Platypnea-Orthodeoxia Syndrome Masked by Delirium in an 85-Year-Old Woman

On February 3, 2016, an 85-year-old woman was brought to the emergency department (ED) because of mental confusion and intolerance of the sitting position, which had begun suddenly 2 days before. She had been wheelchair-bound for the past 9 years after a stroke that had left her with mild left-sided hemiparesis but without cognitive impairment. According to her medical records at the ED, she was initially found hypoxemic (SO₂ = 75% in room air) and disoriented. She was diagnosed with pneumonia, and because there was major improvement regarding her oxygenation after hydration (SO₂ = 94% in room air), she was discharged home with a prescription of oral amoxicillin-clavulanate. Six weeks later, during an ambulatory consultation her family reported that she had remained confused and agitated especially during the night and that the patient became distressed every time they attempted to sit her up. They had to offer her food while she was lying down on her bed because she would not tolerate the upright position at all. During consultation, she had an oxygen saturation of 86% in room air while recumbent and was referred for hospital admission on the same day for the assessment of her hypoxemia and other possible organic causes of her mental status change. Platypnea-orthodeoxia syndrome (POS) was determined the cause of her orthostatic intolerance as even on oxygen therapy her oxygen saturation fell from 95% to 84% when changing from decubitus to the upright position.