|Year : 2016 | Volume
| Issue : 1 | Page : 42-47
Evaluation of the analgesic effect of caudal dexamethasone combined with bupivacaine in hypospadias repair surgery
Ahmed Z Mohamed
Department of Anesthesia and Intensive Care, Faculty of Medicine, El-Minia University, Minia, Egypt
|Date of Submission||08-Jul-2015|
|Date of Acceptance||08-Feb-2016|
|Date of Web Publication||15-Jun-2016|
Ahmed Z Mohamed
21 Sarofim Street, Minia, Minia Governorate
Source of Support: None, Conflict of Interest: None
Background Caudal analgesia is the most popular regional technique in infants and children for the infraumbilical surgeries. Its main disadvantage though is its short duration. The aim of this prospective, randomized, double-blind study was to examine the effect of dexamethasone (when added to the caudal bupivacaine) on the duration of postoperative analgesia and the intensity of postoperative pain during hypospadias repair surgeries.
Patients and methods A total of 70 patients aged 2–5 years with American Society of Anesthesiologists (ASA) physical status classification I or II were randomly divided into two equal groups in a double-blinded manner. The first group (group B) (n = 35) received caudal analgesia with 0.25% bupivacaine 1 ml/kg, whereas the second group (group D) (n = 35) received caudal analgesia with bupivacaine 0.25% 1 ml/kg plus 0.1 mg/kg dexamethasone. After inhalational induction with sevoflurane and tracheal intubation, patients were turned to lateral position and were given the caudal analgesia. After the end of surgery, postoperative pain score was measured by using Children's and Infants' Postoperative Pain Score (CHIPPS). The primary outcome of this study was the duration of the postoperative caudal analgesia. Severity of postoperative pain, number of rescue analgesic doses, residual motor block, and side effects like nausea and vomiting (secondary outcomes) were monitored.
Results The second group (group D) showed significantly longer duration of postoperative analgesia when compared with the first (group B) group. CHIPPS was less in group D compared with group B at 3, 6, 12, and 24 h. Number of rescue analgesic doses of was less in group B than in group D. Modified Bromage scale score were comparable in both groups.
Conclusion Adding dexamethasone 0.1 mg/kg to the caudal bupivacaine significantly prolonged the duration of postoperative caudal analgesia and decreased the intensity of postoperative pain during hypospadias repair surgery.
Keywords: bupivacaine, caudal analgesia, dexamethasone, hypospadias
|How to cite this article:|
Mohamed AZ. Evaluation of the analgesic effect of caudal dexamethasone combined with bupivacaine in hypospadias repair surgery. Res Opin Anesth Intensive Care 2016;3:42-7
|How to cite this URL:|
Mohamed AZ. Evaluation of the analgesic effect of caudal dexamethasone combined with bupivacaine in hypospadias repair surgery. Res Opin Anesth Intensive Care [serial online] 2016 [cited 2017 Aug 18];3:42-7. Available from: http://www.roaic.eg.net/text.asp?2016/3/1/42/184077
| Introduction|| |
Caudal analgesia is the most frequently used regional technique in children for the prevention of pain in the infraumbilical operations, whether in the intraoperative or postoperative period , but the main disadvantage of a single dose caudal block is its short duration, and this may lead to inadequate postoperative pain control, and further administration of postoperative analgesics . Multiple additives, whether opioid  or nonopioid, such as ketamine , clonidine, and dexmedetomidine , were added to the local anesthetics to prolong the duration of the caudal postoperative analgesia.
Dexamethasone is high-potency glucocorticoid with little mineralcorticoid activity, has strong anti-inflammatory effects, has been reported to enhance postoperative analgesia when administered whether by oral route or by intravenous route, and, when administered epidurally, could decrease the incidence and severity of postoperative pain in adults . No previous studies have examined dexamethasone as an adjuvant to 0.25% bupivacaine in caudal analgesia during hypospadias repair surgeries.
The aim of this prospective, randomized, double-blind study was to evaluate the effect of caudal dexamethasone 0.1 mg/kg combined with caudal bupivacaine 0.25% on the intensity of postoperative pain and the duration of postoperative analgesia during hypospadias repair surgeries.
