Updated July 2026 · 7 min read

PEEP Titration for ICU Nurses 2026 — The Pressure That Keeps the Lung Open

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Positive end-expiratory pressure, or PEEP, is the pressure the ventilator holds in the airways at the end of exhalation so the small air sacs do not collapse. It is one of the two or three numbers on the vent that a nurse watches most, because changing it changes oxygenation, lung mechanics, and blood pressure all at once. Respiratory therapists and physicians set PEEP, but the nurse is at the bedside continuously, and is usually the first to see whether a PEEP change is helping the patient breathe or quietly dropping their blood pressure. Understanding what PEEP does turns a mysterious number into something you can reason about.

What PEEP actually does

At the end of a normal breath the lung does not fully empty; a residual volume keeps the alveoli propped open. In sick, wet, or injured lungs that residual splinting is lost, and alveoli collapse at end-exhalation, then have to be forced back open on the next breath. That repeated collapse-and-reopen is itself injurious — it shears the delicate alveolar walls. PEEP restores the end-expiratory pressure that keeps those units open, so more lung is available to exchange gas across the whole breath. The immediate reward is better oxygenation: with more recruited lung, the same amount of oxygen crosses more efficiently, and the team can often turn the FiO2 down away from toxic ranges.

Because raising PEEP tends to improve oxygenation, it is one of the main levers — alongside FiO2 — used to manage hypoxemia in ARDS and other diffuse lung injury. ARDS protocols often pair the two on a table, matching a given FiO2 with a target PEEP.

High PEEP vs low PEEP — the ARDS question

How much PEEP a patient needs is not settled by a single formula, and reasonable protocols differ. The general idea is that sicker, more collapsible lungs benefit from more PEEP to hold them open, while healthier lungs need less. ARDS ventilation strategies use standardized FiO2/PEEP tables so the team escalates both together in a predictable way rather than guessing.

The point for the nurse is not to pick the number, but to recognize that PEEP is always a compromise: enough to keep the lung open, not so much that it over-inflates good lung or strangles the circulation.

The bedside signs a PEEP change is helping — or hurting

When PEEP is increased appropriately, oxygen saturation and PaO2 improve and the FiO2 can come down. But the same maneuver raises pressure inside the chest, and that pressure pushes back on the heart. Higher intrathoracic pressure reduces the venous blood returning to the right heart, so cardiac output and blood pressure can fall — sometimes sharply, especially in a patient who is already volume-depleted.

The nursing bottom line

PEEP is the ventilator's way of keeping the lung propped open at the end of each breath, and it is a genuine balancing act: it buys oxygenation and lets you escape toxic FiO2, but it raises chest pressure that can over-distend the lung and drop the blood pressure. The nurse is the continuous monitor — correlating a PEEP change with the oxygen saturation, the plateau pressure, and above all the hemodynamics, and protecting hard-won recruitment by avoiding needless circuit disconnections. You are not setting the number, but you are the one who sees, in real time, whether it is working.

Related: Mechanical ventilation basics · Prone positioning in ARDS · ABG interpretation · Capnography & EtCO2

Educational content for licensed clinicians. Always follow your facility's protocol and provider orders. Not medical advice.