What Does Plateau Pressure Measure in the Lungs?

Plateau pressure is a measurement taken during mechanical ventilation, a life-supporting treatment that helps patients breathe when they cannot do so adequately on their own. This measurement provides information about the pressures within a patient’s lungs. It is a parameter medical professionals monitor for safe and effective breathing support.

What Plateau Pressure Represents

Plateau pressure refers to the static pressure within the small air sacs, or alveoli, of the lungs at the end of inspiration when there is no airflow. This measurement is obtained by briefly pausing the airflow from the ventilator, allowing the pressures to equalize throughout the breathing system. During this pause, the measured pressure reflects the force on the lung tissue and alveoli.

This pressure indicates the “stretch” or distension of the lung tissue. Unlike peak inspiratory pressure (PIP), which includes the resistance encountered as air flows through the airways, plateau pressure isolates the pressure applied to the lung’s elastic structures. By removing the influence of airway resistance, plateau pressure provides a more accurate assessment of the pressure experienced by the lung units. It helps medical teams understand the mechanical stress on the lungs.

Why Measuring Plateau Pressure is Crucial

Measuring plateau pressure is important for managing patients on mechanical ventilation because it indicates lung health and potential for injury. High plateau pressure can signal that the lungs are stiff, a condition known as low lung compliance, meaning they require more pressure to expand. It can also indicate overdistension, where parts of the lung are stretched beyond their safe limits. Both stiff lungs and overdistension can lead to damage to the lung tissue.

Monitoring this pressure helps prevent ventilator-induced lung injury (VILI), a complication that can occur when ventilation parameters are not optimally set. Excessive pressure can cause barotrauma (physical damage from too much pressure), while excessive volume can lead to volutrauma (damage from overstretching). By monitoring plateau pressure, clinicians can identify when the lungs are under too much stress. This measurement is valuable in conditions like Acute Respiratory Distress Syndrome (ARDS), where the lungs are inflamed and susceptible to injury.

How Plateau Pressure Informs Medical Decisions

Medical professionals use plateau pressure readings to make informed decisions about adjusting ventilator settings and guiding patient treatment. If plateau pressure is consistently too high (generally above 30 cmH2O), it signals a risk of lung injury. In such cases, the medical team modifies ventilator parameters to protect the lungs.

One common adjustment is to reduce the tidal volume, which is the amount of air delivered with each breath. Lowering the tidal volume reduces the stretch on the alveoli, decreasing plateau pressure. Doctors might also adjust the positive end-expiratory pressure (PEEP), which is the pressure maintained in the lungs at the end of exhalation. These adjustments aim to keep the plateau pressure within a safe range (typically below 30 cmH2O) to minimize the risk of barotrauma and volutrauma. The measurement guides safe ventilation limits, ensuring breathing support does not contribute to lung damage.