A comparative study on morphologic and functional changes in lung after cryoablation or radiofrequency ablation for liver tissue in rats

Abstract

Objective To compare the morphologic and functional changes in lung after cryoablation(CA)or radiofrequency ablation(RFA)for liver tissue in rats.Methods In this study,seventynine Sprague-Dawley rats were randomized into 2 groups.Rats in group A(n= 47)was treated with cryoablation by liquid nitrogen,which was performed in 15～20 s.Animals in group B(n= 32)was treatment with RFA by using a cooled-tip technique.The energy output was 15 W×(60～90)s.All rats were sacrificed at prescheduled time and then the serum and tissue samples from the lung were collected for subsequent analysis.Serum concentrations of tumor necrosis factor-α(TNF-α)and interleukin-8 (IL-8) were measured by enzyme-linked immunosorbent assay(ELISA) before and 1,3,6,and 24 h after ablation.Histological features of lung tissue and death in early stage were compared between the 2 groups.Results In group A,serum TNF-α and IL-8 levels were markedly increased in rats 1 h after hepatic ablation as compared with group B(P＜0.01,group A vs B).They peaked at 3 h and returned to baseline after 24 h.Histologic lung sections after cryoablation showed local parenchymal hemorrhage and multiple foci of perivenular inflammation,with activated foamy macrophages and neutrophils.In animals undergoing RFA,inflammation foci were slight.In addition,cryoablation of liver resulted in a 25.5% mortality rate within 48 h of treatment,whereas 5.4% treated in RFA group(P＜0.05).Conclusion Hepatic tissue cryoablation results in a series of severe side effects including acute lung injury and high mortality.However,an approximate volume of liver parenchyma undergoing RFA induces a light impact,which could be a safe therapy for liver tumor. Key words: Cryosurgery; Radiofrequency ablation; Acute lung injury