The present study hypothesized that adding dexamethasone to the caudal bupivacaine would prolong postoperative analgesia (primary outcome) and decrease the severity of postoperative pain (secondary outcome).
| Patients and Methods|| |
After obtaining approval of the local research ethical committee of the Faculty of Medicine, El-Minia University and a written informed consent from parents or guardians of the children, this prospective, randomized, double-blind study was conducted on 70 boys with ASA physical status I or II, aged from 2 to 5 years, and scheduled for a surgical repair of hypospadias at El-Minia University Hospital in the period from May 2012 to July 2014. Patients with coagulation disorders, spine deformity, infection at the block site, or allergy to any of the used drugs were excluded from the study. Using a random allocation software (Windows software, version 1.0, May 2004), patients were randomly assigned to two study groups, with 35 patients in each group; the allocation ratio was 1 : 1, and the group identification paper was put in a sealed and opaque envelop to hide allocation. For the purpose of blindness, the test solution was prepared by another anesthesiologist not included in the study in bottles labeled B or D. At the end of the study, these labels were removed and it was known that B stood for 0.25% bupivacaine alone and D for bupivacaine plus 0.1 mg/ml dexamethasone. Patients fasted for 6 h before the procedure and were allowed to take clear fluid till 3 h from anesthesia. Patients were premedicated with rectal midazolam 0.5 mg/kg 30 min before surgery. On arrival to the operation room, inhalational induction with 8% sevoflurane in oxygen through the face mask until loss of consciousness was carried out, and then a 22-G cannula was inserted. Standard monitors as noninvasive blood pressure, pulse oximetry (SPO2), and ECG were connected to the patients. Blood pressure, heart rate, and oxygen saturation were recorded every 10 min till the end of surgery. Tracheal intubation with endotracheal tube of suitable size was facilitated with atracurium 0.5 mg/kg. Anesthesia was maintained with isoflurane 1–2% in oxygen with mechanical ventilation. Patients were turned to the left lateral position with their both hips and knees flexed, and after complete sterilization of the back of the children, identification of the sacral hiatus and introduction of 22-G needle to the caudal space which was identified by the pop felt when penetrating the sacrococcygeal ligament, sudden loss of resistance and Whoosh test using 0.5 ml of air . After correct placement of the needle in the caudal space, 1 ml/kg of the blinded study solution was injected. The entire caudal anesthesia was carried out by the same anesthesiologist, and all the surgeries by the same urologist. The surgery was allowed to start 10 min after caudal analgesia had been administered. Effective caudal analgesia was defined when the hemodynamic reaction to the surgical incision was less than15% of the baseline values. In case of inadequate analgesia, the patient was given 1 μg/kg fentanyl for analgesia and was excluded from the study. At the end of the surgery, anesthesia was discontinued and the muscle relaxant was reversed, after which extubation was carried out when the protective airway reflexes (cough, gag, and swallowing) retuned. Duration of the surgery (time from skin incision to the end of surgery) and the emergence time (time from the discontinuation of isoflurane till spontaneous eye opening) were recorded. After full recovery the patients were transferred to the postanesthesia care unit where they were observed for heart rate, blood pressure, and oxygen saturation every 15 min. Analgesic regimen of oral acetaminophen 15 mg/kg every 6 h was given to the patients. Pain was assessed by the nursing staff blinded of the group of the patients. Children's and Infants' Postoperative Pain Scale (CHIPPS) ([Table 1]) was used to evaluate the postoperative pain in children; this scale consists of five items each of which scored from 0 to 2. The sum of the five items ranges from 0 (the best) to 10 (the worst pain) . Pain score was measured at 30 min, 1, 2, 4, and 6 h following recovery from anesthesia in the postanesthesia care unit, then at 12 and 24 h in the ward. Duration of absolute analgesia (time from caudal injection to the pain score of ≥2 or until first analgesic request) was recorded. If CHIPPS was 4 or more, a rescue analgesic dose of 30 mg/kg rectal paracetamol was given. If two consequent measurements 5 min apart were 5 or more, a rescue analgesic dose of fentanyl 0.5 μg/kg was given and the number of the rescue analgesic doses was recorded for each group. Residual motor block was recorded at 30 min, 1, 2, 4, and 6 h after recovery using the modified Bromage scale, which consisted of 4 points: 0 = full motor strength (flexion of knees and feet), 1 = flexion of knees, 2 = little movement of feet only, and 3 = no movement of knees or feet. Younger children who could not move their legs on command were stimulated by taping on their legs and feet. After transporting them to the ward, the following parameters were monitored: CHIPPS, number of patients needed rescue fentanyl, and incidence of side effects – for example, nausea, vomiting, hypotension, bradycardia, and respiratory depression were monitored by the nursing staff not aware of the type of test drugs for 24 h.
