A comparative study of the effects of spontaneous ventilation versus one-lung mechanical ventilation on ipsilateral lung injury during thoracic surgery: an empirical analysis based on a rat model.

Background: One-lung ventilation (OLV) is prone to adverse reactions, particularly ventilator-induced lung injury (VILI). Spontaneous ventilation (SV) is supposed to reduce this risk. To investigate the effects of the ventilated lung during surgery, we established a rat model for research. Methods: Forty-two rats were randomly divided into 7 groups: control, OLV, and SV [OLV/SV group was subdivided into 3 time points (10, 20, 30 min)]. Blood gas analysis, bronchoalveolar lavage fluid (BALF) test, and lung tissue wet-to-dry ratio were performed. Hematoxylin and eosin (HE), Masson and immunohistochemical for tumor necrosis factor-α (TNF-α) examinations were conducted. Results: At 30 minutes of ventilation, compared to the OLV group, the SV group had higher arterial oxygen partial pressure and lower carbon dioxide partial pressure (P<0.05). Moreover, the wet-to-dry ratio in the OLV group significantly exceeded that in the SV group (P<0.01). Results from BALF, HE and Masson staining all indicated that the inflammatory response induced by OLV was stronger than that of SV. Based on HE staining, quantitative analysis of bronchial inflammation in the ventilated lung of each group showed that the degree of terminal bronchiole injury (P<0.0001), alveolar capillary congestion, and inflammatory cell infiltration (P<0.01) were more severe in the OLV group compared to the SV group. Additionally, in the immunohistochemical staining measurement of TNF-α, the expression level of TNF-α in the OLV group was higher than that in the SV group. Conclusions: Based on the rat model in this study, we can infer that during unilateral open pneumothorax surgery, with 30 minutes of ventilation, lung injury caused by OLV is more severe than that caused by SV in the ventilated lung.