Oral clonidine reduces thiamylal requirement for induction of anesthesia in adult patients

Although preanesthetic clonidine, an α-2 agonist, is known to reduce anesthetic requirements, the effect of preanesthetic oral clonidine medication per se on the requirement of thiamylal in adult humans has not yet been examined. One hundred and sixty-one adult patients (14–78 years of age) were randomly assigned to groups that received oral clonidine (5μg·kg⁻¹ (n=51), 2.5μg·kg⁻¹ (n=55), or none (n=55)) in addition to 20mg oral famotidine 90min before anesthesia induction. Thiamylal was injected at the rate of 25mg every 15 s until the eyelash reflex disappeared, while blood pressure and heart rate were recorded at 30-s intervals from the start of the induction. Thiamylal requirements were significantly less in both clonidine groups (2.95±0.09 and 3.14±0.10 mg·kg⁻¹ (mean±SE) for patients receiving 5μg·kg⁻¹ and 2.5μg·kg⁻¹ clonidine, respectively) than in the control group (3.81±0.11 mg·kg⁻¹,P<0.05); however, no difference was found between the two clonidine groups. Although mean blood pressure and heart rate during the study period were significantly lower in both clonidine groups than in the control group, no profound hypotension or marked bradycardia were noted in the clonidine groups.     

The effects of preanesthetic oral clonidine on total requirement of propofol for general anesthesia

Study Objective: To investigate the effects of preanesthetic oral clonidine on total propofol requirement for uniform minor surgery (breast conservative surgery: breast cancer removal with axillary lymph node dissection), and to compare the action of clonidine with that of preanesthetic oral diazepam, a commonly used benzodiazepine.

Design: Randomized double-blinded study.

Setting: Operating room ASA physical status I and II room and recovery room of the cancer center.

Patients: 80 breast cancer patients scheduled for surgery.

Interventions: Patients were randomized to one of four treatment groups (placebo, clonidine 75 μg, or 150 μg of clonidine, or 10 mg of diazepam were orally administered 60 min before induction of anesthesia); n = 20 per group. After evaluating the sedation and anxiety levels of patients using a visual analog scale, anesthesia was induced with propofol (1.5 mg/kg), and maintained with oxygen (O₂): nitrous oxide (N₂O) (30:70) with a continuous infusion of propofol. The propofol infusion was started at 10 mg/kg/h for 10 minutes, then decreased to 8 mg/kg/h, and 6 mg/kg/h thereafter, and the rate of infusion was adjusted to obtain adequate anesthesia (maintaining hemodynamic parameters within 20% of that prior to premedication). Fentanyl 0.2 mg (each 0.1 mg was given for intubation and axillary lymph node dissection, respectively) was administered.

Measurements and Main Results: Preanesthetic oral clonidine (150 μg) and diazepam (10 mg) induced anxiolysis without sedation. The total requirement (the mean infusion rates) of propofol in placebo, clonidine 75 μg, clonidine 150 μg, and 10 mg of diazepam groups were 841 ± 70 (9.0 ± 0.3), 720 ± 63 (7.1 ± 0.4), 491 ± 39 (5.6 ± 0.2), and 829 ± 77 mg (7.9 ± 0.4 mg/kg/h), respectively. The cost of propofol in these groups was $51.0 ± 3.8, $45.5 ± 3.2, $33.5 ± 2.3, and $50.5 ± 4.4, respectively.

Conclusions: Preanesthetic oral clonidine (150 μg) but not diazepam (10 mg) reduced the total requirement of propofol while stabilizing hemodynamic parameters. In addition, 150 μg of oral clonidine attenuates the hemodynamic responses associated with tracheal intubation.     

