Using non-invasive bi-level positive airway pressure ventilator via tracheostomy in children with congenital central hypoventilation syndrome: two case reports.

INTRODUCTION: Due to the economic downturn in Thailand, two baby girls with congenital central hypoventilation syndrome had to wait for several months to obtain definite diagnosis and long-term mechanical ventilation. Genetic investigation later revealed 20/25 polyalanine expansion of PHOX2B gene in both girls. In this report we highlight the use of non-invasive bi-level positive airway pressure ventilators via tracheostomy, overnight end-tidal carbon dioxide trend graphs and outcomes of the patients whose diagnosis and treatment were delayed.

CASE PRESENTATION: Case 1: A Thai baby girl showed symptoms of apnea and cyanosis from birth and required invasive mechanical ventilation via tracheostomy during sleep. At 5 months, she unfortunately was discharged from the hospital without any ventilatory support due to financial problems. She subsequently developed cor pulmonale, respiratory failure and generalized edema and was referred to us when she was 9-months old. An overnight polysomnogram was consistent with a central hypoventilation disorder, in which the severity of oxygen desaturation and hypercapnia was worsening during non-rapid eye movement compared to rapid eye movement sleep. At 12 months she was allowed to go home with a conventional home ventilator. The ventilator was changed to bi-level positive airway pressure when she was 4-years old. After she received adequate home ventilation, she thrived with normal growth and development. Case 2: A Thai baby girl developed apnea and cyanosis from the age of 5 weeks, requiring ventilatory support (on and off) for 5 months. After being extubated, she had been put on supplemental oxygen via nasal cannula for 2 months. She was then referred to us when she was 7-months old. An overnight end-tidal carbon dioxide trend graph revealed marked hypercapnia without increase in respiratory rate. An overnight polysomnogram was consistent with a central hypoventilation disorder. Since 9 months of age she has been on home bi-level positive airway pressure via tracheostomy without any complications. Genetic testing confirmed 20/25 polyalanine expansions of PHOX2B gene in both girls.

CONCLUSIONS: Bi-level positive airway pressure, originally designed as a non-invasive ventilator, was found to work effectively and safely, and may be used as an invasive ventilator via tracheostomy in young children with congenital central hypoventilation syndrome.