Lung Protection By Perfusion With Hypothermic Protective Solution To Pulmonary Artery During Cardiopulmonary Bypass

Objective: To study lung protection by perfusion with hypothermic protective solution to the pulmonary artery during cardiopulmonary bypass.Methods: Twenty-seven cases undergoing mitral valve replacement (MVR) were randomly divided into lung protective group (n=12) and control group(n=15). Hypothermic protective solution was infused to the main pulmonary artery in the protective group, and Sodium Chloride was infused to the main pulmonary artery in the control group. Patients'lung functions were monitored. Concentrations of plasma malondialdehyde (MDA), tumor necrosis factor-α(TNF-α) and interleukin-6(IL-6) were measured at different time point before and after cardiopulmonary bypass; Lung biopsy specimens were obtained after operations to study histological changes.Results: The oxygen index was higher in the lung protect group than that in the control group at 0h, 6h, 12h and 24h after CPB (t = 6.296, p < 0.01; t = 4.502, p < 0.01; t = 6.197, p< 0.01; t = 2.390, p< 0.05 respectively). In both groups, compared with the baseline values, plasma levels of MDA, IL-6 and TNF-αwere gradually increased after CPB. However, compared to the control group, the level of MDA was lower in the lung protective group at 0h, 6h, 12h and 24h after CPB (t = - 6.238, p < 0.01; t = - 6.352, p < 0.01; t = - 5.368, p < 0.01; t = - 2.834, p < 0.01 respectively). The level of IL-6 was lower in the lung protective group than in the control group at 0h, 6h, 12h and 24h after CPB (t = - 6.853, p < 0.01; t = - 6.082, p < 0.01; t = - 2.227, p < 0.05; t = - 3.035, p < 0.01 respectively). The level of TNF-αwas lower in the protective group than that in the control group at 0h, 6h, 12h and 24h postoperatively (t = - 9.667, p < 0.01; t = -13.59 , p < 0.01 ; t = - 9.85 , p < 0.01; t = - 4.846 , p < 0.01 respectively). Histologic analyses showed intra-alveolar edema, capillary hyperemia and neutrophil accumulated in the control group, whereas no significant changes in the lung protective group.Conclusions: (1) CPB could induce the increasing of MDA, IL-6 and TNF-αlevels in patient's plasma after heart surgery; (2) Hypothermic protective solution perfused through pulmonary artery can significantly inhibit the increasing of MDA, IL-6 and TNF-αlevels in plasma after CPB and reduce the pathological changes in lung, so pulmonary artery perfusion with hypothermic protective solution during CPB demonstrates the effects of lung protection.