PEEP
This means that you must know the patient’s exhaled tidal volume, static compliance, and level of PEEP in order to calculate the plateau pressure.
For example, let’s say a patient has the following:
- Tidal volume: 500 mL
- Static compliance: 22 mL/cmH2O
- PEEP: 5 cmH2O
To calculate the plateau pressure, you can plug the numbers in the formula, which would look like this:
Plateau pressure = (500 mL / 22 mL/cmH2O) + 5 cmH2O
= 27.7 cmH2O
As you can see, the formula for calculating plateau pressure is relatively simple. However, it is important to note that the numbers must be accurate in order for the calculation to be accurate.
Peak Pressure vs. Plateau Pressure
Peak inspiratory pressure (PIP) is the highest pressure that occurs in the lungs during the inspiratory phase of breathing. It represents the amount of pressure needed to overcome airway resistance and chest wall compliance in order to deliver a breath.
Plateau pressure (Pplat) is the pressure in the lungs in the absence of airflow. It is measured by performing an inspiratory pause at end-inspiration for 0.5–2.0 seconds.
The peak pressure is reached during inspiration, but then the pressure decreases to the plateau pressure during the inspiratory hold.
Therefore, the plateau pressure should always be lower than the peak pressure during volume-controlled ventilation. That is because airway resistance affects the peak pressure as air flows through the lungs.
However, the plateau pressure can exceed the peak pressure in pressure-regulated ventilator modes if the patient’s inspiratory efforts generate larger tidal volumes and significantly negative pleural pressures.
Conditions that cause an increased airway resistance (e.g., bronchoconstriction) will result in higher peak pressures. Plateau pressure, on the other hand, is not affected by airway resistance since it is measured during a period of no airflow.
Rules of Thumb
- Peak pressure: The pressure generated by the ventilator that is required to overcome airway and alveolar resistance.
- Plateau pressure: The pressure in the lungs after a tidal volume breath has been delivered.
- Normal Pplat and increased PIP: A normal plateau pressure with an increased peak pressure indicates an increased airway resistance.
- Increased Pplat and increased PIP: An increased plateau and peak pressure indicates that the patient has an issue with lung compliance.
What is Driving Pressure?
Driving pressure in mechanical ventilation is measured by subtracting the positive-end expiratory pressure (PEEP) from the plateau pressure (Pplat).
Driving pressure = Pplat – PEEP
It is often considered to be the amount of energy that is applied to the lungs.
Therefore, the higher the driving pressure, the higher the amount of energy that is being applied to the lungs. This also means that the patient is at a higher risk of developing a ventilator-induced lung injury.
Therefore, in order to minimize this risk, the driving pressure should be kept below 15 cmH2O. This can be achieved by using a lower tidal volume with proper levels of PEEP.
What is an Inspiratory Pause in Mechanical Ventilation?
An inspiratory pause is a control mechanism on the ventilator that allows practitioners to measure a patient’s plateau pressure. Although rarely used for therapeutic purposes, an inspiratory pause maneuver may also be used for the following clinical purposes:
- To improve the distribution of inspired air
- To improve the PaO2
- To improve the delivery of inhaled bronchodilators
- To ensure full inspiration during a chest radiograph
However, the most common reason for performing an inspiratory pause is to measure the plateau pressure, which is the pressure inside the lungs when no air is moving.
This is accomplished by using the control to perform an inspiratory hold for 0.5–2.0 seconds at end-inspiration.
If the end-inspiratory pause maneuver is performed too frequently, it can lead to patient-ventilator asynchrony. This is especially true in patients who are breathing spontaneously.
Other Names for Plateau Pressure
Plateau pressure is often used interchangeably with other terms, such as:
- Peak alveolar pressure
- Intrapulmonary pressure
- Transpulmonary pressure
These terms are related, but they are not synonymous with one another. However, it is still quite common for plateau pressure to be used interchangeably with these other terms.
Can a Patient Breathe During a Plateau Pressure Measurement?
