although caudal epidural block was described by campbell in 1933 , it has evolved to become the most popular regional anaesthetic technique for intra- and post - operative pain relief in children from the 1980s . caudal block is probably the most easily learned and mastered technique of all regional anaesthetic procedures . a major limitation of this technique is the relatively short duration of post - operative analgesia even with long - acting local anaesthetics . catheter placement into the caudal space adds to the risk of infection and tends to prevent early mobilisation and hence is not very popular . prolongation of analgesia with caudal technique has been achieved with addition of various adjuvants to local anaesthetic agents , opioids being the most widely used adjuvant medication . however , the restricted availability of opioids ( as low as 0.4% for the needy in india ) , due to strict regulations , and some of its unpleasant side effects compel the clinician to seek non - opioid drugs such as clonidine , s - ketamine , neostigmine , midazolam and dexmedetomidine as adjuvant for caudal epidural anaesthesia . some of these newer agents such as dexmedetomidine have unwanted haemodynamic effects . in this study , we have selected two easily available and inexpensive drugs as adjuvant with local anaesthetic ropivacaine that may have a better safety profile compared to bupivacaine . the aim of this study was to compare the efficacy of caudally administered tramadol and midazolam as adjuvant to ropivacaine , compared to ropivacaine alone for post - operative analgesia in paediatric patients undergoing subumbilical surgical procedures . after obtaining the institutional research and ethics committee approval , sixty american society of anesthesiologists physical status i children in the age group of 15 years of either gender scheduled for elective subumbilical surgeries were randomly divided into three groups . a random number generating software was used to allocate children into three groups , and blinding was assured by drug preparation by a consultant anaesthesiologist not involved in the further follow - up of the study . patients were excluded if they had a history of allergy to local anaesthetic , bleeding disorder or any evidence of infection , either local or systemic , or there were any neurological deficit or spinal deformities were suspected . written informed parental consent was obtained with respect to type of anaesthesia , the study being conducted , mode of pain relief and nature of surgery . adequate fasting  6 h for solids , 4 h for breast milk and 2 h for clear fluids  was ensured . premedication with syrup triclofos 75 mg / kg mixed with atropine 40 g / kg was given orally 1 h before induction of anaesthesia . baseline values for heart rate ( hr ) , respiratory rate ( rr ) , spo2 and blood pressure ( bp ) were recorded once the child was brought to operation theatre . intravenous access was secured with 22 gauge cannula after inhalational induction with 50% oxygen ( o2 ) and 50% nitrous oxide ( n2 o ) with 8% sevoflurane . anaesthesia was maintained with n2o and o2 in the ratio of 2:1 along with 0.5%1% halothane by mask ventilation using jackson rees modification of ayer 's t - piece . injection ketamine 1 mg / kg was given intravenously to all patients 1 min before caudal epidural needle placement . the child was then positioned in left lateral decubitus , and caudal epidural was placed under strict aseptic precautions using drugs prepared by primary consultant anaesthesiologist not involved in the further follow - up of the cases . caudal epidural block was performed using a 23 gauge scalp vein set with drug volume of 1 ml / kg up to a maximum of 20 ml . group r received 1 ml / kg of 0.2% epidural ropivacaine , group rt received 1 ml / kg of 0.2% epidural ropivacaine with 2 mg / kg of tramadol and group rm received 1 ml / kg of 0.2% epidural ropivacaine along with 50 g / kg of midazolam . the tramadol and midazolam used as adjuvants were preservative - free preparations ( supridol and mezolam from neon laboratories ltd , mumbai - 400 093 , maharashtra , india ) . all patients were monitored for hr , rr , bp and spo2 and documented at 5 min interval . an increase in hr or rr of 15% or more from baseline value was taken as inadequate analgesia and supplemented with 12 g / kg fentanyl , and these children were excluded from the analysis . quality of pain relief was assessed by modified children 's hospital of eastern ontario pain scale ( mcheops ) [ table 1 ] . postoperatively , patients were monitored for hr , rr and spo2 in the recovery room for 1 h. respiratory depression was defined as rr < 10/min or o2 saturation < 94% . modified children 's hospital of eastern ontario pain scale in the post - operative ward , children were observed hourly up to 6 h and then 3 hourly for next 6 h and then at 24 h. rescue analgesia was given when the mcheops score was 6 or more and children were given oral paracetamol 15 mg / kg body weight . the time interval from the caudal block to the administration