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From the *Department of Anesthesiology and Critical Care, Dr. Ali Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran; Department of Surgery, Dr. Ali Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran; Tehran University of Medical Sciences, Tehran, Iran; Research Development Center, Dr Ali Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran; and ||Liverpool John Moores University, Liverpool, United Kingdom.
Address correspondence and reprint requests to Ali Movafegh, MD, Department of Anesthesiology and Critical Care, Dr Ali Shariati Hospital, North Karegar Street, Tehran 1411713135, Iran. Address e-mail to movafegh{at}sina.tums.ac.ir
Abstract
BACKGROUND: Different drugs have been used to enhance postoperative neuraxial opioid analgesia and reduce adverse effects.
METHODS: We randomized 60 patients into 2 groups to receive either 2 mL saline or 0.1 mg/kg dexamethasone IV before the administration of intrathecal anesthesia (15 mg and meperidine 15 mg). After surgery, patients were asked to score their pain at 6, 12, 18, and 24 h. The presence of postoperative nausea and vomiting (PONV), pruritus and respiratory depression were recorded.
RESULTS: The total dose of diclofenac (P < 0.05), visual analog scale pain score at 6-h intervals (P < 0.001), and the incidence of PONV (P < 0.05) were significantly lower in the dexamethasone group.
CONCLUSIONS: Administration of IV dexamethasone prior to intrathecal meperidine injection enhances analgesia and reduces PONV.
Intrathecal opioids, including meperidine, are frequently administered to patients undergoing major surgery to alleviate postoperative pain; however, they may cause adverse effects such as nausea, vomiting, pruritus, urinary retention, and respiratory depression (1–5).
As the analgesia and the side effects of intrathecal opioids are dose-dependent, a multimodal approach may enhance analgesia while minimizing the side effects (4).
The purpose of the current study was to determine whether administration of IV dexamethasone prior to the administration of intrathecal meperidine and spinal bupivacaine anesthesia would enhance analgesia and minimize postoperative nausea and vomiting (PONV) compared with a control group.
METHODS
The protocol was approved by the Institutional Ethics Committee and informed written consent was obtained from the patients. Sixty male patients, 25–45 years, classified as ASA physical Status I and II who were undergoing inguinal herniorrhaphy, were enrolled in this randomized, double-blind, and placebo-controlled study. Patients who received opioids or antiemetic therapy within 48 h of surgery; those with a history of motion sickness, PONV or addiction; those with any contraindication to spinal anesthesia or dexamethasone or meperidine administration; and patients currently receiving steroid medication were excluded from the study. Patients who required rescue analgesia for pain during surgery were also excluded. All drug solutions were prepared by an anesthesiologist who was not involved in anesthesia administration or in patient observation. Patients were randomly assigned into two groups of either control (Group c, n = 30) or dexamethasone (Group d, n = 30) using a computer-generated randomization list.
On arrival in the operating room, an 18-gauge cannula was inserted and lactated Ringer's solution 7 mL/kg was administered. The patients in group c received 2 mL saline IV and those in Group d received an IV dose of 0.1 mg/kg (maximum 8 mg) dexamethasone (diluted with distilled water to 2 mL) just prior to administration of spinal anesthesia. Then, using an aseptic technique, a 25-gauge Quincke needle was inserted intrathecally via a midline approach into the L3–4 or L4–5 interspace with the patient in the left lateral decubitus position. Both groups received 15 mg 0.5% hyperbaric bupivacaine and meperidine 15 mg diluted in saline (to a final volume of 5 mL).
The severity of postoperative pain was measured and recorded using a 10-cm visual analog scale (VAS), where 0 = no pain and 10 = the worst possible pain. Patients were asked to score the pain during coughing or movement at 6, 12, 18, and 24 h after surgery. Patients could request rescue analgesia at any time after surgery. IM 75 mg diclofenac injection was given as a rescue analgesic at 6-h intervals. IM diclofenac is the only injectable nonsteroidal antiinflammatory drug in Iran.
The incidence of nausea, vomiting and pruritus was evaluated by a "yes" or "no" survey. Respiratory depression was defined as a respiratory rate <8 breath/ min. All evaluations were performed and recorded at 6 h intervals for 24 h after operation.
In the absence of historical data, the necessary sample size was estimated based on a pilot study of 10 patients (5 in each group). Dexamethasone reduced the mean overall VAS pain score from 4.4 ± 2.5 to 2.0 ± 1.6 compared with the control. It was estimated that a minimum of 19 patients in each group would be required to have a 95% power of detecting a 3 score difference at a significance level of 0.05. Statistical analysis was performed using SPSS package (SPSS, Chicago, IL, USA), version 11.5.
For statistical analysis of demographic data and for comparison of groups, repeated measures analysis of variance ANOVA, 
2, Mann–Whitney U-test and independent t-test analyses were performed.
RESULTS
Three patients were excluded from the study. Patient characteristics, preoperative fluid administration, level of sensory blockade, and the duration of surgery were similar in the two groups (Table 1) IM diclofenac requirements and the incidence of PONV were significantly lower in the dexamethasone group than the control group (P < 0.05) (Table 2). The VAS pain scores at 6-h intervals were significantly lower in the dexamethasone group (P < 0.001) (Table 2). Pruritus and respiratory depression were not observed in any of the patients (Table 2).
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DISCUSSION
The current study demonstrates that IV administration of 0.1 mg/kg dexamethasone prior to intrathecal administration of meperidine and spinal bupivacaine anesthesia reduces the intensity of postoperative pain and the incidence of PONV and diclofenac rescue doses.
The present study indicates that there is a synergistic or an additive interaction between dexamethasone and intrathecal meperidine that leads to superior postoperative analgesia and reduction of PONV. However, further studies are needed to evaluate whether this interaction is synergistic or additive. Although corticosteroids have been used successfully for postoperative pain relief (6,7), some studies have not corroborated these reports (8). In one study, IV dexamethasone did not influence the intensity of postoperative pain in patients receiving epidural morphine (9). However, low VAS pain scores were reported during the first 24 h after surgery. Thus, an additive analgesic effect may not have been detected due to the long duration of epidural morphine.
The mechanism of the analgesia induced by corticosteroids is not fully understood. This effect is suspected to be mediated by their antiinflammatory or immune-suppressive effects (10).
The administration of IV dexamethasone in conjunction with intrathecal meperidine to relieve postoperative pain has not been evaluated. Most frequently, IV dexamethasone 8–10 mg has been used in the prevention of PONV (8). We administrated a weight-based dose of 0.1 mg/kg of IV dexamethasone. Adverse effects with a single dose of dexamethasone are probably extremely rare and minor, and previous studies have demonstrated that short-term (<24 h) use of dexamethasone was safe (11).
However administration of a corticosteroid may not be safe in all patients. For example, diabetic patients may experience hyperglycemia, and patients with a current infectious process may be detrimentally affected by the antiinflammatory effects of steroids (10).
In many institutions, herniorrhaphy is performed as an outpatient procedure. Therefore, it must be noted that administration of a long-acting opioid such as meperidine is only appropriate as an inpatient procedure in a hospital.
In conclusion, we demonstrate that IV administration of dexamethasone (0.1 mg/kg) is a valuable treatment as it enhances the analgesic effect of intrathecal meperidine and reduces emesis postoperatively.
REFERENCES
-adrenergic agonists: epinephrine versus clonidine. Anesth Analg 1997;84:1333–9.[Abstract]
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