右美托咪定和可乐定硬膜外给药对硬膜外罗哌卡因麻醉效果的影响

目的 比较右美托咪定(dexmedetomidine,Dex)和可乐定硬膜外给药对罗哌卡因阻滞效果的影响. 方法 全组75例患者美国麻醉医师协会(ASA)分级Ⅰ或Ⅱ级,年龄55岁～65岁,拟行阴式子宫切除术.按随机数字表法分为硬膜外给予0.75％罗哌卡因15 ml含100 μg Dex组(RD组)、硬膜外给予0.75％罗哌卡因15ml含100 μg可乐定组(RC组)和硬膜外给予0.75％罗哌卡因15ml含生理盐水组(C组). 结果 RD组麻醉平面到达T10起效时间[(8.5±2.4)min]短于RC组和C组[(10.4±3.4) min和(12.7±4.3)min],RD组在较短的时间内[(13±4)min]达到最高阻滞平面,明显短于RC组和C组[(15±4) min和(18±4) min];RD组完全运动阻滞时间[(18±5)min]短于RC组和C组[(21±4) min和(24±4)min;(P＜0.05和P＜0.01)].RD组术后24 h曲马多用量[(87±17)mg]也显著少于RC组和C组[(101±21) mg和(146±19) mg;(P＜0.01)].RD组和RC组寒战发生率明显低于C组(P＜0.01),未发现1例呼吸抑制. 结论 硬膜外给予Dex可增强罗哌卡因硬膜外阻滞效果,与可乐定比较麻醉起效快、围术期呼吸循环稳定,减少术后镇痛药的应用.     

Oral clonidine premedication does not alter the efficacy of epidural test doses in adult patients anesthetized with isoflurane

Clonidine premedication has been increasingly used in clinical anesthesia. Though clonidine was found to alter pressor responses to various sympathomimetics, its effect on epidural test dose efficacy to detect intravascular injection has never been evaluated. Eighty healthy patients were randomly assigned to one of four groups, each of which was anesthetized with 1% end-tidal isoflurane and 67% nitrous oxide in oxygen after endotracheal intubation. The control-epinephrine group (n=20) given no clonidine premedication received 3 ml of 1.5% lidocain with 15 μg epinephrine (1:200000) intravenously to simulate an intravenously administered epidural test dose. The control-saline group (n=20) given no clonidine premedication received 3 ml of normal saline intravenously. The clonidine-epinephrine and clonidine-saline groups (n=20 each) were identical to the control groups, but were premedicated with oral clonidine, approximately 5 μg·kg⁻¹, 90 min before induction of general anesthesia. Heart rate (HR) and systolic blood pressure (SBP) were measured by a blinded observer at 20-s intervals for 4 min after intravenous injections of the test dose or saline. Following intravenous test dose injection, there were no significant diferences between the control-epinephrine and the clonidine-epinephrine groups in mean maximum increments of both HR (28±3vs 30±3 bpm, [mean±standard error], respectively) and SBP (46±6vs 45±4 mmHg, respectively). Six patients in the control-epinephrine and 4 in the clonidine-epinephrine group developed negative HR responses (HR increment <20 bpm). Since HR and SBP were essentially unchanged in the two groups receiving saline, sensitivities (negative predictive values) based on the HR criterion (positive if ≥20 bpm increase in HR) were 80% and 70% (83% and 77%) with and without clonidine premedication, respectively (P>0.05 between groups). However, when a modified HR criterion (positive if ≥10 bpm increase in HR) was used, sensitivities, specificities, and positive and negative predictive values were all 100% with or without clonidine. On the other hand, all of 20 patients in the control-epinephrine and the clonidine-epinephrine groups exhibited positive SBP responses (SBP increment ≥15 mmHg). Therefore, based on the SBP criterion, sensitivities, specificities, and positive and negative predictive values were all found to be 100% regardless of the presence of clonidine. We conclude that oral clonidine 5μg·kg⁻¹ premedication alters neither (a) hemodynamic responses to the intravenously administered epidural test dose containing 15 μg epinephrine, nor (b) the efficacy for detecting intravascular injection based on either criterion in adult patients under stable isoflurane anesthesia. Presented in part at the annual meeting of the American Society of Anesthesiologists, San Francisco, CA, USA, October 1994     

患儿口服可乐定术前用药的效果

目的评价患儿口服可乐定术前用药的效果。方法择期行脑室腹腔分流术患儿45例，年龄2～8岁，体重10～27kg，随机分为3组，每组15例，D组、C2组和C4组分别于麻醉前90min口服安定0．2mg／kg、可乐定2、4μg／kg。记录患儿术前镇静评分、与父母分开接受程度评分、面罩接受程度评分、术后镇痛、镇静情况及围术期不良反应的发生情况。结果与D组相比，C2组和C4组术前镇静、与父母分开接受程度、面罩接受程度的评分较高，术后镇痛补救率、寒颤发生率较低（P〈0．05）；与C2组相比，C4组术前镇静评分较高（P〈0．05）。结论患儿麻醉前90min口服可乐定2μg／kg术前用药可产生良好的镇静、抗焦虑和术后镇痛的效果，且副作用小。     

