6. While all of the aforementioned studies achieved successful recruitment, Gattinoni, et al11 studied 68 adults with late ARDS (5±6 days ventilation at enrollment) who failed to successfully recruit. Recruitment maneuvers included pressure-controlled ventilation with peak pressure of 45 cm H2O, PEEP of 5 cm H2O, and respiratory rate of 10. PEEP levels were subsequently applied in random order, between 5 and 15 cm H2O. He found that study patients had only 13±11% recruitable lung by CT scan. Amongst all patients, he found that 24% of lung tissue was non-recruitable, even at airway pressures of 45 cm H2O. No markers of gas exchange were measured.