Objective To compare the effects of different pressure on early resuscitation of rats with uncontrolled hemorrhagic shock (UHS).   Methods UHS was induced by transecting a branch of splenic artery. Forty-eight Sprague-Dawley rats were divided into 6 groups (n=8 in each group) according to different early resuscitation pressure: non-resuscitation control group

40  mmHg group

50  mmHg group

60  mmHg group

70  mmHg group and 80  mmHg group. When the mean arterial pressure (MAP) reached 40  mmHg after injury

hypotensive resuscitation was done to maintain MAP at different level in each group for 1 h with lactated ringer’s solution plus hydroxyethyl starch (2∶1). No fluid was infused at this stage in control group. Then the splenic artery was ligated

and animals in all groups received all-out resuscitation for 2 h. Hemodynamic parameters

blood loss

hematocrit

blood gas values

hepatic biochemical parameters and survival time were monitored.   Results Blood loss in 60

70 and 80  mmHg groups was significantly higher than that in the other 3 groups. Survival time of 50  mmHg group was significantly longer than that of control and 80  mmHg groups. Hemodynamic parameters in 40

80  mmHg groups were worse than those in 50

60 and 70 mmHg groups. Acidosis in 70 and 80  mmHg groups was less severe than that in 40  mmHg group. Hematocrit in 40-60  mmHg group was significantly higher than in  80  mmHg groups. Hepatic biochemical parameters in 40  mmHg group were significantly higher than those in 50

60 and 70  mmHg groups.   Conclusion In early resuscitation after UHS

high pressure increases blood loss and shortens survival time

but low pressure restrains cardiac function and aggravates liver damage. So 50-60  mmHg is the appropriate pressure.