Platypnea-orthodeoxia syndrome


Platypnea-orthodeoxia (P-O) syndrome is an under-diagnosed condition characterized by dyspnea and deoxygenation when changing from a recumbent to an upright position

  • It is usually caused by increased right-to-left shunting of blood on assuming an upright position, with normal pressure in the right atrium
  • It may also be caused by intrapulmonary shunting combined with extensive pulmonary lesions or severe V/Q mismatching



  • Atrial septal defect (ASD) or persistent foramen ovale (PFO) (present in ~20-25% of the population)
    • position-dependent shunting, often in combination with one of the rarer conditions below.
    • right-to-left shunt causes hypoxia, from either
      1. right atrial pressure > left atrial pressure, or
      2. mechanical distortion – of either the fossa ovalis itself or the flow of blood from the IVC to the ASD/PFO


  • Other Cardiac
    • Pericardial effusion
    • Constrictive pericarditis
    • Aortic aneurysm
    • Tricuspid regurgitation
    • Mediastinal shift
  • Pulmonary
    • Multiple pulmonary emboli
    • Pulmonary emphysema
    • Radiation-induced bronchial stenosis
    • Hepatopulmonary syndrome
    • Amiodarone toxicity of the lungs
    • Pulmonary A-V communications
    • PCP pnuemonia
    • fat embolism syndrome
  • Autonomic
    • Parkinson disease
    • Bilateral thoracic sympathectomy
  • Abdominal
    • Hepatic cirrhosis
    • Ileus


  • failure of correction of hypoxia during 100% oxygen test
  • supine and upright PaO2 measurement
    • with upright deoxia
  • tilt transesophageal echocardiogram with bubble study (<100% sensitive) - diagnosis of the shunt can be difficult
    • A syringe filled with 9 ml saline and 1 ml air is agitated, macroscopic bubbles expelled and the remaining microbubble emulsion injected IV
    • The test is positive if microbubbles are seen in the left atrium within two to three cycles of the initial appearance in the right atrium
    • Injection of contrast via the leg may increase the sensitivity of the test as most shunting occurs via the IVC
  • look for other underlying causes


  • Closure of the ASD or PFO
    • temporary closure by balloon occlusion
    • permanent occlusion by open surgery or percutaneous intervention
  • Treat any associated condition, examples include:
    • A case associated with Parkinson’s disease was attributed to postural hypotension and improved with fludrocortisone
    • A case associated with radiation-induced bronchial stenosis was relieved by bronchial dilation initially, and later by bronchial stenting
    • A case associated with bilateral thoracic sympathectomy (van Heerdon 2004) was treated initially with noradrenaline and almitrine

  • Cheng TO. Mechanisms of platypnea-orthodeoxia: what causes water to flow uphill?. Circulation. 2002;105(6):e47. [article]
  • Cheng TO. Platypnea-orthodeoxia syndrome: etiology, differential diagnosis, and management. Cathet Cardiovasc Interv. 1999; 47: 64–66. PMID: 10385164 [article]
  • Jacob L, Bonnet F, Pavie A, et al. Severe hypoxemia revealing traumatic tricuspid regurgitation with right-to-left intracardiac shunt. J Trauma. 1985;25(7):659-61. PMID: 4009773
  • Lee CH, Cheng ST. Shortness of breath while sitting up: hepatopulmonary syndrome. CMAJ. 2011 Jan 11;183(1):80. PMC3017258.
  • Ptaszek LM, Saldana F, Palacios IF, M Wu S. Platypnea-Orthodeoxia Syndrome in Two Previously Healthy Adults: A Case-based Review. Clin Med Cardiol. 2009 Apr 9;3:37-43. PMC2872575.
  • Salvetti M, Zotti D, Bazza A, Paini A, Bertacchini F, Chiari E, Coletti G, Rosei EA, Muiesan ML. Platypnea and orthodeoxia in a patient with pulmonary embolism. Am J Emerg Med. 2013 Apr;31(4):760.e1-2. PMID: 23380102.

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Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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