胸段硬膜外腔注射可乐定对上腹部手术术后膈肌功能的影响

目的　观察胸段硬膜外腔注射可乐定对上腹部手术 (UAS)术后膈肌功能的作用。方法　在连续硬膜外神经阻滞麻醉下行剖腹胆囊切除术病人 2 0例 ,均分为可乐定 (A)组与生理盐水(B)组。术后 2小时A组经硬膜外导管注入可乐定 4μg/kg ,B组注入生理盐水。记录注药前、注药后30分钟、2小时有无反常呼吸运动以及RR、VT。结果　A组注射可乐定 30分钟后膈肌功能改善 :反常呼吸运动消失 ,RR减慢 (由 2 0 0± 1 8降到 15 2± 1 7,P <0 0 0 1)、VT 增加 (由 2 19 8± 2 6 8ml/m2 增到 2 91 0± 2 5 5ml/m2 ,P <0 0 0 1) ,连续观察 2小时 ,膈肌功能仍优于注药前。B组注射生理盐水后上述指标无明显变化。结论　胸段硬膜外腔注射可乐定可改善UAS术后膈肌功能     

Effect of clonidine premedication on postoperative sore throat and hoarseness after total intravenous anesthesia

To determine the effect of oral clonidine premedication on postoperative sore throat and hoarseness, we evaluated the incidence and severity of each of these complications in patients who underwent elective surgery in the supine position. The subjects were 82 patients, American Society of Anesthiologists (ASA) status I–III, aged 15–82 years. They were premedicated with either 150 μg oral clonidine and 20 mg raftidine (clonidine group; n = 41) or with 20 mg raftidine only (control group; n = 41) 2 h before anesthesia induction. General anesthesia was maintained with propofol, ketamine, fentanyl, and vecuronium, with or without epidural anesthesia. Postoperative sore throat and hoarseness were evaluated immediately after surgery and on the day after surgery. The incidences of sore throat and hoarseness tended to be higher in the clonidine group than in the control group; however, the difference did not reach statistical significance. There were no significant differences in the severity of these symptoms between the two groups. In conclusion, oral premedication with 150 μg clonidine did not prevent postoperative sore throat or hoarseness, and may have exacerbated these symptoms.     

可乐定和新斯的明复合罗哌卡因用于硬膜外分娩镇痛的临床效果观察

目的:研究可乐定和新斯的明复合罗哌卡因用于硬膜外分娩镇痛的效果。方法:80例单胎初产妇随机分为两组,每组40例。研究组硬膜外首剂量给予可乐定75μg、新斯的明500μg和罗哌卡因10mg用生理盐水稀释至10ml;对照组硬膜外给予罗哌卡因10mg用生理盐水稀释至10ml;以0.1%罗哌卡因患者自控镇痛(PCA,6ml,锁定时间15min)持续镇痛。观察分娩情况、分娩过程中疼痛的视觉模拟评分(VAS)、罗哌卡因用量和不良反应。结果:两组产妇分娩方式、新生儿评分、运动阻滞和不良反应发生率差异均无显著性。研究组硬膜外首剂量镇痛时间显著延长,罗哌卡因用量显著降低。结论:可乐定和新斯的明用于硬膜外分娩镇痛可以提高镇痛效果,降低罗哌卡因用量,没有明显的不良反应。     

可乐定-氯胺酮硬膜外给药在剖宫产术的应用

目的观察剖宫产术中硬膜外并用氯胺酮和可乐定对产妇和新生儿的影响。方法80例择期剖宫产产妇,随机分为四组氯胺酮组(LK组);可乐定组(LC组);氯胺酮 可乐定组(LKC组);对照组(L组)。麻醉生效后,硬膜外腔给予氯胺酮0·6mg/kg和/或可乐定1μg/kg。术中常规监测SBP、DBP、ECG、HR和SpO2。每组于用药前(T0)、切皮时(T1)、胎儿娩出时(T2)及术毕(T3)对产妇进行疼痛视觉模拟评分(VAS)和镇静评分,并取产妇静脉血2ml、脐动静脉血各2ml,测定血浆肾上腺素(E)、去甲肾上腺素(NE)、皮质醇(Cor)浓度。记录术中不良反应。胎儿娩出后1min和5min行Apgar评分。结果四组产妇SBP、DBP和SpO2在各时点差异均无显著意义;与L组相比,LC组与LKC组HR明显下降(P<0·05)。在T1、T2、T3时LK、LC和LKC组VAS均较L组明显降低(P<0·05),LKC组降低尤为明显(P<0·01);镇静评分均明显升高,LKC组升高更为明显(P<0·01)。在T1时L组和LK组产妇E、NE、Cor浓度较T0时均有明显升高(P<0·05),但在LC和LKC组升高不明显;在T2时各组E、NE、Cor浓度较T0时均有明显升高(P<0·05),但LKC组较其他组升高较少;在T3时L组E、NE、Cor浓度较T0时仍有明显升高(P<0·05),但LK组、LC和LKC组均有不同程度下降(P<0·05),LKC组下降尤其明显(P<0·01)。在脐动、静脉血,LK组、LC和LKC组E、NE、Cor浓度较L组均有降低(P<0·05),其中LKC组降低尤其明显(P<0·01)。四组新生儿出生后1min及5minApgar评分差异均无显著意义。L组有5例出现寒战,LK组有4例产妇出现兴奋多语。结论氯胺酮可乐定联合硬膜外给药,能更好地消除产妇术中疼痛,降低母婴的应激反应,减少二者单独应用时对母婴的不良影响。     

