Effect of Dexmedetomedine in Subtenon's Block on Emergence Agitation in Pediatric Strabismus Surgery

Effect of Dexmedetomedine in Subtenon's Block on Emergence Agitation in Pediatric Strabismus Surgery Under Sevoflurane Anesthesia

The study is conducted to evaluate the effects of dexmedetomedine in subtenon's block in conjunction to general anesthesia under sevoflurane anesthesia on emergence agitation, intraoperative hemodynamic stability, postoperative pain, nausea and vomiting in patients undergoing strabismus surgery.

Emergency agitation is a clinical status of postoperative excitement or emergence delirium when the patient is awake but is disorientated. It is described as mental disturbances that consist of confusion, hallucinations and delusions which is manifested by restless involuntary physical activity and thrashing about the bed. Its incidence has been observed especially in pediatric ophthalmology care units due to many factors such as pain, mental status, time of operation, age, lack of ability to see outside, and a history of previous hyperthermia. Strabismus surgery is one of the most frequently performed pediatric ocular operations. However, it can cause unfavorable side effects during intraoperative and postoperative periods. Typically, the major problems associated with strabismus surgeries include increased risk of the oculocardiac reflex, postoperative pain, nausea and vomiting. Subtenon's block is one of the regional anesthetic techniques used in ocular surgery. Dexmedetomidine has been used as an adjuvant to local anesthetics for regional anesthesia in various clinical fields including the subtenon's block.There is evidence that dexmedetomidine decreases the incidence of agitation after sevoflurane anesthesia in children undergoing different surgical procedures. Therefore, this study is conducted to evaluate the effect of dexmedetomedine in subtenon's block on emergence agitation in pediatric strabismus surgery under sevoflurane anesthesia. This prospective, randomized, clinical study includes 100 children who are scheduled for elective strabismus surgery under general surgery in Mansoura ophthalmology center. Informed written consent is obtained from parents of all subjects in the study after ensuring confidentiality.The study protocol is explained to parents of all patients in the study who are kept fasting prior to surgery. Patients are randomly assigned to two equal groups according to computer-generated table of random numbers using the permuted block randomization method.The collected data are coded, processed, and analyzed using SPSS program. All data are considered statistically significant if P value is ≤ 0.05.

Laryngeal mask airway is inserted and anesthesia is maintained with sevoflurane. Subtenon's block is performed and local anesthetic solution is injected, in addition to dexmedetomedine.

Laryngeal mask airway is inserted and anesthesia is maintained with sevoflurane. Subtenon's block is performed and local anesthetic solution is injected.

Capnography connected to laryngeal mask airway is introduced after adequate jaw relaxation and oral airway tolerance; its size is chosen according to the body weight of the child.

Subtenon's block is performed in the eye undergoing surgery under sterile conditions where a 19-gauge curved blunt metallic cannula (25 mm) is inserted into sub-tenon's space.

The local anesthetic solution is injected with a dose of 0.5% bupivacaine (0.08 ml/kg), in addition to dexmedetomedine (0.5 μg /kg)

Agitation is assessed using the 5- step Cravero scale (1-5) every five minutes from awakening and for 30 minutes.(1:Obtunded with no response to stimulation, 2:Asleep but responsive to movement or stimulation, 3:Awake and responsive, 4:Crying, 5:Thrashing behaviour that requires restraint)

Emergence time (min) is recorded; from the discontinuation of sevoflurane to the first response on verbal command.

If there is dysrhythmia or rapid reduction in HR by more than 25% from the baseline, it is considered as an oculocardiac reflex.

Pain score from 0 to 10 (0 = no pain and 10 = the worst imaginable pain) is assessed every two hours up to 24 hours after the procedure.

The amount of paracetamol consumption given as a rescue analgesia to patients is measured all over the 24 hours.

Inclusion Criteria: American Society of Anesthesiology (ASA) I and II patients. Scheduled for strabismus surgery. Exclusion Criteria: Parental refusal of consent. Contraindication to use of supraglottic airway device as gastroesophageal reflux and oropharyngeal pathology. Hyperactive airway disease or respiratory diseases. Children with developmental delays, mental or neurological disorders. Bleeding or coagulation diathesis. History of known sensitivity to the used anesthetics. Previous surgery in the same eye