CHA Gumi Medical Center, CHA University, Gumi, Korea

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1 Anesth Pain Med 2014; 9: Clinical Research Comparison of 0.5% ropivacaine with fentanyl and 0.75% ropivacaine used in extension of a preexisting labor epidural for emergency cesarean section: retrospective study Department of Anesthesiology and Pain Medicine, CHA Bundang Medical Center, CHA University, Seongnam, *CHA Gangnam Medical Center, CHA University, Seoul, CHA Gumi Medical Center, CHA University, Gumi, Korea Yun-Sic Bang, Hyeonjeong Yang, Su-jeong Nam, Seo-min Park, Kum-Hee Chung, Su Yeon Lee*, Dong Wook Shin, and Duk-Hee Chun Background: Various regimens have been studied in extension of a preexisting labor epidural for emergency cesarean section. Lumbar epidural analgesia for delivery is safe and efficient. We compared retrospectively 0.5% ropivacaine with fentanyl and 0.75% ropivacaine in extension of a preexisting labor epidural for emergency cesarean section. Methods: We investigated medical records of 61 parturients in extension of a preexisting labor epidural for emergency cesarean section. There were two regimens which was 0.5% ropivacaine with fentanyl (group 1) and 0.75% ropivacaine (group 2). We recorded demographic data, local anesthetic dose, surgical readiness time, maximum level of sensory block, surgery time, intravenous supplementation, number of hypotension and total dose of ephedrine between two groups. Results: There were no differences between the study groups in demographic data, surgical readiness time, maximum sensory block level, intravenous supplementation, incidence of hypotension and total dose of ephedrine. Local anesthetic volume was larger in group 1 than group 2, but local anesthetic doses were lower in group 1 than group 2. Conclusions: 0.5% Ropivacaine with fentanyl regimen is as fast and efficacious as 0.75% ropivacaine in extension of a preexisting labor epidural for cesarean section and reduces the requiring total local anesthetic dose. (Anesth Pain Med 2014; 9: 65-69) Key Words: Cesarean section, Epidural analgesia, Ropivacaine. INTRODUCTION In various techniques for management of pain in labor, Received: May 5, Revised: 1st, August 16, 2013; 2nd, September 3, 2013; 3rd, September 25, 2013; 4th, October 1, Accepted: October 7, Corresponding author: Hyeonjeong Yang, M.D., Department of Anesthesiology and Pain Medicine, CHA Bundang Medical Center, CHA University, 351, Yatap-dong, Bundang-gu, Seongnam , Korea. Tel: , Fax: , yanghj@medigate.net lumbar epidural analgesia is known as safe and efficient technique. Also, when obstetrician decided to proceed to emergency cesarean section because of a difficult condition to proceed spontaneous vaginal delivery, lumbar epidural analgesia has the advantage of easy conversion to epidural anesthesia. Local anesthetics like lidocaine, ropivacaine, bupivacaine, levobupivacaine have been employed for epidural anesthesia for a long time [1-3], and adding fentanyl μg produce a synergistic effect that enhance analgesia [4,5]. Ropivacaine has a similar structure to bupivacaine, but minimum local anesthetic concentration potency of ropivacaine is only 0.6 ( ) compare to potency of bupivacaine [6]. Thus, 0.75% ropivacaine has been used to provide similar effect of 0.5% bupivacaine for cesarean section. However, epidural 0.5% ropivacaine is recommended as appropriate concentration for cesarean section and the Food and Drug Administration also recommends ropivacaine 0.5% as epidural anesthesia for cesarean section [7,8]. There were many studies comparing the effects of local anesthetics during epidural anesthesia for cesarean section [3,9,10], but few studies comparing the effects of local anesthetics used in extension of a preexisting labor epidural for emergency cesarean section. And there was no previous study comparing 0.5% ropivacaine with 0.75% ropivacaine when converting labor epidural analgesia to epidural anesthesia for surgery. Thus, we compared retrospectively 0.5% ropivacaine with fentanyl and 0.75% ropivacaine in cesarean section with extended epidural anesthesia. MATERIALS AND METHODS After ethics committee approval, we investigated medical 65

