Immersion pulmonary oedema

Pulmonary oedema of immersion is a rare complication of scuba diving. A case and brief discussion of the differential diagnosis and pathophysiology are presented. Onset of symptoms typically occurs during the dive, and is characterized by dyspnoea, cough and frothy sputum. Spontaneous recovery frequently occurs once the diver leaves the water. If investigated, the findings are of hypoxaemia and chest X-ray changes typical of pulmonary oedema. The differential diagnosis includes decompression illness, pulmonary barotrauma, near drowning, salt water aspiration syndrome and non-diving causes of pulmonary oedema. The condition may be precipitated by the increase in pulmonary capillary hydrostatic pressure that occurs on immersion, coupled with the imposition of a pressure gradient between mouth pressures and hydrostatic pressure at the chest in the upright diver, and the imposition of more negative intra-alveolar pressures during breathing of a denser gas or from a poorly tuned regulator. Divers with heart disease, hypertension, or taking negative inotropic agents may be at greater risk.