| Background:Severe preeclampsia often accompanied by multiple organ function damage, but maternal deaths caused by cerebral hemorrhage, pulmonary edema, DIC, fetal stop growing and premature birth. Termination of pregnancy is an important means of treatment of severe preeclampsia patients.However termination of pregnancy require cesarean section under general anesthesia, stress response caused by endotracheal intubation was intense. Stress response generated by endotracheal intubation in patients with severe preeclampsia can lead to maternal intracranial pressure, pulmonary edema, heart failure and death.At the same time, the increasing catecholamine concentration of maternal will reduce placental perfusion, resulting in fetal hypoxia-ischemia. In particular, preeclampsia is associated with increased sympathetic activity with elevated plasma norepinephrine levels. Thus, close control of stress responses during anaesthesia for caesarean delivery is required in patients with severe preeclampsia. Remifentanil is a new type of opioid agonist, has a rapid onset, short duration of action and fast metabolism, which increasingly widely used in clinical anesthesia.Studies have shown that remifentanil is metabolized quickly through the placenta, Apgar score of newborns, but can lead to maternal mild respiratory depression and sedation. It has been shown to attenuate the increases in systolic arterial pressure(SAP) and heart rate (HR) following induction and tracheal intubation for caesarean delivery during general anaesthesia in healthy pregnant women. Park,remifentanil may decrease the stress response in patients with severe pre-eclampsia under general anesthesia during cesarean section, and also have a short term newborn respiratory depression affected. This study was aimed to determine ED50 (medianeffective dose) and ED95 (95% effective dose) values of remifentanil to attenuate the pressor response to tracheal intubation during induction of general anaesthesia.Objective:To investigate ED50 and ED95values of remifentanil to attenuate the pressor response to tracheal intubation during induction of general anaesthesia.MethodsIn this study,we enrolled 100 severely preeclamptic women who were scheduled to undergo elective or urgent caesarean delivery under general anaesthesia. Patients were randomly allocated to receive one of five doses of remifentanil,0.25μg/kg (R0.25,n=20), 0.5μg/kg (R0.5,n=20),0.75μg/kg (R0.75,n=20),1.0 μg/kg (R1.0,n=20), or 1.25μg/kg (R1.25, n=20). All patients were premedicated with intramuscular atropine 0.5 mg and phenobarbital 0.1 g 30 min before the operation. At the same time open upper limb venous pathway. Intravenous labetalol 25 mg if SBP>160 mmHg or diastolic blood pressure≥110 mmHg. ECG, HR and SpO2, radial artery catheterization invasive blood pressure were monitored after entering the operation room. Anesthesia induction,5 groups respectively intravenous remifentanil (batch number:6130106, yichang f pharmaceutical, diluted saline to 10 ml),0.25μg/kg (R1),0.50μg/kg (R2),0.75μg/kg (R3), 1.00μg/kg (R4) and 1.25μg/kg (R5), propofol 1.5-2.0mg/kg, succinylcholine 1.5mg/kg, mechanical ventilation were underwent after endotracheal intubation, Setting VT 8-10ml/kg, RR10-12 times/min, inspiratory to expiratory ratio of 1:2. Anesthesia to maintain:Before the fetus was delivered 2% sevoflurane inhalation, after the baby is delivered intravenous midazolam 30μg/kg, fentanyl 6μg/kg, cis atracurium 0.2mg/kg, intravenous infusion of propofol 4-7 mg-kg-1-h"1, remifentanil 0.2 μg-kg-1-h"1. SAP<160 mmHg for more than 1 min following tracheal intubation was defined positive.SBP<90 mmHg, intravenous injection of ephedrine 6～10 mg;HR<50 beats/min, the intravenous injection atropine 0.2-0.5 mg. Record amount of intraoperative blood loss and the time from induction of anesthesia to the fetus childbirth; Before induction of anesthesia(TO), Before endotracheal intubation(Tl),immediately after endotracheal intubation(T2),fetal childbirth(T3)immediately record SBP and HR;Record the T3 radial artery and umbilical.artery blood gas analysis;Neonatal 1,5min Apgar score; Plasma catecholamine concentrations was monitored at T0,T2,T3.Using SPSS 19.0 and SAS statistical software analysis. Measurement data were expressed as mean±standard (X±S) deviation. Intergroup differences were analyzed using one-way ANOVA, intragroup differences were analyzed using repeated measures analysis of variance design. Count data were analyzed using chi-square. The result was considered statistically significant if the probability value was less than 0.05. Calculated ED50, ED95 and 95% confidence intervals(CI) by using Probit analysis, and fitting the dose-response curve.Results:There was no statistically significant difference in patients with general characters between the five groups. Immediately after endotracheal intubation, the value of plasma epinephrine of group R1.0 and R1.25 was significantly lower than baseline values; When fetal childbirth, each group of plasma noradrenaline values were higher than basic value;R0.25, R0.50 group, the value of plasma epinephrine R0.75 group were higher than basic values.Neonatal Apgar score has no statistical significance. There was no statistically significant difference in patients with maternal and umbilical arterial blood gas analysis, systolic blood pressure, heart rate between the five groups. Compared with basic values, intubation baseline systolic blood pressure was significantly lower than before (P< 0.05);Immediately after intubation, systolic blood pressure of group R0.25, R0.50 was significantly higher,and R1.0 and R1.25 was significantly reduced and systolic blood pressure of group R0.25, R0.50, R0.75 were higher than R1.25 group(P< 0.05); Systolic blood pressure were lower than basic values after fetal childbirth (P< 0.05);The statistics analysis of heart rate is the same of systolic blood pressur. Effective dose was defined if there were no episodes of SAP <160 mmHg for more than 1 min following tracheal intubation.R0.25 group in 2 cases (10%), effective R0.50 group effective 8 cases (40%), R0.75 effective 12 cases (60%), effective R1.0 group 16 cases (80%), effective R1.25 group 19 cases (95%).Conclusions:The ED95 of remifentanil for attenuating the hypertensive response to tracheal intubation during induction of anaesthesia in severely preeclamptic patients undergoing caesarean delivery under general anaesthesia was 1.30 ug/kg. Dose-dependent reaction of remifentanil decreased the rise of systolic blood pressure and heart rate caused by intubation. Remifentanil effectively attenuated stress responses to tracheal intubation with transient neonatal respiratory depression in pre-eclamptic patients undergoing Caesarean delivery under general anaesthesia.So,we must prepare neonatal resuscitation equipment in advance. |
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