|Year : 2016 | Volume
| Issue : 4 | Page : 493-500
Comparison of caudal epidural clonidine with fentanyl as an adjuvant to ropivacaine 0.25% for postoperative analgesia in children undergoing various infraumbilical surgeries: A prospective randomized study
Sudheendra Saini, Veena Patodi, Surendra K Sethi, Neena Jain, Pooja Mathur, Beena Thada
Department of Anaesthesiology, JLN Medical College and Hospital, Ajmer, Rajasthan, India
|Date of Submission||02-Nov-2015|
|Date of Acceptance||10-Jul-2016|
|Date of Web Publication||12-Jan-2017|
Department of Anaesthesiology, JLN Medical College and Hospital, Ajmer, Rajasthan, 305001
Source of Support: None, Conflict of Interest: None
Caudal epidural block is commonly used as a safe, reliable, easy-to-administer technique for abdominal and lower limb surgeries in pediatric patients and allows rapid recovery from anesthesia with effective postoperative analgesia. The aim of our study was to compare the efficacy of clonidine versus fentanyl when used as an additive to ropivacaine during single-shot caudal epidural analgesia in pediatric patients for postoperative pain relief.
Patients and methods
This randomized prospective double-blind study was conducted on 60 children of American Society of Anesthesiologists grades I and II aged 1–7 years scheduled for various infraumbilical surgical procedures who were randomly allocated into two groups to receive either ropivacaine (0.25%, 1 ml/kg) and clonidine (2 μg/kg) (group RC) or ropivacaine (0.25%, 1 ml/kg) and fentanyl (1 μg/kg) (group RF). Caudal epidural block was performed after induction of general anesthesia. Postoperatively, patients were observed for duration of analgesia, sedation score, recovery time, hemodynamics, and side effects or complications.
Both groups were similar with respect to patient’s demographic profile, baseline hemodynamic parameters, and duration of surgery. The analgesic properties and hemodynamics were also comparable in both groups (P>0.05). The mean recovery time and sedation score were significantly lower in group RC as compared with group RF (P<0.05). Side effects such as nausea, vomiting, and respiratory depression were seen only in group RF.
From our study we concluded that both clonidine (2 μg/kg) and fentanyl (1 μg/kg) can be used as an adjuvant to single-shot caudal epidural anesthesia using 0.25% ropivacaine for effective postoperative analgesia in children. Because of its more favorable side-effect profile, with less respiratory depression, nausea, vomiting, and more patient comfort, clonidine is a better choice for use as an adjuvant to caudal epidural anesthesia in children.
Keywords: caudal epidural, clonidine, fentanyl, pediatric, postoperative analgesia, ropivacaine
|How to cite this article:|
Saini S, Patodi V, Sethi SK, Jain N, Mathur P, Thada B. Comparison of caudal epidural clonidine with fentanyl as an adjuvant to ropivacaine 0.25% for postoperative analgesia in children undergoing various infraumbilical surgeries: A prospective randomized study. Ain-Shams J Anaesthesiol 2016;9:493-500
|How to cite this URL:|
Saini S, Patodi V, Sethi SK, Jain N, Mathur P, Thada B. Comparison of caudal epidural clonidine with fentanyl as an adjuvant to ropivacaine 0.25% for postoperative analgesia in children undergoing various infraumbilical surgeries: A prospective randomized study. Ain-Shams J Anaesthesiol [serial online] 2016 [cited 2018 Jul 17];9:493-500. Available from: http://www.asja.eg.net/text.asp?2016/9/4/493/198252
| Introduction|| |
In pediatric patients, the pain management is an essential component of care provided by pediatric anesthesiologists. For many years, it has been recognized that pediatric patients are more likely to have pain treated less aggressively as compared with their adult counterparts ,.
In pediatric patients, although general anesthesia is the commonly used technique, regional anesthesia can be used for intraoperative as well as postoperative pain relief as an analgesic adjunct. Caudal epidural block is commonly performed as it is a safe, reliable, and easy-to-administer technique for infraumblical surgeries in children . In comparison with bupivacaine, ropivacaine is considered to be a better agent for caudal epidural analgesia in children ,,. The addition of an analgesic adjuvant not only increases the effectiveness of a local anesthetic but also causes reduction in dose of local anesthetic agents, with rapid recovery and effective postoperative analgesia . Many adjuvants can be used to prolong the duration of sensory blockade (e.g. clonidine, opioids, and ketamine) . Opioids can be given but are associated with various side effects such as confusion, itching, nausea, vomiting, and respiratory depression.
