Sheep Lung Injury Model Used to Study Effect of Vaporized Perfluorocarbon. Hübler et al. (page 1414)
After inducing lung injury in nine anesthetized sheep with oleic acid injection, Hübler et al. randomized the sheep to one of two ventilation protocols. Animals in the treatment group (n = 4) were ventilated for 30 min with vaporized perfluorocarbon using a modified isoflurane vaporizer. The remaining animals (n = 5) served as controls. The multiple inert gas elimination technique was used to assess gas exchange at five time points during the experiments: at baseline, at time of oleic acid–induced injury, and at 30, 60, and 120 min after injury. Exhaled gas specimens were collected and maintained at a temperature of less than 40°C before analysis to avoid condensation. Concentrations of inert gases were measured using gas chromatography.
Changes in relative pulmonary blood flow (Q̇rel) were assessed using fluorescent-labeled microspheres injected at the same time intervals as gas specimen measurements. The sheep were killed at the conclusion of experiments, and their lungs were excised, dried, and coated with foam to facilitate core slicing. Samples were then examined for presence of fluorescence using a luminescence spectrophotometer. Animals treated with perfluorocarbon vapor showed improved gas exchange by a higher ventilation/perfusion ratio than the control animals. The microsphere data revealed a redistribution of Q̇reldue to oleic acid injury. The Q̇relshifted from initially high-flow areas to areas that had been low-flow, and this was true of both experimental and control group animals. After lung injury, Q̇relin the control animals was redistributed to the nondependent lung areas, whereas in the animals receiving perfluorocarbon, there was no change in Q̇relredistribution.