of rescue analgesic was taken as the duration of analgesia . a four - point sedation score was used to assess the level of sedation : 0 - awake , 1 - mild sedation , 2 - tending to sleep and 3 - deep sleep , unable to awaken . time for spontaneous eye opening from the time of discontinuation of anaesthesia is taken as the duration of sedation . motor block was assessed every 30 min for 3 h using modified bromage scale as below : score 0 - no motor block , 1 - inability to raise extended legs , 2 - inability to flex knee and 3 - no movement possible . side effects such as nausea , vomiting and pruritus were also noted . in a study comparing bupivacaine and bupivacaine plus tramadol , it was found that the difference in mean duration to rescue analgesic was 2.8 h between the two groups . assuming similar difference at the minimum , the sample size calculated was 18 in each group . statistical analysis was performed using the statistical package spss v19.0 ( ibm india pvt ltd , bangalore , india ) . statistical comparison among the three groups was carried out using one - way anova with post hoc analysis using bonferroni . for qualitative variables , the groups were comparable with respect to patient age , sex , weight and duration of surgery [ table 2 ] . intraoperatively , hr , rr , bp or spo2 did not show any significant change in any group indicating haemodynamic stability . demographic data comparison between the three groups pain scores using mcheops were comparable between the groups at all timeframes except at 9 h when there was a significant difference in the pain score . the mean value of mcheops in group r ( 3.79  1.58 ) was higher than that in group rt ( 2.45  0.76 ) and the group rm ( 2.65  1.27 ) at 9 h ( p = 0.010 ) [ figure 1 ] . the mean duration of time to rescue analgesia for group r was 437.75  75.68 min . for group rt , it was 913.00  315.50 min , and for group rm , it was 769.25  331.99 min . the differences in mean time for rescue analgesia were statistically significant between the group r and the other two groups ( p < 0.001 ) [ figure 2 ] . there was no significant difference in mean time for rescue analgesia between group rt ( 913.00  315.50 min ) and group rm ( 769.25  331.99 min ) ( p = 0.361 ) . there was significant difference in modified children 's hospital of eastern ontario pain scale at 9 h ( p = 0.010 ) . r = ropivacaine , rt = ropivacaine + tramadol , rm = ropivacaine + midazolam comparison of time to rescue analgesia and time to spontaneous ambulation . r = ropivacaine , rt = ropivacaine + tramadol , rm = ropivacaine + midazolam the mean duration of time to spontaneous ambulation for group r was 189.25  75.68 min , for group rt 165.00  67.98 min and for group rm 190.75  80.48 min ( p value 0.479 ) . the mean duration of time to spontaneous eye opening for group r was 20.35  8.89 min , for group rt 17.00  5.56 min and for group rm 15.00  5.88 min ( p = 0.056 ) . the mean duration to spontaneous micturition for group r was 342.40  62.70 min , for group rt 331.25  93.06 min and for group rm 307.75  65.08 min ( p = 0.335 ) [ figure 3 ] . r = ropivacaine , rt = ropivacaine + tramadol , rm = ropivacaine + midazolam no significant side effects were noted in any group . one child in group r and one in group rt had vomiting in the post - operative ward . post - operative pain in children is mostly undertreated due to unique problems such as non - acceptance of injections , difficulty in correctly assessing pain and fear of side effects of opioids . with improvement in surgical technique and awareness of physiological processes , the number of surgical procedure and the need to treat paediatric pain is increasing day by day . caudal epidural block is extensively used for post - operative analgesia in children undergoing lower abdominal , perineal and genitourinary surgeries . the short duration of action ( 48 h ) of local anaesthetics alone in caudal block has forced the anaesthesiologists to search for additives to enhance the duration of analgesia in children . continuous caudal analgesia with catheter technique has added risk of infection and delay in mobilisation . although excellent analgesia with extradural opioids is well established , unpleasant side effects and restricted availability have been responsible for a decline in their popularity , especially in paediatrics . in a retrospective study , clinically significant respiratory depression was observed when 0.07 mg / kg morphine was given caudally . as the time period of respiratory depression is unclear , all children after caudal opioids needed postoperative intensive care admission with 24 h spo2 monitoring . high incidence of other complications such as nausea - vomiting and urinary retention with extradural morphine was also reported . in the present study , we have attempted to compare the two commonly used , easily available and relatively inexpensive agents , tramadol and midazolam , as adjuvant in caudal anaesthesia along with ropivacaine , an amino amide local anaesthetic agent . studies have established the