Clonidine is a centrally acting selective α2 agonist, which was used previously as an antihypertensive but nowadays increasingly used for sedation, premedication, and also as an analgesic adjuvant. Epidural clonidine exerts its analgesic action by inhibiting the release of nociceptive neurotransmitters in the dorsal horn of the spinal cord and also crosses the blood–brain barrier and interacts with α2 adrenoceptors at spinal and supraspinal sites to produce analgesia ,. Epidural fentanyl also has been widely used as an analgesic adjuvant. The site of action of epidural fentanyl is the substantia gelatinosa on the dorsal horn of the spinal cord, which blocks fibers carrying nociceptive impulses both presynaptically and postsynaptically .
We planned this randomized, prospective, double-blind study to compare the analgesic properties of clonidine and fentanyl as an analgesic adjunct in caudal epidural block with ropivacaine in children aged 1−7 years, as the anatomy of the sacral hiatus is more easily appreciated in younger children and calcification of the sacrococcygeal ligament might render caudal epidural difficult in older children.
| Patients and methods|| |
After obtaining approval from the Institutional Ethical Committee and written informed consent from the parents, children aged 1–7 years, weighing 5–25 kg, of American Society of Anesthesiologists (ASA) grades I and II, posted for various elective infraumbilical surgical procedures (hernia repair, orchidopexy, circumcision, hypospadias repair, and urethroplasty) were enrolled in our study.
Exclusion criteria were as follows: presence of local infection of the caudal area, less than 1 year of age or more than 7 years of age children, ASA grade III or more, a history of allergic reactions to drug used in the study, bleeding diathesis, pre-existing neurological or spinal diseases, neuromuscular disorders, surgery of more than 1 h, and need for intubation.
Sixty children of ASA grades I and II aged 1–7 years were allocated randomly into two groups of 30 each by opening sealed envelope. Group RC received ropivacaine (0.25%, 1 ml/kg) and clonidine (2 µg/kg) and group RF received ropivacaine (0.25%, 1 ml/kg) and fentanyl (1 µg/kg).
Preanesthetic checkup of all children was carried out 24 h before surgery and written informed consent from parents was taken. On arrival in the operation theater, patient’s weight, fasting status, consent, and preanesthetic checkup were checked. All baseline hemodynamic parameters, oxygen saturation (SpO2), heart rate (HR), noninvasive blood pressure, and ECG were recorded. Intravenous line was secured and Isolyte-P drip (B Braun Medical, Inc., Irvine, CA, USA) was started through it. Premedication with intravenous glycopyrrolate (0.005 mg/kg) and tramadol (2 mg/kg) were given. Anesthesia was induced with inhalational technique using nitrous oxide (67%), oxygen (33%), and halothane (2−3%) through Jackson Rees circuit with spontaneous breathing through a face mask. For each patient, an anesthesiologist not involved in the study added clonidine (2 μg/kg) or fentanyl (1 μg/kg) to 0.25% ropivacaine to prepare the required solution (final volume: 1 ml/kg). After induction of anesthesia, the child was placed in the lateral decubitus position. The caudal space was identified and caudal block was performed with appropriate drugs under full asepsis with a 23-G short bevel hypodermic needle. Nitrous oxide and halothane were discontinued and anesthesia was maintained with oxygen and propofol infusion (100 μg/kg/min) with a face mask using the Jackson Rees circuit throughout the intraoperative period. Propofol infusion was stopped after closure of skin incision, and time of recovery from sedation was noted and patients were shifted to the postoperative ward (POW) when fully awake and breathing room air. HR, mean arterial pressure (MAP), and SpO2 were recorded before induction of anesthesia, after induction but before caudal anesthesia, 5 min after caudal anesthesia, and every 5 min thereafter until the patient was shifted to the POW.