不同剂量可乐定复合罗哌卡因硬膜外麻醉的效应

目的 评价不同剂量的可乐定复合罗哌卡因硬膜外麻醉的临床效应。方法 60例ASAⅠ-Ⅱ级妇科手术患者，硬膜外随机双盲接受不含或含50、100、150μg可乐定的0.75%罗哌卡因25ml，分为R、R－C50、R－C100、R－C150四组。记录感觉镇痛、运动阻滞起效时间及持续时间，术中镇痛质量及不良反应。结果 R－C100组、R－C150组运动阻滞起效时间缩短，术中内脏牵拉痛发生率及氯胺酮需要量减少，镇痛持续时间延长，寒战发生率降低。然而，R－C150组低血压发生率、麻黄碱需要量及输液量增加。结论 可乐定100μg与0.75％罗哌卡因25ml合用于硬膜外麻醉，可改善罗哌卡因阻滞特征而不增加低血压、心动过缓等副作用。     

Usefulness of oral hypnotic premedication for volatile induction of anesthesia in adults

Purpose. We investigated the effects of oral hypnotic premedication for smooth anesthetic induction and for the patient's comfort under anesthesia, using sevoflurane without nitrous oxide. Methods. Adult patients were divided into four groups: control (n= 12), triazolam (0.25 mg; n= 12), zopiclone (7.5 mg; n= 12), and clonidine (0.15 mg; n= 12) groups. Each premedication was given to each patient 1 h before the anesthesia. The patients breathed out to residual volume and then the anesthetic mask was fitted. The repeated vital capacity breathing technique was used, with 5% sevoflurane in 10 l·min⁻¹ oxygen. Induction time, specific induction side effects, and acceptability of this technique by the patients were recorded by an independent observer. Results. Induction time in the premedicated groups ranged from 66 ± 12 s (mean ± SD) to 76 ± 14 s, and these values were significantly shorter than that in the control group (92 ± 16 s). The number of patients in whom adverse effects occurred during anesthetic induction was significantly greater in the control group (4 patients; 33%) than in the premedicated groups (1 patient each; 8%). Acceptability of the smell of sevoflurane was significantly higher in the premedicated groups (8–10 patients; 67%–83%) than in the control group (5 patients; 42%). Conclusion. Oral hypnotic premedications with either triazolam (0.25 mg), zopiclone (7.5 mg), or clonidine (0.15 mg) are recommended for smoother volatile anesthetic induction and for the patient's comfort in adults. Received: January 28, 2002 / Accepted: April 26, 2002     

胸部手术实施全身麻醉联合硬膜外麻醉的效果观察

目的观察分析胸部手术实施全身麻醉联合硬膜外麻醉的效果。方法将42例SASⅠ~Ⅱ级胸部手术患者随机分为两组,各21例。对照组实施全身麻醉,观察组予以全身麻醉联合硬膜外麻醉,观察分析两组麻醉效果。结果 42例患者停止麻药后,自主呼吸恢复时间5~10 min。观察组患者麻醉药剂量明显少于对照组,且清醒时间早,两组比较,差异有统计学意义(P0.05)。结论采用全身麻醉联合硬膜外麻醉进行胸部手术,能降低麻药对循环及呼吸的抑制,缩短患者清醒时间,提高手术效果,值得临床推广应用。     

Comparison of combined spinal epidural anesthesia and epidural anesthesia for cesarean section

