Efficacy of entropy index in monitoring nociceptive stimulus in patients undergoing propofol-remifentanil general anesthesia

Abstract

To evaluate the efficacy of reflex entropy (RE)/state entropy (SE) in monitoring the response to nociceptive stimulus during propofol-remifentanil infusion. After the approval of the hospital ethics committee, sixty American Society of Anesthesiologists (ASA) classification 1-2 patients, aged 18-65 years, receiving the hypogastrium operation undergoing general anesthesia, were randomly allocated to groups A and B with different remifentanil concentrations. After the concentration of propofol and remifentanil reached balance, tetanic stimulation, intubation, and incision were performed respectively with certain intervals. RE and SE were monitored during this procedure. Twelve patients were withdrawn from this study due to the use of vasoactive drugs. Finally, there were 28 cases in group A and 20 cases in group B. The RE and SE were not significantly changed before and after the tetanic stimulation in both groups (all P>0.05). Both RE and SE were significantly increased after intubation in group B (both P<0.05) and after skin incision in both groups (all P<0.05). Under the same stimulation, RE and SE showed no significant difference among groups administered with different levels of remifentanil (P>0.05). Under the anesthesia with propofol+remifentanil, nociceptive response may cause the increase of RE and SE. Therefore, RE and SE may be useful parameters for monitoring the nociceptive response during general anaesthesia.