Pulmonary oedema of immersion.

Acute pulmonary oedema has been described in individuals participating in three aquatic activities: (i) scuba diving; (ii) breath-hold diving; and (iii) endurance swimming. In this review, 60 published cases have been compiled for comparison. Variables considered included: age; past medical history; activity; water depth, type (salt or fresh) and temperature; clinical presentation; investigations; management; and outcome. From these data, we conclude that a similar phenomenon is occurring among scuba, breath-hold divers and swimmers. The pathophysiology is likely a pulmonary overperfusion mechanism. High pulmonary capillary pressures lead to extravasation of fluid into the interstitium. This overperfusion is caused by the increase in ambient pressure, peripheral vasoconstriction from ambient cold, and increased pulmonary blood flow resulting from exercise. Affected individuals are typically healthy males and females. Older individuals may be at higher risk. The most common symptoms are cough and dyspnoea, with haemoptysis also a frequent occurrence. Chest pain has never been reported. Radiography is the investigation of choice, demonstrating typical findings for pulmonary oedema. Management is supportive, with oxygen the mainstay of treatment. Cases usually resolve within 24 hours. In some cases, diuretics have been used, but there are no data as to their efficacy. Nifedipine has been used to prevent recurrence, but there is only anecdotal evidence to support its use.