The Effect Of Hypotensive Resuscitation Combined With Polydatin On Microcirculation In Uncontrolled Hemorrhagic Shock Of Pregnant Rabbit

Massive obstetric hemorrhage is a major cause of matemal death and morbidity; abruptio placentae,placenta praevia and postpartum hemorrhage being the main cause.The main goals of resuscitation are to stop the source of hemorrhage and to restore circulating blood volume.Four issues should be considered when treating hemorrhagic shock:type of fluid to give,how much,how fast,and what the therapeutic end-points are.The ideal fluid for resuscitation has not been established. The three-to-one rule has been applied to the classification of hemorrhage to establish a baseline for guiding therapy.However,recent data question the practice of initial aggressive resuscitation of hemorrhagic shock.Non-pregnancy animal models suggests that excessive fluid resuscitation can be lethal when severe hemorrhage is not present.Our former uncontrolled hemorrhagic shock model of pregnant rabbits demonstrated the consistent finding:hypotensive resuscitation to MAP of 60 mmHg with Ringer's solution ameliorate metabolic derangement,and improve long term survival compared with aggressive fluid resuscitation to MAP of 80mmHg or delayed fluid resuscitation until the surgical controlled of bleeding.Polydatin is extracted from a traditional Chinese herbal medicine,Polygonum cuspidatum,3,4',5 trihydroxystibene-3-monoglucoside,and has a special effect in shock treatment in terms of improvement of heart function and microcirculatory insufficiency.OBJECTIVEWe sought to test the efficacy of hypotensive resuscitation with Ringer's solution combined with polydatin on hemodynamic parameters,peripheral microcirculation and long-term survival in a clinically relevant model of uncontrolled hemorrhagic shock in pregnancy.METHODS30 anesthetized New Zealand white rabbits at 15—25 days' gestational age were fitted with a ear chamber window and underwent uncontrolled hemorrhagic shock by transecting a small artery of diameter 3-5 mm in mesometrium,followed by bleeding via femoral artery to mean arterial pressure(MAP) of 40-45mmHg.The experiment consisted of three phases,shock phase(0-30min),simulated prehospital resuscitation phase(30-90min) and simulated hospital resuscitation phase(90-180min).Animals were randomly divided into three groups(n=10 per group);Groupâ… ,hypotensive resuscitation in the prehospital phase with bolus dose of 4ml/Kg of normal saline followed by Ringer's solution to MAP of 60 mmHg(NS);Groupâ…¡,Thirty minutes after hemorrhage induction,animals received a single volume infusion of 4ml/Kg (2mg/Kg) of polydatin followed by hypotensive resuscitation with Ringer's solution to MAP of 60 mmHg(PD30);Groupâ…¢,hypotensive resuscitation in the prehospital phase with Ringer's solution to MAP of 60 mmHg followed by a single volume infusion of 4ml/Kg(2mg/Kg) of polydatin at sixty minutes after hemorrhage induction(PD60).Finally,in the hospital resuscitation phase,animals in groupâ… ,â…¡andâ…¢received hemorrhage controlled and fully resuscitated with half of the heparinized shed blood and Ringer's solution to MAP of 80mmHg.At T180min,the laparotomy incision was reopened,and free intra-abdominal blood was collected on preweighed pieces of cotton.The amount of blood loss was determined by the difference in wet and dry weights.The cannulas were then removed from the animals after ligation of the femoral artery,femoral vein and small artery in the mesometrium, the incisions were closed.The animals were placed in a caged with food and water and observed for 7 days survival.Hemodynamic(MAP) and microcirculatory (arteriole and venule diameter,functional capillary density) parameters were continuously monitored,Blood samples for hematocrit(Hct),lactate,pH,base excess (BE),Po2,Pco2 were taken at baseline,the end of shock phase,prehospital resuscitation phase and hospital resuscitation phase.RESULTSHemodynamic parametersMAP of the rabbits before hemorrhage was 96±5 mmHg and declined to 41±2 mmHg during shock,a level maintained for 25 minutes.Immediately after polydatin infusion,the MAP of PD30 group recovered to 65±2 mmHg,which was significantly higher than the NS group(60±3mmHg) and PD60 group(61±2mmHg),and remained at that level for about 15 minutes.After that,MAP was gradually decreased to 55±2 mmHg,then we began fluid resuscitation with Ringer's solution to target MAP of 60 mmHg in prehospital phase.While 60min after hemorrhage,animals in PD60 group received bolus infusion of 4 ml/Kg of polydatin, keep relatively higher MAP after that,increased to 70±2 mmHg after 15 min and remained above 60mmHg until the end ofprehospital resuscitation phase.Blood loss,infused volume and HctControlled blood withdrawl volume via the femoral artery for induction and maintenance of shock was not significantly different among groups and varied between 20±2.3 ml per kilogram of body weight.The uncontrolled intra-abdominal blood loss and subsequent infusion volume required to reach target MAP in the PD60 group(2.7±0.3 ml/Kg,30.0±3.3 ml/Kg) were significantly lower than that in PD30(3.4±0.4,40.1±3.7ml/Kg) and NS