My approach to setting PEEP in ARDS

The problem with guidelines is that they say "use high PEEP" without defining what high actually means. As one intensivist put it, the ATS and European society recommendations just say "high PEEP" — but that leaves clinicians guessing. This episode walks through a practical, physiology-grounded approach to setting PEEP in ARDS, using a case to illustrate the reasoning.

The case that sets up the problem

A 55-year-old man with hypertension and obesity (BMI 34) presents with four days of fever, myalgia, cough, and progressive shortness of breath. He's 88% on room air, improves initially on high-flow nasal cannula, but deteriorates over 24 hours. He's breathing 35-40 times per minute and fatiguing. You intubate him for viral pneumonia.

Post-intubation settings: volume control, tidal volume 7 mL/kg predicted body weight (about 450-500 mL), PEEP 8, FiO2 100%. Plateau pressure is 30. Blood gas: pH 7.29, PaCO2 60, PaO2 200. Driving pressure is 22 (30 minus 8). He has ARDS, and neither his plateau pressure nor his driving pressure are at goal.

The question becomes: what do you do next?

Why PEEP alone isn't the answer