EFFECTS OF HYPOCALORIC DIET ON BREATHING DISORDERS IN PRADER-WILLI-SYNDROME

Background - Prader-Willi syndrome (PWS) is a multisystem disorder wit h hyperphagia and obesity. Breathing disorders such as snoring, sleep apnea syndrome, and sleep hypoventilation have also been reported. Cas e report. - Jonathan was born with the typical features of PWS. He dev eloped exercise dyspnea, cyanosis and nocturnal sweating at the age of 3 years. A few months later, a respiratory failure required his admis sion to the intensive care unit. His weight was then 48 kg (300% ideal body weight (IBW)); physical examination showed polypnea (60 breaths/ min), cyanosis, far deposition on the chest wall. Transcutaneous oxyge n saturation was 65%, carbon dioxyde tension 81 mmHg (capillary sample ). Pulmonary hypertension was found (mean arterial pulmonary pressure = 55 mmHg). Polysomnography detected hypoventilation with persistent h ypoxemia increasing during the night and transient dips of oxygen satu ration with bradycardia. He was treated with oxygen, mechanical ventil ation (facial mask) and a low caloric diet (600 cal/day). Four months later, he weighed 33 kg (200% IBW); the respiratory features had resol ved and gazometric values and pulmonary pressure returned to the norma l ranges. Polysomnography showed only obstruction apnea and hypopnea w ithout oxygen desaturation. Conclusions. - Patients with PWS may devel op respiratory symptoms sufficient by severity to be life threatening. They are related to morbid obesity and are influenced by a hypocalori c diet. Follow-up of patients with this syndrome must include repeated respiratory evaluation.