Role of lung surfactant in cerebral decompression sickness

Five dogs have been embolized by air infusion into the venous system, then sacrificed and the pulmonary vasculature isolated by ligatures while ventilation was maintained for a further hour. In a sixth animal, the embolization was omitted. The lungs were back-perfused with plasma from the same dog and successive aliquots of the back-flushings analysed by thin-layer chromatography (TLC), each spot being removed for phosphorus determination. The results showed that the major lipid component was the phosphatidyl cholines, while lysophosphatidyl cholines, phosphatidyl ethanolamines, and sphingomyelins were also identified in significant quantities. A phosphorus balance for the lungs showed a significant migration of phospholipids from the tissue into pulmonary blood, phosphatidyl cholines increasing by a factor of 10.6. This migration of surfactant is discussed as an important factor in determining whether trapped pulmonary air emboli are released into the arterial system when their surface area is reduced by pressurization, suggesting that recompression should not be too rapid.