During the intraoperative period adequacy of analgesia was gauged by hemodynamic stability. An increase or decrease in the HR greater than 20% from the baseline values was considered as tachycardia or bradycardia. Similarly, an increase or decrease in MAP greater than 20% was considered as hypertension or hypotension. Absence of rise of HR or MAP of more than 20% compared with baseline values recorded just before surgical incision was considered as adequate analgesia. An increase in HR or MAP (>20%) 15 min after administration of caudal anesthesia was defined as failure of analgesia. After exclusion of other causes of increased or decreased HR and MAP, if HR and MAP increased 45 min after surgical incision it was considered as inadequate analgesia. Patients with failed caudal or inadequate analgesia were excluded from the study .
In the POW, analgesia, sedation, HR, MAP, SpO2, and side effects were monitored by a blinded observer hourly until 12 h, and then at 16 and 24 h after caudal block. Pain was assessed using the Children and Infants Postoperative Pain Scale  ([Table 1]). If patients had a score of 4 or more on at least two occasions or showed obvious signs of pain, they were given paracetamol syrup 10 mg/kg orally. The duration of postoperative analgesia was defined as the time interval between caudal anesthesia and first complaint of pain. Assessment of sedation (Ramsay Sedation Score ) was carried out at 30 min, 1, 2, 3, and 4 h after surgery ([Table 2]). SpO2 was monitored continuously and SpO2 less than 95% was defined as desaturation on oxygen mask. Time of micturition is defined as the time from administration of caudal block to spontaneous voiding of urine. Side effects such as nausea, vomiting, respiratory depression, pruritus, hypotension, and bradycardia were also noted.
Before conducting this study, the number of patients for sample size required in each group was determined after a power calculation [power of study calculated using PS: Power and Sample Size Calculation (version 2.1.30) software (William D. Dupont and Walton D. Plummer, Vanderbilt University School of Medicine, Nashville, TN)] according to data obtained from previous studies. According to the above hypothesis, a sample size of 30 patients in each group was considered to be adequate. All data were expressed as mean±SD. Statistical comparisons among the two groups were performed using a two-way analysis of variance to compare changes within each group and paired Student’s t-test to compare different group data. Moreover, statistical analysis was performed with the help of SPSS software version 13.0 (SPSS Inc., Chicago, IL, USA) using Student’s t-test and the χ2-test. A P-value less than 0.05 was considered to be statistically significant.
| Results|| |
In demographic profile, both groups were comparable with regard to age, weight, and sex. The duration of surgery, HR, MAP, and SpO2 before induction (baseline) were also not significantly different between the two groups (P>0.05) ([Table 3]).
At all time intervals, the P-value was more than 0.05 (unpaired t-test) and hence the differences in the HR, MAP, and SpO2 between the two groups were insignificant ([Figure 1],[Figure 2],[Figure 3]). At 10 min, there was a significant change in SpO2 in both groups, but it was clinically nonsignificant ([Table 4]).
|Figure 1: Comparison of intraoperative heart rate (HR) (beats/min). Difference in mean HR between the two groups was statistically nonsignificant (P>0.05).|
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|Figure 2: Comparison of intraoperative mean arterial pressure (MAP) (mmHg). Difference in MAP between the two groups was statistically nonsignificant (P>0.05).|
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|Figure 3: Comparison of intraoperative oxygen saturation (SpO2). Difference in mean SpO2 between the two groups was statistically nonsignificant (P>0.05).|
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There was no incidence of pain score greater than and equal to 4 until the first 8 h in either group. At the end of 10th hour, four (13.33%) children in group RF and none of the children in group RC had a pain score of greater than and equal to 4. At the end of 12th hour, 13 (43.33%) children in group RC and 20 (66.67%) children in group RF had pain score greater than and equal to 4, which was statistically nonsignificant ([Figure 4]). The difference was not significant between the two groups in the remaining time interval with regard to analgesic efficacy ([Table 5]).
|Figure 4: Incidence of pain score greater than and equal to 4 at various time intervals. There was difference in the incidence of pain score greater than 4 between two groups at 10th, 12th, and 14th hour but statistically nonsignificant (P>0.05).|
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|Table 5: Incidence of pain score greater than and equal to 4 at various time intervals|
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The mean duration of analgesia was 732.67±53.56 min in group RC with a range of 630−810 min. In group RF, the mean duration of analgesia was 708.33±54.08 min with a range of 600−780 min. The difference in the mean duration of analgesia was statistically not significant (P>0.05) ([Figure 5]). The mean recovery time was 7.07±2.07 min in group RC compared with 15.67±2.86 min in group RF. The difference in the mean duration of recovery time was statistically significant (P<0.05) ([Figure 6]). The Ramsay Sedation Score [median (interquartile range)] at the end of 30 min was 2.5 (1) in group RC and 4 (0) in group RF, indicating a significant difference in the sedation score between the groups at that time (P<0.05). At the end of fourth hour the sedation score was 1 (0) in group RC and 2 (0) in group RF and the children were cooperative and oriented. There was a significant difference in the sedation scores between the groups at all time intervals until 4 h (P<0.05) ([Table 6] and [Figure 7]).
