PFO is not uncommon in the adult population. In
situations where right sided pressure exceeds the left
sided pressure, the right to left intracardiac shunt may
result in hypoxemia. Hypoxemia is common in post
cardiac surgical/cardiology patients and is either due
to respiratory dysfunction or congestive heart failure.
We conclude that TOE is a vital investigating tool,
which should be considered early for the diagnosis
of suspected postoperative hypoxemia refractory to
oxygen therapy.