Comparative study of epidural morphine and epidural dexmedetomidine used as adjuvant to levobupivacaine in major abdominal surgery

Analgesic, cardiorespiratory effects and motor block characteristics of epidural levobupivacaine alone or in combination with methadone or dexmedetomidine in bitches undergoing unilateral total mastectomy

The aim of this study was to evaluate the latency, extent of analgesia, and duration of motor block of levobupivacaine alone and combined with methadone or dexmedetomidine after epidural administration during and after mastectomy in dogs. Twenty-four mature, mixed-breed female dogs were randomly divided into three experimental groups with eight animals each, according to the agents used in lumbosacral epidural analgesia: levobupivacaine 0.75% alone (1.5mg/kg - control group), levobupivacaine 0.75% (1.5 mg/kg) + methadone 1% (0.3 mg/kg), or levobupivacaine 0.75% (1.5 mg/kg) + dexmedetomidine 0.05% (3 µg/kg). During surgery, cardiorespiratory parameters were evaluated. Rescue analgesia was given when there were signs of nociception and was necessary in all three treatment groups. Since all animals received rescue analgesia during the surgery and immediately post-surgery, the duration of the sensitive block were not evaluated. The extent of sensory block was between the 12º and 13º thoracic vertebrae for the control group, 7º thoracic vertebra to 5º lumbar vertebra (methadone group), and 8º thoracic vertebra to 4º lumbar vertebra for the dexmedetomidine group. Methadone or dexmedetomidine combined with levobupivacaine increased the extent of the sensory block and the duration of the motor block in bitches when administered via the epidural route.

Efficacy and Safety of Dexmedetomidine as an Adjuvant in Epidural Analgesia and Anesthesia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND AND OBJECTIVE

Several clinical trials have examined and indicated the usefulness of epidural dexmedetomidine therapy. However, there has been no systematic analysis of the findings of these trials to date. We undertook this systematic review and meta-analysis to investigate the efficacy and safety of epidural dexmedetomidine adjunctive therapy in different surgical procedures.

MATERIALS AND METHODS

We searched EMBASE, PubMed, the Cochrane Library, and the Clinical Trials.gov database to identify randomized controlled trials investigating the effects of epidural dexmedetomidine adjunctive therapy. The article search was conducted without language or date restrictions. The date of the last search was 27 July 2016. The mean differences (MD) or standardized mean differences (SMD) with 95% confidence intervals (CIs) were calculated for continuous variables, and risk ratios (RRs) were presented for dichotomous outcomes. Heterogeneity was assessed using τ ², χ ² and I ² analyses.

RESULTS

Twelve randomized controlled trials were included in the final analysis. Compared with the control treatment, epidural dexmedetomidine administration prolonged the duration of analgesia (P < 0.0001), reduced the time to sensory block (P = 0.002), decreased the requirement for rescue analgesia (P < 0.00001) and achieved a significantly higher sedation score (P < 0.0001). Although dexmedetomidine adjunctive therapy did not affect mean arterial pressure (P = 0.33), systolic blood pressure (P = 0.32) or diastolic blood pressure (P = 0.28), it significantly lowered heart rate (P = 0.0009). Symptoms indicative of hypotension and bradycardia events were more common in the dexmedetomidine group, but the difference in the overall risk of hypotension and bradycardia was statistically insignificant (P > 0.05) in comparison with that reported for the control therapies. Furthermore, dexmedetomidine effectively reduced post-operative pain (P = 0.03), whilst the occurrence of other side effects, such as pruritus, dizziness, dry mouth, nausea and vomiting did not differ significantly from that reported for the control therapies, except the risk of shivering was significantly higher with control therapies (P = 0.03).

CONCLUSION

This systematic review and meta-analysis demonstrates that dexmedetomidine as an adjuvant in epidural procedures is generally safe and well tolerated. Furthermore, dexmedetomidine acted synergistically and provided an improved sedation and analgesic profile.