The primary outcome of this study was the duration of the postoperative caudal analgesia, which was calculated as the time from caudal injection to a CHIPPS score of greater than or equal to 2 or until the first analgesic request. The secondary outcomes were the severity of postoperative pain according to CHIPPS, number of rescue analgesic doses in the first 24 h after operation, residual motor block, and side effects like nausea and vomiting.
The primary outcome of the study was the duration of postoperative analgesia with the power of 90% and type I error of 0.05. To detect a 20% difference between the two groups the sample size was calculated as 32 patients in each group; it was increased to 35 for greater accuracy. Sample size was calculated by using the PASS software program (Power Analysis and Sample Size Calculation) by NCSS, LLC, USA.
All statistical analyses were carried out using IBM, SPSS statistics 20 (SPSS Inc., Chicago, Illinois, USA). Data were expressed and presented as mean ± SD. Numerical data (e.g. age, weight, heart rate, blood pressure) were expressed as mean ± SD. Comparison between the two groups was carried out by using the unpaired t-test. Categorical data (e.g. sex, adverse events) were expressed as percentage. Comparison between the two groups was carried out by using the c 2-test. Data of CHIPPS were expressed as range and median, and were compared using the Mann–Whitney test. A P value of less than 0.05 was considered statistically significant.
| Results|| |
The current study included 70 patients who were randomly divided into two groups of 35 patients each. The current study showed that there was no significant difference between the two groups as regards age, weight, ASA classification, site of the distal opening of hypospadias, and the duration of the surgery, as shown in [Table 2].
There were no significant differences between the two groups as regards heart rate, blood pressure, and oxygen saturation.
There was no significant difference as regards the emergence time between the two groups ([Table 3]).
|Table 3: Duration of absolute analgesia, emergence time, number of patients received rescue fentanyl, and number of patients received rescue paracetamol|
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As regards the duration of analgesia, it was significantly longer in the dexamethasone/bupivacaine group, where it was 9.2 ± 0.9 h, when compared with the bupivacaine group, where it was 4.8 ± 1.1 h ([Table 3]).
There was a significant difference between the two groups as regards the number of patient who received rescue doses of rectal paracetamol; it was 20/35 in the dexamethasone/bupivacaine group compared with 33/35 in the bupivacaine group, as shown in [Table 3]. There was a significant difference between the two groups as regards the number of patients who received rescue analgesic doses of fentanyl; it was 5/35 in the dexamethasone/bupivacaine group compared with 14/35 in the bupivacaine group, as shown in [Table 3].
The CHIPPS scores were lower in the dexamethasone/bupivacaine group than in the bupivacaine group, and this difference became significant at 3, 6, 12, and 24 h, as shown in [Table 4].
|Table 4: Comparison of Children's and Infants' Postoperative Pain Score in both groups|
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There was no significant difference between the two groups as regards the modified Bromage scale scores at all the study times.
