Prone ventilation and NO-inhalation are combined and fortunately her gas exchange improves. Gradually her FiO₂ can be reduced to 60% and PEEP comes down to 10 cm H₂O. What you are left wondering is 'Did she improve all by herself or can I attribute this to my hard work and dedication?' Too bad there aren't any published trials to support your belief that Proning and NO work better together...