Addition of epinephrine to intrathecal tetracaine augments depression of the bispectral index during intraoperative propofol sedation

Abstract

Purpose

Epinephrine added to local anesthetic agents for spinal anesthesia is frequently used to prolong the duration of anesthesia. Epinephrine stimulates the Α-adrenoceptor, and it is known that the Α2-adrenoceptor agonists have a central inhibitory effect. We investigated the effect of intrathecal epinephrine during propofol sedation with spinal anesthesia, using a bispectral index (BIS) monitor.

Methods

Twenty adult patients, scheduled for spinal anesthesia, were allocated to the control group (n = 10) or epinephrine group (n = 10). Patients in the control group received 14 mg of tetracaine, whereas the epinephrine group received 14 mg of tetracaine and 0.2 mg of epinephrine. Immediately after the pinprick test, propofol was administered at 0.5 mg·kg⁻¹ by infusion for the initial dose, then continuously at 2 mg·kg⁻¹·h⁻¹ in both groups. BIS scores were recorded before subarachnoid block, and then every 5 min for 90 min after subarachnoid block.

Results

There were significant differences in the BIS score between the two groups at 45–55 min and at 60–70 min after subarachnoid block.

Conclusion

Intrathecal epinephrine augments the sedative effect of propofol during spinal anesthesia.