The impact of performing spirometry on shunting across a patent foramen ovale

Ian Maddox, David Smart, Warrick Bishop

Research output: Contribution to journalArticlepeer-review


Transient changes in intrathoracic pressure can alter left and right intra-atrial pressures, and may provoke shunting of blood across a patent foramen ovale (PFO). Spirometry causes a transient rise and subsequent fall in intrathoracic pressure that, if performed following a dive on compressed air, could raise the risk of decompression illness by arterialisation of venous bubbles across a PFO. To assess whether spirometry can provoke right-to-left shunting across a patent foramen ovale, a subject with a known PFO, previously identified by bubble contrast transthoracic echocardiography, where shunting was only evident on performing a Valsalva manoeuvre, underwent re-examination whilst performing spirometry. Right-to-left shunting was not evident at rest, but was provoked by performing spirometry. If spirometry is to be performed within two hours of surfacing, this should be regarded as a potential risk for decompression illness.
Original languageEnglish
Pages (from-to)213-215
Number of pages3
JournalDiving and Hyperbaric Medicine
Issue number4
Publication statusPublished - Dec 2009


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