A suitable sedative dose of remifentanil for both mother and fetus in fetoscopic surgery

We observed the impact of different intravenous pumping rates of remifentanil on the mother and fetus under combined spinal epidural anesthesia (CSEA) in fetoscopic surgery. Thirty patients with twin-twin transfusion syndrome (TTTS) pregnancies undergoing fetoscopic laser photocoagulation were randomized into three groups (R1, R2 and R3, ten cases per group, 0.02micro-g/kg/min, 0.05micro-g/kg/min and 0.08micro-g/kg/min), according to different rates of remifentanil administration. Anesthesia induction of CSEA was done 5min before remifentanil administration. Intravenous remifentanil was administrated before operation and stopped after laser photocoagulation. During the period, we monitored fetal movement through ultrasonic test. Operation started when fetal immobilization. We recorded the time of fetal immobilization and fetal movement recovering. Fetal movement and Kreb's score for fetal heart rate were simultaneously recorded. Maternal changes in oxygen saturation (SpO2), respiratory rate (RR), mean arterial pressure (MAP), heart rate (HR), and anxiety visual analog test (AVAT)were recorded at the following time points, before induction of anesthesia (T0), 5 min after CSEA (T1), the time when fetal immobilization after remifentanil administration (T2), incision (T3), and laser coagulation (T4). Maternal arterial oxygen partial pressure(PaO2) and arterial carbon dioxide partial pressure(PaCO2) were measured on T0 and T4. Maternal cardiopulmonary function remained stable after remifentanil administration. PaCO2 showed no significant difference in three groups on T0 and T4(P>0.05). SpO2, RR, MAP, HR, PaO2, AVAT values and Kreb's scores were decreased in turn from R1 to R3 group (p<0.05). There were two cases of fetal movements during laser photocoagulation in R1 groups, but none in R2 and R3 groups. The time for fetal immobilization fetal movement recovering were shorten in turn from R1 to R3 group (p<0.05). In fetoscopic surgery for TTTS, CSEA combined with a suitable dose of remifentanil can improve the maternal and fetal sedative effects without adverse effects. We propose that the appropriate rate of remifentanil dose in combination with CSEA during TTTS surgery is 0.05micro-g/kg/min.