Plateau Pressure During Mechanical Ventilation (2024)

Plateau pressure is a critical concept in mechanical ventilation, providing insight into the compliance of the lungs and chest wall during ventilation.

Unlike peak airway pressure, which can be influenced by airway resistance, plateau pressure is measured during a pause at the end of inspiration when airflow ceases, offering a more accurate reflection of the pressure applied to the alveoli.

Understanding and monitoring plateau pressure is essential for protecting the lungs from ventilator-induced lung injury (VILI) and optimizing the care of patients requiring mechanical ventilation.

What is Plateau Pressure?

Plateau pressure is the pressure applied to the small airways and alveoli in the lungs during mechanical ventilation when there is no airflow. It is measured at the end of the inspiratory phase after a brief pause in airflow, allowing for the equalization of pressure within the lungs.

This pressure is an important indicator of lung compliance, reflecting how easily the lungs can expand. High plateau pressures can indicate poor lung compliance, which can be due to conditions such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis, or other factors leading to stiff lungs.

Monitoring plateau pressure is crucial for preventing ventilator-induced lung injury by ensuring that the pressure exerted on the lungs does not exceed safe levels.

Why is Plateau Pressure Important?

Plateau pressure is important because it provides a more accurate measure of the pressure exerted on the alveoli, the small air sacs in the lungs, during mechanical ventilation.

Unlike peak airway pressure, which includes the pressure caused by airway resistance, plateau pressure isolates the pressure that directly affects the lung tissue itself.

This makes it a crucial parameter for assessing lung compliance—the ability of the lungs to expand and contract—during ventilation.

Monitoring plateau pressure is essential for several reasons:

• Preventing Ventilator-Induced Lung Injury (VILI): High plateau pressures can lead to overdistension of the alveoli, increasing the risk of barotrauma (damage caused by excessive pressure) and volutrauma (damage caused by excessive volume). By keeping plateau pressure within safe limits (typically below 30 cm H₂O), healthcare providers can minimize the risk of VILI.
• Optimizing Ventilator Settings: Plateau pressure helps guide adjustments to ventilator settings, such as tidal volume and positive end-expiratory pressure (PEEP), to ensure that ventilation is effective without causing harm to the lungs.
• Assessing Lung Compliance: Changes in plateau pressure can indicate alterations in lung compliance. For example, rising plateau pressures might suggest that the lungs are becoming stiffer, which could be due to worsening lung conditions like ARDS or pulmonary edema.
• Guiding Clinical Decision-Making: Plateau pressure is a key factor in making informed decisions about a patient’s ventilatory management, including the need for adjustments in ventilation strategy or even the consideration of alternative modes of ventilation.

Note: Plateau pressure is a vital parameter in the management of mechanically ventilated patients, playing a critical role in protecting lung health and improving patient outcomes.

Plateau Pressure Normal Value

The normal value for plateau pressure in mechanically ventilated patients is generally considered to be less than 30 cm H₂O.

Keeping plateau pressure below this threshold is important to minimize the risk of ventilator-induced lung injury (VILI), such as barotrauma and volutrauma. When plateau pressure exceeds 30 cm H₂O, it indicates that the lungs are under excessive pressure, which can lead to damage to the alveoli and other lung structures.

Therefore, maintaining a plateau pressure below 30 cm H₂O is a key goal in the management of mechanical ventilation to ensure safe and effective respiratory support.

Causes of Increased Plateau Pressure

Increased plateau pressure can occur due to several factors, most of which are related to changes in lung or chest wall compliance.

Here are some common causes:

Decreased Lung Compliance

• Acute Respiratory Distress Syndrome (ARDS): This condition causes the lungs to become stiff due to inflammation and fluid accumulation, leading to reduced compliance.
• Pulmonary Fibrosis: The scarring of lung tissue reduces lung elasticity, making it harder for the lungs to expand.
• Pulmonary Edema: Fluid in the lungs can reduce lung compliance and increase plateau pressure.
• Atelectasis: Collapse of lung tissue can increase the pressure required to ventilate the remaining functional lung areas.

Chest Wall Compliance Issues

• Obesity: Excess body weight can restrict chest wall movement, reducing overall compliance.
• Pleural Effusion: Fluid accumulation in the pleural space can compress the lungs, reducing compliance.
• Kyphoscoliosis: Abnormal curvature of the spine can restrict chest wall expansion, increasing plateau pressure.

