Epidural analgesia in labour using intermittent doses determined by midwives

Since 1985 midwives have been responsible for choice of drug and timing of epidural top-up doses for women in labour at Flinders Medical Centre. The midwife may choose from one of three different prescribed preparations, namely: bupivacaine 12.5 mg plus pethidine 25 mg, bupivacaine 25 mg, and bupivacaine 50 mg - each made up in a volume of 10 ml. This prospective study examined the incidence of adverse effects and level of patient satisfaction with midwife-managed epidural analgesia. Between 1987 and 1992, 6935 women received midwife-managed epidural analgesia. The pethidine/bupivacaine mixture was generally used for the first dose (75% of women) with a shift towards bupivacaine 25 mg or 50 mg for subsequent top-ups. Sixty-one per cent of women had normal vaginal deliveries, 25% instrumental and 14% caesarean deliveries. The most common side-effects were shivering, hypotension and itch. Shivering occurred following 11% of bupivacaine, and 2% of bupivacaine/pethidine top-ups. Itching was more common after bupivacaine/pethidine (3%) than after bupivacaine (1%). Women reported a high level of satisfaction with the overall experience of childbirth, though this was lower for instrumental and caesarean deliveries than for vaginal deliveries. On the other hand, satisfaction with pain relief provided by the epidural was greater in women who had caesarean or instrumental deliveries. The most commonly cited benefits of epidurals were good pain relief (83%), ability to cope (74%), feeling relaxed (67%), and being aware (60%), while feeling numb (23%) and experiencing severe pain at delivery (17%) were the most common causes of dissatisfaction.     

Continuous epidural infusion of bupivacaine and buprenorphine for postoperative pain relief]

The efficacy for postoperative analgesia and side-effect of combined epidural infusion of bupivacaine and buprenorphine in comparison with each of these drugs alone were evaluated in 150 patients. All patients received initially bupivacaine 8 ml and buprenorphine 0.1 mg. In a random order, epidural infusion of 5 micrograms.ml-1 buprenorphine 1 ml.h-1 (group A; n = 50), 0.25% bupivacaine 1 ml.h-1 (group B; n = 50), or a combination of the two drugs 1 ml.h-1 (group C; n = 50) was continued for 48 h by a portable disposable device. The analgesic efficacy in group C was superior to that in group A or group B. No significant difference in the incidence of side-effect was found among the three groups. We conclude that epidural analgesia with the combination of buprenorphine and bupivacaine is safe, and easy to manage, giving pain relief superior to that provided by each of these drugs alone.     

A comparative study of techniques of postoperative analgesia following caesarean section and lower abdominal surgery

A double-blind, within-patient trial was carried out to compare intramuscular pethidine 100 mg, epidural pethidine 50 mg and epidural bupivacaine 25 mg for pain relief on the day after caesarean section or lower abdominal gynaecological surgery. Analgesia was assessed on a visual analogue pain scale. Forced expiratory volume in one second (FEV 1.0) and venous plasma catecholamine levels were measured immediately before and approximately thirty minutes after each treatment. At the completion of the study the treatments were ranked in order of patient preference. Nineteen patients completed the trial. Analgesia provided by epidural pethidine 50 mg was superior to intramuscular pethidine 100 mg (p less than 0.05) but not statistically better than epidural bupivacaine. There was no significant difference in the duration of analgesia between the active treatments. A mean increase in FEV 1.0 of 18% occurred after both of the epidural treatments, but this did not achieve statistical significance. There was no significant change in catecholamine levels after any of the treatments. Epidural pethidine was preferred by patients over and above intramuscular pethidine and epidural bupivacaine (p less than 0.05).     

Two in one: patient-controlled epidural analgesia (PCEA) to prevent erection and control pain in adult hypospadias-surgery patients.

Following penile surgery, erections are painful and may prejudice the result, because the sutures may not withstand a rigid erection. Therefore, prevention of erection and management of pain are extremely important following hypospadias repair, especially in adult patients. In this prospective study, we aimed to achieve these goals by using an epidural block with patient-controlled analgesia. We allocated 20 adult patients scheduled for hypospadias repair randomly either to receive or not to receive epidural analgesia. Postoperative pain was scored according to a standardised scoring system, based on a 10 point visual analogue scale. In group I (n = 10), analgesia was provided by a 3 ml h(-1) continuous infusion of fentanyl (2 microg) and bupivacaine solution (0.125%) in 1 ml saline via an epidural catheter for the first 3 days. Patient-controlled epidural analgesia was administered with an additional 5 ml of the same solution when the pain score was high (> 4). After 3 days, fentanyl was excluded from the treatment protocol, and analgesia was maintained with bupivacaine (0.125%). In group II (n = 10, control group), an epidural catheter was not inserted, and analgesia was maintained with pethidine (1 mg kg(-1)). Pain management was found to be more effective in group I. No erections occurred in group I, but the erection rate in group II was mean +/- s.d. = 1.7 +/- 0.2. The differences were found to be statistically significant (P<0.05). We highly recommend the technique described here, which offers efficient analgesia and control of erection in adult hypospadias patients.     

