Inhaled Nitric Oxide in Severe Obesity

For participants with acute hypoxemic respiratory failure Inclusion Criteria: * Acute hypoxemic respiratory failure, defined as persistent hypoxemia (PaO2/FiO2 ≤ 300 mmHg or SpO2/FiO2 ≤ 315) and on invasive mechanical ventilation for \< 72 hours * Presence of an arterial and central venous catheter (for blood gas measurement) * Admitted to a participating MGH ICU Exclusion Criteria: * Age \< 18 years * Pregnancy or known active breastfeeding * Prisoner or Incarceration * Inability or unwillingness of subject or legal surrogate/representative to give written informed consent * Use of inhaled or oral pulmonary vasodilatory therapy within the 24 hours preceding study enrollment * Contraindication to inhaled NO * Baseline Methemoglobin ≥ 3% * Known left ventricle ejection fraction \< 20% * Known history of G6PD deficiency or cytochrome issues * Prior adverse reaction to inhaled nitric oxide * Presence of pneumothorax or acute pulmonary embolism * Chronic hypoxemia requiring home supplemental non-invasive oxygen (nasal cannula or positive pressure ventilation) or home mechanical ventilation * Chronic pulmonary vascular disease on home chemical vasodilator support (e.g., sildenafil) * History of lung resection or transplant * Hemodynamic instability at the time of potential study enrollment defined as: * Persistent systolic blood pressure \< 90 mmHg or \>180 mmHg despite the use of vasopressor or vasodilators or * Requiring an increment in inotropic-vasopressors o…