The effect of oxygen at high pressure on the mechanical properties on pathogen free rat lungs

The effect of OHP on pathogen-free rat lungs was studied. All experiments, except one at 5 ata., were done with OHP at 4 ata. Both lung-thorax and isolated lung preparations were used. No changes in the static pressure-volume curves were seen, indicating that the pulmonary alveolar surfactant had not changed at this point early in the evolution of pulmonary oxygen toxicity. Any surfactant effect must be small and terminal. A large decrease in resistance to air flow ten minutes after gasping in OHP at 4 ata, was seen, both in isolated and lungs in the intact chest. This decrease was not due to pressure alone, but is probably due to bronchodilatation, and is accompanied by a shift to the left of the static inflation pressure-volume curve of isolated lungs