Spontaneous One-Lung Ventilation Increases the Lung Inflammatory Response: An Experimental Pilot Study

Study objective: The purpose of this study was to investigate if spontaneous one-lung ventilation would induce any type of inflammatory lung response when compared to spontaneous two-lung ventilation and its intensity, by quantification of inflammatory cells in lung histology at the end of the procedure. Design: In vivo prospective randomised animal study Setting: University research laboratory Subjects: New Zealand rabbits Interventions: Rabbits (n=20) were randomly assigned to 4 groups (n=5 each group). Groups 1 and 2 were submitted to one-lung ventilation, during 20 and 75 minutes respectively; groups 3 and 4 were submitted to two-lung ventilation during 20 and 75 minutes and considered controls. Ketamine/xylazine was administered for induction and maintenance of anesthesia. One-lung ventilation was achieved by administration of air into the interpleural space, and left lung collapse was visually confirmed through the centre of the diaphragm. Measurements: Lung histology preparations were observed under light microscopy for quantification of the inflammatory response (light, moderate and severe). Main results: All subjects had at least light inflammatory response. However, rabbits submitted to one-lung ventilation had a statistically significant value for the occurrence of moderate inflammation (p<0.05). The inflammatory response found included mainly eosinophils, with an average proportion of 75/25 to other polymorphonuclear cells. No differences between groups were found regarding gas exchange, heart rate and respiratory rate. Conclusions: In this spontaneous one-lung ventilation model, lung collapse was positively associated with a greater inflammatory response when compared to normal two-lung ventilation