Clinical Research About The Effect Of Mild Hypothermia On Platelet Aggregation And Adhesion In Perioperative Cerebral Surgery Patients

IntroductionSurgery patients often incur mild hypothermia in perioperative. The incidence of mild hypothermia is about 50% ~70% for the patients undergoing surgery. We usually regard the centre temperature in 34 ~36 degrees Centigrade as mild hypothermia on clinic. Organism usually maintains the centre temperature in 37. 0 ±0. 4℃ through body heat regulation system. The patients often take place mild hypothermia because the anaesthetic or anaesthesia method inhibited body heat regulation system. It is also/or because patients exposed in the cold environment during anaesthetizing before the operation. Hypothermia is often used in the organ protecting such as heart, brain, etc, because it can make the tissue and organ metabolic rate reduce. But it has more unfavorable impact on the other hand, such as cool response, delay revive after surgery, the resistance of infection decrease, intention delay and coagulation disorders etc.The changes of the patients are comparatively complicated during perioperative period. Many factors such as different general state, different duration, blood loss, blood or fluid transfusion and temperature etc may affect the function of blood clotting. Some studies indicated that hypothermia could induce coagulation disorder, especially in traumatic patients. And coagulopathy resulted from hypothermia is also one of important factors that caused traumas patients dead. Hypothermia affected on coagulation function has already aroused the attentions of people gradually. Some researches on abroad had certificated that enzyme activity slowed, platelet activity altered, but fibrinolysis was not significantly affected in hypothermia patients. However, these researches were majority focused on moderate or deep hypothermia that core temperature is below 33 degreesCentigrade. The clinic studies on mild hypothermia affected coagulation function were few. The relevant report about the effect of hypothermia on the function of blood coagulation in domestic is none at present. Therefore, we tried to find whether to maintain the normal body temperature will improve blood coagulation in order to prevent latent blood loss in surgery.We used turbidity method and glass ball method to monitor blood platelet aggregation and adhesion of cerebral surgery patients undergoing mild hypothermia in perioperative. The study can offer more effective guidance for anaesthetize and perioperative manage.Materials and methods1. General materialsThirty patients undergoing neurosurgery by general anesthesia were randomly divided in two groups;hypothermia ( H, n = 15 ) and warm - up ( W, n = 15). ASA I — II, all of the patients' cardiac, pulmonary, hepatic and renal functions were normal. And bloods clotting functional examinations were normal. No thromboembolic disease, no hemorrhagic tendency or hemorrhage recently. All of patients did not take medicine that could affect blood platelet function, such as Aspirin, Dipyridamole etc, in three months before the operation, and did not need blood donor in the operation.2. Anaesthesia methodTwo groups of patients were intramuscular injection Phenobarbital 0. lg, Atropine 0. 5mg in 30 minutes before anaesthesia. General anesthethesia was induced by Midazolam 2mg, Fentanyl 5|xg * kg'1, Diprivan 2-2. 5mg ? kg" , Pipecuronium bromide 0. lmg ? kg" . Mechanical ventilation was started with inhalation 50% N2O after trachea intubation. Fentanyl and Pipecuronium bromide were injected intermittently. Diprivan inject was used TCI during operation.3. Monitoring methodUsing Detax Ohmeda S/5 monitoring instrument to monitor the noninvasive BP, ECG, SpO2. Wrote down the crystal, colloidal liquid importing amount,bleeding amount, urine amount and duration of operation.Temperatures of nasopharyngeal ( core temperature) and operation room were monitored by using Mallinckrodt monitoring instrument of the body temperature. Track recorded core and operation room temperature at regular interval of 30 minutes during operation.4. Temperature manageHypothermia;Did not exert any intervening measure in the temperature during operation. Patients with core temperature 34 ~ 36T! were included in group H.Warm -"up;Patients with forced - air warming system in the trunk to maintain core temperature close to 371 were included in group W. heating from 45 minutes before induction of anaesthesia till operation over. Infusion fluids were warmed up to 37°C using warming system before injection.5. Blood collectionBlood samples were taken 6 ml from peripheral vein before anaesthesia (To) and at 60 minutes (T,) and 120 minutes (T2 ) after induction and kept in EDTA anticoagulation tubes, then were sent to laboratory immediately.6. Blood measurement(1) Platelet aggregation test2. 7 ml blood was withdrawn using 3. 8% sodium citrate as an anticoagulant (the blood to sodium citrate ratio was 9:1 by volume). Then we used regular method to obtain platelet rich plasma ( PRP) and platelet poor plasma ( PPP). Adjusted platelet counts of PRP to 200 109/L. Measured platelet aggregation by using Chronolog platelet aggregation meter ( made in U. S. A). Inductors were 10|xmol/L adenosine diphosphate ( ADP, final concentration) and 2. 0|xg/L collagen ( COLL, final concentration). Measured platelet aggregation functions of H group and W group by using inductors above - mentioned.(2) Platelet adhesion test2. 7ml blood sample was filled with 0. 3ml 3.8% sodium citrate kept in si-licification tube, took 1. 5ml blood sample to a globular glass bottle which capacity was 10 ~ 12ml, counted platelet, then was rotated 15 minutes by speed of 3r/min. Counted platelet again. Platelet adhesion reaction rate was calculatedby the formula calculation below;Plate adhesion reaction rate = (platelet number before rotation - platelet number after rotation ) / ( platelet number before rotation) x 100%7. Experiment materialRoutine narcotics and apparatus, globular glass bottle, light microscope , blood platelet counting plate, Mallinckrodt monitoring instrument of the body temperature, forced - air warming system, adenosine diphosphate ( ADP) and collagen (COLL).8. Statistical analysisThe date were all expressed as mean standard ± deviation. Statistical analysis use paired samples t test in one group. And use two independent sample t test in two groups. Statistical analysis was significant at P <0.05.ResultsThere was no dfference of age, gender, body weight, duration of operation, temperature in operation room and transfusion amount in operation in both groups.Core temperatures of two groups were different. In H group, core temperature was significantly decreased at 1 hour after induction and was below 36 degrees Centigrade. It decreased gradually afterward. However in W group, core temperature maintained 37 degrees Centigrade on the whole.Amount of blood loss was not significant different in two groups ( P > 0. 05). Amount of blood loss was increased a little in H group, compared with W group.We found that platelet maximal aggregation rate of H group was significantly decreased in 60 minutes and 120 minutes after induction, as compared with pre induction (P<0. 05). It was also significantly decreased as compared with W group (P<0.05).The platelet adhesion rate of H group was significantly decreased in 60 minutes and 120 minutes after induction, as compared with pre induction ( P <0. 05 ). As compared with W group, the platelet adhesion rate was significantly in-hibited (P<0.05).ConclusionsMild hypothermia in perioperative inhibited functions of platelet adhesion and aggregation. And maintaining normotherima was good for preventing patients occurring potential blood loss in operation.