No, the plateau pressure reading will be inaccurate if the patient is breathing while the measurement is obtained
An inspiratory pause maneuver performed on a patient who is breathing spontaneously will result in patient-ventilator asynchrony.
What Errors Can Occur While Measuring Plateau Pressure?
If a patient exhales during the inspiratory hold of a plateau pressure measurement, it may result in a reading that is falsely high. Patients with higher than normal external chest wall resistance (e.g., obese patients) may also have falsely high readings.
This is because excess body fat in the thoracic region is pushing against the patient’s chest, resulting in pressure readings that are higher than what is actually present in the lungs.
What Determines Plateau Pressure?
Plateau pressure is determined by a number of factors, including:
- Tidal volume: The amount of air that is inhaled or exhaled with each breath.
- Respiratory rate: The number of breaths per minute.
- Inspiratory time: The amount of time that is spent inhaling.
- PEEP: The level of positive end-expiratory pressure that is applied.
- Static compliance: The amount of expansion that occurs in the lungs when there is no airflow.
Each of these factors can influence plateau pressure. For example, a higher tidal volume or PEEP will result in a higher plateau pressure, while higher static compliance will result in a lower plateau pressure.
How to Decrease Plateau Pressure
There are a number of ways to decrease plateau pressure, including:
- Decrease the tidal volume
- Decrease the PEEP
- Decrease the flow
- Increase the level of sedation
In general, delivering a smaller tidal volume is a strategy to reduce both plateau pressure and driving pressure. This may be considered in patients at risk of ventilator-induced lung injury (VILI).
What is the Difference Between PEEP and Plateau Pressure?
PEEP is the level of positive end-expiratory pressure that is applied, while plateau pressure is the pressure inside the lungs when no air is moving. PEEP is one of the factors that determine plateau pressure.
PEEP can be used to decrease plateau pressure, but it can also be used to increase it. This is because PEEP can either increase or decrease the amount of air that is in the lungs at the end of expiration.
If PEEP is increased, more air will be in the lungs at the end of expiration and the plateau pressure will increase. If PEEP is decreased, less air will be in the lungs at the end of expiration and the plateau pressure will decrease.
Does Plateau Pressure Increase With ARDS?
Acute respiratory distress syndrome (ARDS) is a serious lung condition characterized by alveolar fluid and refractory hypoxemia. It often requires mechanical ventilation with high levels of PEEP in order to maintain adequate oxygenation.
An effective treatment method for ARDS patients on the ventilator is to receive lower tidal volumes. This is a strategy to achieve lower driving pressure and plateau pressure, which reduce the risk of ventilator-induced lung injuries.
What Does Plateau Pressure Measure?
Plateau pressure measures the end-inspiratory distending pressure of the lungs. This occurs when the lungs are fully inflated and there is no airflow.
Plateau pressure is also helpful in measuring static compliance, airway resistance, and the initial pressure support setting for a patient on the ventilator.
How to Fix High Peak Pressures
Peak pressure refers to the highest pressure in the lungs during inhalation. There are several potential causes of increased peak pressure, including:
- Airway obstruction
- Mucus plug
- Increased inspiratory flow rate
- Patient biting the endotracheal tube
- Kink in the endotracheal tube
In order to fix an increased peak pressure, the underlying cause must be identified and treated. For example, if the patient is wheezing due to bronchospasm, they may be treated with an inhaled bronchodilator.
If excess mucus has accumulated in the patient’s airways, they may be treated with airway suctioning or chest physiotherapy. By getting rid of the mucus, the airways will be cleared and peak pressure should return to normal.
- Tidal volume
- Static compliance
- Airway resistance
Respiratory therapists are required to manage patients who are receiving mechanical ventilation. Therefore, they must learn and fully understand the importance of the plateau pressure measurement.
Hopefully, this guide can help! Be sure to check out our full guide on the different mechanical ventilation settings if you want to learn more. Thanks for reading!
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.
- Egan’s Fundamentals of Respiratory Care. 12th ed., Mosby, 2020.
- Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
- Pilbeam’s Mechanical Ventilation: Physiological and Clinical Applications. 6th ed., Mosby, 2015.