RESUMO
BACKGROUND: Evidence has accumulated that opioids can produce potent antinociceptive effects by interacting with opioid receptors in peripheral tissues. Bupivacaine is potent analgesic with early peak onset in the postoperative period. The combination of intra-articular bupivacaine and morphine has been suggested as an ideal analgesic after knee arthroscopy. METHODS: Thirty patients scheduled for knee arthroscopy under general anesthesia were allocated randomly to two groups. Group 1 received morphine 5 mg in normal saline 25 ml, group 2 received morphine 5 mg in 0.25% bupivacaine 25 ml intraarticularly, and all solutions contained 1:200,000 epinephrine. Tourniquet was inflated above knee joint for 10 minutes after injection in each of the patients. Postoperative pain was assessed using the visual analogue scale at 1, 2, 3, 4, 6, 12 and 24 hours after the intra-articular injection. The need for supplemental analgesic was recorded. RESULTS: Patients in the group 2 had lower pain scores than group 1 at first and second hour. There were no significant differences from 3 hours to 24 hours postoperative period. Supplemental analgesic requirements were significantly greater in group 1 than group 2 for the first 3 hours. CONCLUSIONS: It is concluded that, after knee arthroscopy, intra-articular morphine 5 mg in 0.25% bupivacaine 25 ml results in satisfactory analgesia with small amount of supplementary analgesic.