[Can the addition of clonidine improve the analgesic efficacy of low dose intrathecal morphine? A randomised double-blind trial]

Efficacy and safety of intrathecal morphine for analgesia after lower joint arthroplasty: a systematic review and meta-analysis with meta-regression and trial sequential analysis

Widespread adoption of intrathecal morphine into clinical practice is hampered by concerns about its potential side‐effects. We undertook a systematic review, meta‐analysis and trial sequential analysis with the primary objective of determining the efficacy and safety of intrathecal morphine. Our secondary objective was to determine the dose associated with greatest efficacy and safety. We also assessed the impact of intrathecal morphine on respiratory depression. We systematically searched the literature for trials comparing intrathecal morphine with a control group in patients undergoing hip or knee arthroplasty under spinal anaesthesia. Our primary efficacy outcome was rest pain score (0–10) at 8–12 hours; our primary safety outcome was the rate of postoperative nausea and vomiting within 24 hours. Twenty‐nine trials including 1814 patients were identified. Rest pain score at 8–12 hours was significantly reduced in the intrathecal morphine group, with a mean difference (95%CI) of −1.7 (−2.0 to −1.3), p < 0.0001 (19 trials; 1420 patients; high‐quality evidence), without sub‐group differences between doses (p = 0.35). Intrathecal morphine increased postoperative nausea and vomiting, with a risk ratio (95%CI) of 1.4 (1.3–1.6), p < 0.0001 (24 trials; 1603 patients; high‐quality evidence). However, a sub‐group analysis by dose revealed that rates of postoperative nausea and vomiting within 24 hours were similar between groups at a dose of 100 µg, while the risk significantly increased with larger doses (p value for sub‐group difference = 0.02). Patients receiving intrathecal morphine were no more likely to have respiratory depression, the risk ratio (95%CI) being 0.9 (0.5–1.7), p = 0.78 (16 trials; 1173 patients; high‐quality evidence). In conclusion, there is good evidence that intrathecal morphine provides effective analgesia after lower limb arthroplasty, without an increased risk of respiratory depression, but at the expense of an increased rate of postoperative nausea and vomiting. A dose of 100 µg is a ‘ceiling’ dose for analgesia and a threshold dose for increased rate of postoperative nausea and vomiting.

The Role of Intrathecal Morphine for Postoperative Analgesia in Primary Total Joint Arthroplasty under Spinal Anesthesia: A Systematic Review and Meta-Analysis

OBJECTIVE

To assess the efficacy and safety of intrathecal morphine (ITM) for postoperative analgesia in primary total joint arthroplasty (TJA) under spinal anesthesia and to explore the dose-response relationship for analgesic efficacy or risk of side effects.

METHODS

We searched MEDLINE, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov for any studies meeting the inclusion criteria. All the data were summarized using the random effects model. Subgroup analyses were performed based on the surgical procedure and dose of ITM. Meta-regression was used to explore the dose-response relationship.

RESULTS

Eighteen randomized controlled trials were included. Compared with the placebo or blank control, ITM reduced the postoperative 24-h morphine consumption by 10.07 mg and prolonged the duration of analgesia. However, ITM significantly increased the risk of pruritus by 2.79 fold, with a tendency to increase the risk of postoperative nausea and/or vomiting (P = 0.08). No difference was observed regarding the length of stay (LOS) and incidence of respiratory depression or urinary retention. Furthermore, meta-regression showed a linear dose-response relationship for the postoperative 24-h morphine consumption but no linear dose-response relationship for the risk of side effects.

CONCLUSIONS

Adding morphine to intrathecal anesthetics provides a prolonged and robust analgesic effect without significantly increasing the risk of side effects other than pruritus. Although we found a linear dose-response relationship for the postoperative 24-h morphine consumption, the optimal dose of ITM remains to be further explored in high-quality RCTs with a large sample size.

Efficacy of adding clonidine to intrathecal morphine in acute postoperative pain: meta-analysis

BACKGROUND

Clonidine may be used along with intrathecal morphine for single-dose postoperative analgesia in adults. The efficacy of this is not clear.

METHODS

A meta-analysis was performed for two endpoints of efficacy: the time to first postoperative analgesia request and the amount of systemic morphine used during the first 24 h after operation. A Bayesian inference supporting direct statements about the probability of the magnitude of an effect was also used. The frequency of the five adverse events (postoperative nausea or vomiting, sedation, respiratory depression, pruritus, and hypotension) was analysed.

RESULTS

Clonidine increased the duration of analgesia by 1.63 h [95% confidence interval (CI): 0.93-2.33]. There is a 90% probability that clonidine increases the duration of postoperative analgesia by more than 75 min compared with morphine alone. Clonidine reduced the amount of postoperative morphine by a mean of 4.45 mg (95% CI: 1.40-7.49 mg). There is a probability of 90% to obtain a decrease >2.3 mg but only 35% to obtain a decrease >5 mg. The incidence of hypotension was the only adverse event increased by clonidine (odds ratio 1.78; 95% CI: 1.02-3.12).

CONCLUSIONS

The addition of clonidine to intrathecal morphine extends the time to first analgesia and decreases the amount of morphine used. However, as the effects are small, and the results heavily influenced by a study in which intrathecal fentanyl was also given, this must be balanced with the increased frequency of hypotension.

