Discussion
loss of consciousness, hypotension
HYPERTENSION
The reduction in MAP in the remimazolam and target-controlled propofol groups during induction of anesthesia in middle-aged and elderly patients was not significantly different between the groups, and the mean difference was very small. Moreover, the changes in HR, CO, and SV were not significantly different between the groups. The time until loss of consciousness was significantly shorter in the remimazolam group than in the propofol group. The time until loss of consciousness had no significant effect on the decrease in MAP and SV. A prolonged time until loss of consciousness correlated with greater degree of decline in HR and CO. Despite adjusting the time until loss of consciousness, MAP, HR, CO, and SV were not significantly different between the groups.Previous studies showed that remimazolam administration for induction or maintenance of anesthesia led to a lesser reduction in blood pressure than propofol [In the present study, 35% and 55% of patients in the remimazolam and propofol groups, respectively, experienced hypotension (MAP < 65 mmHg over 2.5 min) during induction of anesthesia, although without significant differences between the groups. The number of cases (Eleven (55%) and 6 (30%) patients in the remimazolam and propofol groups, respectively, had medications for hypertension, without significant differences between the groups. Some antihypertensive drugs are reported to contribute to hypotension during anesthesia [We used remimazolam or propofol in combination with remifentanil for induction of anesthesia. Remifentanil may have influenced the results of this study, given its cardiovascular depressant effects [This study has some limitations. First, we measured non-invasive blood pressure every 2.5 min. More detailed data may have been obtained if arterial blood pressure was continuously measured, such as by radial artery cannulation. However, invasive methods are deemed inappropriate based on patients’ background. Second, for safety reasons, ephedrine was administered to treat persistent hypotension in the patients. The differences between the two groups can be more thoroughly examined if the blood pressure was monitored to its lowest level without treatment, although it is unethical. Third, we used the TCI system for administration of propofol, but not remimazolam. The comparison would have been more appropriate if the same administration method was used; however, administration of remimazolam by the TCI system is not established nor approved in Japan. Remimazolam was continuously administered at 12 mg/kg/h and propofol at 3 μg/mL using the TCI system in this study. Thus, the results may not apply for different doses and drugs. Fourth, the esCCO was used to estimate CO and SV that may differ from the actual values of CO and SV. However, the trending ability of esCCO is clinically acceptable and comparable with the currently available methods using arterial waveform analysis. As esCCO is better at evaluating relative than absolute values, we evaluated CO and SV based on percent changes [