Caudal block is commonly used in pediatric patients undergoing lower abdominal and limb surgeries due to its ability to provide safe and effective perioperative pain relief.

Single dose of caudal levobupivacaine or ropivacaine provides analgesia for 4–8 hours and has become popular due to its high success rates and low incidence of side effects.1, 2 Research has shown that adding some drugs to local anesthetics can increase the duration of caudal analgesia.3  Commonly used adjuvants are clonidine (42.3%),

ketamine (37.5%), opioids (18.1%), adrenaline (1.8%), and midazolam (0.3%).4

Caudal block is performed using a single high-dose local anesthetic, but reducing the anesthetic dose can help reduce local tissue and systemic toxicity. Adjuvants are usually used to decrease local anesthetic dose apart from prolonging the analgesic effect. The minimum local anesthetic concentration (MLAC) is a standard measure used to assess the relative efficacy of commonly used local anesthetics.5-7 Various studies examined the effect of additives on MLAC of local anesthetics in caudal blocks. Clonidine and dexmedetomidine were shown to reduce the MLAC of levobupivacaine in a dose-dependent manner previously. 8-9

Some of the factors assessing quality of block include 1. Volume of the drug 2.Total dose of the drug  3.Concentration of the drug. There are different formulas based on weight or age for determining the volume of local anesthetic to be used.10

The current guidelines recommend established Formula based on weight or age introduced by Armitage in 1979 –where by 0.5ml/kg would give adequate sacral block, 1ml/kg for a thoracolumbar block and 1.25 ml/kg mid –thoracic block. Spiegal Formula and Modified Spiegal Formula are commonly used.

Some of the indications for caudal block include It can be given for both elective lower abdominal and lower limb surgeries. Elective: Usually

combined with light general anaesthesia

Repair of inguinal hernia,

Labour analgesia

Umbilical hernia and hydrocele

Orchidopexy

Anorectal and genito urinary surgeries

Pelvic, and Lower extremity surgeries, Phimosis

Caudal blocks are preferred over lumbar blocks as they provide a sensory and motor block of sacral roots with limited sympathectomy and are associated with a reduced risk of dural puncture. Ketamine, a widely used adjuvant, has also been proven to provide effective and prolonged postoperative analgesia with minimal adverse effects. But, the impact of caudal ketamine on the MLAC of ropivacaine remains unclear. So, this randomized study was undertaken. Given less literature on the efficacy of adjuvants in caudal block among children, the current study was undertaken.

Objectives:

To compare duration of analgesia, hemodynamic parameters and complication in children after caudal analgesia with Ropivacaine alone and Ropivacaine with Ketamine.

• Study design: Randomized controlled study
• Study location: Tertiary care center- Katuri Medical College
• Study Duration: 3 months: December 2024 to February 2025
• Randomization was done using simple random sampling by computer-generated software.
• Study Population: Children aged 1 to 10 years
• Sample size: 100.

Groups: Group R: 30 children were included- patients were given only ropivacaine.

Groups: Group RK: 30 children were included- patients were given ropivacaine and ketamine.

Inclusion criteria:

1. Children aged below 10 years
2. Both genders
3. Children (if they can understand through child assent form) and parents who provided informed consent

Exclusion criteria:

1. Children with severe respiratory, cardiovascular and hepatic diseases
2. Children with known allergies to drugs used in the study
3. Malignancy, severe hepatic or renal disorders, HIV, TB
4. Surgeries requiring anesthesia above T10 level
5. Children with incomplete data

Parameters assessed:

Demography- Age, gender

FLACC score

Hemodynamics: Heart rate (HR), oxygen saturation (SPO2)

Time for 1st rescue analgesia.

Complications

Methodology: 60 children were randomly allocated into 2 equal groups. Group A received ropivacaine 0.2% 1 ml/kg via caudal route. Group B received ropivacaine 0.2% 1 ml/kg plus ketamine 2 μg/kg in the same route. Caudal block was given in lateral position under all aseptic precaution with a 25 gauge i.m needle. After confirming the position of the needle with Whoosh test, the allocated drug was given. The severity of pain was assessed using the Face, Legs, Activity, Cry, Consolability scale, or FLACC scale at 0 hours, 4 hours, 8 hours, and 24 hours. Motor blockade was measured with Bromage scale at 0 and 2 hours. Rescue analgesic was given when the FLACC scale score exceeded 3. The time of first rescue analgesic was recorded.