Onset of spinal block is more rapid with isobaric than hyperbaric bupivacaine

PURPOSE: To compare isobaric with hyperbaric 9.75 mg bupivacaine injected intrathecally, and to evaluate the effects of subsequent injection of lidocaine 2% into the epidural space. METHODS: Patients in group 1 (n = 30) received isobaric 9.75 mg bupivacaine and in group 2 (n = 30) hyperbaric 9.75 mg bupivacaine injected into the subarachnoid space in a combined spinal-epidural technique. They were undergoing urological, gynecological, orthopedic, gastro-intestinal or vascular surgery. Using a double blind technique, the followings parameters were measured: cutaneous analgesia to pinprick, motor blockade, time for two segment regression, time for complete regression of the motor block, quality of anesthesia. In 12 patients the effect of epidural injections of 3 ml lidocaine 2% was observed. RESULTS: Motor and sensory block developed more rapidly (five minutes) in the isobaric group (P<0.05). Maximum upper level (T7+/-2), two-segment regression (52 min in both groups), motor recovery (160 vs. 157 min), and quality of anesthesia did not differ between the two groups. Thirty nine epidural injections of 3 ml lidocaine 2% were given in 12 patients 10 min after spinal injection, 28 were in the hyperbaric group (P<0.05). Twenty six of the epidural injections produced an increase in sensory block of 0 or 1 dermatome, and 13, of 2 or more. CONCLUSION: The block developed more rapidly in the isobaric group, but both isobaric and hyperbaric 9.75 mg bupivacaine produced adequate upper levels of analgesia for surgery. The effect of epidural injections of 3 ml lidocaine 2% was usually minimal.     

Combined spinal epidural vs epidural labour analgesia: does initial intrathecal analgesia reduce the subsequent minimum local analgesic concentration of epidural bupivacaine?

Labour analgesia initiated using a combined spinal-epidural (CSE) technique may reduce subsequent epidural bupivacaine requirements compared with an epidural-only technique. We compared the minimum local analgesic concentrations (MLAC) of epidural bupivacaine following initial intrathecal or epidural injection. In a prospective, double-blind study, 115 women requesting epidural analgesia were randomly assigned to receive either an epidural with bupivacaine 20 mg and fentanyl 40 μg or a CSE with intrathecal bupivacaine 2.5 mg and fentanyl 5 μg. Analgesia was assessed using a visual analogue pain score. When further analgesia was requested, bupivacaine 20 ml was given, and the concentration was determined using the technique of up-down sequential allocation. The MLAC of bupivacaine in the epidural group was 0.032% wt/vol (95% CI 0.020-0.044) compared with 0.047% wt/vol (95% CI 0.042-0.052) in the CSE group. Bupivacaine requirements for the second injection were increased following intrathecal analgesia by a factor of 1.45 (p = 0.026) compared with epidural analgesia.     

Comparison of 15 mg and 25 mg of bupivacaine both with 50 microg fentanyl as initial dose for epidural analgesia

Bupivacaine 15 mg is commonly used as a test dose prior to the initial dose for epidural analgesia in labour. When 15 mg or 25 mg of bupivacaine (15 ml of 0.1% or 0.167%) with 50 microg fentanyl was administered blindly to two groups of labouring women, as an initial dose, 83% and 90% of women respectively, achieved analgesia within 20 min. All the remaining women achieved analgesia with a further dose of 10 mg bupivacaine (10 m10.1%) with fentanyl 2 microg per ml given at 20 min.     

