Mass General - Division of Clinical Research

All patients (age 18 and older) will be eligible for inclusion if they meet all of the following consensus criteria for sepsis and ARDS3,4 or if they meet the criteria for pneumonia as described below. - Patients with sepsis are defined as those with life-threatening organ dysfunction caused by a dysregulated host response to infection: 1. Suspected or proven infection: Sites of infection include thorax, urinary tract, abdomen, skin, sinuses, central venous catheters, and central nervous system 2. Increase in Sequential Organ Failure Assessment (SOFA) Score ≥ 2 over baseline - ARDS is defined when all four of the following criteria are met: 1. A PaO2/FiO2 ratio ≤ 300 with at least 5 cm H2O positive end-expiratory airway pressure (PEEP) 2. Bilateral opacities on frontal chest radiograph (not fully explained by effusions, lobar/lung collapse, or nodules) within 1 week of a known clinical insult or new or worsening respiratory symptoms 3. A need for positive pressure ventilation by an endotracheal or tracheal tube 4. Respiratory failure not fully explained by cardiac failure or fluid overload; need objective assessment (e.g., echocardiography) to exclude hydrostatic edema if no risk factor is present - Pneumonia (without ARDS or sepsis) will be defined as a unilateral or bilateral lung infiltrate on chest X-ray or chest CT (not fully explained by effusions, lobar/lung collapse or nodules) in the setting of receiving mechanical ventilation, a new suspected respiratory infection, an increase in SOFA score less than 2 at the time of randomization (baseline). - Pneumonia (with sepsis, without ARDS) will be defined as a unilateral or bilateral lung infiltrate on chest X-ray or chest CT (not fully explained by effusions, lobar/lung collapse or nodules) in the setting of receiving mechanical ventilation and a new suspected respiratory infection with an increase in SOFA score of ≥ 2 over baseline at the time of randomization. Pneumonia with bilateral opacities, PaO2/FiO2 ratio ≤ 300, or an increase in SOFA score greater than or equal to 2 over baseline will continue to be considered ARDS and sepsis.

An individual who meets any of the following criteria will be excluded from participation in this study: 1. Age less than 18 years 2. Greater than 168 hours since ARDS onset 3. Pregnant or breastfeeding 4. Prisoner 5. Patient, surrogate, or physician not committed to full support (exception: a patient will not be excluded if he/she would receive all supportive care except for attempts at resuscitation from cardiac arrest) 6. No consent/inability to obtain consent or appropriate legal representative not available 7. Physician refusal to allow enrollment in the trial 8. Moribund patient not expected to survive 24 hours 9. No arterial line or central line/no intent to place an arterial or central line 10. No intent/unwillingness to follow lung protective ventilation strategy 11. Severe hypoxemia defined as SpO2 < 95 or PaO2 < 90 on FiO2 ≥ 0.9 12. Hemoglobin < 7.0 g/dL 13. Subjects who are Jehovah's Witnesses or are otherwise unable or unwilling to receive blood transfusions during hospitalization 14. Acute myocardial infarction (MI) or acute coronary syndrome (ACS) within the last 90 days 15. Coronary artery bypass graft (CABG) surgery within 30 days 16. Angina pectoris or use of nitrates with activities of daily living 17. Severe cardiopulmonary disease classified as New York Heart Association (NYHA) class IV 18. Stroke (ischemic or hemorrhagic) within the prior 1 month, cardiac arrest requiring CPR within the prior 72 hours, or inability to assess mental status following cardiac arrest 19. Burns > 40% total body surface area 20. Severe airway inhalational injury 21. Use of high frequency oscillatory ventilation 22. Use of extracorporeal membrane oxygenation (ECMO) 23. Use of inhaled pulmonary vasodilator therapy (eg. nitric oxide [NO] or prostaglandins) 24. Diffuse alveolar hemorrhage from vasculitis 25. Concurrent participation in other investigational drug study