>almost exclusively in cold water. While
>this condition seems to be more common
>in cold water, it has also been reported
>in warm waters.
>During immersion in water, blood is
>redistributed from the legs to the heart
>and blood vessels in the lungs. Usually
>the heart and lungs compensate for this,
>but sometimes the resulting increased
>pressure within the blood vessels in the
>lungs causes fluid to traverse the small
>vessels (capillaries) and enter the gascontaining
>spaces of the lungs.
>Sometimes this is caused by an underwater
>myocardial infarction (heart attack),
>abnormalities of the heart muscle or heart
>valves or hypertension. Usually there is
>no obvious cause.
>Cold water may be a predisposing factor
>because immersion can cause the small
>arteries to constrict, increasing the
>resistance to the flow of blood. Vasoconstriction
>in response to cold can be
>exaggerated in people with hypertension
>or those likely to develop it. But some
>people who experience IPE are young
>and healthy, even military recruits.
>Immediate treatment should include
>breathing oxygen while in transit to a
>hospital. Some IPE cases have been fatal,
>although most cases resolve on their own
>during observation in a hospital. A closer
>examination may reveal hypertension,
>a heart attack, cardiac valve disease or
>impaired contraction of the heart.
>Divers who have experienced IPE are
>concerned with the likelihood it will
>recur. Unfortunately, that likelihood is not
>known, so many physicians recommend
>that people with a history of IPE not
>return to diving. Still others recommend
>taking an antihypertensive medication
>before each dive. Before considering a
>return to diving after IPE, DAN recommends
>the diver consult with a doctor
>knowledgeable about the condition.