BACKGROUND: Epidural anesthesia (EA) is popular for cesarean section, but has some drawbacks such as incomplete block, inadequate muscle relaxation and delayed onset. Combined spinal epidural anesthesia (CSEA) has gained increasing interest as it combines the reliability of a spinal block and the flexibility of an epidural block. We investigated the efficacy of CSEA that combines the main spinal and the supporting epidural anesthesia, comparing with pH-adjusted EA, for cesarean section. METHODS: Sixty-four pregnant women at full term were divided into two groups. Patients in the CSEA group (n=32) were given 1.5-1.6 ml of 0.5% hyperbaric bupivacaine intrathecally, followed by 10 ml of 0.25% plain bupivacaine through the epidural catheter 10 min later. Patients in the EA group (n=32) received 20-25 ml of 2% lidocaine which was already mixed with 0.1 ml of 0.1% epinephrine, 100 g of fentanyl and 1.5 ml of 8.4% sodium bicarbonate. The quality and side effects of surgical anesthesia, neonatal state, and postoperative course were compared between the two groups. RESULTS: In the EA group, 22% (7 cases) complained of intraoperative pain but none in the CSEA group (P=0.011). Muscle relaxation and motor block were much better in the CSEA group (P<0.001 and P=0.011 each). Significantly more women in the EA group had shivering (P=0.001). They also had more nausea and vomiting but the differences were not significant. Not only the time to T4 block (9.7 vs. 18.3 min, mean, P<0.001) but also the stay in the postanesthesia care unit, recovery of sensory and motor block and start of postoperative pain were all significantly shorter in the CSEA group. No one in either group had postdural puncture headache (PDPH). CONCLUSION: We can conclude that, when combining the main spinal and the supporting epidural anesthesia, CSEA has greater efficacy and fewer side effects than the pH-adjusted EA in cesarean sections.     

Oral clonidine premedication for elderly patients undergoing intraocular surgery.

In a randomized double-blind study, the effects of clonidine premedication as a sedative, anxiolytic, analgesic and oculohypotensive agent were studied in 100 elderly patients (62 to 65 +/- 10 years, ASA grade I-II) undergoing elective intraocular surgery under local anaesthesia. The control group (Group A, n = 50) received oral diazepam 0.15 mg/kg 120 min before surgery and Group B (n = 50) received oral clonidine 300 micrograms 120 min before surgery. Two hours after the premedication, there was significantly more sedation (P less than 0.05) and less subjective anxiety (P less than 0.05) in the clonidine group than in the control group. There was a significant fall in intraocular pressure (IOP) from 20 +/- 0.5 to 13 +/- 0.5 mmHg (P less than 0.05) and significant reduction in systolic and diastolic blood pressure (BP) and heart rate (HR) (P less than 0.05) in the clonidine group as compared to the control group. Perioperatively, significantly more supplementation with i.v. diazepam was given in the control group than in the clonidine group (P less than 0.01). The incidence of intra-operative hypertension (P less than 0.01) and tachycardia (P less than 0.05) was significantly greater in the control group than in the clonidine group. A significantly larger number of patients in the clonidine group scored a Post-Anaesthesia Recovery (PAR) score of 10 as compared to the control group (P less than 0.01). There was no statistical difference in the postoperative Visual Analogue Scale (VAS) scores for pain, number of analgesic requests and emesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

不同处理方法对全麻手术病人气管拔管应激反应的影响

目的探讨不同处理方法对全麻病人术后气管拔管应激反应的影响。方法44例气管插管全麻下手术病人,随机分为四组(n=11):对照组(N组)、可乐定组(K组)、硬膜外组(EP组)、可乐定复合硬膜外组(KEP组)。除K组和KEP组病人分别于麻醉前60min口服可乐定5 uuuuuuuuuuuuuuuuuuug/kg外,四组病人其它麻醉前用药相同;分别在麻醉前、拔管前、拔管后1、2、5、10 min经桡动脉采集动脉血7 ml, 测定血浆肾上腺素、去甲肾上腺素(NE)、皮质醇、血糖、血乳酸浓度,并做血气分析,同时记录以上各时点的血液动力学参数。结果与拔管前比较,N组、EP组拔管后1min HR、SBP、DBP升高,拔管后2 min SBP、DBP仍较高;与N组比较,K、EP、KEP组病人拔管后1 min肾上腺素、NE、皮质醇水平均较低, 拔管后2、5min K组、KEP组血浆激素水平较低,K组、KEP组拔管前、拔管后1、2min血乳酸水平较低, 拔管后1、2min血糖水平较低,K组、KEP组拔管后1、2 min HR、SBP、DBP较低(P<0.05或0.01)。与N组比较,K、EP、KEP组病人拔管后1 min血肾上腺素、NE、皮质醇水平均较低,拔管后2、5 min K组、KEP组血浆激素水平较低(P<0.05或0.01)。与N组比较,K组、KEP组拔管前、拔管后1、2min血乳酸升高程度较低;拔管后1、2min血糖升高程度较低(P<0.05或0.01)。N组、EP组拔管后1 min HR、SBP、DBP比拔管前升高,拔管后2 min SBP、DBP仍较高;K组、KEP组拔管后1、2min HR、SBP、DBP较N 组低(P<0.05或0.01)。结论全麻病人麻醉前服用可乐定或拔管时复合硬膜外给药能明显减轻气管拔管引起的应激反应。     

