The effect of gender and age on bispectral index and effective concentration 50 for propofol-remifentanil target-controlled infusion at two clinical end-points -A multi-center clinical research

Abstract

Objective To study the effect of gender and ages on predict blood and effect-site EC50 for propofol and remifentanil TCI and bispectral index at loss of consciousness and response to a standard noxious painful stimulus. Methods 405 ASA Ⅰ-Ⅱunpremedicated Chinese patients in 5 medical centers for elective operation were involved. Patients were allocated to 4 groups according to ages (group1: 18age30, group2: 30≤age40, group3: 40≤age50, group4: 50≤age65). The propofol was started a predict blood concentration of 1.2 mg/L delivered by Diprifusor, and increased by 0.3 mg/L every 30 s until patients lost their consciousness. After that, effect-site concentration of propofol kept constant and infused remifentanil a predict blood concentration of 2.0 μg/L and increased by 0.3 μg/L every 30 s until they lost response to a standard noxious stimulus. Bispectral index was measured. Probit regression was used to estimate population values for predicted blood and effect-site propofol and remifentanil concentrations at the two clinical end-points and BIS. Results The effect-site and the predict blood propofol concentrations EC50 of male and female were similar. The predict blood and effect-site propofol concentrations EC50 of younger were higher than that of older and BIS values were lower. The blood and effect-site remifentanil ancentrations EC50 at no response to painful stimulus of male and female were similar. The blood and effect-site remifentanil concentrations EC50 and BIS values at this point of each group were similar. 50% of male and female patients lost their consciousness at a BIS value with 54.0 and 59.0 respectively; and at loss of response to painful stimulus with 60.8 and 67.3 respectively. Conclusion Gender didn't affect the predicted propofol and remifentanil blood and effect-site concentration but affected the BIS values. The propofol concentrations of older were lower than that of younger. And that of remifentanil were not different between younger and older.