Increased Intra-Abdominal Pressure

• Abdominal Distension: Conditions such as ascites, bowel obstruction, or other causes of abdominal distension can push the diaphragm upward, decreasing lung compliance and increasing plateau pressure.

Mechanical Factors

• Inadequate PEEP (Positive End-Expiratory Pressure): Low levels of PEEP may allow alveoli to collapse, increasing the pressure needed to reopen them during inspiration.
• Excessive Tidal Volume: Ventilating with volumes that are too large for the patient’s lung capacity can lead to overdistension and increased plateau pressure.

Note: Monitoring and addressing the underlying causes of increased plateau pressure is crucial to prevent lung injury and ensure effective mechanical ventilation.

Peak Pressure vs. Plateau Pressure

Peak pressure and plateau pressure are both important parameters in mechanical ventilation, but they represent different aspects of the pressures exerted on the lungs.

Peak Pressure

Peak pressure is the maximum pressure reached in the airways during the inspiratory phase of a breath, and it includes the resistance to airflow in the airways, such as from the endotracheal tube and bronchial passages.

This means that peak pressure is influenced by factors like airway resistance and the flow rate of the ventilator.

Plateau Pressure

On the other hand, plateau pressure is measured after a brief pause in airflow at the end of inspiration, allowing the pressure within the lungs to equalize.

Because plateau pressure is not influenced by airway resistance, it provides a more accurate measure of the pressure being applied to the alveoli and reflects lung compliance more directly.

Note: Understanding the difference between these two pressures is crucial for adjusting ventilator settings to protect the lungs while ensuring adequate ventilation.

How to Measure Plateau Pressure

Measuring plateau pressure is a straightforward process performed during mechanical ventilation.

Here’s how it is typically done:

• Perform an Inspiratory Hold: While the patient is receiving a mechanical breath, the ventilator is paused at the end of the inspiratory phase. This pause is known as an “inspiratory hold” or “end-inspiratory pause.” During this pause, airflow is momentarily halted, allowing the pressures in the airways and alveoli to equilibrate.
• Read the Plateau Pressure: The ventilator displays the plateau pressure on the screen during the inspiratory hold. This value represents the pressure in the alveoli when there is no airflow and reflects the static compliance of the lungs and chest wall.
• Release the Inspiratory Hold: After recording the plateau pressure, the inspiratory hold is released, and normal ventilation resumes.

Important Considerations

• Duration of Inspiratory Hold: The inspiratory hold typically lasts about 0.5 to 2 seconds. If held too long, it can cause discomfort or hemodynamic changes in the patient.
• Patient-Triggered Breaths: The patient should not be actively breathing during the measurement, as spontaneous efforts can affect the accuracy of the plateau pressure reading.
• Use of Sedation/Paralysis: In some cases, sedation or neuromuscular blockade may be required to ensure the patient is not breathing spontaneously during the measurement.

Note: By following these steps, clinicians can accurately measure plateau pressure, helping guide ventilation settings and ensuring the patient’s lungs are ventilated safely.

How to Calculate Plateau Pressure

Plateau pressure is typically measured using an inspiratory hold on a mechanical ventilator, but it can also be calculated using the following formula:

Plateau Pressure = (Tidal Volume / Static Compliance) + PEEP

To calculate plateau pressure, you need to know three key parameters: the patient’s exhaled tidal volume, static compliance, and the level of PEEP (Positive End-Expiratory Pressure).

Example Calculation:

Let’s consider an example where a patient has the following values:

• Tidal Volume: 500 mL
• Static Compliance: 22 mL/cm H₂O
• PEEP: 5 cm H₂O

Using the formula, the calculation would be:

Plateau Pressure = (500 / 22) + 5

Plateau Pressure = 22.7 + 5

Plateau Pressure = 27.5 cm H₂O

As shown, the formula is straightforward, but accuracy is crucial for reliable results. Ensure that the tidal volume, static compliance, and PEEP values are correctly measured and applied to avoid errors in the calculated plateau pressure.

Note: This calculation helps in assessing lung mechanics and ensuring the safety and efficacy of mechanical ventilation.

