50% Effective Concentration of Sevoflurane for Immobility

All anesthetics were administered by a single experienced anesthesiologist. Anesthetic induction was performed progressively with inhaled 1-8% sevoflurane, if the patient was cooperative, otherwise directly to the 8%, and subsequent maintenance 2% in oxygen at 5 L /min. A face mask was connected to a Mapleson C circuit for it. Patients breathed spontaneously, unaided, via a pediatric face mask. A failure was defined as the patient continued to move after following the study protocol for sevoflurane inhalation. Insufficient sedation was treated with increments of 0.5% concentration to achieve the desired effect, ie, maintenance of immobility during botulinum toxin injection. The sevoflurane concentration in the next patient would be adjusted depending on the success or failure for immobility at given sevoflurane concentration ( if successful, 0.5% lower concentration, if failed, 0.5% higher concentration).

The child was recovered from sevoflurane sedation at the end of botulinum toxin injection and transferred to post-anesthetic care unit.

Inclusion criteria

• 3-12 years old children with cerebral palsy receiving sevoflurane inhalation for botulinum toxin injection
• American society of anesthesiologists Physical status 1-2

Exclusion criteria

• Body mass index > 30 kg/m2
• unstable heart disease
• Anticipated difficult airway history including congenital facial or airway anomaly
• Recent upper respiratory tract infection ( < 2 weeks)
• Gastroesophageal reflux
• Allergy history to sevoflurane, remifentanil or any drug used during procedure