Continuous infraclavicular perineural infusion with clonidine and ropivacaine compared with ropivacaine alone: a randomized, double-blinded, controlled study.

Although clonidine has been shown to increase the duration of local anesthetic action and prolong postoperative analgesia when included in single-injection nerve blocks, a controlled investigation of the efficacy of this practice to improve analgesia for continuous perineural local anesthetic infusion has not been reported. In this study, ambulatory patients (n = 34) undergoing moderately painful upper extremity orthopedic surgery received an infraclavicular brachial plexus block (mepivacaine 1.5%, epinephrine 2.5 micro g/mL, and bicarbonate 0.1 mEq/mL) and a perineural catheter before surgery. After surgery, patients were discharged home with a portable infusion pump delivering either ropivacaine 0.2% or ropivacaine 0.2% plus clonidine 1 micro g/mL via the catheter for 3 days (basal, 8 mL/h; patient-controlled bolus, 2 mL every 20 min). Investigators and patients were blinded to random group assignment. Daily end-points included pain scores, patient-controlled bolus doses, oral analgesic use, sleep quality, and symptoms of catheter- or infusion-related complications. Adding clonidine to ropivacaine resulted in a statistically significant decrease in the number of self-administered 2-mL bolus doses on postoperative Days 0 and 1 (P < 0.02), but this decreased actual local anesthetic consumption by an average of only 2-7 mL/d (P < 0.02). There were no statistically significant differences between the two groups for any of the other variables investigated, including sleep quality or oral analgesic requirements. We conclude that adding 1 micro g/mL of clonidine to a ropivacaine infraclavicular perineural infusion does not provide clinically relevant improvements in analgesia, sleep quality, or oral analgesic requirements for ambulatory patients having moderately painful upper extremity surgery.