Background: Sevoflurane is a volatile anesthetic agent with low pungency, non-irritating odor, and low blood/gas partition coefficient that makes it an attractive alternative to halothane. However, a high incidence of emergence agitation (EA) has been reported in pediatric patients after sevoflurane anesthesia. The underlying mechanism of sevoflurane-induced EA remains unclear. Rapid recovery of consciousness (emergence) from sevoflurane anesthesia has been proposed as one possible mechanism. We, therefore, hypothesized that sedatives such as midazolam may counteract sevoflurane's rapid emergence and thus reduce the incidence and the severity of sevoflurane-induced EA.
Methods: A prospective, controlled, single-blinded study was carried out in 88 ASA class I or II pediatric patients scheduled for elective outpatient surgery. Patients were assigned to receive either midazolam (oral midazolam, 0.2 mg/kg as anesthetic premedication) or saline (oral normal saline as premedication) before the conduct of anesthesia. When separation from parents was due its process was watched and evaluated. Induction of anesthesia and maintenance of anesthesia were uniform in both groups. Induction of anesthesia was made possible with 8% sevoflurane and N2O in 50% O2. Intubation was performed straight without the aid of muscle relaxant and the ventilator was set to maintain normocapnia. Anesthesia was maintained with 3% sevoflurane and N2O in 50% O2 until the surgery was over. All matters of relevant time periods were recorded (induction, surgical procedure, extubation and transportation). In the post-anesthesia care unit (PACU), adverse events, the incidence and the severity of EA, analgesic requirement, duration of PACU stay, and parental as well as PACU nurses' satisfaction were evaluated.
Results: A significant lower incidence and less severity of EA were noted in patients premedicated with midazolam. Less postoperaive analgesia was required in patients who had received midazolam. Although midazolam-premedicated patients remained sedated after sevoflurane anesthesia, the duration of the PACU stay was not significantly different from that of saline-treated patients. Both parents and PACU nurses were more satisfied with midazolam as premedication. No solid evidence showed that there was close correlation between the process of separation from parents and the occurrence of EA.
Conclusions: Premedication with oral midazolam is safe, convenient and effective in decreasing the occurrence of sevoflurane-induced EA. It does not delay discharge from PACU and is suitable for outpatient surgery.