Lung tolerance to hyperthermia by in vivo perfusion

In vivo isolated lung perfusion is a novel technique for targeting anticancer therapy to the lung while avoiding systemic toxicity as normal lung toxicity from the antitumour therapy becomes the limiting factor. This study was performed to investigate the effects of hyperthermia on lung function in an intact animal model in which both acute and subacute toxicity could be monitored. Dogs underwent in vivo isolated lung perfusion. A control group was perfused to a lung temperature of 37 degrees C (group 1) and two other groups were treated in an identical manner except that the perfusion temperature was 43 degrees-44.8 degrees C in group 2 and greater than 45 degrees C in group 3. An assessment of lung injury was performed pre-perfusion, immediately post-perfusion and 2 weeks post-perfusion by measurement of extravascular lung water (Qev), serotonin uptake and wet weight to dry weight ratio. Our findings showed that the lung was tolerant to hyperthermia up to about 44 degrees C for 1 h. Analysis of 4 animals who survived perfusion above 3/44.0 degrees C showed a highly significant decrease in serotonin uptake between pre- and post-perfusion values (82.4 +/- 1.2 vs 40.4 +/- 3.9, P less than 0.02); at 2 weeks serotonin uptake had returned to normal in all 3 dogs. Fulminating pulmonary oedema developed at temperatures over 45 degrees C. Serotonin uptake may be a sensitive predictor of thermal lung injury.