Analysis: Analysis was done using SPSS 17.0. Categorical parameters were compared between using the chi-square test, and numerical parameters were assessed using the T-test.

Ethical aspects:  Informed consent was taken from every parent of the child included. Ethical committee approval was taken before starting this study (ethics approval letter dated 09-12-2024 from Katuri Medical college Ethics committee).

Demography:

Overall mean age was 8 years.

There is no significant difference in the gender between two groups. Overall, 56 patients were female.

Table 1: Gender comparison in both groups

FLACC SCORE, BROMAGE GRADE, RESCUE ANALGESIA:

There is no significant difference between FLACC score at baseline, 4 hrs between groups.

There was a significant difference in FLACC score at 8 hours between groups.

There is no significant difference in mean Bromage grade between groups at baseline and at 2 hrs.

There is no significant difference in time for requesting analgesia between groups, but it was earlier in R group compared to RK group. This implies that ketamine is prolonging the duration of pain free period.

Table 2: Comparison of FLACC score, bromage grade and rescue analgesia time

Graph 1: FLACC score comparison between groups

HEMODYNAMIC PARAMETERS:

There is no significant difference in heart rate (HR), oxygen saturation (SPO2) at baseline, 30 min, before extubation, post extubation 5 min, 15 min, 30 min between groups.

Table 3: Comparison of hemodynamic parameters in groups

Graph 2: Comparison of heart rate in groups

Graph 3: Comparison of oxygen saturation in groups

COMPLICATIONS:

There is no significant difference in complications between two groups.

Overall nausea/vomiting were seen among 4 patients. 3 belonged to R group among those 4 patients.

     Table 4: Complications in both groups

Ropivacaine is an amide-local anesthetic with high pKa and low lipid solubility, selectively blocks pain-transmitting nerve fibers (A-delta and C fibers) more than those controlling motor function (A-beta fibers). Its cardiotoxicity is less compared to racemic bupivacaine, with a significantly higher threshold for central nervous system toxicity among healthy volunteers.11-13

Ropivacaine also effectively relieves pain, especially when combined with opioids or other adjuvants. Dural ropivacaine induces less motor blockade at lower concentrations.

Ketamine hydrochloride, or ketamine, is approved by the US Drug Administration (FDA) for use as a general anesthetic either alone or with other medications. It is used as pre-anesthetic medication.

The current study was done on 100 patients. Ropivacaine alone and ropivacaine with ketamine were given to study subjects.

Gunes et al. published a study in 2004. The study was done on 99 children aged 1 to 10 years in Turkey. There was no significant difference in gender between the groups, similar to the current study.

Gunes et al.'s study included three groups of 33 participants each. Pain scores were assessed using the FLACC scale in the current study and the CHEOPS scale in the Gunes et al. Study. In both studies, the duration of

analgesia was significantly longer in the ropivacaine and ketamine group.

Neither study found any significant differences in heart rate (HR) or oxygen saturation (SPO2) between the groups.

The current study reported nausea and vomiting in only 4 patients, and Gunes et al. observed nausea and vomiting in 16 patients, but there was no significant difference in the incidence of complications between the groups in either studies.

Naguib et al. showed satisfactory postoperative analgesia after inguinal hernia repair with caudal administration of ketamine at 0.5 mg/kg. 14

Lee et al. reported significantly longer median duration of analgesia in a group receiving ketamine plus ropivacaine (12 hours) compared to ropivacaine alone (3 hours).15

In a study by Jaitawat et al.16, there were three groups: Group A received a caudal block with bupivacaine at 0.5 ml/kg alone, Group B received a caudal block with bupivacaine along with 1 ml/kg fentanyl, and Group C received a caudal block with bupivacaine 0.25% at 0.5 ml/kg along with 0.5 mg/kg ketamine. The findings of the study concluded that the addition of caudally administered ketamine at a dosage of 0.5 mg/kg with bupivacaine provides prolonged postoperative analgesia compared to the use of fentanyl at 1 μg/kg with bupivacaine, with minimal side effects. These findings were similar to the present study.

Ramazan et al.17 did a study to assess the hemodynamic effects and postoperative pain control efficacy of ropivacaine alone and in combination with ketamine in children undergoing inguinal hernia repair with caudal anesthesia. Results showed that at 45th min. postoperatively, CHEOPS’ score was significantly higher in Group R compared to Group K and Group R+K.

LIMITATIONS:

Small sample size

No follow up

Single center study

Adding caudal ketamine to ropivacaine prolongs the duration of postoperative analgesia.

