Addition of epinephrine to intrathecal tetracaine augments depression of the bispectral index during intraoperative propofol sedation.
OBJECTIVE
Epinephrine added to local anesthetic agents for spinal anesthesia is frequently used to prolong the duration of anesthesia. Epinephrine stimulates the alpha-adrenoceptor, and it is known that the alpha2-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 x kg(-1) by infusion for the initial dose, then continuously at 2 mg x kg(-1) x 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.


CONCLUSIONS
Intrathecal epinephrine augments the sedative effect of propofol during spinal anesthesia.
Department of Anesthesiology, Nippon Medical School, 1-1-3 Sendagi, Bunkyo-ku, 113-8603 Tokyo, Japan.
Toshu
T
Yotsui
Akira
A
Kitamura
Ryo
R
Ogawa
D000328:Adult; D000368:Aged; D000775:Anesthesia, Spinal; D003864:Depression, Chemical; D004357:Drug Synergism; D004569:Electroencephalography / Q000187:drug effects*; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D007278:Injections, Spinal; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000494:pharmacology*; D013748:Tetracaine / Q000494:pharmacology*
D006993:Hypnotics and Sedatives; D013748:Tetracaine; D015742:Propofol; D004837:Epinephrine