LATE-ONSET PREEMPTIVE ANALGESIA ASSOCIATED WITH PREINCISIONAL LARGE-DOSE ALFENTANIL

Few studies using systemic opioids have been adequately designed to de monstrate a preemptive effect. We investigated the preemptive effect o f intraoperative large-dose intravenous (IV) opioids over a 72-h perio d after lower abdominal surgery. Thirty-eight ASA physical status I or II patients undergoing abdominal hysterectomy were studied in a prosp ective, randomized, double-blind design. Group PRE received alfentanil 70 mu g/kg over 10 min before surgical incision; Group POST received alfentanil 70 mu g/kg over 10 min after incision. Patients received no other intraoperative opioid. Pain was treated in the recovery room wi th 2-mg IV boluses of morphine and was subsequently managed via patien t-controlled analgesia (FCA) using morphine sulfate. Visual analog sca le pain scores at rest (VAS-R) and on movement (VAS-M) and PCA morphin e consumption were recorded for 72 hours. VAS-M and VAS-R scores did n ot differ at any point, and morphine consumption was similar in both g roups over the initial 48 h. Group PRE used significantly less morphin e from 48 to 72 h postoperatively (P < 0.02). We conclude that presurg ical incisional (i.e., compared with postincisional) large-dose opioid exposure results in a modest, late decrease in postoperative morphine consumption, with no clinical impact on early postoperative pain. Tim ing of the observed reduction coincides with maximal output of substan ces implicated in experimental hyperalgesia. Implications: When given before surgical incision, alfentanil, a short-acting narcotic, was ass ociated with a reduction in morphine requirements 48-72 h after surger y. Brief interventions may have a delayed and sustained impact on pain perception, possibly by reducing mechanisms of sensitization.