Proposed mechanism of pulmonary gas trapping (PGT) following intravenous perfluorocarbon emulsion administration.

Purpose: To investigate various hypotheses and identify the most likely mechanism preventing the complete collapse of test animal lungs at sacrifice subsequent to intravenous injection of certain perfluorocarbon emulsions.

Protocol: Literature data were reviewed, experimental data were extracted from completed studies and new data were generated in an attempt to delineate reasons why, in certain animals, lungs fail to collapse normally at necropsy if previously injected with certain perfluorocarbon emulsions. The proposed hypothesis involved gas osmosis through endogenous pulmonary surfactant-liquid bridges (micro-bubbles).

Results: The observed effect of incomplete lung collapse upon necropsy was found to correlate with perfluorocarbon vapor pressure. Results indicated that failure to collapse could be attributed to the formation of intra-alveolar micro-bubbles induced by the normal pulmonary elimination of perfluorocarbon vapor. These micro-bubbles result in a phenomenon which could be characterized by the term, pulmonary gas trapping. Reduction of the perfluorocarbon concentration gradient across the bubble films by exposure to a perfluorocarbon vapor-containing atmosphere was found to reduce the effect in-vivo and prevent gas osmosis bubble growth in-vitro.

Conclusion: Experimental observations are consistent with the proposed theory of perfluorocarbon-related gas osmosis through micro-bubbles that prevent complete lung collapse as observed upon opening the thoracic cavity of test animals.