Vascular ARDS Recruitment After Inhaled Nitric Oxide

Inclusion Criteria: * Adult intubated and mechanically ventilated patients (≥ 18 years old) admitted to the intensive care unit (ICU) * ARDS diagnosis with mild to moderate severity by Berlin criteria1 (100 mmHg \< PaO2/FiO2 \<= 300 mmHg) * Presence of an arterial line for blood gas measurement and blood pressure monitoring and of a central line for hypertonic saline injection Exclusion criteria * Suspected pregnancy, pregnancy or less than six weeks postpartum * Younger than 18 years or older than 80 years * Patients with thorax perimeter not within the range of 37.5 - 134cm * Baseline methemoglobin ≥ 5% * Hemoglobin level less than 7 g/dl * Subjects enrolled in another interventional research study * Presence of pneumothorax * Usage of any devices with the electric current generation, such as a pacemaker or internal cardiac defibrillator * Past medical history of severe lung disease * Glucose-6-phosphate dehydrogenase (G6PD) deficiency * Cytochrome b5 reductase deficiency * Sickle cell disease * Patients that are receiving inhaled pulmonary vasodilators at the time of the enrollment * Hemodynamic instability is defined as: * Persistent systolic blood pressure \<90 mmHg and/or \>180 mmHg despite the use of vasopressor or vasodilators, or * Requiring an increment in inotropic vasopressors over the past two hours just before enrollment: more than 15 mcg/min for norepinephrine and dopamine, more than 10 mcg/min in epinephrine, and more than 50 mcg/ min for phenylephrine. * Increase in FiO2 \> 20%, increase in PEEP \> 5cmH2O over the past two hours just before enrollment * Hypernatremia (serum sodium \> 150 mEq/L) * Patients cannot be enrolled for DECT if they have: * History of allergic reaction to intravenous contrast * Renal dysfunction on the day of the study (serum creatinine \> 1.5 mg/dL) * Limited to sub-cohort 2: contraindications to prone positioning.