2 66 Anesth Pain Med Vol. 9, No. 1, 2014 records from January 2011 to June 2012 in extension of a preexisting labor epidural for emergency cesarean section. We investigated American Society of Anesthesiologist physical status classification I II parturients. We excluded multiple pregnancy, high risk pregnant women such as pregnancy induced hypertension, hemolytic anemia, elevated liver enzymes and low platelet count syndrome and placenta previa and inadequate preexisting epidural analgesia. According to our hospital protocol, the epidural catheter was placed with a G tuohy needle in the L 2-3 or L 3-4 interspace using the midline approach and loss of resistance technique with the patients in right lateral decubitus or left lateral decubitus position. Catheter proceeded 3 4 cm upwardly, and was left in the extradural space. Initial top-up doses of 0.1% ropivacaine 14 ml with fentanyl 50 μg were administered. Following this, 0.1% ropivacaine 72 ml with fentanyl 150 μg was continuously infused through the epidural catheter at a rate of 10 ml/hr (Ambix ANAPA R, Ewhabiomedics, Seoul, Korea). An additional bolus of 0.1% ropivacaine 5 ml was supplemented when required. When obstetrician decided to proceed to emergency cesarean section, we stopped the continuous infusion. On arrival in operating room, routine physiological monitoring was applied including electrocardiogram, non-invasive blood pressure (BP), heart rate (HR), and pulse oximetry. BP and HR measurements at 2 min interval were made when patients were stabilized on supine position. All patients received Ringer s lactate solution ml/kg as a preload. Epidural anesthesia was performed with previously sited epidural catheter. The patients were divided into two groups according to the different local anesthetics regimen selected by anesthesiologists. Group 1 (n = 28) was received 0.5% ropivacaine ml with fentanyl 50 μg, and Group 2 (n = 33) was received only 0.75% ropivacaine ml. The epidural drug was administered over 5 minutes. In each group, the administered volume was decided by sensory block dermatome and the patient height. Surgery was started when sensory block was achieved at T6 sensory dermatome level, assessed with pin prick test per 2 minutes. Even though the surgery was started, the maximum sensory block level was investigated till the level was fixed. Ephedrine 4 mg was injected when hypotension occurred. The incidence of hypotension and total dose of intravenous ephedrine were investigated. The results were presented as mean ± standard deviation (SD). Patient s age, height, gestational age, local anesthetics dose, surgical readiness time, and total dose of ephedrine were compared using independent T-test. Visceral pain (squeezing or unpleasant feeling) was treated with propofol before baby coming out from the uterus and fentanyl after out of the placenta from the uterus. Incidence of requiring propofol or fentanyl were compared using Chi-square test. The P value< 0.05 was considered significant. Table 1. Demographic Data Age (yr) Height (cm) Weight (kg) Gestational age (wk) RESULTS There was no significant difference in mean age, height, weight, or gestational age among the patients in the two groups (Table 1). The total volume of local anesthetics was larger in group 1 as 16.9 ± 3.7 ml than group 2 as 15.2 ± 1.9 ml. That results are statistically significant (P = 0.029). However, absolute ropivacaine doses calculated by multiplying the volume and concentration of ropivacaine were significantly lower in group 1 as ± mg than in group 2 as ± mg (P < 0.01) (Table 2). No statistically significant difference was observed in surgical readiness time, maximum level of sensory block and surgery time between two groups (Table 2). There was also no significant difference in incidence of IV supplementation (propofol or fentanyl), hypotension, and total dose of ephedrine during surgery between two groups (Table 2). DISCUSSION To relieve the pain in labor, psychotherapy (Lamaze method), systemic medication (opioid, ketamine), nitrous oxide inhalation, and regional anesthesia has been employed. Among these methods, epidural anesthesia is a safe and effective method of providing analgesia in labor [11-13]. If patient has a previously sited epidural catheter, extending epidural anesthesia can be easily performed when emergency cesarean section is determined. This flexibility is the big advantage of epidural analgesia. The local anesthetics, a long-acting amide Group 1 (n = 28) Group 2 (n = 33) 30.3 ± ± ± ± ± ± ± ± 1.9 Values are means ± SDs. Group 1: 0.5% ropivacaine ml + fentanyl μg, Group 2: 0.75% ropivacaine ml.

