2. Decremental PEEP Titration In a decremental PEEP titration, following a recruiting maneuver, the PEEP is set at a high level, often between 20 and 26 cm H2O. PEEP is decreased incrementally, and markers of lung inflation (e.g. gas exchange or measured lung volume) are followed. When evidence of atelectasis occurs, PEEP is held at or just above this level, often termed 'optimal PEEP.'