Patient-controlled epidural analgesia after major urologic surgeries. A comparison of tramadol with or without bupivacaine

The efficiency and safety of patient-controlled epidural analgesia by using tramadol alone and combined with bupivacaine were investigated for postoperative pain treatment after major urological surgeries. For PCEA: in group I (n = 17) a loading dose of 20 mg tramadol with a continuous infusion of 1 mg/ml tramadol at a rate of 8 ml/h was given. In group II (n = 17), patients received an initial loading dose of 20 ml bupivacaine 0.125% and a supplemental continuous infusion of 8 ml/h. In group III (n = 17), a loading dose of 20 mg tramadol with 20 ml bupivacaine 0.125% were given and a supplemental infusion of 1 mg/ml tramadol in 20 ml bupivacaine 0.125% combination was begun with a rate of 8 ml/h. A demand epidural bolus dose of 5 ml with a lockout time of 30 min was also used in all patients. VAS for pain intensity, vital signs, sedation scale and side effects was monitored at 0, 15, 30 min and 1, 2, 3, 4, 8, 12, and 24 h of the postoperative period. Statistical significance was determined using Kruskal-Wallis, Fisher's exact, analysis of variance for repeated measurements and Tukey tests. The hemodynamic values and sedation scales were insignificantly different (p > 0.05). The adequate analgesia was provided in all patients. However VAS values were significantly lower in group III than in groups I and II at every measurement (p < 0.05). The incidence of side effects in all three groups was low (p > 0.05). In conclusion, we suggested that a combination of tramadol with bupivacaine can provide the most effective and safe postoperative analgesia with minimal risk for side effects.     

Speed of onset of regional analgesia in labour: a comparison of the epidural and spinal routes

This study compares the speed of onset of effective analgesia in two randomly assigned groups of patients requesting analgesia in labour. Patients in the combined spinal-epidural group (n = 69) were given a subarachnoid injection of 1.5 ml containing bupivacaine 2.5 mg and fentanyl 25 microg for initiation of analgesia. Patients in the epidural group (n = 73) were given an epidural injection of 10 ml containing bupivacaine 12.5 mg and fentanyl 50 microg. Mean (SD) onset times to the first pain-free contraction were 10.0 (5.7) min in the combined spinal-epidural group and 12.1 (6.5) min in the epidural group (p = 0.054). Patients in the combined spinal-epidural group suffered a higher incidence of motor weakness and proprioceptive deficit than those in the epidural group (p = 0.01). The incidence of technique failure and side-effects was similar in the two groups. It is our contention that the statistically nonsignificant difference in onset times does not justify the additional potential for side-effects and the extra cost of the equipment involved in the combined spinal-epidural technique.     

The clinical effectiveness of epidural bupivacaine, bupivacaine with lidocaine, and bupivacaine with fentanyl for labor analgesia

STUDY OBJECTIVE: To examine the efficacy of bupivacaine alone and in combination with lidocaine or fentanyl for epidural analgesia during labor. DESIGN: Randomized, single-blind study. SETTING: Labor and delivery unit at a university medical center. PATIENTS: Forty-five primiparas requesting epidural analgesia. INTERVENTIONS: Following epidural placement at L3-4 interspace, patients received either bupivacaine 0.5% (Group 1, n = 15), bupivacaine 0.25% with lidocaine 1% (Group 2, n = 15), or bupivacaine 0.5% with fentanyl 50 micrograms in 10 ml of saline (Group 3, n = 15). Patients in Groups 1 and 2 received 6 to 10 ml of local anesthetic depending on patient height, while patients in Group 3 received 5 ml of local anesthetic plus 50 micrograms of fentanyl in 10 ml of saline. All solutions contained epinephrine 1:200,000. MEASUREMENTS AND MAIN RESULTS: Patients were assessed at regular intervals following administration of the epidural solution. Visual analog scale (VAS) scores were used to measure onset of analgesia, time to complete pain relief, duration of analgesia, and patient satisfaction with therapy. The frequency of shivering and pruritus and the extent of sensory/motor block also were evaluated. There were no intragroup differences in time to complete pain relief or patient satisfaction. However, patients in Group 3 noted the most rapid onset and longest duration of pain relief. Patients in Group 3 also experienced significantly less shivering and had the lowest degree of motor block. Two patients in Group 3 experienced mild pruritus. CONCLUSIONS: Epidurally administered fentanyl safely extended the duration of labor analgesia while reducing bupivacaine dose requirements and magnitude of motor block. In this setting, the combination of bupivacaine and lidocaine offered no clinical advantage over bupivacaine alone.     