3 Yun-Sic Bang, et al:epidural anesthesia for cesarean section 67 Table 2. Comparison of Many Factors between Two Groups Local anesthetics volume (ml) Ropivacaine dose (mg) Surgical readiness time (min) Maximum level of sensory block* Surgery time (min) Intravenous supplementation (Propofol or fentanyl) Number of Hypotension Total dose of ephedrine (mg) Group 1 (n = 28) 16.9 ± 3.7* 84.6 ± ± 7.5 T4 (T1 T6) 67.3 ± 9.9 8/28 (28.6%) 6/28 (21.4%) 1.9 ± 4.3 Group 2 (n = 33) 15.2 ± ± ± 6.0 T4 (T2 T6) 66.2 ± 9.7 9/33 (27.3%) 8/33 (24.2%) 2.6 ± 5.6 Values are means ± SDs. Group 1: 0.5% ropivacaine ml + fentanyl μg, Group 2: 0.75% ropivacaine ml. *Median (ranges) for maximum level of sensory block. P < 0.05 vs Group 2. local anesthetics (bupivacaine, ropivacaine, levobupivacaine), have been used in epidural analgesia and anesthesia. They have shown less effect on motor block and excellent effect on sensory block. Bupivacaine has been the most widely used, but in recent years ropivacaine or levobupivacaine which has less cardiovascular toxicity than bupivacaine is used as attractive alternative as epidural solution. Ropivacaine has potency 0.6 compared to bupivacaine [6] but the same concentration and volume of bupivacaine and ropivacaine provided similar clinical characteristics, except the duration of motor block [14-16]. Also, Choi et al. [9] demonstrated that epidural anesthesia with 0.475% ropivacaine close concentration to 0.5% ropivacaine during cesarean section provided excellent sensory block with less intensive motor block rather than 0.75% ropivacaine. In addition, epidural 0.5% ropivacaine can reduce unnecessary prolonged motor block and provide earlier recovery from motor block than 0.75% ropivacaine. However, conducting studies of this kind were almost comparing local anesthetics administrated by top-up method in parturients undergoing elective cesarean section. Hillyard et al. [10] showed in meta analysis when converting labor epidural analgesia to surgical epidural anesthesia for cesarean section, 2% lidocaine with epinephrine as an epidural top-up solution provided the fastest onset of surgical block. Also, adding fentanyl to top-up solution can shorten onset time and 0.75% ropivacaine is most effective anesthetic solution for pain relief. Previous studies [2,9,17] compared the same volume of two different anesthetic concentration, but in this retrospective study, a different concentration of 0.5% or 0.75% ropivacaine with different volume was administered by the anesthesiologist depending on the sensory block dermatome and the patient height. At these results, the volume of the solution is significantly more in group 1 than group 2, but absolute ropivacaine doses considering the concentration were more in group 2 than group 1. However, there were no significant differences in surgical readiness time defined as obtaining T6 sensory loss (group 1 = 13.2 ± 7.5 min, group 2 = 13.6 ± 6.0 min) between two groups. In the studies of the onset time of sensory block according to ropivacaine concentration, Yang et al. [3] reported that it takes 11.8 ± 8.6 min to obtain T6 sensory block and 17.1 ± 13.2 min to obtain T4 sensory block using 20 ml top-up doses of 0.5% ropivacaine. In another study of continuous epidural analgesia and then changed to epidural anesthesia [2,17], they reported that it took 10 to 11 min to obtain T4 sensory block. Since we did not administer same doses of ropivacaine, a direct comparison between the studies is impossible, but we came up with similar result with previous studies. The difference with previous studies and our study was that we compared two different concentrations of ropivacaine (0.5% ropivacaine adding fentanyl 50 μg and 0.75% ropivacaine) in extension of a preexisting labor epidural. Adding an opioid to the local anesthetic may lead to a shoter onset time for sensory block and reduce the incidence of intraoperative pain. Several electrophysiological studies have shown that opioids inhibit the action potential amplitude of A fiber and C fiber, and its inhibition is not disappear with pretreatment of naloxone [18,19]. But, there were contradicting studies related to epidural anesthesia. Hillyard et al. [10] reported in their meta analysis that adding fentanyl to a local anesthetic resulted in approximately 2 min faster onset, but Hong et al. [20] reported that adding fentanyl did not speed up the onset of the block but improved the quality of analgesia. Malhotra and Yentis [21] reported that there was no benefit of adding fentanyl to local anesthetics, moreover only increased frequency of intraoperative nausea and vomiting. As a result of the study, there were no significant differences observed between group 1 and group 2, in the surgical readiness time and the frequency of intravenous supplementation, which suggests adding fentanyl to local anesthetic has no direct effect in the quality of anesthesia itself. However, as group 1 showed similar clinical efficacy using low concentration of ropivacaine, adding fentanyl may affect both in the onset time and the quality of anesthesia. This study is a retrospective study, so prospective, randomized, controlled study will be necessary. Hypotension is common under spinal anesthesia for cesarean

4 68 Anesth Pain Med Vol. 9, No. 1, 2014 section. The incidence of hypotension reported % under epidural anesthesia for cesarean section [20,22,23]. In our study, although there was no significant difference in incidence of hypotension (21.4 vs 24.2%) and total dose of ephedrine (1.93 ± 4.3 mg vs 2.55 ± 5.6 mg), group 1 has a tendency to show lower incidence of hypotension and less ephedrine consumption. When hypotension occurs, symptom like nausea, vomiting, dizziness, decreased consciousness can appear [24]. We can not specifically investigate the symptom of hypotension because our study is retrospective study and this is the limitation of our study. In conclusion, we found that there was no significant difference in the onset time, the quality of analgesia, and the incidence of hypotension using epidural 0.5% ropivacaine plus fentanyl compared with 0.75% ropivacaine only. 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