safety of tramadol and midazolam as caudal adjuvant without significant adverse effects . however , this is the first study to compare the two adjuvant drugs , midazolam and tramadol , with caudal ropivacaine on duration of analgesia . most of the authors recommended a concentration of 0.2% ropivacaine for effective caudal epidural analgesia without unwanted motor block . studies comparing ropivacaine and bupivacaine show no significant difference in terms of duration of analgesia , and motor block was found to be less with ropivacaine . the analgesic effect of extradurally administered midazolam is through -amino butyric acid ( gaba)/benzodiazepine system of spinal cord , and previous studies have recommended an optimal dose of 50 g / kg for extradural administration . tramadol , a weak opioid , exerts its analgesic effect through  receptors and also inhibits serotonin uptake and is devoid of any respiratory depressant effect . the dose of tramadol used in caudal epidural block in various studies was 12 mg / kg . in our study , the mean duration of analgesia was longer with addition of tramadol ( group rt 913.00  315.50 min ) and midazolam ( group rm 769.25  331.99 min ) compared to ropivacaine alone ( group r 437.75  75.68 min ) . a study on fifty children undergoing herniotomy showed that addition of midazolam to caudal bupivacaine 0.25% significantly prolonged the duration of analgesia without any side effect compared to bupivacaine alone . when used as a sole agent , midazolam in caudal block a randomised controlled study comparing the effects of addition of midazolam , neostigmine or ketamine to caudal bupivacaine in eighty children undergoing inguinal herniotomy showed a significant prolongation of post - operative analgesia with addition of midazolam ( 376  24 min ) , ketamine ( 336  16 min ) or neostigmine ( 442  31 min ) to caudal bupivacaine . we have observed a significant prolongation of rescue analgesia with addition of tramadol to caudal ropivacaine ( 913.00  315.50 min ) compared to ropivacaine alone ( 437.75  75.68 min ) . the unpleasant side effects of tramadol , nausea and vomiting were not significantly observed in our study similar to previous reports . in our study , we have established the efficacy of tramadol and midazolam as effective adjuvant with ropivacaine for prolonging the duration of post - operative analgesia . there was no incidence of respiratory depression or sedation , and the motor block was also minimal . there was no incidence of pruritus or bladder retention in any group . in this study , injection ketamine was used in all patients before caudal anaesthesia keeping in mind the analgesic effect of ketamine . as it was used in all the three groups and the duration of action is about 30 min , it was considered not to compound the post - operative analgesia duration . addition of tramadol or midazolam to caudal epidural block with ropivacaine showed significant prolongation of post - operative analgesia compared to ropivacaine alone . the mean duration of analgesia in tramadol group was more than the midazolam group though this difference was statistically not significant .
background and aims : caudal epidural analgesia is the most commonly used method of post - operative analgesia in children undergoing subumbilical surgeries . 
 many additive drugs have been used to prolong the post - operative analgesia . 
 the aim of this study was to compare the efficacy of tramadol or midazolam addition to caudal ropivacaine for post - operative analgesia in children undergoing subumbilical surgeries.methods:in this prospective , randomised , double - blinded comparative study , sixty children of either gender , in the age group of 15 years and scheduled for elective subumbilical surgeries were randomly divided into three groups of twenty each . 
 children in group r received an epidural injection of 1 ml / kg of 0.2% plain ropivacaine whereas children in group rt received an epidural injection of 2 mg / kg of tramadol plus 1 ml / kg of 0.2% ropivacaine and group rm received an epidural injection of 50 g / kg midazolam plus 1 ml / kg of 0.2% ropivacaine . 
 the primary outcome variable was the duration of time to rescue analgesia . 
 the secondary outcome variables were motor block , sedation score and urinary retention . 
 statistical comparison among the three groups was performed using one - way anova with post hoc analysis using bonferroni . for qualitative variables , 
 chi - square test was used . 
 statistical significance was defined as p < 0.05.results:the mean duration of time to rescue analgesia was significantly longer ( p < 0.001 ) in group rt ( 913  315.5 min ) and group rm ( 769.2  331.9 min ) compared to group r ( 437.75  75.68 min ) . 
 however , there was no significant difference in the duration of time to rescue analgesia between rt and rm groups . motor block and sedation scores were comparable between groups.conclusions:the addition of tramadol or midazolam to caudal epidural ropivacaine prolongs the duration of analgesia without causing significant side effects .