Fig. 4From: Using non-invasive bi-level positive airway pressure ventilator via tracheostomy in children with congenital central hypoventilation syndrome: two case reportsPolysomnographic tracing when the patient was put on bi-level positive airway pressure. There was neither oxygen desaturation nor hypercapnia. Nasal pressure tracing showed a pressure wave form generated by bi-level positive airway pressureBack to article page