To investigate the effective concentration of remifentanil inhibiting the body movement in children undergoing hernia repair with no muscle relaxation.

From January 2017 to February 2018, twenty-eight children (age<12 years old) underwent selective hernia repair and ASA grade I or II in the 82nd Group Military Hospital of PLA were enrolled. Anesthesia induction and maintenance were performed with propofol (Marsh model) and remifentanil (Minto model). BIS was controlled ranging from 45 to 55. The initial effect chamber concentration of remifentanil was 4.0 ng/ml and the next patient's target effect chamber concentration of remifentanil was adjusted according to the positive reaction (no body motion response) in the former child and Dixon up-and-down method, with an adjustment range of 0.2 ng/ml. After seven negative-positive reaction crossovers, the EC50 and EC95 (effective concentration) were calculated based on the mean of the negative-positive reaction pair and Probit regression.

The EC50 of remifentanil in the inhibition of body movement in children undergoing hernia repair was 3.99 ng/ml. The EC50 and EC95 were 3.90 ng/ml and 4.34 ng/ml, respectively, by Probit regression analysis.

The EC50 and EC95 of the effect chambers inhibiting the body motion of children undergoing hernia repair were 3.90 ng/ml and 4.34 ng/ml.