Effect Of Acute Normovolemic Hemodilution On The Concentration Of S-100B In The Serum And Cerebral Oxygen Metabolism In The Rabbit With Cerebral Contusion

Study Background and PurposeTraumatic brain injury is one of the common and frequently-occurred diseases in neurosurgery, and the rate of fatality and disability is very high. Studies have shown that after traumatic brain injury, the body appeared a series of stress responses, one of which is the change in hemorrheology; the whole blood viscosity, plasma viscosity, red blood cells aggregation index all become increased, and the deformation of red blood cell is reduced. This change of hemorrheology is bound to affect velocity of cerebral blood flow and cerebral perfusion, especially in the case of intracranial hypertension. Therefore, the cerebral blood flow may decrease and the state of ischemia-hypoxia may worsen, leading to deterioration of traumatic brain injury and increases of secondary brain damage.Acute normovolemic hemodilution (Acute Normovolemic Hemodilution, ANH) has been proved to be an effective blood conservation measure by a large number of studies. ANH can change the hemorrheology and decrease the whole blood viscosity, plasma viscosity, erythrocyte aggregation index, fibrinogen and so on in which improves blood flow to tissues; ANH can increase deformability of red blood cell and help it go through the capillary easier, thereby improving oxygen supply to the tissues.One study reported that ANH can reduce the brain edema and secondary brain damage in the dogs with experimental traumatic brain injury but not increase the permeability of blood vessels and bleeding tendency. However, another study suggested that ANH can reduce the brain tissue oxygen tension and aggrevate brain injury. So we need to do more researches about the effect of ANH to traumatic brain injury.One of the potential adverse impacts of ANH to patients is the influence of the coagulation, and the other is the oxygen delivery to tissues. The vast majority of researches have shown that ANH does not affect the coagulation function either increase the bleeding tendency in operation. The effect of ANH to the oxygen delivery depends on the degree of hemodilution, and studies have shown that tissues oxygen delivery keeps almost stable if the Hct≥20%, and ANH does not cause hypoxia if the state of hemodynamic is stable.In this study, we established the model of focal cerebral contusion on rabbits then to apply ANH of different degrees with hydroxyethyl starch 130/0.4 to observe its effect on the concentration of S-100B protein in the serum and the brain tissue oxygen metabolism.Methods24 rabbits were randomly divided into 3 groups, control group (group C, n = 8), mild hemodilution group (group H1, n = 8), severe hemodilution group (H2 group, n = 8). Establish the model of focal cerebral contusion on rabbits according to feeney ' s method. group C was not hemodilutioned after the model was set up, H1,H2 group was hemodilutioned immediately after the model established using the hydroxyethyl starch 130/0.4 (Beijing Fresenius Kabi company) for the expansion agent. The target hematocrit (Hct) of H1, H2 group was 30%, 15%respectively. Before attact the brain tissue (T0), after two hours of the attact (T1) ,blood samples were taken from venous for measurement of blood hemorheology, S-100B protein concentration and lactate concentration, venous and arterial blood gas were also assayed.Results1. At T0, the S-100B protein concentration were similar among the groups, and the difference was not significant. At T1, the S-100B concentration were higher than preattact, and group H2 is the highest, group C was lower than group H2 , group H1 was the lowest. The difference was significant in three groups(p <0.05).2. At T0, the hemorrheology parameters were similar in three groups, the difference was not significant. At T1, parameters in the group C increased significantly, group H1 increased not obviously, and H2 group significantly decreased, the difference was significant (p <0.05).3. At T0, SjvO2, VLAC, Da-jvO2 were similar among three groups, the difference was not significant. At T1, SjvO2 were lower than preattact, and group H2 is the lowest, group C was higher than group H2, and group H1 was the highest. At T1, VLAC, Da-jvO2 were higher than preattact, and group H2 is the highest, group C was lower than group H2 , group H1 was the lowest. The difference was significant in three groups(p <0.05).Conclusion1. Two hours after traumatic brain injury, the hemorrheology parameters increased and the level of S-100B protein in the serum increased significantly, SjvO2 decreased and VLAC,Da-jvO2 increased.2. Mild acute normovolemic hemodilution(Hct=30%)can reduce blood viscosity, reduce S-100B levels in the serum and improve tissue oxygen metabolism of the brain.3. Severe acute normovolemic hemodilution(Hct=15%)can significantly reduce blood viscosity, but increase the S-100B levels in serum, and deteriorate the cerebral oxygen metabolic disorders and aggrevate the brain damage.