Emergence agitation (EA) is a post-operative behavioral disturbance was first reported in early 1960s. EA is a term used to describe non purposeful restlessness and agitation, thrashing, crying or moaning, disorientation and incoherence during early stage of recovering from general anesthesia in children, especially those receiving sevoflurane. Generally, the incidence of EA following sevoflurane anesthesia varies from 10% to 66% and is more common in pre-school children. EA is generally short lived without obvious aftereffect. However, it still accompanies with risk of self-injury, and requires extra nursing care, which may delay the discharge and increase the cost of medical care Emergence agitation is diagnosed by a final composite score of greater than or equal to 10 on the Pediatric Anesthesia Emergence Delirium Scale (PAED).(

Sevoflurane induced anesthesia does not cause significant cardiac depression and dysrrhythmias as compared to halothane. Sevoflurane anesthesia is also easy to titrate for maintaining an adequate level of anesthesia, especially for the intubated. It also is a potent bronchodilator, which can offer an added benefit especially in children with a history of asthma. For all above reasons sevoflurane has clearly become the inhalation induction agent of choice.

The exact reasons for a higher incidence of EA with sevoflurane are not well explained. seizure activity in previously nonepileptic patients has been detected with electroencephalography during sevoflurane anesthesia.

One of the proposed treatments for EA is the use of opioids; however, it carries the risk of an extended Post Anesthetic Care Unit (PACU) stay resulting in parents' discomfort and added costs. Therefore, analgesic adjuvants with NMDA (N-methyl-D-aspartate) receptor antagonist functions, such as ketamine and magnesium sulfate have been tried to control this phenomenon in children.

Also, Dexmedetomidine, a selective a-2 adrenoceptor agonist, has sedative, analgesic, and anxiolytic effects. It was proved that α2 agonists decrease emergence agitation by their analgesic effect as well as by minimizing the anesthetic requirements.

In the review of literature this is the first study comparing the effectiveness of the three drugs ketamine, magnesium sulfate and dexmedetomidine infusions together in one study on the incidence of emergence agitation after sevoflurane induced anesthesia in children.

Inclusion Criteria:

• ASA physical status II
• ages from 2-5 years.
• weight more than 6 kg.
• scheduled for cardiac catheterization procedure not exceeding 3 hours.

Exclusion Criteria:

• psychological disorder or cognitive delay.
• chronic or acute intake of any sedative drug or anticonvulsant drugs.
• Any neurological condition that will limit ability to communicate with, or understand a practitioner.
• those with coexisting renal diseases , any reported allergy to the given medications.
• legal guardian refusal .

The anesthesiologist not involved in the study will open envelopes and will prepare the drug. All syringes will be prepared by the same investigator not one of the study researchers. Administration of anesthesia and study drugs will be made by other investigators blinded to the study drugs and not involved in the study. Data collection will be done by investigator who is included in the study.