Risks and side-effects of intrathecal morphine combined with spinal anaesthesia: a meta-analysis

Intrathecal morphine is often used for postoperative analgesia after surgery. We performed a meta-analysis to obtain more detailed information on the frequency of side-effects in patients receiving intrathecal morphine in combination with spinal anaesthesia compared with placebo treated patients. We clustered the analysis to patients receiving placebo, less than morphine 0.3 mg (M < 0.3), or equal to or more than morphine 0.3 mg (M > or = 0.3) and calculated the risk ratios of morphine vs placebo. Twenty-eight studies investigating 46 morphine groups vs placebo were included. A total of 790 patients with intrathecal morphine and 524 patients who received placebo were analysed. Compared with placebo the lower dose of morphine resulted in an increase of nausea (RR 1.4, 95% CI 1.1-1.7), vomiting (RR 3.1, 95% CI 1.5-6.4) and pruritus (RR 1.8, 95% CI 1.4-2.2). The higher dose resulted in an increased risk ratio for pruritus (RR 5.0, 95% CI 2.9-8.6), but not nausea (RR 1.2, 95% CI 0.9-1.6) or vomiting (RR 1.3, 95% CI 0.9-1.9). Overall, intrathecal morphine did not increase respiratory depression. However, the higher dose of intrathecal morphine was associated with more episodes of respiratory depression (7/80) compared with the lower dose (2/247). Intrathecal morphine is associated with a mild increase in side-effects. With a dose < 0.3 mg we found there were no more episodes of respiratory depression than in placebo patients who received systemic opioid analgesia.

The combination of epidural clonidine and S(+)-ketamine did not enhance analgesic efficacy beyond that for each individual drug in adult orthopedic surgery

STUDY OBJECTIVES

To evaluate the benefit of epidural clonidine and S(+)-ketamine combination through the epidural route in adult orthopedic surgery.

DESIGN

Randomized double-blinded study.

SETTING

Teaching hospital.

PATIENTS

Scheduled to undergo knee surgery, 56 American Society of Anesthesiologists physical status 1 and 2 adult patients.

INTERVENTIONS

Patients were randomized to 1 of 4 groups to receive the combined epidural-intrathecal technique. A 10-mL epidural injection of either study drug or normal saline was first administered to all patients. Intrathecal anesthesia was performed with 15 mg of bupivacaine. The control group (CG) received epidural saline. The 0.1-mg/kg S(+)-ketamine epidural group received 0.1 mg/kg epidural S(+)-ketamine. The 0.5-microg/kg clonidine epidural group received 0.5 microg/kg epidural clonidine. The S(+)-ketamine/clonidine group received 0.1 mg/kg epidural S(+)-ketamine plus 0.5 microg/kg epidural clonidine.

MEASUREMENTS AND MAIN RESULTS

Pain and adverse effects were evaluated by visual analog scale. Rescue analgesics were available to patients. The groups were demographically similar. Sensory level to pinprick, surgical and anesthetic time, and visual analog scale scores for pain at first rescue medication were similar among the groups. The time to first rescue analgesic (minute) was lowest in CG (P < .005). The CG required more rescue analgesics in 24 hours than any of the other groups (P < .0005). Patients who received either epidural clonidine, S(+)-ketamine, or both displayed similar analgesia. The frequency of adverse effects was similar among groups (P > .05).

CONCLUSIONS

The association of epidural clonidine or S(+)-ketamine did not result in a greater analgesic effect in the model of acute postoperative pain studied, although the interaction of epidural clonidine and S(+)-ketamine is not attributable to sharing of a common second messenger system.

Spinalan�sthesie bei der Arthroskopie des Kniegelenks

BACKGROUND AND OBJECTIVE

Intrathecal morphine provides effective postoperative analgesia but is associated with the risk of respiratory depression. A dose of only 0.1 mg has been shown to be optimal for effective and safe pain relief after abdominal surgery. This study was designed to determine whether the addition of 0.1 mg of morphine to the local anesthetic for spinal anesthesia produces adequate analgesia following arthroscopic knee joint surgery.

METHODS

A prospective, randomized, placebo-controlled, double-blind clinical trial was performed. Forty ASA I/II patients undergoing knee arthroscopy under spinal anesthesia were randomized to receive either mepivacaine 4% with 0.1 mg of morphine or mepivacaine 4% with saline (placebo) intrathecally. Postoperative analgesia consisted of intravenous morphine delivered by patient-controlled analgesia (bolus: 2 mg, lockout time: 5 min). During the study period of 24 h, pain intensity at rest and on movement (visual analogue scale, 0: no pain, 100: maximum pain), vigilance, and vital parameters were recorded every hour.

RESULTS

There were no statistically significant differences between the two groups in postoperative pain scores, morphine requirements, vigilance, blood pressure, heart rate, and breathing frequency. The patients of the morphine group required 12.3+/-10.2 mg (mean+/-SD) and those of the placebo group 11.6+/-8.4 mg of intravenous morphine from patient-controlled analgesia. The pain scores at rest and on movement were 10.0+/-8.1 and 16.0+/-12.6 in the morphine group and 8.2+/-7.9 and 11.7+/-11.3 in the placebo group. We did not observe severe side effects in any of the patients.

CONCLUSION

Intrathecal administration of 0.1 mg of morphine does not contribute to postoperative analgesia after arthroscopic knee joint surgery.