|Figure 5: Comparison of total duration of analgesia. Total duration of analgesia was statistically nonsignificant between the two groups (P>0.05).|
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|Figure 6: Comparison of recovery time. Mean recovery time was statistically significant between the two groups (P<0.05).|
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|Figure 7: Comparison of Ramsay Sedation Score [median (interquartile range)]. There was a significant difference between sedation score between the two groups at all time intervals until 4 h (P<0.01).|
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The episodes of vomiting were four (13.33%), that of respiratory depression were four (13.33%), and that of bradycardia were three (10%) among children in group RF compared with zero (0%), zero (0%), and four (13.33%) in group RC, respectively. The episodes of nausea were two (6.67%) in group RF compared with zero (0%) in group RC, and the episodes of hypotension was two (6.67%) and that of fever were one (3.33%); it was equal in the two groups. There was no incidence of pruritus in the two groups ([Table 7] and [Figure 8]). The mean duration of first passing urine after caudal block was 375±63.49 min in group RC compared with 479±79.74 min in group RF. The difference in the mean duration of first passing of urine was statistically significant (P<0.01) ([Figure 9]).
|Figure 8: Incidence of complications. Nausea, vomiting, and respiratory depression were significantly different between the two groups (P<0.05).|
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|Figure 9: Comparison of time of first urination. Time of first passing urine was statistically significant between the two groups (P<0.01).|
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| Discussion|| |
Caudal epidural blockade is one of the most popular regional blocks used in pediatric anesthesia. This reliable and safe technique is used widely for many surgical procedures in combination with general anesthesia. It allows rapid recovery from anesthesia with effective postoperative analgesia. The main disadvantage of this technique is the short duration of action following single-shot caudal epidural using only local anesthetic. Recently, several studies have reported caudal use of opioids and other drugs in children to improve postoperative analgesia. Although the caudal opioids like fentanyl can be used to prolong the duration of analgesia, it was associated with side effects such as respiratory depression, pruritus, urinary retention, nausea, and vomiting. Hence, other drugs like clonidine have been used as an adjuvant to local anesthetic to improve analgesia in the postoperative period, thereby reducing the side effects of opioids associated with their use ,,.
The different doses of ropivacaine along with clonidine have been studied in children for single-shot caudal epidural to enhance the quality of analgesia during the postoperative period . In our study, we compared the efficacy of caudal epidural clonidine with fentanyl as an adjuvant to 0.25% ropivacaine for postoperative analgesia in children. In both groups male sex was predominant (>90%). This could be due to inclusion of surgeries such as herniotomy, orchidopexy, and circumcision in our study, similar to the study by Cook and Dayle . The cardiac output in infants and younger children depends on HR, and hence, in view of hemodynamic safety profile, an age group of less than 7 years was chosen for our study other than favorable anatomy of the sacral hiatus in younger children. The dose of clonidine and fentanyl taken in our study was based on previous studies on pediatric age group.
Shukla et al.  compared clonidine with fentanyl and they found that both groups were similar with respect to patient and various block characteristics. The hemodynamics were comparable in both groups (P>0.05), which is similar to the findings in our study. Manickam et al.  also concluded that clonidine with ropivacaine prolongs the duration and quality of analgesia as compared with plain ropivacaine without significant sedation in children .
Pain assessment is the most important and critical component of pain management. In our study, we have used the Children and Infants Postoperative Pain Scale, which is a valid, objective, and reliable method of pain assessment in children between 1 and 7 years of age. If the pain score is more than or equal to 4 at two consecutive intervals of 10 min, supplementary analgesic with oral syrup paracetamol (10 mg/kg) was given. In our study, addition of clonidine and fentanyl to ropivacaine was effective in providing prolonged intraoperative as well as postoperative analgesia. The patients in group RF required analgesic supplementation earlier in the postoperative period compared with group RC, as evaluated by pain scores at different time intervals postoperatively. The results of our study were similar to the study by Shukla et al. . Bajwa et al.  found that the mean duration of analgesia was 8.5 h with 0.25% plain ropivacaine and 13.4 h with 0.25% ropivacaine and clonidine (2 μg/kg). In our study, the mean duration of analgesia was 732.67±53.56 min in group RC and 708.33±54.08 min in group RF, which were comparable (P>0.05) but slightly prolonged in group RC as compared with group RF.
