ABSTRACT
Objective To investigate the effects of limited resuscitation on hepatic ischernia-reperfusion in-jury in rots with hemorrhagic shock. Method Uncontrolled hemorrhagic shock was induced in 54 rats by transect-ing the middle branch of the splenic artery to produce standardized massive splenic injury. Resuscitation started when the mean arterial pressure (MAP) reached 40 mmHg. The rats were randomly divided (n = 9per group) in-to sham-operated group (SS), or one of five treatment groups in which infusion of Ringer' s solution was continually administrated to maintain MAP at 40 (RS40), 50 (RS50), 60 (RS60), 80 (RS80) or 100 mmHg (RS100) for 45 minutes (T45 point). After the bleeding was controlled, resuscitation was continued with Ringer's solution and whole blood (2:1) to increase the MAP to 100 mmHg for 120 minutes (T165 point), which was followed by obser-vation for 240 minutes (T405 point). All animals were observed for 240 minutes or until death. Blood specimens were collected at TO, T45, T165 and T405 for determination of blood lactate levels. At the end of the experiment,a small amount of hepatic tissue was collected to measure tissue blood perfusion, total antioxidative capacity (TAOC), Na+K+ ATPase activity and malondialdehyde (MDA) levels. Results At T405, the blood lactate lev-els in the RS80 and RS100 groups [(3.60±0.68) and (3.84 ± 1.09) mmol/L, respectively] were significantly higher than those in the SS, RS40, RS50 and RS60 groups [(2.00±0.66),(2.74±1.45),(2.43 +0.94) and (2.07±0.95) mmol/L, respectively;all:P < 0.05]. The MDA levels were significantly higher in the RS80 and RS100[(7.32±0.31) and (7.71±0.23) nmol/mg,respectively] than those in the SS, RS40, RS50 and RS60 groups[(4.95±0.80),(6.14±0.94),(6.42±0.48) and (6.84±0.36) nmol/mg, respeetively;all: P <0.05]. The Na+ K+ ATPase and TAOC levels were significantly lower in all of the RS groups than those in the SS group (all: P < 0.05), and those in the RS80 and RS100 groups was significantly lower than those in the RS40,RS50 and RS60 groups (all: P <0.05). Blood perfusion in the RS80 and RS100 groups was significantly lower than that in the other groups (all: P < 0.05). Conclusions If hemorrhage is uncontrolled, limited resuscitation appears to balance the needs for organ perfusion, improve the microcircttlation and decrease lactate levels. Fur-thermore, limited resuscitation could decrease ischemia-reperfusion injury in liver tissue.