Intraoperative small-dose ketamine enhances analgesia after outpatient knee arthroscopy

Ketamine may prevent postoperative hyperalgesia. In patients undergoing art hroscopic meniscectomy using general anesthesia, we tested whether a single intraoperative dose of ketamine enhanced postoperative analgesia and impro ved functional outcome compared with a typical multimodal analgesic regimen . After the induction of anesthesia, 50 patients were randomly as signed to ketamine (0.15, mg/kg IV just after the induction of anesthesia) or a vehi cle placebo. Standardized general anesthesia included propofol, alfentanil, and nitrous oxide. Bupivacaine (0.5%) and morphine (5 mg) were given intra articularly at the end of surgery. Postoperative analgesia was initially pr ovided with morphine and subsequently with naproxen sodium (550 mg orally t wice daily) and Di-Antalvic (R) (400 mg acetaminophen and 30 mg: dextroprop oxyphene) as needed. Pain scores, analgesic requirements, side effects, and ability to walk were assessed in the ambulatory unit and at home for three postoperative days. Times to awakening and to discharge were similar in th e two groups. However, the Ketamine group had significantly less postoperat ive pain at rest and during mobilization on Days 0, 1, and 2. Furthermore, they consumed significantly fewer Di-Antalvic (R) tablets than the control group (13 [7-17] vs 27 [16-32], median [25%-75% interquartile range]). Pati ents given ketamine were also able to walk for longer periods of time on th e first postoperative day. In conclusion, adding small-dose ketamine to a m ultimodal analgesic regimen improved postoperative analgesia and functional outcome after outpatient knee arthroscopy.