Posture Dependent Hypoxia Following Lobectomy: The Achilles Tendon of the Lung Surgeon?

Background: Platypnoea-Orthodeoxia Syndrome is an uncommon phenomenon characterized by dyspnea/arterial desaturation in the standing position, resolving in recumbency. Some patients present with Platypnoea-Orthodeoxia Syndrome in the early-or-late post-operative period after major lung resection (lobectomy/pneumonectomy). The main cause of Platypnoea-Orthodeoxia Syndrome is an intracardiac anomaly (Patent Foramen Ovalis/Atrial Septal Defect) leading to right-to-left shunt.Objectives: To identify the causes of post-lobectomy Platypnoea-Orthodeoxia Syndrome, and the possible pathophysiologic mechanism.Methods A Pubmed database-EMBASE systematic review was performed in order to find all reports, reporting the occurrence of dyspnea/hypoxemia after lobectomy.Results: 8 studies were found concerning ten patients during the period from 1983-2019.There was 6 male/4 female. The mean age was 62 years. All patients underwent resection of the right lung. The time-interval between the operation and the Platypnoea-Orthodeoxia Syndrome was from 2 days to 3 years. A Patent Foramen Ovalis was present in 90% and in 10% an Atrial Septal Defect was diagnosed. The mean Right Atrial Pressure was 7.5 mmHg, the mean Left Atrial Pressure was 6.6 mmHg and the mean Pulmonary artery pressure was 18.5 mmHg. The mean size of the interatrial communication was 1.62 cm. The inter-atrial communication was closed by open-chest surgical procedure in 3 cases (30%) and in 7 patients (70%) a percutaneous transcatheter device was implanted.Conclusions: Platypnoea-Orthodeoxia Syndrome after lobectomy is a rare cause of post-operative dyspnea/hypoxia. It is the result of right-to-left shunt via an interatrial communication. Mediastinal relocation, stretching of the atrial septum and aortic root dilatation are among the functional elements necessary for the Platypnoea-Orthodeoxia Syndrome manifestation.