The Effect of Preemptive Ankle Block using Ropivacaine and Dexamethasone on Postoperative Analgesia in Foot Surgery

BACKGROUND Peripheral nerve blocks have become an increasingly popular form of anesthesia. Preemptive analgesia reduces central sensitization, postoperative pain, and analgesic consumption. Different additive has been used to prolong regional blockade and improve postoperative analgesia. AIM This study was conducted to evaluate whether preemptive ankle block using combination of ropivacaine and dexamethasone would succeed in improving the postoperative analgesia after foot surgery in patients receiving general anesthesia. STUDY DESIGN Randomized double-blind clinical trial. PATIENTS AND METHODS The study was done on forty American Society of Anesthesiologists physical Status I and II, patients undergoing elective forefoot and midfoot surgery under general anesthesia after written informed consent and Ethical Committee approval, general anesthesia was induced as usual, the patients were breathing spontaneously, laryngeal mask airway was inserted, and anesthesia was maintained using inhalational anesthetic. Ankle block was performed before surgery using 20 ml containing 18 ml ropivacaine 0.75% and 2 ml containing 8 mg dexamethasone in Group I and 20 ml containing 18 ropivacaine 0.75% plus 2 ml normal saline in Group II. Evaluation of ankle block was performed by testing the motor response to electric nerve stimulation of both the posterior tibial nerve and the deep peroneal nerve. The absence of any motor responses indicated success of the block. Surgery was started in 30 min after the block. After recovery from anesthesia, the following was measured, visual analog score at 1, 4, 6, 12, and 24 h, the time to the first rescue analgesic, the analgesic requirements, and any side effects. STATISTICAL ANALYSIS Data were presented as means (standard deviation). Mann-Whitney U-test were used for continuous data. Student's t-test was used for normal distributed data. RESULTS Patients were similar as regard to demographic data, type, and duration of surgery. Pain intensity was significantly lower in dexamethasone group (P < 0.05). Time to first rescue analgesic was prolonged in dexamethasone group (110 ± 3.3 min vs. 66 ± 7.9 min; P = 0.001) The analgesic consumption was significantly lower in dexamethasone group. The complication was minor and self-controlled in both groups. CONCLUSION The addition of dexamethasone to ropivacaine improved preemptive ankle block analgesia by decreasing postoperative pain intensity and analgesic consumption with minimal postoperative complication.