Sponsor: Self

Conflicts of interest: None

Authors contribution:

The study was planned by Dr Srinivas Data collection was done by Dr Sowmya, Data analysis and drafting was done by Dr Saranya. N

1. Locatelli B, Ingelmo P, Sonzogni V, Zanella A, Gatti V, Spotti A, Di Marco S, Fumagalli R. Randomized, double-blind, phase III, controlled trial comparing levobupivacaine 0.25%, ropivacaine 0.25%, and bupivacaine 0.25% by the caudal route in children. Br J Anaesth. 2005;94(3):366–71.
2. Kim EM, Lee JR, Koo BN, Im YJ, Oh HJ, Lee JH. Analgesic efficacy of caudal dexamethasone combined with ropivacaine in children

3. undergoing orchiopexy. Br J Anaesth. 2014;112(5):885–91.
4. Ansermino M, Basu R, Vandebeek C, Montgomery C. Nonopioid additives to local anaesthetics for caudal blockade in children: a systematic review. Paediatr Anaesth. 2003;13(7):561–73.
5. Menzies R, Congreve K, Herodes V, Berg S, Mason DG. A survey of pediatric caudal extradural anesthesia practice. Paediatr Anaesth. 2009;19(9):829–36.
6. Deng XM, Xiao WJ, Tang GZ, Luo MP, Xu KL. Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school-age children. Anaesthesia. 2010;65(10):991–5.
7. McLeod GA, Dale J, Robinson D, Checketts M, Columb MO, Luck J, Wigderowitz C, Rowley D. Determination of the EC50 of levobupivacaine for femoral and sciatic perineural infusion after total knee arthroplasty. Br J Anaesth. 2009;102(4):528–33.
8. Ingelmo P, Frawley G, Astuto M, Duffy C, Donath S, Disma N, Rosano G, Fumagalli R, Gullo A. Relative analgesic potencies of levobupivacaine and ropivacaine for caudal anesthesia in children. Anesth Analg. 2009;108(3):805–13.
9. Disma N, Frawley G, Mameli L, Pistorio A, Alberighi OD, Montobbio G, Tuo P. Effect of epidural clonidine on minimum local anesthetic concentration (ED50) of levobupivacaine for caudal block in children. Paediatr Anaesth. 2011;21(2):128–35.
10. She YJ, Zhang ZY, Song XR. Caudal dexmedetomidine decreases the required concentration of levobupivacaine for caudal block in pediatric patients: a randomized trial. Paediatr Anaesth. 2013;23(12):1205–12.
11. Kaushal S, Singh S, Sharma A. A randomised study comparing the extent of block produced by spinal column height and body weight-based formulae for paediatric caudal analgesia. Indian J Anaesth. 2020 Jun;64(6):477-82. doi: 10.4103/ija.IJA_824_19. Epub 2020 Jun 1. PMID: 32792711; PMCID: PMC7398024.
12. Simpson D, Curran MP, Oldfield V, Keating GM. Ropivacaine: a review of its use in regional anaesthesia and acute pain management. Drugs. 2005;65(18):2675-717.
13. Casati A, Vinciguerra F. Intrathecal anesthesia. Curr Opin Anaesthesiol. 2002 Oct;15(5):543-51.
14. Wulf H, Peters C, Behnke H. The pharmacokinetics of caudal ropivacaine 0.2% in children. A study of infants aged less than 1 year and toddlers aged 1-5 years undergoing inguinal hernia repair. Anaesthesia. 2000 Aug;55(8):757-60.
15. Naguib M, Sharif AMY, Seraj M, et al. Ketamine for caudal analgesia in children: comparison with caudal bupivacaine. Br J Anaesth. 1991; 67:559–64.
16. Lee CR, Mc Tavish D, Sorkin EM. Tramadol. Drugs. 1993; 46:313–40.
17. Jaitawat SS, Kushwaha R, Nagina, Gupta S. Comparison of Caudal Bupivacaine with Additives Fentanyl or Ketamine for Post-Operative Pain Relief in Children: A Randomized Controlled, Double Blinded Study. Indian J Clin Anaesth. 2015;2(4):246–50.
18. Ödeş R, Erhan ÖL, Demi̇rci̇ M, Göksu H. Pediyatrik kaudal blokta ropivakaine eklenen ketaminin etkinliği Effects of ketamine added to ropivacaine in pediatric caudal block. Journalagent.com. 2010. 22(2): 53-60