Comparison of midwife top-ups, continuous infusion and patient- controlled epidural analgesia for maintaining mobility after a low-dose combined spinal--epidural

We studied 133 women given a combined spinal-epidural for analgesia in labour. The initial intrathecal dose contained bupivacaine 2.5 mg with fentanyl 25 micrograms. When the mothers were comfortable, they were allocated randomly to one of three groups: continuous infusion (group Cl, n = 46), midwife top-ups (group MW, n = 43) or patient-controlled epidural analgesia (group PCEA, n = 44), to maintain analgesia throughout labour. All epidural solutions contained 0.1% bupivacaine and fentanyl 2 micrograms ml-1. Motor block was assessed by the mother's ability to straight leg raise (SLR). Four hours after combined spinal-epidural analgesia, 88.1% of women could SLR in group MW, 83.7% in group PCEA and 57.8% in group Cl (P = 0.002). Total use of bupivacaine was highest in group Cl (mean 11.3 (SD 3.3) mg h-1) compared with group MW (7.5 (3.1) mg h-1) and group PCEA (9.1 (2.1) mg h-1) (P < 0.001). Analgesia was similar between groups and overall satisfaction was equally high.      

Comparison of continuous epidural infusion of fentanyl-bupivacaine and morphine-bupivacaine in management of postoperative pain

The short duration of epidural fentanyl has limited its direct comparison with epidural morphine in previous reports. The following study was performed of continuous postoperative epidural infusions at 5 ml/hr fentanyl 10 micrograms/ml (n = 59) or morphine 0.1 mg/ml (n = 48), both with bupivacaine 0.1%, in patients having cesarean sections. Postoperative evaluations included the frequency and magnitude of clinically evident respiratory depression, the adequacy of analgesia, nausea, pruritis, the ability to ambulate, and other side effects for 24 hours. Analgesia and the number of supplemental narcotic injections needed were similar in both groups. The incidence of nausea and pruritis was significantly less in the patients receiving fentanyl. No patient developed respiratory depression in either group. Patient and staff acceptance of the continuous epidural technique was excellent because there were only minor catheter-related problems associated with its use. It is concluded that continuous epidural fentanyl combined with bupivacaine offers excellent postoperative analgesia with minimal side effects.     

Randomized controlled comparison of epidural bupivacaine versus pethidine for analgesia in labour

We compared the incidence of Caesarean delivery in nulliparouswomen randomized to receive epidural analgesia with those randomizedto intramuscular (i.m.) pethidine. On admission to the deliverysuite in established labour, 802 nulliparae had already agreedto be randomized with respect to their first analgesia. Onehundred and eighty-eight women required either no analgesiaor 50% nitrous oxide in oxygen (Entonox) only. Of the remaining614 women, 310 were randomly allocated to receive i.m. pethidineup to 300 mg and 304 to receive epidural bupivacaine. Labourmanagement was standardized according to the criteria for activemanagement of labour. The intention-to-treat analysis showedsimilar Caesarean section rates in those randomized to epidural(12%) or pethidine analgesia (13%). The difference in Caesareanrate was –1.1% with 95% confidence intervals from –6.3%to +4.1%. The normal vaginal delivery rates were similar (epidural,59%; pethidine, 61%).     

The addition of pethidine to epidural bupivacaine in labour--effect of changing bupivacaine strength.

The effects of varying the strength of bupivacaine used in epidurals for the relief of labour pain was examined. The trial randomly allocated sixty women in the first stage of labour to one of three groups. All women were of ASA status 1 or 2 and had uncomplicated pregnancies. Subjects in each group received pethidine 25 mg in 10 ml of either 0.125%, 0.1875%, or 0.25% bupivacaine. Pain scores for each patient were then assessed over the following thirty minutes. Duration of analgesia and subsequent dose requirements were examined. No difference in pain scores between groups at thirty minutes after injection of the test solutions was found. The 0.25% solution group did however have a more rapid onset of analgesia with the majority of patients in this group achieving their maximum effect between ten and twenty minutes after injection. Duration of analgesia was not prolonged by using the stronger solutions. This study suggests that when epidural pethidine 25 mg is added to local anaesthetic solutions of bupivacaine, adequate analgesia for the first stage of labour is achieved with the 0.125% bupivacaine solution. The use of stronger solutions of bupivacaine achieves no greater degree of analgesia nor longer duration of action, although the onset of analgesia may be faster with the stronger solutions. Further investigations are needed to determine if 25 mg of pethidine is the best choice of dose to use under these circumstances.     

