[Effects of hypocaloric diet on respiratory manifestations in Willi-Prader syndrome].

Background: Prader-Willi syndrome (PWS) is a multisystem disorder with hyperphagia and obesity. Breathing disorders such as snoring, sleep apnea syndrome, and sleep hypoventilation have also been reported.
Case Report: Jonathan was born with the typical features of PWS. He developed exercise dyspnea, cyanosis and nocturnal sweating at the age of 3 years. A few months later, a respiratory failure required his admission to the intensive care unit. His weight was then 48 kg (300% ideal body weight (IBW); physical examination showed polypnea (60 breaths/min), cyanosis, fat deposition on the chest wall. Transcutaneous oxygen saturation was 65%, carbon dioxide tension 81 mmHg (capillary sample). Pulmonary hypertension was found (mean arterial pulmonary pressure = 55 mmHg). Polysomnography detected hypoventilation with persistent hypoxemia increasing during the night and transient dips of oxygen saturation with bradycardia. He was treated with oxygen, mechanical ventilation (facial mask) and a low caloric diet (600 cal/day). Four months later, he weighed 33 kg (200% IBW); the respiratory features had resolved and gazometric values and pulmonary pressure returned to the normal ranges. Polysomnography showed only obstruction apnea and hypopnea without oxygen desaturation.
Conclusions: Patients with PWS may develop respiratory symptoms sufficient by severity to be life threatening. They are related to morbid obesity and are influenced by a hypocaloric diet. Follow-up of patients with this syndrome must include repeated respiratory evaluation.