EC(50) of remifentanil to prevent withdrawal movement associated with injection of rocuronium.
OBJECTIVE
Various strategies have been studied to reduce the discomfort of rocuronium injection. This study was designed to determine the effect-site target concentration (Ce) of remifentanil at which there was a 50% probability of preventing movement from pain in response to the injection of rocuronium (EC(50)).


METHODS
Anesthesia was induced with a propofol target-controlled infusion (TCI, Marsh model) and remifentanil TCI (Minto model). Effect-site target concentration of propofol was 3 microg/ml. Ce of remifentanil for the first patient started at 2.0 ng/ml. Ce of remifentanil for each subsequent patient was determined by the response of the previous patient by the Dixon up-and-down method with an interval of 0.5 ng/ml. After both drugs reached target concentration, rocuronium 0.8 mg/kg was administered, and the pain response was observed.


RESULTS
The EC(50) of remifentanil was 1.5 +/- 0.45 ng/ml by Dixon's up-and-down method. From probit analysis, the EC(50) of remifentanil was 1.37 ng/ml (95% confidence limits, 0.69-2.15 ng/ml), and the EC(95) was 3.19 ng/ml (95% confidence limits, 2.31-11.24 ng/ml).


CONCLUSIONS
The EC(50) of remifentanil to blunt the withdrawal responses to rocuronium injection was 1.37-1.5 ng/ml during 3 microg/ml propofol TCI anesthesia.
Yoon
Ji Young
JY
Department of Anesthesia and Pain Medicine, School of Medicine, Pusan National University, 1-10 Ami-dong, Seo-gu, Busan, 602-739, Korea.
Kim
Hae Kyu
HK
Kwon
Jae Young
JY
Shin
Sang Wook
SW
Kim
Kyung Hoon
KH
Kim
Won Sung
WS
Kim
Tae Kyun
TK
D000293:Adolescent; D000328:Adult; D000368:Aged; D000732:Androstanols / Q000008:administration & dosage* / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects* / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000139:chemically induced / Q000517:prevention & control; D010880:Piperidines / Q000493:pharmacokinetics* / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D000077208:Remifentanil; D000077123:Rocuronium; D055815:Young Adult
D000732:Androstanols; D006993:Hypnotics and Sedatives; D003473:Neuromuscular Nondepolarizing Agents; D010880:Piperidines; D000077208:Remifentanil; D000077123:Rocuronium