Comparison of the effects of intrathecal morphine and pethidine on shivering after Caesarean delivery under combined-spinal epidural anaesthesia

We performed a prospective, randomised, double blind study to compare the antishivering effect of morphine and pethidine when added to intrathecal hyperbaric bupivacaine during elective Caesarean delivery under combined-spinal epidural anaesthesia. Spinal anaesthesia consisted of either 8-10 mg of 0.5% bupivacaine alone (group B; n = 30) with 0.1 mg morphine (group BM0.1; n = 29), with 0.2 mg morphine (group BM0.2; n = 30), or with 10 mg pethidine (group BPeth10; n = 30). The incidences of shivering were 23.3% (7/30) in group B, 17% (5/29) in group BM0.1, 13.3% (4/30) in group BM0.2 and 3.3% (1/30) in group BPeth10 (p < 0.05). The shivering intensity for each patient was significantly higher in group B than the other groups. In conclusion, intrathecal pethidine added to hyperbaric bupivacaine reduces the incidence and intensity of shivering more than does morphine (0.1 or 0.2 mg).     

Continuous epidural administration of midazolam and bupivacaine for postoperative analgesia

BACKGROUND: Midazolam has been reported to have a spinally mediated analgesic effect. Clinically, single-shot epidural or spinal administration of midazolam has been shown to have an analgesic effect on perioperative pain. In this study, we investigated the analgesic effect of continuous epidural administration of midazolam with bupivacaine on postoperative pain. METHODS: Four groups of 20 patients who underwent gastrectomy or cholecystectomy were studied. Continuous epidural infusion of bupivacaine 100 mg (Group C), bupivacaine 100 mg + midazolam 10 mg (Group M10), or bupivacaine 100 mg + midazolam 20 mg (Group M20) in 40 ml per 12 h was started after surgery using the balloon infuser. Group I received intermittent epidural bupivacaine (2.5 mg.ml-1) 6 ml every 2 h. When necessary, an indomethacin suppository and then a single epidural shot of bupivacaine (2.5 mg.ml-1) 6 ml was administered. Blood pressure, heart rate, respiratory rate, analgesic area, analgesia score, and sedation score were monitored for 12 h postoperatively. Memory and frequencies of supplemental analgesia (indomethacin suppositories and epidural bupivacaine) were also checked. RESULTS: Group M20 showed a significantly wider area of pinprick analgesia and better analgesia scores than other groups. The need for rescue analgesics were significantly less in Group M20. Sedation and amnesia were more pronounced in Group M20 than the other groups. CONCLUSION: Adding midazolam (10 to 20 mg per 12 h) to continuous epidural infusion of bupivacaine for postoperative pain can provide a better analgesia, amnesia and sedation than bupivacaine alone.     

Effect of epidural opioids on gastric emptying in labour

The effect of epidural opioids on gastric emptying was studied in 36 women in labour. Women who had received one dose of epidural bupivacaine were randomised to receive 10 ml of bupivacaine 0.25% alone (n = 8) with fentanyl 50 microg (n = 8) or with diamorphine 2.5 mg (n = 8), or 10 ml of bupivacaine 0.125% alone (n = 4) or with fentanyl 100 microg (n = 4) or with diamorphine 5 mg (n = 4) when they first requested a top-up. Mean+/-SD fentanyl concentrations measured at delivery were, in maternal venous plasma (MV) 0.72+/-0.19 ng/ml and in umbilical venous plasma (UV) 0.75+/-0.3 ng/ml. The mean dose-delivery interval was 280 min (range 107-608 min) and there was a negative correlation between UV/MV and dose-delivery interval. Gastric emptying was assessed by measuring paracetamol absorption following an oral dose of 1.5 g given 30 minutes after the study top-up. Time to peak plasma paracetamol concentration was significantly delayed in the groups given fentanyl 50 and 100 microg and diamorphine 5 mg, compared to the groups given bupivacaine alone, and peak concentration was significantly reduced in the group given diamorphine 5 mg. It is concluded that epidural fentanyl 50 and 100 mg and epidural diamorphine 5 mg delay gastric emptying. The addition of 2.5 mg diamorphine has no significant effect.     

