Context and aim
The addition of alpha-2 agonists clonidine and dexmedetomidine to intra-articular (IA) infiltration of local anaesthetics (LA) may prolong the duration of action of analgesia following arthroscopic knee surgery. The objective of this systematic review and meta-analysis was to evaluate the analgesic effect of addition of alpha-2 agonists to LA when used for day case arthroscopic knee surgery.
Methods
PubMed, EMBASE, Cochrane Library, Google Scholar, conference abstracts and bibliographic references were searched for RCTs comparing IA LA to IA LA+ adjuvant. The primary outcome was the duration of analgesia (determined by the time to first request for additional analgesia post-operatively). Secondary outcomes were Visual Analogue Scale (VAS) scores at various time intervals, opiate consumption over 24 h and incidence of hypotension and bradycardia. The data were analysed using RevMan software.
Results
Eight trials (390 patients) were included with patients receiving dexmedetomidine and clonidine in addition to LA. Alpha-2 agonists significantly prolonged the duration of action of LA [SMD 3.00 [95%CI2.39, 3.62] (p < 0.00001)] (Mean Difference 282 min). VAS scores were statistically significantly lower at one [SMD −1.06 [95% CI −1.98, −0.13] (p = 0.02)], two [SMD −1.29 [95% CI −2.11, −0.47] (p < 0.002)] and eight hours [SMD −0.86 [95% CI −1.25, −0.47] (p < 0.0001)], when alpha-2 agonists were used. Total opiate consumption was reduced in the experimental group (SMD −3.19 [95% CI, −4.74, −1.64] (p < 0.0001)] (Mean Difference 15.45 mg). There were no significant differences in adverse effects.
Conclusions
Addition of alpha-2 agonists to IALA significantly prolongs duration of analgesia and reduces VAS scores in the immediate postoperative period following day case arthroscopic knee surgery.