Dexmedetomidine is a selective a-2 adrenergic agonist that provides sedative and analgesic effects. Intranasal dexmedetomidine has a slower and gradual onset compared to intravenous injection , with low incidence of nasal discomfort. Dexmedetomidine was tested at various doses and modes of administration, as well as different types of surgery and co-anesthetic drugs, as a single injection or continuous infusion. The authors have not agreed on the ideal clinical dose. The hypothesis is that intranasal dexmedetomidine 3mcg /kg will decrease the incidence of emergence agitation after strabismus surgery than dexmedetomidine 2 mcg/kg

Strabismus surgery is typically performed under general anesthesia in pediatric patients. Pediatric patients undergoing strabismus surgery often experience emergence delirium (ED), with rates ranging from 40-86%.(1) ED includes confusion, crying, non-purposeful aggressive movements, and inconsolability during the early stages of recovery from general anesthesia (GA). Adverse effects of ED include increased risk of suture dehiscence, accidental removal of intravenous catheters, self-injury, longer postanesthesia care unit (PACU) stay, and undesirable postoperative behavior.(2,3) Preschool age, preoperative anxiety, pain, otorhinolaryngologic and ocular surgery, certain anesthetic drugs, and rapid awakening from anesthesia are all risk factors for ED.(4) Strabismus surgery is also strongly related to these characteristics. Our hospital performs numerous strabismus operations on preschool children daily. Preoperative anxiety affects up to 60% of young children undergoing surgery and can lead to ED.(5,6) Pharmacological medications have been used to lessen the prevalence of ED. Dexmedetomidine is a selective a-2 adrenergic agonist that provides sedative and analgesic effects. Intranasal dexmedetomidine has a slower and gradual onset compared to intravenous injection , with low incidence of nasal discomfort.(7,8, 9) Dexmedetomidine was tested at various doses and modes of administration, as well as different types of surgery and co-anesthetic drugs, as a single injection or continuous infusion. The authors have not agreed on the ideal clinical dose. The hypothesis is that intranasal dexmedetomidine 3mcg /kg will decrease the incidence of emergence agitation after strabismus surgery than dexmedetomidine 2 mcg/kg

Aim of the work:

The present study aims to compare the effect of use of two different doses of intranasal dexmedetomidine on incidence of emergence agitation after strabismus surgery.

Primary outcome:

• Incidence of emergence agitation using pediatric anesthesia emergence delirium ( PAED) scale.

Secondary outcomes:

• Incidence of intraoperative hemodynamic changes: bradycardia and hypotension
• Postoperative pain score
• Modified Yale Preoperative Anxiety Scale (mYPAS) upon separation from parents
• PACU discharge time

Patients :

Study settings:

This study will be conducted in ophthalmology department, Alexandria university hospitals.

Study design:

Double blind, randomized, prospective study

Sample size calculation:

Study population:

All patients will be randomized 1:1 using a sealed envelope method. Patients will be divided into two equal groups:

Group 1 (high DEX group): patients will receive 3 mcg/kg intranasal dexmedetomidine 45minutes before surgery

Group 2 (low DEX group): patients will receive 2 mcg/kg intranasal dexmedetomidine 45minutes before surgery

Methods:

Preoperative evaluation and preparation:

During preoperative visit, evaluation of patients will be carried out through proper history taking, clinical examination and routine laboratory investigations.

Pre-anesthetic preparation and premedication:

All children will fast 8 h for any solid food, 6 h for milk, and 2 h for clear liquid. All of the patients will be brought to the holding area 45min before the surgery and will be treated according to the group assignment. Intranasal dexmedetomidine will be given to all patients using MAD Nasal intranasal atomization device.

After the application of standard monitoring, including blood pressure, electrocardiography, pulse oximetry and capnography, general anesthesia will be started by tidal volume inhalation induction with 8% sevoflurane and 5 L/min 100% oxygen. IV access will be obtained, and an appropriately sized laryngeal tube will be inserted when a suitable anesthetic depth was obtained. Then, 1 mcg/kg fentanyl will be administered, and the sevoflurane concentration will be adjusted to 2-4% to maintain anesthesia. Spontaneous breathing will be maintained during surgery. If the PETCO2 will be more than 50 mmHg, assisted ventilation will be conducted. At the end of the surgery, sevoflurane will be turned off, and after dressing of the eye and while patients still in the deep level of anesthesia LMA will be removed and patients will be transferred to PACU.

Inclusion Criteria:

• Age: 3-6 years, both sexes
• ASA physical status class I , II.

Exclusion Criteria:

• history of neurological and psychiatric disease
• body mass index > 20 kg m-2
• allergy to dexmedetomidine
• patients on medical treatment which has any sedative effect
• mentally retarded children