The Effects of Increasing Aortic Occlusion Times at the Level of the Highest Renal Artery (Zone II) in the Normovolemic Rabbit Model

The purpose of this study was to evaluate the effects of increasing zone II resuscitative endovascular balloon occlusion of the aorta (REBOA) occlusion times on physiological, end-organ and inflammatory responses in rabbits to assess the safe aortic occlusion time in a normovolemic rabbit model.The zone ll aorta was occluded with a balloon in 32 rabbits (8 animals each for 15, 30, 60, and 90 min). 8 rabbits served as a control. ELISAs were used to examine the serum levels of ALT, AST, Cr, BUN, MDA, SOD, IL-8, IL-6, and TNF-α; HE staining was used to identify the morphological changes in the kidney; RT-PCR was used to detect the mRNA levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus; and Western blotting was used to measure the protein expression levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus.Plasma concentrations of liver markers, kidney markers, inflammatory factors and oxidative stress indicators were significantly increased at the end of reperfusion in the 30 min, 60 min and 90 min groups. Damage to the kidney occurred in the 30 min, 60 min and 90 min groups. The mRNA and protein expression levels of IL-6, IL-8, TNF-α and NF-κB in the kidney and uterus were significantly increased at the end of reperfusion in the 30 min group, and as the time of occlusion extended, these levels continued to increase.Activation of systemic inflammation and ischaemia-reperfusion injury of end-organs occurred when the occlusion time reached 30 min. Therefore, 15 min should be regarded as a safe period of REBOA in zone II.