Ultra-Low Tidal Volume Mechanical Ventilation in ARDS Through ECMO

Inclusion Criteria: 1. Age ≥ 18 years 2. Endotracheal mechanical ventilation for ≤ 5 days 3. Early moderate-severe ARDS (Berlin Definition) - all of the following conditions for ≤ 48 hours i. PaO2/FiO2 ≤200 with PEEP \> 5 cmH2O ii. bilateral opacities not fully explained by effusions, lobar/lung collapse, or nodules iii. respiratory failure not fully explained by cardiac failure or fluid overload iv. within one week of a known insult of new or worsening respiratory symptoms 4. ARDS severity criterion - either 1 of: 1. PaO2/FiO2 ≤ 150 mm Hg, on PEEP ≥ 10 cm H2O and FiO2 ≥ 0.5 Exclusion Criteria: 1. Currently receiving any form of ECMO (e.g., venovenous, venoarterial, or hybrid configuration) 2. Chronic hypercapnic respiratory failure defined as PaCO2 \> 60 mmHg in the outpatient setting 3. Home mechanical ventilation (non-invasive ventilation or via tracheotomy), not CPAP 4. Actual body weight exceeding 1 kg per centimeter of height 5. Severe hypoxemia with PaO2/FiO2 \< 80 mmHg 6. Expected mechanical ventilation duration \< 48 hours 7. Treating team is in the process of moving to a palliative mode of care 8. Moribund patient not expected to survive 24 hours despite ongoing life-sustaining therapies 9. Confirmed diffuse alveolar hemorrhage from vasculitis 10. Contraindications to limited anticoagulation (e.g., active GI bleeding, bleeding diathesis) 11. Pregnancy - due to unknown effects of PaCO2 changes on placental blood flow