Effect of chemotherapy on effect-site concentration of propofol for loss of consciousness in colorectal cancer patients.

Background The depth of anesthesia is an important factor in surgical prognosis. The neurotoxic effect of chemotherapeutic drugs affects the sensitivity to anesthetics. The purpose of this study is to find out whether the effect-site concentration (Ce) of propofol for loss of consciousness (LOC) differs in patients with preoperative chemotherapy treatment. Methods 60 patients scheduled for surgery for colorectal cancer under general anesthesia were included in this study. Those who had chemotherapy were the experimental (C) group, and those without prior history of chemotherapy were the control (N) group. Propofol was administered as an effect-site target-controlled infusion and the Modified Observer's Assessment of Alertness/Sedation scale (MOAA/S) was evaluated. When the plasma concentration and the Ce became the same, if the MOAA/S score did not change, the target Ce was increased by 0.2 μg∙ml-1, otherwise Ce was maintained for 2 min and then increased. Results The values of Ce of propofol for LVC in group C and N were 2.40 ± 0.39 and 2.29 ± 0.39 μg∙ml-1 (P = 0.286), and for LOC in group C and N were 2.69 ± 0.43 and 2.50 ± 0.36 μg∙ml-1 (P = 0.069), respectively. There was no significant difference in Ce values between the two groups. Conclusions Chemotherapy did not affect the Ce of propofol for LVC and LOC in colorectal cancer patients.