Post-operative pain relief in children following caudal bupivacaine and buprenorphine--a comparative study.TK Anilkumar, SA Karpurkar, VS Shinde
Dept of Anaesthesiology, KEM Hospital, Parel, Bombay.
Eighty-five paediatric patients (age range: 6 mths-12yrs) undergoing lower abdominal surgery were studied for post-operative pain relief following either caudal bupivacaine (GpI: n = 43) or buprenorphine (GpII: n = 42). Bupivacaine was administered as 0.5ml/kg body weight of 0.25% solution and buprenorphine as 4 micrograms/ml and volume of 0.5 ml/Kg body weight in normal saline. Post-operatively pain was graded on a 4-point scale and behaviour on a 5-point scale. Any post-operative complications and need for additional analgesia were also noted. Bupivacaine provided good pain relief in the early post-operative hours but buprenorphine provided pain relief lasting for 24 hrs or more post-operatively. Post-operative behaviour of 10 patients receiving buprenorphine was graded as cheerful as compared to 2 from bupivacaine group. Till the end of observation period (i.e. 8 hr post-operatively), majority of patients receiving buprenorphine remained cheerful.
Keywords: Analgesics, Opioid, pharmacology,therapeutic use,Anesthesia, Caudal, Anesthetics, Local, pharmacology,therapeutic use,Bupivacaine, pharmacology,therapeutic use,Buprenorphine, pharmacology,therapeutic use,Child, Child, Preschool, Comparative Study, Human, India, Infant, Pain, Postoperative, drug therapy,
Eighty - five paediatric patients, aged between 6 months and 12 yrs, undergoing lower abdominal surgeries like circumcision, hypospadias repair, herniotomy, etc. and having ASA grade 1 risk were included in the study.
Patients were examined clinically, including the sacral area to rule out any anatomical abnormalities. Routine investigations like complete hemogram and urine examination were done for all the patients. Informed consent was taken from the parents.
Atropine 0.02mg/kg body weight orally was given as pre-medication 30-45 mins before surgery. All were operated under general anaesthesia, which was induced with sodium thiopentone (4-5 mg/kg body weight, 2.5% solution) and was maintained with 60% nitrous oxide, 40% oxygen. Depending upon the nature of surgery, depolarising / non-depolarising muscle relaxant was used.
After induction of general anaesthesia, patients were given lateral position for caudal epidural block, with flexion at knees and hips. Patient's back was prepared using antiseptic solution. The buttocks were covered with a sterile towel. With left thumb, tip of the coccyx was felt and was traced cephalad. A triangular depression was felt at the upper end of intergluteal cleft. When thumb was moved up and down, 2 nodules were felt at the base of the triangle, these being the 'sacral cornu', which confirmed the sacral hiatus. Thumb was fixed at the tip of the hiatus. Using a No.22 disposable hypodermic needle, skin and subcutaneous tissue were punctured at an angle of 50 to the skin. The needle was inserted for about 1 to 1.5 cm and then the hub of the needle was depressed and advanced. When the needle pierced the sacrococcygeal ligament, a "give way" was felt. It meant that the needle had entered the caudal epidural space.
After confirming negative aspiration of cerebrospinal fluid or blood, either bupivacaine, 0.5 ml/kg body weight of 0.25% solution (Group I) or buprenorphine 4 ?g/kg body weight, (Gp II) was injected in a random manner. A position for surgery was given following this procedure.
Post-operative assessment for pain relief was carried out at 0, 2nd, 4th, 8th and 24th hr of surgery. Pain experienced by the patients was graded as 1 = no pain; 2 = mild; 3 = moderate; 4 = severe.
Similarly, post-operative behaviour was recorded at 0 hr, 1st, 2nd, 4th, 8th hr as 1 = cheerful; 2 = calm: 3 = restless: 4 = tearful S = rowdy. To evaluate both analgesic effect and behaviour, 0 hour assessment was done as soon as surgery was over and anaesthetic agents were discontinued.
Patients were also observed for any side effects like nausea, vomiting, pruritus, respiratory depression, urinary retention, etc. The need for any additional analgesics was also noted.
[Table - 1] illustrates age-wise distribution of patients in Group I and II. The minimum weight was 5 kgs (Group I) and maximum weight was 30 kgs (Group II).
Of the 85 patients included in the study, 5 patients were excluded, as caudal block could not be given in these patients due to difficulty in getting the caudal epidural space. The data of remaining 80 patients was analysed (40 in each group).
Post-operative pain relief: The severity of pain could not be assessed in 14 patients of Group I and 3 patients of Group II, as they were below the age of 1 ½ yrs.
Most of the patients from both groups had satisfactory analgesia in the immediate post-operative period (hr) and at 2nd and 4th hr postoperatively. [Table - 2], At 8th hr, buprenorohine provided better analgesia (25 patients with score 1) compared to bupivacaine (4 with score 1) the difference was statistically significant (p < 0.05).
