Small-dose S(+)-ketamine reduces postoperative pain when applied with ropivacaine in epidural anesthesia for total knee arthroplasty.
Reduction of nociceptive input through blockade of N-methyl-D-aspartate (NMDA) receptors has been reported. We compared the effects of epidural S(+)-ketamine versus placebo on postoperative pain in a randomized, double-blinded study in 37 patients undergoing unilateral knee arthroplasty. After lumbar epidural anesthesia with ropivacaine (10 mg/mL, 10-20 mL), 19 patients received 0.9% epidural saline, and 18 patients received 0.25 mg/kg epidural S(+)-ketamine 10 min before surgical incision. After surgery, patient-controlled epidural analgesia with ropivacaine was provided. During the first 8 h after surgery, visual analog scale pain rating was similar between groups. Twenty-four and 48 h after surgery, patients anesthetized with ropivacaine had higher visual analog scale ratings at rest and during movement (P < 0.05) than patients anesthetized with S(+)-ketamine and ropivacaine. Forty-eight hours after surgery, patients anesthetized with ropivacaine also consumed more ropivacaine (558 +/- 210 mg) (P < 0.01) than those anesthetized with S(+)-ketamine and ropivacaine (319 +/- 204 mg). Adverse events were similar between groups. Patients who received S(+)-ketamine and ropivacaine rated the quality of their pain therapy better than those who received ropivacaine alone (P < 0.05). We conclude that the combination of S(+)-ketamine and ropivacaine in epidural anesthesia increases postoperative pain relief when compared with ropivacaine.


CONCLUSIONS
Epidural S(+)-ketamine applied with ropivacaine before surgery is a rational approach to decrease injury-induced pain sensitization. Epidural blockade with an N-methyl-D-aspartate receptor antagonist and a local anesthetic may provide better analgesia in the postoperative period than a local anesthetic alone.
Himmelseher
S
S
Klinik für Anaesthesiologie, Technische Universität München, Ismaningerstr. 22, D-81675 München, Germany. S.Himmelseher@lrz.tu-muenchen.de
Ziegler-Pithamitsis
D
D
Argiriadou
H
H
Martin
J
J
Jelen-Esselborn
S
S
Kochs
E
E
D000368:Aged; D000577:Amides / Q000008:administration & dosage* / Q000009:adverse effects; D015360:Analgesia, Epidural; D016058:Analgesia, Patient-Controlled; D000700:Analgesics / Q000008:administration & dosage* / Q000009:adverse effects; D000767:Anesthesia, Epidural; D000779:Anesthetics, Local / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007649:Ketamine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D017060:Patient Satisfaction; D011446:Prospective Studies; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D000077212:Ropivacaine
D000577:Amides; D000700:Analgesics; D000779:Anesthetics, Local; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine; D000077212:Ropivacaine