group(3.8±0.4,44.5±3.9ml/Kg),there was also a difference between PD30 and NS group in both intra-abdominal blood loss volume and infusion volume(P＜0.05).All groups showed a significant reduction of Hct after hemorrhagic shock(32.2±2.3%for baseline,23.3±2.4%after shock).Resuscitation further decreased to HCT in a similar slow level in NS(18.7±2.3%) and PD30(20.5±2.9%) group at the end of hospital resuscitation,which were significantly lower than PD60 group(22.3±2.5%)(P＜0.05).Blood gas parameter and Lactate level30 minutes hemorrhagic shock period induced typical hyperventilation in all the groups,with Po₂ increased to 106.4±7.4 mmHg and Pco₂ decreased to 28.2±3.5 mmHg respectively at the end of the shock period when compared with 82.2±5.6 and 36.5±5.2 mmHg at baseline.There was significant metabolic acidosis as shown by the decreased in pH from 7.41±0.03 to 7.32±0.05 and the decreased in BE from 5.6±0.3 to 2.0±0.3 mmol/L and lactate increased from 1.4±0.2 to 6.3±0.8 mmol/L.After resuscitation,all the groups tended to recover from the hyperventilation as evidenced by decreased Po2 and increased Pco2 level compared with corresponding values in hemorrhagic shock period.However,except PD60group,Po₂ and Pco₂ value recovered to baseline value at the end of hospital phase,the other two groups remained slightly hyperventilated at all time points with significant differences in comparison with baseline values.Although,lactate tended to decrease,and pH,BE value tended to increase at the end of hospital resuscitation phase in all the groups compared with shock period(P＜0.05),all of which had not recovered.However,in PD60 group,lactate was significantly lower,while BE and pH value were significantly higher than corresponding values in the other two groups.Microvascular responses to hemorrhage and fluid resuscitationHemorrhagic shock resulted in a similar and significant constriction of arterial diameter(0.64±0.06 of baseline) and venule diameter(0.76±0.08 of baseline). After resuscitation,arteriole diameter in all the groups were increased and reached significant difference among three groups,from the highest to lowest value is PD60 (0.93±0.06),PD30(0.82±0.10) and NS(0.71±0.01) respectively.Although all groups tended to recover from venule constriction after resuscitation to 0.87±0.07 of the baseline values;these changes,however,remained significantly lower than baseline values and did not reach significant difference among groups. Hemorrhagic shock also caused a significant reduction of FCD in all animals with values being lowered to 42.8±6.7 of baseline.Although resuscitation increased FCD in all animals relative to the shock period,normal values could not be reestablished.At the end of hospital resuscitation,FCD levels were 58.8±5.6% (NS),69.9±5.0%(PD30),93.4±7.7%(PD60) relative to baseline,respectively, with significant differences between groups.All the groups were remained at significantly lower values than the baseline values.Survival timeMedian survival time in PD60(4.2±0.6 days) was significantly longer than PD30(2.6±0.3 days) and NS(2.3±0.2 days) group(P＜0.05).CONCLUSIONCompared with hypotensive resuscitation alone,the later combination with polydatin stabilize macro-circulation and improve microcirculation insufficiency simultaneously,finally prolong survival time in uncontrolled hemorrhagic shock model of pregnant rabbit.SUMMARY1.We established clinically relevant model which mimic uncontrolled hemorrhagic shock in pregnancy and test the efficacy of hypotensive resuscitation with Ringer's solution combined with polydatin on hemodynamic parameters, peripheral microcirculation and long-term survival.A principal finding of our study is that compared with hypotensive resuscitation alone,the later combination with polydatin stabilize macro-circulation,improve microcirculation,and prolong survival time.For this reason,it is reasonable to conclude that the combination of hypotensive resuscitation with later polydatin injection maybe a better resuscitation strategies during the prehospital phase when surgical controlled of bleeding is impossible. Due to small sample size,the effects on major organ perfusion and inflammatory response remain unknown and need to be further studied.2.Elucidate the mechanism of superiority of hypotensive resuscitation combined with later polydatin injection in uncontrolled hemorrhagic shock in pregnancy. â‘ modest increase in blood pressure in prehospital phase reduces blood loss and total fluid requirements,which might attenuates the derangement of internal enviroment;â‘¡prevents severe hemodilution,maintains proper Hct,enhances systemic oxygen delivery,which benefits for further resuscitation;â‘¢improve microcirculatory insufficiency as indicated by the dilation of arteriole and venule diameter and enhancement of FCD,which results in better tissue perfusion;â‘£alleviates hyperventilation and metabolism derangement as present by attenuate the increase of lactate and the decrease of pH and BE,resulting in higher survival rate.In summary,we elucidate the efficacy and mechanism of hypotensive resuscitation combined with polydatin in a rabbit of uncontrolled hemorrhagic shock in pregnancy.