After 24 hrs of operation, buprenorphine provided adequate analgesia (31/40 patients). But most patients who received bupivacaine had mild to moderate pain (23/40) [Table - 2].
Post operative behaviour: In the immediate postoperative period, 39/40 from Group I and 33/40 from Group II remained cheerful or calm [Table - 3]
Similar pattern was observed at 1st and 2nd hr of operation in both the groups.
At 4 hrs of surgery, 10 patients of Group II were cheerful and none from Group I.
The difference in patient's post-operative behaviour became further evident at 8th hr of surgery. Twenty-four from Group 1 wore restless with no one from Group It. Thirteen patients who received buprenorphine were cheerful at this time point whereas only 2 patients from bupivacaine group. The observed difference was statistically significant (p < 0.05).
Post-operative complications: Some patients were catheterised intra-operatively for surgical need. The remaining patients passed urine either immediately on operation table or within 2 hrs of surgery. None of the patients from Group I suffered from nausea, vomiting, urinary retention, pruritus or respiratory depression. On the other hand, 10 patients from Group II complained of nausea and vomiting was present in 8.
Additional analgesia was needed in the form of local application of 2% lignocaine jelly in 2 patients in Group I and one patient in Group II. This was given at 8th and 14th hr of surgery for former patients and at 5th hr for the latter (Group II)
The discovery of opiate receptors in substantia gelatinosa of spinal cord has given a new dimension to pain relief using opiates by spinal and epidural routes. Caudal epidural block has now been established as a standard method for post-operative pain relief in children for lower abdominal surgeries. Caudal block, when performed before surgery, is useful for penile surgery, as it reduces bleeding, prevents erection, avoids laryngeal spasm, reduces the requirement of anaesthesia and also provides post-operative analgesia.
Bupivacaine has been used by caudal epidural route for intra and post-operative analgesia. Bupivacaine at 0.5ml/kg body weight of 0.25% solution was proved to be an effective analgesic by caudal epidural route in a study by Armitage and also in our study.
In children, caudal bupivacaine was found to provide analgesia to superior intra-muscular morphine in post-operative periods.
Buprenorphine, a potent narcotic agent, has got a longer duration of action than morphine and is used extensively for post-operative pain relief by extradural route. Buprenorphine has high opioid receptor affinity and high lipid solubility, which decreases diffusion from spinal cord into blood stream.
In an early study, intramuscular buprenorphine has been compared with caudal bupivacaine as paediatric post-operative analgesics. In the present study both bupivacaine and buprenorphine were administered by caudal epidural route for post-operative pain relief in children. Our findings showed that both the drugs provided good analgesia in the immediate post-operative period. These results are similar to the clinical study by Girofra, et al.
In bupivacaine group, 10-15 mins after caudal injection, the requirement of anaesthesia was much less. In the last 10 mins, most of the patients were either only on oxygen or oxygen and nitrous oxide.
The pain relief was better with buprenorphine, as duration of pain relief was prolonged. The analgesic effect of bupivacaine was seen after 8 hrs. This observation was also found in the study of Girofra, et al. The requirement of additional analgesia also indicates partial action of analgesics given caudally.
This was encountered in 2 patients receiving bupivacaine and one patient given buprenorphine.
Patients who received buprenorphine were better behaved as post-operative pain relief was prolonged. At 8th hr post-surgery, many patients of this group were either calm or cheerful whereas in bupivacaine group, most patients were restless. The grade for behaviour was tearful for 3 patients in bupivacaine group at 4th and 8th hour post-operatively.
Buprenorphine usually causes nausea and vomiting when given orally, intravenously or intramuscularly. Even by caudal epidural route, nausea and vomiting were commonly encountered post-operatively with buprenorphine. Bupivacaine has minimal side effects both by systemic and caudal routes. We did not notice any side effect in bupivacaine group.
In our study, one patient, who had received caudal bupernorphine, developed generalised convulsions 14 hrs of surgery. No definite cause could be established.
As with any regional block, caudal epidural route is subject to problems like blood tap, failed block, etc. In our study, caudal block could not be established in 5 patients because of (a) blood tap on aspiration through the needle (1 patient from each group) and (b) subcutaneous injection resulting in local swelling (2 patients from Group I and 1 from Group II)
Additional analgesics provided post-operatively might indicate partial action of analgesic drugs given caudally. This was encountered in 2 patients of Group I and one patient of Group II.
Therefore, we conclude that buprerorphine (4 ?g/ kg and volume of 0.5 ml/kg) provides as much pain relief as bupivacaine 0.5 ml/kg of 0.25% solution in early post-operative period. Further, buprenorphine provides analgesia lasting upto 24 hrs or more while analgesia due to bupivacalne lasts for 5 to 6 hrs. Patients in buprenorphine group remain more comfortable than bupivacaine group.
[Table - 1], [Table - 2], [Table - 3]