The mean recovery time was 7.07±2.07 min in group RC as compared with 15.67±2.86 min in group RF. The difference in the mean duration of recovery time was statistically significant (P<0.05), which means recovery time was prolonged in the fentanyl group. This may be attributed to clinically favorable side-effect profile of clonidine with minimal sedation with better quality of analgesia at this particular dose in caudal epidural, as shown by previous studies . Moreover, it was also reported that epidural clonidine did not prolong the recovery from general anesthesia. Lee and Rubin  noted significant sedation with 2 μg/kg clonidine and bupivacaine and concluded that the sedative effects reflect improved quality of analgesia in children. However, some other studies have shown absence of significant sedation with 2 μg/kg clonidine. In our study, children in group RC had less sedation scores as compared with group RF, which was statistically significant at all time intervals (P<0.05). At the end of fourth hour the sedation score [median (interquartile range)] was 1 (0) in group RC and 2 (0) in group RF and the children were cooperative and oriented. The optimal epidural dose of clonidine in children are not well documented in the literature; however, in children, the doses of 1–3 μg/kg were not associated with any adverse respiratory and hemodynamic effects, whereas these variations were observed only at higher doses (>5 μg/kg). The epidural clonidine showed significant sedative effects in adults; however, this was of lesser degree in younger children as reported by some studies, which is seen in our study, with the clonidine group having lower sedation scores. However, this was clinically not significant as all children look comfortable, easily arousable with adequate sedation and analgesia, and it is always difficult to distinguish between sedation and analgesia in pediatric age group and should not be regarded as an adverse effect associated with fentanyl .
Shukla et al.  concluded that the analgesic properties of clonidine and fentanyl as additives to ropivacaine in single-shot caudal epidural in children are comparable but clonidine offers a more favorable side-effect profile, which was consistent with the findings in our study. In the study by Shukla et al. , eight of 45 patients had vomiting in the fentanyl group compared with none of the patients having vomiting in the clonidine group.
Nausea, vomiting, pruritus, and respiratory depression are expected side effects of fentanyl, and hypotension and bradycardia are expected side effects of epidural clonidine in adults and depends on the dose administered ,,. However, in children the hemodynamic effects of epidural clonidine are less pronounced than in adults ,,. No patient in group RC had nausea, vomiting, respiratory depression, and pruritus, whereas two patients had nausea, four had vomiting, and four had respiratory depression in group RF. There was no incidence of pruritus in the two groups. These results showed the favorable side-effect profile in patients with the clonidine group. The epidural opioids are well known for their nausea and vomiting effect, whereas clonidine has antiemetic properties when administered orally or intravenously. The favorable side-effect profile of clonidine may be an indication for the use of clonidine rather than fentanyl as an adjuvant to local anesthetics when prolongation of analgesia is required along with minimal side effects.
| Conclusion|| |
From our study we concluded that both clonidine (2 μg/kg) and fentanyl (1 μg/kg) may be used as adjuvant to single-shot caudal epidural anesthesia using 0.25% ropivacaine for effective postoperative analgesia in children. Clonidine is preferred over fentanyl as it does not produce undesirable side effects such as nausea, vomiting, respiratory depression, and pruritus. We recommend the use of clonidine as an adjuvant to ropivacaine in caudal epidural anesthesia, especially in younger children, as it has lesser side effects as compared with fentanyl with adequate postoperative analgesia and lesser sedation, which might have a role in early recovery of children at this particular dose.
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| References|| |
Walco GA, Cassidy RC, Schechter NL. Pain, hurt, and harm. The ethics of pain control in infants and children. N Engl J Med 1994; 331:541–544.
Eland JM. Children's communication of pain [Master thesis, Educational Psychology]. Iowa City, Iowa: University of Iowa 1974.
De Beer DA, Thomas ML. Caudal additives in children-solutions or problems? Br J Anaesth 2003; 90:487–498.
