Comparative study of early liquid resuscitation in controlled and uncontrolled hemorrhagic shock

Objective To compare the effects of routine liquid resuscitation on hemorrhagic shock in uncontrolled and controlled states for exploring the strategy of liquid resuscitation. Methods Twenty-eight healthy male SD rats were randomly divided into three groups: control (n=8), controlled hemorrhagic shock (CHS, n=10), and uncontrolled hemorrhagic shock (UHS, n=10). In the CHS and UHS groups, the rats were made to bleed from the femoral artery till the blood pressure declined to 30 mmHg within 15 minutes. Thereafter, the roots of the rat tails in the three groups were cut. The trunks of the tails were ligated to stop the bleeding in the control and CHS groups, but it was not ligated in the UHS group, and no treatment was given. Imitating war condition, the animals were divided into three phases: pre-hospital period (30–90 minutes), hospital period (90–150 minutes), and recovery period (150 minutes to 72 hours). The blood pressure was maintained at 60mmHg in the pre-hospital period by transfusion. The bleeding point was ligated in the hospital period, and the blood pressure was maintained at 90mmHg by blood and fluid transfusions. In the recovery period, the observation time was maintained up to 72 hours. The mean arterial pressure (MAP), central venous pressure (CVP), heart function, blood gas analysis, hematocrit, and blood lactic acid were determined. The amount of bleeding, quantity of infusions, and survival time of animals were observed and recorded. Results Based on the design of the experiment, the MAP of rats in the CHS and UHS groups was maintained at 60mmHg and 90mmHg in the pre-hospital period and hospital period by liquid resuscitation, respectively. There was no significant difference in the MAP and CVP between the CHS and UHS groups. However, the hematocrit of the rats in the UHS group in the pre-hospital period was clearly lower than that in the CHS group. Starting from the pre-hospital period, blood lactic acid content increased continuously in the UHS group, while there was no obvious increase after the hospital period in the CHS group. The speed for increment of heart rate and maximum intraventricular pressure were clearly lower in the UHS group than in the CHS group starting from the hospital period. Acidosis and hypoxemia improved significantly in the CHS group after fluid resuscitation. However, the rats in UHS group were still in the state of acidosis and hypoxemia. The quantity of infusion fluid in the CHS group in the pre-hospital period (44.5±10.1ml/kg) was lower than that in the UHS group (74.5±11.4ml/ kg, PConclusion Compared with the controlled hemorrhagic shock group, rapid liquid resuscitation in rats with uncontrolled hemorrhage can cause an increment of blood loss, hemodilution, damage to cardiac function, and increased mortality.