Study Design: Single-center randomized controlled trial (150 children per arm) using REDvent (intervention arm) as compared with usual care ventilator management including a standardized daily SBT (control arm). Acute phase randomization will occur upon study enrollment, and patients who fail the first SBT will undergo a weaning phase randomization. The investigators will obtain serial measurements of respiratory system capacity, load, effort of breathing, and diaphragm architecture throughout the course of MV.