Other Names for Plateau Pressure

Plateau pressure is also referred to by several other names, which can vary depending on the context or the specific aspects of lung mechanics being discussed.

Some of these alternative terms include:

• Peak Alveolar Pressure: This term emphasizes that plateau pressure represents the pressure in the alveoli at the end of inspiration, where it peaks in a static condition.
• Intrapulmonary Pressure: This term is sometimes used interchangeably with plateau pressure to indicate the pressure within the lungs, particularly when airflow has ceased during an inspiratory hold.
• Transpulmonary Pressure: While not identical to plateau pressure, transpulmonary pressure refers to the difference between alveolar pressure (which plateau pressure approximates) and pleural pressure. It’s important to note that transpulmonary pressure specifically highlights the pressure across the lung tissue itself.

Note: These terms, while related, can sometimes have different connotations or specific uses in clinical practice, so it’s important to understand the context in which each term is used.

What is Driving Pressure?

Driving pressure is a key concept in mechanical ventilation that refers to the difference between plateau pressure and positive end-expiratory pressure (PEEP).

It represents the pressure needed to inflate the lungs during mechanical ventilation, effectively reflecting the pressure required to overcome the elastic recoil of the lungs.

The formula for driving pressure is:

Driving Pressure = Plateau Pressure − PEEP

Driving pressure is considered a crucial factor in preventing ventilator-induced lung injury (VILI). Research has shown that maintaining a lower driving pressure is associated with better outcomes in patients with acute respiratory distress syndrome (ARDS).

A high driving pressure can indicate poor lung compliance, meaning that the lungs are stiffer and require more pressure to inflate, which can increase the risk of lung injury.

In clinical practice, optimizing driving pressure by adjusting tidal volume and PEEP settings is an important strategy for protecting the lungs during mechanical ventilation.

Keeping driving pressure within safe limits (generally considered to be below 15 cm H₂O) is essential for minimizing the risk of barotrauma and other forms of lung injury.

FAQs About Plateau Pressure

Can a Patient Breathe During a Plateau Pressure Measurement?

No, a patient should not breathe during a plateau pressure measurement, as spontaneous breathing can lead to inaccurate readings.

If the patient breathes during the inspiratory pause maneuver, it can cause patient-ventilator asynchrony, which distorts the plateau pressure measurement.

For accurate results, it’s essential that the patient remains still and does not initiate any breaths during the measurement.

What Errors Can Occur While Measuring Plateau Pressure?

Several errors can occur during the measurement of plateau pressure:

• Spontaneous Exhalation: If the patient exhales during the inspiratory hold, the resulting plateau pressure reading may be falsely elevated, leading to an inaccurate assessment of lung mechanics.
• External Chest Wall Resistance: Patients with increased external chest wall resistance, such as those with obesity, may have falsely high plateau pressure readings. This is because the excess body fat around the thoracic region exerts additional pressure on the chest wall, inflating the pressure readings beyond what is actually present in the lungs.

What Determines Plateau Pressure?

Plateau pressure is influenced by several factors:

• Tidal Volume: The volume of air inhaled or exhaled with each breath. Higher tidal volumes increase plateau pressure.
• Respiratory Rate: The number of breaths per minute can affect lung mechanics and pressure readings, particularly if it influences lung volume.
• Inspiratory Time: The duration of inhalation impacts how much pressure builds up in the lungs.
• Positive End-Expiratory Pressure (PEEP): The level of pressure maintained in the lungs at the end of expiration. Higher PEEP levels contribute to higher plateau pressures.
• Static Compliance: The ability of the lungs to expand when no airflow is present. Higher compliance generally leads to lower plateau pressure, while lower compliance results in higher pressures.

Note: Each of these factors can influence the plateau pressure, with higher tidal volumes, PEEP, and lower compliance generally resulting in increased plateau pressure.

What is an Inspiratory Pause During Mechanical Ventilation?

An inspiratory pause during mechanical ventilation is a brief pause at the end of the inspiratory phase, where airflow into the lungs is temporarily halted.

This pause allows the air pressure in the lungs to equalize, providing a more accurate measurement of plateau pressure, which reflects the pressure in the small airways and alveoli.

The inspiratory pause is crucial for assessing lung compliance and ensuring that the ventilation settings are appropriate to avoid lung injury. It is typically used in critical care settings to optimize ventilator management and improve patient outcomes.

