Idiopathic Central Alveolar Hypoventilation wherein Sleep Disordered Breathing Was Considered Well-controlled by the Continuous Positive Airway Pressure Tracking System but Not Controlled by Polysomnography.

A 54-year-old man whose awake percutaneous arterial oxygen saturation (SpO2) was 94% was diagnosed with obstructive sleep apnea by polysomnography (PSG). His apnea-hypopnea index (AHI) was 138.8 (AI: 4.7 and HI: 134.1), so he was treated with continuous positive airway pressure (CPAP), and his condition was considered well-controlled by the CPAP tracking system (AHI=3.4), with improvement seen in his symptoms when he left our hospital. However, he returned to our hospital 4 years later with recurrent sleepiness and hypercapnia despite the well-controlled status (AHI=3.8) according to the tracking system. His hypercapnia improved following voluntary hyperventilation. Idiopathic central alveolar hypoventilation was diagnosed, with the AHI considered to be well-controlled by the CPAP tracking system but not at all according to PSG.

Platypnoea-orthodeoxia syndrome affects nocturnal oxygen desaturation: A case report.

A woman in her late 20s who had received an implantable cardioverter defibrillator in childhood for ventricular arrhythmia was diagnosed with severe obstructive sleep apnoea (apnoea-hypopnoea index, 77.1/h), and she began continuous positive airway pressure treatment. Before initiating this treatment, she had moderate hypoxaemia of unknown cause. She was admitted for adjustment of the position of her implantable cardioverter defibrillator, which had caused purple discoloration and ulceration of the overlying skin. On admission, she had dyspnoea and her arterial oxygen saturation by pulse oximetry significantly decreased while sitting. This led to detection of a patent foramen ovale and a right-to-left shunt while sitting. We diagnosed platypnoea-orthodeoxia syndrome with an atrial septal defect. Atrial septal defects should be suspected in hypoxic patients with obstructive sleep apnoea.