There was no significant difference between the two groups as regards the incidence of side effects such as shivering, postoperative nausea, and vomiting, as shown in [Table 5].
| Discussion|| |
The present study demonstrated that a single-dose administration of caudal dexamethasone in a dose of 0.1 mg/kg in combination with caudal bupivacaine 0.25% markedly reduced the intensity of postoperative pain and prolonged the duration of postoperative analgesia in children undergoing hypospadias repair surgery compared with a dose of bupivacaine 0.25% alone. In their study, Kim et al.  found that the addition of dexamethasone 0.1 mg/kg to the caudal ropivacaine 0.15% in children aged between 6 months and 5 years undergoing orchipexy increased the analgesic duration of caudal block with ropivacaine, reduced pain severity and analgesic consumption when compared with ropivacaine 0.15% alone. El-Feky et al. , who compared fentanyl, dexmedetomidine, and dexamethasone as additives to caudal mixture of lidocaine 1% and bupivacaine 0.25% in children 3–10 years old scheduled for lower abdominal surgeries, found that both dexamethasone and dexmedetomidine when combined with the local anesthetics in the caudal analgesia prolonged the postoperative analgesia similar to what fentanyl does but with an added advantage of fewer side effects. Yousef et al. , in their randomized double-blinded study, found that the addition of dexamethasone 0.1 mg/kg or magnesium sulfate 50 mg to ropivacaine 0.15% in caudal analgesia of children aged 1–6 years undergoing inguinal hernia repair prolongs postoperative analgesia, increase the time to the first analgesic dose, and decrease the need for postoperative rescue analgesics without an increase in the side effects. In their study, Thomas and Beevi  examined the effect of preemptive epidural administration of 5 mg dexamethasone with or without bupivacaine in adult patients undergoing laparoscopic cholecystectomy under general anesthesia and reported a significant reduction of postoperative pain and analgesic requirements in the dexamethasone group. Khafagy et al.  compared the administration of epidural dexamethasone 4 mg combined with bupivacaine with fentanyl combined with bupivacaine in 90 adult patients undergoing lower abdominal surgery, followed by general anesthesia, and they found that the dexamethasone-bupivacaine combination had almost the same analgesic potency as that of the fentanyl-bupivacaine combination, with added antiemetic effects. In their study, Hefni et al.  examined the analgesic effect of different doses (4, 6, 8 mg) of epidural dexamethasone added to epidural bupivacaine 0.25% in women undergoing abdominal hysterectomy under general anesthesia, and they found that dexamethasone reduced the severity of postoperative pain, and prolonged the postoperative analgesia of epidural bupivacaine 0.25%, and this effect increased with any increase in the dose of epidural dexamethasone to 8 mg, without an increase in blood glucose.
On the other hand, Blanloeil et al.  did not find epidural corticosteroid (methylprednisolone) having analgesic effects when they were administered in the operation of lateral thoracotomy; this could be attributed to the type of surgery, and the different potency of methylprednisolone in comparison with dexamethasone used in the current study.
Multiple mechanisms have been suggested for the analgesic effects of caudal dexamethasone. Steroids when administered caudally bind directly to glucocorticoid receptors, leading to altered protein synthesis and gene transcription; the administration of corticosteroid may suppress bradykinin synthesis  and the neuropeptides release from the nerve ending  both of which can enhance nociception in the inflamed tissues. It inhibits synthesis of cyclooxygenase isoform-2 in peripheral tissues and in the central nervous system, resulting in a reduction in prostaglandin production, which contributes to analgesia . Johansson et al. , in their study, suggested that corticosteroid may have a local anesthetic effect on nerves by direct membrane action and suggested that local administration of corticosteroid suppresses transmission in thin unmyelinated C-fibers.
One of the limitations of this study was that it could not be certain whether the analgesic effect of caudal dexamethasone was not related to its systemic effects, especially when several studies have suggested that intravenous dexamethasone has analgesic effects , but McIntyre et al.  found that intravenous dexamethasone in a dose of 0.3 mg/kg did not reduce the postoperative pain during dental rehabilitation, and so it is not suspected that 0.1 mg/kg will produce analgesic effect; in addition, Hermans et al. , in their study evaluating the analgesic effects of dexamethasone injected through the intravenous route, found that dexamethasone decreased postoperative pain on the second day and not on the first day. Systemic effects of dexamethasone could also be investigated by hyperglycemia and adrenal suppression, which need frequent blood sampling, which would not be appropriate for children ([Figure 1]).
| Conclusion|| |
The addition of 0.1 mg/kg of dexamethasone to 0.25% bupivacaine administered caudally decreased the intensity of postoperative pain and prolonged the duration of postoperative caudal analgesia after hypospadias repair surgeries.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]