Factors affecting the transfer of ropivacalne across the single cotyledon of term human placenta / 中华麻醉学杂志

ABSTRACT

Objective To study the transfer of ropivacaine across the single cotyledon of the term human placenta and the effects of maternal hypoproteinemia and fetal acidemia on the transfer. Methods Eighteen placentas were obtained from healthy full term parturients within 5 min after vaginal or cesarean section delivery. The dual perfused human placental model was made. The placentas were randomly divided into three groups of 6 placentas (A) control group in which 100% fresh frozen plasma was used in both maternal and fetal circulation with pH maintained at 7.4 on both sides; (B) fetal academia group in which 100% fresh frozen plasma was used in both circulations but fetal pH was reduced to 7.0; (C) maternal hypoproteinemia group in which 50% fresh frozen plasma used in maternal circulation and 100% fresh frozen plasma in fetal circulation, pH was maintained at 7.4 on both sides. Samples were taken from the perfusate in the reservoir at 15, 30, 60, 90, 120 min after ropivacaine (2?g?ml-1) and antipyrine (10 ?g?ml-1 ) were added in maternal circulation for determination of concentrations of ropivacaine, antipyrine, glucose and lactate. Glucose consumption rate, lactate generation rate and relative and absolute transfer ratio of ropivacaine were calculated. Results Absolute transfer ratio of ropivacaine was gradually increasing with perfusion time, reaching 8.7?1.0% (A) , 10.5 ?1.6% (B) and 11.8?1.1% respectively at 120 min. Relative transfer ratio of ropivacaine was relatively constant during 120 min perfusion and was significantly higher at each time point in group B and C than in group A ( P