Mechanical ventilation has transformed the care of patients with acute respiratory distress syndrome (ARDS), but ventilator support itself can contribute to additional lung injury if not carefully managed. One of the most important and challenging aspects of mechanical ventilation is determining the appropriate level of positive end-expiratory pressure (PEEP).

Recent research published in the British Journal of Anaesthesia reviews the evolving science behind PEEP optimization and reinforces an important principle in modern critical care. There is no single "ideal" PEEP setting for every patient.

Understanding PEEP

PEEP is the pressure maintained in the lungs at the end of exhalation during mechanical ventilation. By preventing complete collapse of the alveoli, PEEP helps improve oxygen exchange, maintain lung volume, and reduce repetitive opening and closing of fragile air sacs, one of the major contributors to ventilator-induced lung injury.

However, both insufficient and excessive PEEP can be harmful. Too little pressure allows alveoli to collapse repeatedly, while too much pressure may overstretch healthy portions of the lung, impair circulation, and increase the risk of additional injury.

Why One Size Does Not Fit All

ARDS affects the lungs unevenly. Some regions remain relatively healthy, while others become filled with inflammatory fluid or collapse entirely. This creates a highly variable pattern of lung injury and gas distribution from one patient to another.

Because of this heterogeneity, ventilator settings that benefit one patient may actually worsen lung injury in another. Rather than relying solely on standardized ventilator protocols, individualized PEEP strategies tailored to each patient's physiology and treatment response are required.

Beyond Oxygen Levels

Historically, clinicians often adjusted PEEP primarily according to improvements in blood oxygen levels. While oxygenation remains an important clinical measure, it does not always reflect what is happening within the lungs.

A patient may demonstrate improved oxygen saturation while simultaneously developing excessive stretching of healthy lung tissue. Conversely, oxygenation may remain relatively unchanged despite meaningful recruitment of previously collapsed lung regions.

For this reason, incorporating additional physiological measurements when determining optimal ventilator settings refines treatment.

New Approaches to PEEP Titration

Several techniques are now being used to individualize PEEP more effectively.

Monitoring respiratory system compliance and driving pressure helps clinicians assess how efficiently the lungs expand during ventilation. Lower driving pressures are generally associated with less mechanical stress on the lungs and improved patient outcomes.

Some intensivists use esophageal pressure monitoring to estimate pressures surrounding the lungs. This allows better discrimination between the effects of the chest and those of the lungs, providing a more accurate assessment of the pressures actually experienced by the alveoli.

The Growing Role of Imaging

Advances in bedside imaging are providing clinicians with additional tools to guide ventilator management.

Computed tomography (CT) remains the most detailed method for evaluating lung recruitment but is often impractical for critically ill patients because transportation to the scanner carries inherent risks.

Electrical impedance tomography (EIT) is an emerging bedside technology that continuously displays regional ventilation throughout the lungs in real time. This allows clinicians to identify areas of collapse or overdistension while adjusting ventilator settings.

Lung ultrasound performed at the bedside provides important information regarding lung aeration, consolidation, and recruitment.

Clinical Perspective

This review highlights an important evolution in critical care medicine. The objective is no longer simply to improve oxygenation but to protect the lungs while minimizing additional injury caused by mechanical ventilation.

No single measurement provides every answer. Instead, the best outcomes are likely achieved by integrating multiple sources of information—including respiratory mechanics, imaging findings, gas exchange, and the patient's overall clinical condition—to guide ventilator adjustments.

As our understanding of ARDS continues to advance, personalized ventilator management will become the standard of care. Matching ventilator settings to each patient's unique physiology offers the potential to reduce ventilator-induced lung injury, shorten time on mechanical ventilation, and improve outcomes.

Bottom Line

PEEP effectiveness depends on careful individualization. Rather than relying solely on oxygen levels, physiological measurements &  imaging can help determine the safest and most effective ventilator strategy for each patient. This personalized approach represents an important step toward improving outcomes while minimizing complications associated with mechanical ventilation. The dynamic nature of acute lung injury increases this challenge!

Reference

Servetti A, Battaglini D, Patroniti NA, et al. Optimizing Positive End-Expiratory Pressure in Acute Respiratory Distress Syndrome: A Narrative Review of Approaches to Titration. British Journal of Anaesthesia. Published online January 27, 2026. doi:10.1016/j.bja.2025.12.048.