Experimental Study Of Hepatic And Renal Protection On Controlled Low Central Venous Pressure In Rabbits Under Hepatic Ischemia Reperfusion Injury

Objective Observing the change of controlled low central venous pressure(CLCVP) on hepatic and renal hemodynamics and function, acid-base balance of rabbits after hepatic ischemia reperfusion injury (IRI), to discuss the protection of CLCVP on liver and kidney.Methods 32 New Zealand white rabbits (male and female randomed, weighing 2.02±0.07 kg) were randomly divided into four groups(n=8 each group): control group (group C), simple CLCVP group (group L), hepatic IRI (group IR) and CLCVP combined hepatic IRI (group LIR). All rabbits were anesthetized by injected 3% pentobarbital 30 mg/kg through ear marginal vein, then intubated and mechanically ventilated. Blood pressure was measured through left internal carotid artery; Central venous pressure(CVP) was measured through right internal jugular vein. Pumped into nitroglycerin(10³0μg·kg^-1·min^-1, 3.6 mg/ml) and dopamine(30⁴0μg·kg^-1·min^-1, 4.8mg/ml) to establish the CLCVP rabbits model (CVP 4⁵cmH₂O, MAP≥80mmHg). Hepatic IRI rabbits model was established like that after subcostal incision, a microaneurysm clip was applied to the hepatic triad above the bifurcation to clamp the flow of the hepatic artery, portal vein, and bile duct. Removed the microaneurysm clip to reperfusion after 0.5 h of ischemic. Mean-envelped blood flow velocity(Vm), resistance index(RI) of hepatic and renal artery, blood flow velocity of hepatic and renal venous was monitored by color-coded Doppler sonography. Alanine transaminase (ALT), spartate transaminase (AST), creatinine (Cr), prothrombin time (PT), activated partial thromboplastin time (APTT), serum blood gas analysis, The concentrations of lactic acid (LD) were measured after anesthesia (T0) and at immediately (T₁), 0.5 h (T₂), 1 h (T3), 2 h (T4), 4 h (T5), 6 h (T6) after CLCVP modeling or hepatic reperfusion. Ultramicrostructure of liver and kidney was observed by transmission electronic microscope (TEM).Results (1) Compared with group C, it was significantly slower of blood mean flow velocity (Vm), higer of resistance index (RI) at T_1～5 of hepatic artery and T_<sub>1～4 of renal artery in group IR, and renal vein blood flow velocity of group IR was slow down at T_<sub>1～4 (P<0.05). It was significantly slower of hepatic artery Vm at T₂⁴,6, higer of hepatic artery RI at T_<sub>1～2 than group C(P<0.05). Compared with group IR, it was significantly faster at T_<sub>1～2,5 of hepatic artery and at T_<sub>1～4 of renal artery Vm, lower at T₁,3⁴ of hepatic artery and at T₂ of renal artery RI of group LIR. It was significantly faster at T₁⁶ of hepatic vein and at T_<sub>1～4 of renal vein blood flow velocity than group C (P<0.05). Compared with group IR, it was significantly faster at T_<sub>1～2,5 of hepatic artery and at T_<sub>1～4 renal artery Vm of group LIR, lower at T_1,3～4 of hepatic artery and at T₂ of renal artery RI (P<0.05). It was significantly faster at T_1～6 of hepatic vein and at T_<sub>1～4 of renal vein blood flow velocity than group IR (P<0.05). The remaining results monitored by color-coded Doppler sonography shows no significant difference (P>0.05).(2) Compared with group C, AST, ALT and APTT were significantly higher at T_1～6 in group IR and group LIR, PT was higher at T_1～6 of group IR and at T_3～5 of group LIR(P<0.05). The concentration of Cr was higer at T_1～6 in group IR than group C (P<0.05). Compared with group IR, ALT at T_1,4～6 and AST at T_1～6 of group LIR was reduced, and PT at T_1～6 and APTT at T_1～5 was slow down (P<0.05). The concentration of Cr was less at T_1～6 was increased of group LIR than group IR (P<0.05). The urine volume at T4⁶ of group IR and at T4 of group LIR was less than group C, and the urine of volume at T4 of group LIR was less than group IR (P<0.05).The remaining results of hepatic and renal function was no significantly difference (P>0.05).(3) Compared with group C, the value of pH was significantly reduced at T_<sub>2～5, the concentration of LD was increased at T_1～6 in group IR and LIR (P<0.05). It was significantly reduced at T_1～5 in group LIR than group IR (P<0.05).(4) There was no significant difference in ultramicrostructure of liver and kidney between group C and L. The damage to liver tissue was significantly ameliorated in group LIR.Conclusions (1) There is neither significant change about hepatic and renal hemodynamics and function, acid-base balance of rabbit when applied CLCVP for 6h.(2) Hepatic IRI results in hepatic and renal dysfunction, which caused by hepatic and renal perfusion disorder, metabolic acidosis hepatic and renal function.(3) CLCVP can alleviate dysfunction of hepatic and renal and acid-base imbalance after hepatic IRI. The mechanism maybe that CLCVP can alleviate blood stagnation, improve microcirculation of organ.