A randomized comparison of programmed intermittent epidural bolus with continuous epidural infusion for labor analgesia

Bolus injection through an epidural catheter may result in better distribution of anesthetic solution in the epidural space compared with continuous infusion of the same anesthetic solution. In this randomized, double-blind study we compared total bupivacaine consumption, need for supplemental epidural analgesia, quality of analgesia, and patient satisfaction in women who received programmed intermittent epidural boluses (PIEB) compared with continuous epidural infusion (CEI) for maintenance of labor analgesia. The primary outcome variable was bupivacaine consumption per hour of analgesia. Combined spinal epidural analgesia was initiated in multiparas scheduled for induction of labor with cervical dilation between 2 and 5 cm. Subjects were randomized to PIEB (6-mL bolus every 30 min beginning 45 min after the intrathecal injection) or CEI (12-mL/h infusion beginning 15 min the after the intrathecal injection). The epidural analgesia solution was bupivacaine 0.625 mg/mL and fentanyl 2 microg/mL. Breakthrough pain in both groups was treated initially with patient-controlled epidural analgesia (PCEA) followed by manual bolus rescue analgesia using bupivacaine 0.125%. The median total bupivacaine dose per hour of analgesia was less in the PIEB (n = 63) (10.5 mg/h; 95% confidence interval, 9.5-11.8 mg/h) compared with the CEI group (n = 63) (12.3 mg/h; 95% confidence interval, 10.5-14.0 mg/h) (P < 0.01), fewer manual rescue boluses were required (rate difference 22%, 95% confidence interval of difference 5% to 38%), and satisfaction scores were higher. Labor pain, PCEA requests, and delivered PCEA doses did not differ. PIEB combined with PCEA provided similar analgesia, but with a smaller bupivacaine dose and better patient satisfaction compared with CEI with PCEA for maintenance of epidural labor analgesia.     

A comparison of opioid solutions for patient-controlled epidural analgesia

Sixty patients took part in a randomised, double-blind study to compare the analgesic and side effects of three opioid-containing solutions for patient-controlled epidural analgesia following abdominal surgery. Patients in group 1 received a solution containing bupivacaine 0.125% with fentanyl 10μg. ml⁻¹, group 2 bupivacaine 0.125% with diamorphine 125μg. ml⁻¹, group 3 pethidine 2.5 mg. ml⁻¹. All groups received 4 ml.h⁻¹ background infusion and 3 ml boluses every 20 min if necessary. There were no significant differences between the groups in visual analogue scale pain scores (p = 0.537) or volumes of solution used at 24 h (p = 0.351) or 48 h (p = 0.105). Motor block was significantly higher in group 2 (p < 0.004) and pruritis occurred significantly less in group 3 (p < 0.05). We conclude that these three solutions produce equivalent analgesia but that pethidine 2.5 mg. ml⁻¹ may be associated with fewer side effects.     

Efficacy of three doses of ketamine with bupivacaine for caudal analgesia in pediatric inguinal herniotomy

BACKGROUND AND OBJECTIVES: Ketamine administered systemically is a potent analgesic at subanesthetic plasma concentrations. Addition of ketamine to bupivacaine for caudal epidural block significantly prolongs the duration of postoperative analgesia. The purpose of this prospective, randomized double-blind study is to identify the optimal dose of ketamine that produces the maximum duration of caudal analgesia with minimal adverse effects as an adjuvant to bupivacaine for caudal epidural block. METHODS: Sixty children, aged 6 months to 10 years, undergoing inguinal herniotomy were allocated randomly to receive 1 of 3 solutions for caudal epidural block. Group 1 received 0.75 mL/kg of bupivacaine 0.25% with preservative-free ketamine 0.25 mg/kg, group 2 received 0.75 mL/kg of bupivacaine 0.25% with ketamine 0.5 mg/kg, and group 3 received 0.75 mL/kg of bupivacaine 0.25% with ketamine 1 mg/kg. Postoperative pain was assessed using the All India Institute of Medical Sciences pain discomfort scale. Rescue analgesia in the form of pethidine 1 mg/kg intramuscularly was administered when this score exceeded 4. RESULTS: The mean duration of caudal analgesia was 8.8 hours in group 1 compared with 22.1 hours in group 2 (P <.001) and 25.2 hours in group 3 (P <.001). Supplemental analgesia requirements with pethidine were significantly less in group 2 (4 subjects) and group 3 (no subject) when compared with group 1 (18 subjects). There were no differences between the groups in the incidence of motor blockade, urinary retention, emesis, or sedation. Group 3 had a significantly higher incidence of behavioral side effects such as odd behavior, agitation, or restlessness than groups 1 and 2. CONCLUSIONS: The optimal dose of ketamine in our study was 0.5 mg/kg added to 0.75 mL/kg bupivacaine 0.25% for caudal epidural block without an increase in side effects.