Dead Space and Inhaled Nitric Oxide in Pediatric Acute Respiratory Distress Syndrome

Inclusion Criteria:

• Age >37 weeks corrected gestational age to 21 years, including adults lacking thecapacity to consent.

• Within 72 hours of the start of invasive mechanical ventilation and meet thecriteria for pediatric ARDS (new infiltrate on chest imaging and a known ARDS riskfactor within 7 days of the onset of hypoxemia) and either meet criteria formoderate or severe pediatric ARDS between 4-72 hours of IMV (OI ≥ 8 or OSI ≥ 7.5) ORhave an OI ≥ 20 or an OSI ≥ 14 x 15 minutes between 0-4 hours of IMV.

• Subgroup of children eligible for longituduinal Blood Collection: Children withsevere PARDS (OI ≥ 16 or an OSI ≥ 12 between 4-72 hours of IMV) or those with an OI ≥ 20 or an OSI ≥ 14 for 15 minutes between 0-4 hours of IMV will be eligible forcollection of longitudinal plasma samples.

Exclusion Criteria:

• Non-conventional invasive mechanical ventilation (i.e. High Frequency OscillatoryVentilation, Airway Pressure Release Ventilation) at the time of ICU admission

• ECMO or iNO (or other inhaled pulmonary vasodilator therapy) at the time of ICUadmission

• Significant lower airways obstruction (examination of ventilator and capnographywaveforms by site study or medical team)

• Air leak >20% (endotracheal tube, tracheostomy tube, or thoracostomy tube)

• Home Invasive Mechanical Ventilation

• Cyanotic Congenital Heart Disease

• Previous enrollment in the DiNO study

• Do not resuscitate order at the time of pediatric ARDS diagnosis.

• Blood gas not obtained prior to initiation of ECMO, iNO, or non-conventionalventilation.