Reiz S, Haggmark S, Johansson G, Nath S. Cardiotoxicity of ropivacaine: a new amid local anaesthetic agent. Acta Anaesthesiol Scand 1989; 33:93–98.
Markham A, Faulds D. Ropivacaine: a review of its pharmacology and therapeutic use in regional anaesthesia. Drugs 1996; 52:429–449.
Hannallah RS, Broadman LM, Belman AB, Abramowitz MD, Epstein BS. Comparison of caudal and ilioinguinal/iliohypogastric nerve blocks for control of post-orchiopexy pain in pediatric ambulatory surgery. Anesthesiology 1987; 66:832–834.
Sethna NF, Berde CB. Paediatric regional anaesthesia. In: Gregory GA, editor. Paediatric anaesthesia. 4th ed. New York, NY: Churchill Livingstone Inc.; 2003. 267–268.
Lonngvist PA. Adjuncts to caudal block in children. Quo Vadis? Br J Anaesth 2005; 95:431–433.
Shukla U, Prabhakar T, Malhotra K. Postoperative analgesia in children when using clonidine or fentanyl with ropivacaine given caudally. J Anaesthesiol Clin Pharmacol 2011; 27:205–210.
Nishina K, Mikawa K, Shiga M, Obara H. Clonidine in paediatric anaesthesia. Paediatr Anaesth 1999; 9:187–202.
Cousins MJ, Mather LE. Intrathecal and epidural administration of opioids. Anesthesiology 1984; 61:276–310.
Buttner W, Finke W. Analysis of behavioral and physiological parameters for the assessment of postoperative analgesic demand in newborns, infants and young children: a comprehensive report on seven consecutive studies. Paediatr Anaesthesia 2000; 10:303–318.
Kollef MH. The Washington manual of critical care. 2nd ed. Philadelphia: Wolters and Kluwer/Lippincott Williams & Wilkins; 2012. 56:463.
Cook B, Dayle E. The use of additives to local anaesthetic solutions for caudal epidural blockade. Paediatr Anaesth 1996; 6:353–359.
Basker S, Singh G, Jacob R. Clonidine in paediatrics – a review. Indian J Anaesth 2009; 53:270–280.
Bosenberg A, Thomas J, Lopez T, Lybeck A, Huizar K, Larsson LE. The efficacy of caudal ropivacaine 1, 2 and 3 mg 1(-1) for postoperative analgesia in children. Paediatr Anaesth 2002; 12:53–58.
Manickam A, Vakamudi M, Parameswari A, Chetan C. Efficacy of clonidine as an adjuvant to ropivacaine for caudal analgesia in children undergoing subumbilical surgery. J Anaesthesiol Clin Pharmacol 2012; 28:185–189
Bajwa SJ, Kaur J, Bajwa SK, Bakshi G, Singh K, Panda A. Caudal ropivacaine-clonidine: a better postoperative analgesic approach. Indian J Anaesth 2010; 54:226–230.
Lee JJ, Rubin AP. Comparison of a bupivacaine-clonidine mixture with plain bupivacaine for caudal analgesia in children. Br J Anaesth 1994; 72:258–262.
Jamali S, Monin S, Begon C, Dubousset AM, Ecoffey C. Clonidine in paediatric caudal anaesthesia. Anesth Analg 1994; 78:663–666.
Eisenach JC, de Kock M, Klimscha W. Alpha(2) adrenergic agonist for regional anaesthesia: a clinical review of clonidine (1984–95). Anaesthesiology 1996; 85:655–674.
Campbell FA, Yentis SM, Fear DW, Bissonnette B. Analgesic efficacy and safety of a caudal bupivacaine-fentanyl mixture in children. Can J Anaesth 1992; 39:661–664.
Jones RD, Gunawardene WM, Yeung CK. A comparison of lignocaine 2% with adrenaline 1:200000 and lignocaine 2% with adrenaline 1:200000 plus fentanyl as agents for caudal anaesthesia in children undergoing circumcision. Anaesth Intensive Care 1990; 18:194–199.
Motsch J, Bottiger BW, Bach A, Bohrer H, Skoberne T, Martin E. Caudal clonidine and bupivacaine for combined epidural and general anaesthesia in children. Acta Anaesthesiol Scand 1997; 41:877–883.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]