Small Dose-Clonidine Prolongs Postoperative Analgesia after Sciatic-Femoral Nerve Block With 0.75% Rovpivacaine for Foot Surgery

Abstract

Background: Foot surgery is associated with severe pain that can extend significantly up to 48 hours and often requires large amounts of parenteral opioids. . The benefit of adding clonidine to LAs for peripheral nerve blocks is less clear, although it is widely believed that clonidine improves quality and duration of a LA block. The aim of this study was to evaluate the effects of adding 1 mg/kg clonidine to 0.75% ropivacaine during combined sciatic-femoral nerve block for hallux valgus repair. Subjects and Methods: Thirty six ASA physical status I and II patients, scheduled for elective hallux  valgus repair under combined sciatic-femoral nerve block, were enrolled in the study. By using a sealed envelope technique, patients were randomly allocated to receive sciatic-femoral nerve block with 30 mL of either 0.75% ropivacaine alone (group Ropivacaine, n 5 15) or 0.75% ropivacaine plus 1 mg/kg clonidine (group Ropivacaine- Clonidine, n 5 15). Standard monitoring was used throughout the study, including noninvasive arterial blood pressure, heart rate, and pulse oximetry. The time from the end of anesthetic injection to resolution of motor block at the ankle of the operated foot and first request for postoperative analgesic was recorded. At discharge from the orthopedic ward and 3 wk after hospital discharge, patients were also evaluated regarding the occurrence of neurological complications. Results: No differences in the time required to achieve surgical anesthesia were observed between patients receiving only 0.75% ropivacaine (10 [5–20] min) and those receiving the ropivacaine-clonidine mixture (10 [5–30] min).  The mean time from block placement to first request for pain medication was shorter in group Ropivacaine than in group Ropivacaine- Clonidine (P = 0.03,. No differences in postoperative consumption of ketoprofen were observed between patients. Conclusion: Adding 1mg/kg clonidine to 0.75% ropivacaine provided a 3-h delay in first request for pain medication after hallux valgus repair, with no clinically relevant side effects.