预先肌注曲马多对硬膜外麻醉后病人寒战的影响

目的 探讨肌肉注射曲马多对硬膜外麻醉后寒战的预防效果。方法 选择80例准备在硬膜外麻醉下行下腹、下肢或脊柱手术的成年患者,随机分为四组（每组20例）：肌注曲马多和氟哌利多组（TD组）;单纯曲马多组（T组）或氟哌利多组（D组）;对照组（C组）。于硬膜外注药前30分钟,TD组肌注曲马多1．5mg/kg和氟哌利多5mg;T组肌注曲马多1．5mg/kg;D组肌注氟哌利多5mg;C组不用药。观察麻醉及手术过程中寒战的发生率、寒战的严重程度及寒战发生前后体温变化。结果 寒战发生率TD组和T组均为5％,D组和C组分别为25％和35％,TD组和T组与C组比较差异显著（P＜0．05）。TD组哮睡发生率、T组恶心发生率较高。结论 肌注曲马多有助于预防低位硬膜外麻醉后寒战,应用时复合氟哌利多可减少曲马多的副作用。     

Ropivacaine produces sensory blockade in the lumbar sacral region more frequently than mepivacaine in lower thoracic epidural anesthesia

Purpose The first sacral nerve has the largest diameter among the spinal nerves and is resistant to local anesthetics. Ropivacaine is a newly developed local anesthetic. There is a possibility that a difference in chemical properties between ropivacaine and other local anesthetics produces a difference in the blockade of the S1 dermatome by lower thoracic epidural anesthesia. Mepivacaine, 2%, is frequently used for epidural anesthesia and produces a level of blockade similar to that of bupivacaine, 0.5%. The purpose of this study was to examine the sensory blockade in the sacral region induced by ropivacaine with that induced by mepivacaine administered in the lower thoracic epidural space.Methods Eighteen adults undergoing lower thoracic epidural anesthesia (thoracic 11/12 interspace) were studied in a double-blind fashion. Patients were assigned to one of two groups: those who received 2% mepivacaine, 18ml (group M; n = 9), and those who received 1% ropivacaine, 12ml (group R; n = 9). The cephalad levels of sensory blockade to cold, pinprick, and touch in the L2, S1, and S3 dermatomes were assessed at 10, 20, and 35min after injection.Results There were no differences in the cephalad levels of sensory block to cold (T4 [range, T4–T2] and T4 [range, T6–T2]), pinprick (T4 [range, T6–T4] and T4 [range, T6–T4]), or touch (T6 [range, T6–T4] and T6 [range, T6–T4]) between group M and group R respectively, at 35min (P > 0.05). In the L2 and S3 dermatomes, there were no significant differences in the numbers of patients who obtained sensory block to cold or pinprick at 20 and 35min after study drug administration. However, in the S1 dermatome, significantly higher numbers of patients in group R obtained sensory block to cold at 20 and 35min after study drug administration than in group M (8 and 0; 9 and 0; P = 0.001 and P < 0.001; 20min and 35min after administration, respectively). Also in the S1 dermatome, significantly higher numbers of patients in group R obtained sensory block to pinprick at 20 and 35min after study drug administration than in group M (6 and 0; 9 and 0; P = 0.027 and P < 0.001; 20min and 35min after administration, respectively). A significantly higher number of patients in group R had sensory block to touch in the S3 dermatome at 35min (7 and 2; group R and group M, respectively; P = 0.01).Conclusion Ropivacaine, 1%, administered in the lower thoracic epidural space, induces sensory blockade to cold and pinprick in the S1 dermatome more frequently than 2% mepivacaine.