Epidural clonidine for postoperative pain after total knee arthroplasty: a dose-response study.
BACKGROUND
Combinations of epidural clonidine, local anesthetics, and opioids have improved postoperative analgesia after total knee arthroplasty. In this study we sought to determine the optimal epidural bolus dose of clonidine, which provides the best analgesia and fewest side effects.


METHODS
Eighty ASA I-III patients, who underwent total knee arthroplasty were randomly assigned to one of four groups of 20 patients each. Identical epidural anesthesia procedures were used for all groups. After surgery, groups C0, C1, C2, and C4 received patient-controlled epidural analgesia (PCEA) with clonidine (0, 1.0, 2.0, or 4.0 mug/mL, respectively) and morphine (0.1 mg/mL) in 0.2% ropivacaine. The analgesia effect was estimated by PCEA consumption volume and visual analog pain scale at rest and with movement at 1, 2, 4, 12, 24, 48, and 72 h after surgery. Systolic blood pressure, heart rate, sedation, and sensory and motor blockade were also recorded for 72 h after surgery.


RESULTS
The PCEA consumption volume for groups C0, C1, C2, and C4 were 71.8 +/- 19.5 mL, 49.6 +/- 12.3 mL, 48.1 +/- 9.3 mL, and 39.4 +/- 9.0 mL, respectively. The clonidine groups experienced less postoperative pain (P = 0.002). In the C4 group, four patients had prolonged sensory blockade and one patient had both severe sedation and prolonged sensory motor blockade. No significant statistical difference in analgesic consumption (P = 0.78) and pain intensity (P = 0.66) between groups C1 and C2 were noted.


CONCLUSIONS
The optimal amount of epidural clonidine in a solution of morphine and ropivacaine for postoperative pain management is 1.0 microg/mL.
Huang
Yuan-Shiou
YS
Department of Anesthesiology, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan, Republic of China.
Lin
Liu-Chi
LC
Huh
Billy K
BK
Sheen
Michael J
MJ
Yeh
Chun-Chang
CC
Wong
Chih-Shung
CS
Wu
Ching-Tang
CT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015360:Analgesia, Epidural / Q000379:methods*; D019645:Arthroplasty, Replacement, Knee; D003000:Clonidine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D010149:Postoperative Pain / Q000188:drug therapy* / Q000503:physiopathology
D004338:Drug Combinations; D003000:Clonidine