Abstract: 　Objective　To explore the characteristics of sleep apnea syndrome in Prader-Willi syndrome (PWS) in children. Methods　The clinical features and polysomnography of a severe obese school-age child with PWS before and after non-invasive positive pressure ventilator were retrospective analyzed. The key words of "PWS, obstructive sleep apnea syndrome (OSAS), obesity hypoventilation syndrome (OHS) and children" were searched in the databases of PubMed, WanFang and CNKI from 1980 to 2018 for the data of PWS patients with OSAS and OHS. The characteristics and influencing factors of sleep apnea were analyzed. Results　A 10-year-old boy with a body weight of 60 kg, height of 124 cm and BMI of 39.02 (> P97) was admitted to the hospital due to cough and cyanosis of lips. At admission, he was conscious, and took 40 breaths / min. His breathing sounds in both lungs were coarse, with dry and wet rales, and muscle tone in his limbs was weak. The blood oxygen saturation was 82%, and the arterial PCO2 in waking state was 115 mmHg. After endotracheal intubation and mechanical ventilation, combined with anti-infection treatment, the condition was controlled, and then the ventilator was removed. The SpO2 in conscious state was 85%~92%. Nocturnal apnea and hypoxia happened frequently. All night polysomnography showed that apnea hypopnea index was 31.7 times per hour, and the lowest pulse oxygen was 46%, indicating severe sleep apnea syndrome and severe hypoxemia. Conclusions　Sleep breathing disorder in PWS is complex complication which can be combined with severe sleep apnea syndrome and OHS. Polysomnography plays an important role in its diagnosis and differentiation. Noninvasive ventilator treatment is effective.

Key words: 　Prader-Willi syndrome;　polysomnography;　obstructive sleep apnea syndrome;　obesity hypoventilation