Immersion pulmonary oedema (IPO) was previously thought to be rare or present only in older divers with health complications, but new data shows that IPE can affect divers who are young and healthy, making this serious condition a hot topic for hyperbaric medical researchers.
What is IPO and who is susceptible?
A condition experienced by divers and swimmers, immersion pulmonary oedema (IPO) is the sudden development of fluid in the lungs. IPE was first reported in 1989 and was originally thought to occur only in cold water. However, cases in warm water have since been reported, too.
IPO is uncommon, and the causes of this condition are still not fully understood. Although IPO generally resolves quickly, respiratory distress in divers is very dangerous. As with many other health conditions in diving, it’s imperative to learn the signs.
Symptoms
Like drowning, IPO is the buildup of fluids in the air-containing spaces of the lungs, interrupting breathing. But unlike drowning, the obstructing fluid comes from within the body rather than from inhalation of surrounding water. The obstructing fluid results from abnormal leakage from the bloodstream into the microscopic air sacs within the lungs (alveoli). This can be the result of heart failure or other cardiac problems, but IPE can also manifest in people for no apparent medical reason. Symptoms include coughing, shortness of breath, and sometimes bloody and frothy phlegm.
Unlike pulmonary decompression sickness (“the chokes”), chest pain is not a symptom of IPO.
Cases cover the spectrum of mild to severe and are analysed based on factors including diver age, water temperature, and previously existing cardiac conditions. Once the diver leaves the water, there is often spontaneous recovery, however, sometimes diuretics — standard treatment for pulmonary oedema — are needed. And IPO is not depth-dependent; it can occur even in very shallow water. If symptoms occur during a dive, the affected person should communicate with their buddy and end the dive as quickly and safely as possible. Once safely out of the water, the diver should be provided oxygen if respiratory distress or any other symptoms persist, their exertion should be limited, and they should be evaluated by a doctor.
Return to Diving
Experiencing IPO does not disqualify someone from participating in future dives, but caution going forward will be necessary. A return to diving should be based on full recovery from a previous episode, a diver’s physical condition and medical history, their doctor’s evaluation, and the type of diving they intend to do. A return to diving should be considered on a case-by-case basis.
A younger diver with no history of cardiac problems who developed a mild case of IPO should not be disqualified from future dives, however, if IPO symptoms ever develop again, more extensive evaluation may be warranted before any return to diving. For divers with medical conditions who developed severe IPO and needed hospitalisation, further cardiac evaluation may be needed before they are permitted to return to diving. A doctor may want to look for underlying artery blockages or heart valve issues. Anyone who experiences recurrent episodes of IPO should probably stop diving.
Mysterious IPO
It is still unclear why some individuals are more susceptible than others to IPO. While there may be a link to cardiovascular conditions or hypertension, there are numerous scenarios in which a diver has experienced IPO without any apparent underlying conditions. Until individual susceptibility is better understood, it’s too difficult for doctors to make recommendations as to how it can be avoided.
Hopefully, future research can reveal more about its causes, and doctors can better predict who is at an increased risk of developing it. Because it can happen in the absence of underlying conditions, all divers need to be aware of this condition so symptoms can be recognised and appropriate actions taken.
