Abstract
Necessary and sufficient opioids should be administered for safe and stable anesthesia. However, opioid sensitivity varies among individuals. We previously reported that sympathetic responses to nociceptive stimuli under propofol anesthesia could be predicted by measuring the minimum evoked current of the vascular stiffness value (MEC(K)). However, this result has only been proven under propofol anesthesia. We propose that MEC(K) could be used under anesthesia with a volatile anesthetic. Thirty patients undergoing laparotomy with sevoflurane anesthesia received 0.7 minimum alveolar concentration (MAC) sevoflurane and intravenous remifentanil at a constant concentration of 2 ng/mL, followed by tetanic stimulation, to measure MEC(K). After tetanic stimulation, the same anesthetic conditions were maintained, and the rate of change in systolic blood pressure (ROC(BP)) during the skin incision was measured. The correlation coefficient between the MEC(K) and ROC(BP) during skin incision under sevoflurane anesthesia was R = - 0.735 (P < 0.01), similar to that in a previous study with propofol (R = - 0.723). Thus, a high correlation was observed. The slope of the linear regression equation was - 0.27, similar to that obtained in the study on propofol (- 0.28). These results suggest that, as with propofol anesthesia, MEC(K) can be used as a predictive index for ROC(BP) under 0.7 MAC sevoflurane anesthesia.Clinical trial registration: Registry, University hospital Medical Information Network; registration number, UMIN000047425; principal investigator's name, Noboru Saeki; date of registration, April 8, 2022.