372 PLATYPNEA-ORTHODEOXIA SYNDROME CAUSING POSITIONAL DYSPNEA AND ARTERIAL DESATURATION IN AN ELDERLY WOMAN: A CASE REPORT


 A 72-years-old woman was admitted to the Emergency Department due to acute stroke in April 2022. Some days later the patient developed acute respiratory failure with oxygen arterial desaturation (SpO2 <80%). Interestingly, she experienced deep hypoxia when she was in the orthostatic position, with partial resolution in the supine position, thus necessitating continuous oxygen therapy. Her pertinent medical history included hypertension for which she was taking valsartan 80 mg daily and bisoprolol 2.5 mg daily, obstructive sleep apnea syndrome under treatment with nocturne continuous positive airway pressure, thyroidectomy for multinodular goiter in replacement therapy with levothyroxine 100 mcg daily, and anxious-depressive syndrome for which she was taking trazodone 75 mg daily and escitalopram 10 mg daily. Given her presentation, our top differential diagnosis included acute pulmonary embolism, pneumonia, Sars-CoV-2 infection, and platypnea-orthodeoxia syndrome. The patient was then admitted to the Pneumology Department, where she underwent computed tomography angiography, which was negative for acute pulmonary embolism and pneumonia, and two SARS-CoV-2 nasal swabs, which were both negative. The transcranial Doppler showed a high-grade shunt (curtain effect). The transesophageal echocardiography with bubble test showed a lipomatous and aneurismatic interatrial septum with a massive right-to-left shunt through a patent foramen ovale (PFO) during the Valsalva maneuver. In the absence of other obvious cause of the positional desaturation and hypoxia, a diagnosis of platypnea-orthodeoxia syndrome was made. Platypnea-orthodeoxia syndrome is a rare clinical condition difficult to diagnose. However, it represents a potentially reversible cause of positional dyspnea and arterial desaturation. The patient then underwent percutaneous PFO closure with the Gore Septal Occluder 30/30 mm (W.L. Gore and Associates, Inc.) through intracardiac echocardiography guidance without any residual shunt. Although unfavorable anatomical features were present (atrial septal aneurism and lipomatous septum), the procedure was straightforward and without complication. The oxygen saturation on pulse oximeter, which was 91% in supine position with oxygen therapy with FiO2 60% during the procedure, rapidly became 97% soon after the placement of the prosthesis. The patient then experienced relief of the dyspnea and the oxygen therapy was stopped. The clinical follow-up performed three weeks later showed an asymptomatic patient with no limitation of daily physical activity.