How to Decrease Plateau Pressure?

To decrease plateau pressure, several strategies can be employed:

• Decrease Tidal Volume: Reducing the tidal volume is a primary method for lowering plateau pressure, particularly in patients at risk for ventilator-induced lung injury (VILI).
• Decrease PEEP: Lowering PEEP can reduce the overall pressure exerted on the lungs.
• Decrease Flow Rate: Slowing the flow of air into the lungs can reduce the pressure buildup during inspiration.
• Increase Sedation: Ensuring adequate sedation can minimize spontaneous breathing efforts, reducing the likelihood of asynchrony and high pressures.

Note: Delivering smaller tidal volumes and carefully adjusting PEEP are key strategies to manage and reduce plateau pressure, helping to protect the lungs from potential injury.

What is the Difference Between PEEP and Plateau Pressure?

Positive end-expiratory pressure (PEEP) and plateau pressure are both important parameters in mechanical ventilation, but they serve different purposes and represent different aspects of lung mechanics.

PEEP is the pressure maintained in the lungs at the end of expiration to prevent alveolar collapse and improve oxygenation. It helps keep the airways open and can be adjusted to optimize lung function.

Plateau Pressure is the pressure within the lungs during an inspiratory pause when there is no airflow. It reflects the pressure in the alveoli and provides insight into lung compliance.

PEEP influences plateau pressure because increasing PEEP adds more air to the lungs at the end of expiration, which can elevate plateau pressure. Conversely, decreasing PEEP reduces the amount of air in the lungs at the end of expiration, which can lower plateau pressure.

Does Plateau Pressure Increase With ARDS?

Yes, plateau pressure often increases in patients with acute respiratory distress syndrome (ARDS), a severe lung condition characterized by fluid-filled alveoli and refractory hypoxemia.

ARDS typically requires mechanical ventilation with higher levels of PEEP to maintain adequate oxygenation. However, high plateau pressures in ARDS can indicate reduced lung compliance and increased risk of ventilator-induced lung injury (VILI).

To mitigate this risk, lower tidal volumes are often used as part of a lung-protective ventilation strategy, which helps to keep both driving pressure and plateau pressure within safer limits.

What Does Plateau Pressure Measure?

Plateau pressure measures the end-inspiratory distending pressure of the lungs, which occurs when the lungs are fully inflated and airflow is paused.

It provides valuable information about:

• Static Lung Compliance: How easily the lungs expand during ventilation.
• Airway Resistance: Although plateau pressure is less influenced by airway resistance than peak pressure, it still reflects the pressure needed to keep the alveoli open.
• Ventilator Settings: It helps in setting the initial pressure support and adjusting ventilator settings to prevent lung injury.

How to Fix High Peak Pressures?

High peak pressures during mechanical ventilation indicate that more pressure is required to deliver a breath, which can be due to various factors:

• Airway Obstruction: This can be caused by secretions, mucus plugs, or a kink in the endotracheal tube.
• Bronchospasm: Narrowing of the airways can increase resistance, leading to higher peak pressures.
• Increased Inspiratory Flow Rate: Faster airflow can raise peak pressures.
• Patient Factors: Coughing, biting the endotracheal tube, or other patient actions can elevate peak pressures.

To address high peak pressures, it’s essential to identify and treat the underlying cause. For instance:

• Bronchospasm: Treat with an inhaled bronchodilator to relax the airway muscles.
• Airway Secretions: Perform airway suctioning or chest physiotherapy to clear mucus and reduce airway resistance.
• Endotracheal Tube Issues: Ensure the tube is not kinked and that the patient is not biting it.

Note: By resolving these issues, peak pressures can be normalized, ensuring safer and more effective ventilation.

Final Thoughts

Plateau pressure is a key indicator of lung health in mechanically ventilated patients, helping clinicians tailor ventilation strategies to minimize lung injury and improve patient outcomes.

By closely monitoring and adjusting plateau pressure, healthcare providers can protect fragile lung tissues, ensuring that mechanical ventilation supports recovery while reducing the risk of complications.

As our understanding of lung mechanics continues to evolve, the importance of plateau pressure in guiding ventilation practices remains a cornerstone of critical care.