IPE is the abnormal leakage of fluid from the bloodstream into the alveoli, the microscopic air sacs in the lungs. Symptoms include shortness of breath, coughing up bloody sputum, and respiratory distress. Leakage into the alveoli results in fluid buildup in the lungs, and interrupts gas exchange, similar to drowning. It is important to note that fluid resulting from IPE comes from within the body, rather than from inhalation of surrounding water.

However you define your expedition it is important to recognize that once you begin planning it you have crossed out of the realm of normal recreational or technical and entered a world that requires serious oversight, preparation, and risk mitigation. Expedition diving does not have to be technical or extreme – a recreational diving trip to a destination like Truk Lagoon could put you hours or days away from the nearest medical help and require expedition level preparations for medical treatment and evacuation.

Modern discussion has led to a wide variety of recommendations on the topic from a number of sources, leading to some confusion. While some agencies and physicians recommend diving conservatively with a known PFO, others recommend surgical closure, and still others advise that there may not be a benefit to closure and that divers should just be aware of their condition.