Propofol Versus Sevoflurane Anesthesia in Pediatric Strabismus Surgery: Feasibility of BIS Monitoring

Strabismus surgery can cause unfavorable side effects during intraoperative and postoperative periods including increased risk of the oculocardiac reflex, hemodynamic instability, emergence agitation, postoperative pain, nausea and vomiting. Sevoflurane is an inhalation anesthetic widely used in pediatric anesthesia with minimal airway irritation. Propofol is an intravenous sedative-hypnotic agent with amnestic properties that causes loss of consciousness. Bispectral index monitor provide some more evidence that deeper anesthesia can provide some protection against the oculocardiac reflex. Therefore, this study is conducted to evaluate the role of BIS monitoring in comparing the use of propofol and sevoflurane anesthesia in pediatric strabismus surgery.

This prospective, randomized, comparative clinical study will include 100 children who are scheduled for elective strabismus surgery under general anesthesia 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.

• Bispectral Index Monitor (Device), also known as BIS Monitoring: Bispectral Index (BIS) sensor electrodes are applied over the patient's forehead after cleaning the forehead thoroughly with an alcohol swab.
• Laryngeal Mask Airway (Device), also known as Supraglottic Airway Device: 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.
• Sevoflurane (Drug), also known as Inhalational Anesthesia: Anesthesia is induced inhalationally by face mask with 8% sevoflurane in 100% oxygen, then decreased to 2-3% in 40% oxygen thoroughout the operation for maintenance of anesthesia.
• Propofol (Drug), also known as Intravenous Anesthesia: Anesthesia is induced by propofol (2mg/kg), then maintained using an infusion of fixed concentration (10-15 mg/kg/h) as titrated by the anesthesiologist .

Primary outcomes

• Incidence of oculocardiac reflex [Up to the end of the surgery]: Any dysrhythmia or rapid reduction in HR by more than 25% from the baseline is taken as oculocardiac reflex.

Secondary outcomes

• Changes in bispectral index [Up to the end of the surgery]: Bispectral index values (0-100) are recorded every five minutes until the end of the surgery
• Changes in heart rate [Up to the end of the surgery]: Heart rate (beat/min) is recorded at five-minute intervals until the end of the surgery
• Changes in mean arterial blood pressure [Up to the end of the surgery]: Mean blood pressure (mmHg) is recorded at five-minute intervals until the end of the surgery
• Changes in postoperative emergence agitation scale [Up to 30 minutes after surgery]: 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)
• Changes in postoperative pain score [Up to 24 hours after surgery]: Pain score from 0 to 10 (0 = no pain and 10 = the worst imaginable pain) is assessed every two hours for 24 hours after surgery.
• First analgesic request [Up to 24 hours after surgery]: The time of the first analgesic request for paracetamol is recorded.
• Total analgesic requirements of paracetamol [Up to 24 hours after surgery]: The amount of paracetamol consumption given as a rescue analgesia to patients is measured all over the 24 hours.
• Incidence of postoperative nausea and vomiting [Up to 24 hours after surgery]: Incidence of postoperative nausea and vomiting is assessed during the first 24 hours post-operatively.

Sex: All, ages: 3 Years to 8 Years

Inclusion Criteria:

* American Society of Anesthesiology (ASA) I and II patients.
* Scheduled for elective Strabismus surgery.

Exclusion Criteria:

* Parental refusal of consent.
* 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.
* Children with previous surgery in the eye.

• Sameh M El-Sherbiny, MD, Principal investigator, Mansoura Faculty of Medicine