A Comparison of the effect of Dexmedetomidine and Magnesium Sulfate as adjuvants to Ultrasound - Guided Nerve Blocks on the incidence of Rebound Pain after Foot and Ankle Surgery.

INTERVENTION: Intervention1: Plain 0.375 per cent Ropivacaine: 22.5ml of plain Ropivacaine adjusted to 30ml using normal saline to produce a final study solution of 30ml of 0.375% Ropivacaine given perineurally with 20ml for popliteal sciatic nerve block and 10ml for saphenous nerve block Control Intervention1: DEXMEDETOMIDINE: 0.75mcg/kg Demedetomidine added to 22.5 ml of 0.5% ropivacaine with total study solution volume adjusted to 30ml using normal saline given perineurally with 20ml of study solution for popliteal sciatic nerve block and 10ml for saphenous nerve block Control Intervention2: MAGNESIUM SULFATE: 150mg of Magnesium Sulphate added to 22.5ml of 0.5% ropivacaine with total study solution volume adjusted to 30ml using normal saline given perineurally with 20ml of study solution for popliteal sciatic nerve block and 10 ml for saphenous nerve block CONDITION: Health Condition 1: S90‐S99‐ Injuries to the ankle and foot PRIMARY OUTCOME: Incidence of rebound pain within 48 hours after regression of peripheral nerve block, defined as transition from well controlled pain i.e., NRS score less than or equal to 3 to severe pain i.e., NRS score greater than or equal to 7.Timepoint: NRS scores will be measured at PACU, 2 hour, 6 hour, 12 hour, 24 hour, 36 hour and 48 hour interval. SECONDARY OUTCOME: Adverse effects : ; 1. Bradycardia ; 2. Hypotension ; 3. Nausea and Vomiting ; 4. Dizziness ; 5. Persistent paraesthesia ; 6. Neurologic deficits ; 7. Local anesthetic systemic toxicityTimepoint: upto 48 hours Analgesic Outcome : ; 1. Time to first pain sensation ; 2. Time to first rescue analgesic ; 3. Duration of analgesia i.e., the time interval between completion of peripheral nerve block and first rescue analgesic requestTimepoint: NRS pain scores at rest and movement will be measured at PACU, 2 hour, 6 hour, 12 hour, 24 hour, 36 hour and 48 hour interval. Chronic post surgical pain: Pain persisting in the operative area at 3 months after surgery will be assessed as an exploratoy outcome.Timepoint: Pain will be assessed at Day 7, 1 month and 3 months. Hemodynamic Variable : ; 1. Heart Rate ; 2. Systolic blood pressure ; 3. Diastolic blood pressure ; 4. Mean arterial pressureTimepoint: Intraoperatively Opioid Consumption : Total opioid consumption during the first 24 and 48 hours will be measured.Timepoint: Total opioid consumption at 24 hours and 48 hours will be recorded Patient Satisfaction: Patient satisfaction with post operative analgesia will be recorded using Likert scale.Timepoint: Upto 48 hours Rebound Pain Characteristics: ; 1. Time to rebound pain onset ; 2. Peak rebound pain score ; 3. Rebound pain severityTimepoint: NRS scores will be measured at PACU, 2 hour, 6 hour, 12 hour, 24 hour, 36 hour and 48 hour. Sedation : Sedation will be assessed using Ramsay Sedation Score at PACU, 2 hours and 6 hours post operatively.Timepoint: Sedation will be assessed at PACU, 2 hours and 6 hour interval Sleep Quality: Sleep disturbance during the first post operative night will be assessedTimepoint: At 24 hours INCLUSION CRITERIA: Patients aged between 18 and 70 years having ASA I ‐ III grading and are scheduled for elective unilateral foot and ankle surgery