Severe pediatric acute respiratory distress syndrome (PARDS) is a life-threatening and frequent problem experienced by thousands of children each year. Little evidence supports current supportive practices during their critical illness. The overall objective of this study is to identify the best positional and/or ventilation practice that leads to improved patient outcomes in these critically ill children. We hypothesize that children with high moderate-severe PARDS treated with either prone positioning or high-frequency oscillatory ventilation (HFOV) will demonstrate more days off the ventilator when compared to children treated with supine positioning or conventional mechanical ventilation (CMV).

PROSpect is a two-by-two factorial, response-adaptive, randomized controlled clinical trial of supine/prone positioning and conventional mechanical ventilation (CMV)/high-frequency oscillatory ventilation (HFOV). About 60 pediatric intensive care units (PICUs), two thirds U.S. and one third international, with at least 5 years of experience with prone positioning and HFOV in the care of pediatric patients with severe Pediatric Acute Respiratory Distress Syndrome (PARDS), that can provide back-up extracorporeal membrane oxygenation (ECMO) support, are participating. Eligible consecutive subjects with high moderate-severe PARDS will be randomized to one of four groups: supine/CMV, prone/CMV, supine/HFOV, prone/HFOV. Subjects who fail their assigned positional and/or ventilation therapy for either persistent hypoxia or hypercapnia may receive the reciprocal therapy while being considered for ECMO cannulation. Our primary outcome is ventilator-free days (VFD) through day 28, where non-survivors receive zero VFD. We hypothesize that children with severe PARDS treated with either prone positioning or HFOV will demonstrate ≥ 2 more VFD. Our secondary outcome is nonpulmonary organ failure-free days. We will also explore the interaction effects of prone positioning with HFOV on VFDs and also investigate the impact of these interventions on 90-day in-hospital mortality and, among survivors, the duration of mechanical ventilation, PICU and hospital length of stay, and the trajectory of post-PICU functional status and health-related quality of life (HRQL). Up to 600 subjects with severe PARDS will be randomized, stratified by age group and direct/indirect lung injury. Adaptive randomization will first occur after 300 patients are randomized and have been followed for 28 days, and every 100 patients thereafter. At these randomization update analyses, new allocation probabilities will be computed based on ongoing intention-to-treat trial results, increasing allocation to well performing arms and decreasing allocation to poorly performing arms. Data will be analyzed per intention-to-treat for the primary analyses and per-protocol received for primary, secondary and exploratory analyses.

Inclusion criteria:

Intubated and mechanically ventilated with high moderate-severe PARDS for <48 hours per PALICC guidelines (chest imaging consistent with acute pulmonary parenchymal disease and OI ≥12 or OSI ≥10). We require two blood gases meeting moderate-severe PARDS criteria (separated by at least 4 ± 2 hours during which time the clinical team is actively working to recruit lung volume and optimize the patient's hemodynamic status per PALICC guidelines; specifically, incremental and decremental PEEP changes to optimize lung volume). A second blood gas is not required for OI ≥16.

Exclusion criteria:

• Perinatal related lung disease
• Unrepaired congenital diaphragmatic hernia or congenital/acquired diaphragm paralysis
• Respiratory failure explained by cardiac failure or fluid overload
• Cyanotic heart disease
• Cardiomyopathy
• Unilateral lung disease
• Primary pulmonary hypertension
• Intubated for status asthmaticus
• Obstructive airway disease (e.g., Severe airways disease without parenchymal involvement or disease characterized by hypercapnia with FiO2 <0.30 and/or evidence of increased resistance visible on the flow - time scalar and/or presence of intrinsic PEEP)
• Active air leak
• Bronchiolitis obliterans
• Post hematopoietic stem cell transplant; specifically, patients receiving continuous supplemental oxygen for three or more days prior to intubation; receiving noninvasive ventilation for more than 24 hours prior to intubation; receiving more than one vasoactive medication at time of meeting inclusion criteria; spending more than four days in the PICU prior to intubation; supported on or with immediate plans for renal replacement therapies; with two or more allogeneic transplants; who relapsed after the transplant; or with diffuse alveolar hemorrhage
• Post lung transplant
• Home ventilator dependent with baseline Oxygen Saturation Index (OSI) >6
• Neuromuscular respiratory failure
• Critical airway (e.g., post laryngotracheal surgery or new tracheostomy) or anatomical obstruction of the lower airway (e.g., mediastinal mass)
• Facial surgery or trauma in previous 2 weeks
• Head trauma (managed with hyperventilation)
• Intracranial bleeding
• Unstable spine, femur or pelvic fractures
• Open abdomen
• Currently receiving more than 6 consecutive hours of either prone positioning or HFOV
• Supported on ECMO during the current admission
• Family/medical team not providing full support (patient treatment considered futile)
• Previously enrolled in current study
• Enrolled in any other interventional clinical trial not approved for co-enrollment
• Known pregnancy

Per NHLBI policy, we will provide a deidentified dataset and all the data-related documentation necessary to utilize the study data (dictionary, calculated variables and standard operating procedures) to the NHLBI. We will submit this dataset to the NHLBI Data Repository managed by the BioLINCC (Biologic Specimen and Data Repository Information Coordinating Center).

3 years after the final follow-up interview or 2 years after the primary paper has been published, whichever comes first.

Subject to the approval of the (1) PROSpect Ancillary Study Committee, (2) PROSpect Executive Committee, and (3) National Heart, Lung, and Blood Institute (NHLBI).