All Parents will be explained about the anaesthetic technique and written informed consent will be taken during pre-anesthetic visit.Patients will be randomly allocated into two groups by computer generated random envelope method.First anesthesiologist will prepare the solution and second anesthesiologist will administer the block and monitor the patient.Nil per oral (prior to the procedure) will be ensured in all the patients as per fasting guidelines.Patient will be pre-medicated with Syrup Triclofos 50 mg/kg 2 hours prior to surgery.Patient will be shifted into the operation theatre and the monitors ECG, Pulse oximeter and Blood pressure cuff will be attached. Baseline values will be recorded.All the surgical procedures will be done under general anaesthesia.Injection Glycopyrolate 0.01mg/kg intravenous will be given.Injection fentanyl 2mcg/kg intravenous will be used for analgesia.Patients will be pre-oxygenated with 100% oxygen for 3 minutes via face mask.All patients will be induced with Injection Propofol 2mg/kg intravenous.Appropriate size Classic Laryngeal Mask Airway will be inserted.Anaesthesia will be maintained with oxygen and nitrousoxide in 1:1 ratio and Sevoflurane as inhalational agent with the patient breathing spontaneously via Jackson-Rees breathing system.Caudal block will be performed under aseptic conditions with the child in a left lateral position.Volume of drug will be defined by Modified Armitage formula.(0.25ml/kg for sacral surgery,0.5ml/kg for lumbar surgery,0.75ml/kg for lower abdomen surgery) Patients in Groups A (n=30), will receive injection Ropivacaine 0.2%+ injection Dexmedetomidine 1µgm/kg . Patients in Groups B (n=30) will receive injection Ropivacaine 0.2%+ injection Dexmedetomidine 2µgm/kg.The child will be turned to supine position immediately.At the end of the surgery, Classic Laryngeal Mask Airway will be removed in the deeper plane of anaesthesia. Patient will be observed for pulse rate, B.P. SpO2 and sedation in recovery area & will be shifted to post-operative ward when the sedation score =3.An intra- or postoperative decrease of MAP or HR more than 30% from baseline values will be defined as hypotension or bradycardia respectively.Hypotension will be treated with a rapid infusion of fluids .If it is unresponsive to fluid, hypotension can be treated by injection Ephedrine. Bradycardia will be treated with injection atropine, as appropriate.If the patient complains of pain within 2 hours of surgery, it will be considered as failed caudal block, which will be excluded from the study. Sedation will be assessed by the Ramsay Sedation Score.(1= anxious and agitated, 2=cooperative, calm. 3=responsive to commands 4= brisk response to glabellar tap, 5 = light response to glabellar tap, 6 =unresponsive).The rescue analgesia will be given in the form of Intravenous Paracetamol 15mg/kg if Wong-baker pain score is more than 4.Duration of post-operative analgesia is defined as the time interval between the administration of caudal block and the first requirement of rescue analgesia postoperatively. All patients will be observed for any side-effects like nausea, vomiting, bradycardia and hypotension.