| Objective:Sufentanil was synthesized in1974, and was introduced to our country in2003. In2005, China-made sufentanil entered the clinic. Since its pharmacological properties are superior to that of fentanyl in many respects, sufentanil has been gradually replacing fentanyl and being used in all kinds of surgery anesthesia and postoperative analgesia, including obstetric anesthesia and analgesia. It also has opioids side effects:respiratory depression, bradycardia, nausea, vomiting, and so on. These adverse reactions may affect the fetus as the drug transfering across placenta. The use of in vitro human placenta model in studying drug placental transfer has got increasingly mature. Only a few foreign study reports the influnce factors of sufentanil placental transfer, China has not yet published similar reports. Our experiment objective is to study the influnce factors of China-made sufentanil placental transfer in countrymen by using in vitro human placenta model established by foreigners.Method:We select18parturients who are healthy and full-term, undergo either normal delivery or cesarean section. The placentae were carried to the perfusion laboratory as soon as possible (within10minutes) after delivery. Spray4℃heparinized Krebs-Ringer buffer(composition:KC14.7mmol/L NaCl120mmol/L, NaHCO330mmol/L, KH2PO41.2mmol/L, CaCl2·2H2O3.3mmol/L, MgSO4·H2O2.4mmol/L, Glucose1g/L, Heparin25IU/ml, pH=7.4) to the surface of the placenta, at the same time, the perfusion of4℃heparinized Krebs-Ringer buffer through two umbilical arteries was in progress. The perfusion will not stop untill the fluid of umbilical vein was limpid in order to make sure the blood was washed out. Choose the whitish intact cotyledon whose supply vessels were clearly visible, cannulate its artery and vein with infant trocars and fixed it. Ligature blood vessels which had communicating branches with other cotyledons or used electrocoagulation. And then, cut off this cotyledon from the placenta, perfused through the artery, the selection of cotyledon was successful if venous and arterial flow rates were equal. The action should be gentle during the whole process, and we controlled the time within30min. Place the cotyledon in a perfusion chamber with the maternal side facing upward, the maternal side was perfused by inserting three blunt-tipped19-Pgauge needles2-3mm below the maternal plate, the umbilical vessel cannulas were connected to two polyethylene pipe to simulate the fetal side circuit. Put the placenta box into the thermostatic water cabinet. Connect the cotyledon to peristaltic pump and reservoir through polyethylene pipe. The perfusate was pumped to the maternal intervillous space through blunt-tipped needles, and then was collected to maternal reservoir through opened veins and that was pumped to placenta through atery cannula and then back into fetal reservoir on the fetal side. The volumes of the reservoirs were250ml and100ml for maternal and fetal circuits, respectively. Thus the closed circuit formed. Temperature control:the whole model was placed into thermostatic water cabinet; Oxygenation and pH control:The perfusates were both oxygenated by a mixed gas of95%oxygen and5%carbon dioxide, the pH of both perfusates was adjusted to7.4±0.05by changing the flow of carbon dioxide in the mixed gas; Perfusation control:the flow rate was maintained at10-12ml/min and1-3ml/min for maternal and fetal, respectively, the pressure was keeped at35-45mmHg and60-75mmHg, respectively. Monitor the whole circuits’temperature, pH and pressure by using digital thermometer, digital pH meter and pressure transducer. Our experiment was divided into three groups(control group, low protein group, fetal low pH group, n=6). Sufentanil (lOng/ml) and antipyrine (1μg/ml) were added to the maternal reservoir after the perfusion reached equilibrium30-min later, then allowed to equilibrate for2h. lml Perfusate samples were collected from both fetal and maternal reservoirs at regular time points (15,30,60,90,120min) after the addition of the twodrugs. The concentration of sufentanil and antipyrine was determined by using the method of high performance liquid chromatography tandem mass spectrometry. Sample extraction method: transfered the lml sample to a15ml glass tube, added15μl fentanil internal standard working solution(concentration:lng/ul) and2ml acetonitrile to the glass tube, mixed the solution for5minutes by using vortex oscillator and then2ml dichloromethane and chloroform2ml was added and mixed5more minutes. Centrifuged for10min (2000r/min). Transfered the lower organic solvent to another glass centrifuge tube, evaporated solvent under the N-EVAP with temperature of30℃. Dissolved the residual material with lml ultrapure water and mixed for1minutes. Transfered the solution to the automatic sampling bottle, the HPLC/MS/MS system extracted lOul to analyse it. Calculate the sufentanil transfer rate, antipyrine transfer rate and sufentanil/an-tipyrine transfer ratio according to the concentration and formula and then3groups were compared. Glucose consumption and lactate production were me-asured by biochemical analyer.Result:The sufentanil transfer rates of group B and C were significantly increased over those observed in group A(P<0.05). Antipyrine transfer rates was not significantly different between3groups(P>0.05). The sufentanil/ant-ipyrine transfer ratios of group B and C were significantly increased over those observed in group A(P<0.05). Glucose consumption and lactate produ-ction were all in the range considered normal.Conclusion:By using the dual-perfused, single-cotyledon human placenta model, we studied the the influnce factors of China-made sufentanil placental transfer in countrymen. The results indicated that the sufentanil transfer rate and sufentanil/antipyrine transfer ratio were all increased significantly when reducing fetal pH and maternal plasma protein concentration. |
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