Tramadol does not modify the Bispectral Index during anaesthesia with sevoflurane and remifentanil

Background. The aim of this study was to investigate the effectsof tramadol administered with ketorolac on the Bispectral Index(BIS) during anaesthesia with sevoflurane and remifentanil. Methods. Forty-six adult patients, ASA I–III, scheduledfor elective minor surgical procedures were studied. Patientswere premedicated with remifentanil infusion 0.4 µg kg^–1min^–1 and anaesthesia was induced 4–5 min laterwith propofol 1.5 mg kg^–1 and maintained with air–oxygen( 0.4), remifentanil 0.1–0.15 µg kg^–1 min^–1 and sevoflurane, adjusted to keep theBIS between 40 and 50. After 20 min of stable anaesthesia, thesubjects were allocated randomly to receive i.v. tramadol 1.5mg kg^–1 and i.v. ketorolac 0.3 mg kg^–1 (tramadolgroup) or saline (control group). BIS values, mean arterialpressure, heart rate and end-tidal carbon dioxide were recordedevery 5 min for 20 min. Results. Mean BIS values after tramadol administration werenot significantly different from those recorded in patientsreceiving saline throughout the period of observation. Therewere no patients who presented explicit recall of events underanaesthesia. No significant changes in mean arterial pressure,heart rate and end-tidal carbon dioxide were noted after tramadolinjection. Conclusion. Tramadol, given with ketorolac to prevent postoperativepain, during anaesthesia maintained with sevoflurane and remifentanilat BIS between 40 and 50, does not modify the BIS value.