Effective Dose of Atracurium in Korean Adults

Kim, Ji Yoon; Kim, Tae Gyun; Lee, Seung Cheol; Lee, Soo Il; Lee, Jong Hwan

Abstract

BACKGROUND: Atracurium is non-depolarizing neuromuscular blocking agent with intermediate duration of action. The purpose of this study is to determine the effective dose (ED) of atracurium in Korean adults.
METHODS
We studied 100 patients, aged 18-59 yr, who had given informed consent and belonged to class I or II of ASA physical status. We excluded patients who had cardiac, pulmonary, renal, hepatic, neurological, psychiatric, muscular, inflammatory or endocrine disease, as were pregnant women and patient with recent exposure (< 72 hr) to medications known to interfere with neuromuscular transmission. In all patients, anesthesia was induced with intravenous propofol 2 mg/kg and fentanyl 2microgram/kg. Anesthesia was maintained with continous infusion of propofol 5 mg/kg and 100% oxygen through mask, supplemented with fentanyl as required. The electrodes were applied over the ulnar nerve at the wrist. Then, the patients were stimulated with a 50 Hz supramaximal tetanic stimulation for 4 seconds and a 1 Hz single twitch for 5 minutes to stablize muscle contraction and then a control value was obtained with acceleromyography (TOF-Guard(R), Organon Technika BV , Netherland). Thereafter, a 0.1 Hz single twitch of adductor pollicis was kept during the study. The 100 patients were randomly divided to five groups. The patients in each group received 90microgram/kg, 120microgram/kg, 150microgram/kg, 180microgram/kg, 210microgram/kg of atracurium. We measured the maximal response (% reduction) and time to achieve maximal blockade of single twitch. Values were expressed as mean +/- SD or 95% confidence intervals. ED values were obtained from the regression analysis using probit model. A P value of < 0.05 was considered statistically significant.
RESULTS
There were no significant defferences in age, body mass index and temperature among dose groups. ED50 and ED95 of atracurium were 128microgram/kg, 236microgram/kg, respectively. For men, ED50 and ED95 were 127microgram/kg, 249microgram/kg, respectively. For women, ED50 and ED95 were 128microgram/kg, 236microgram/kg, respectively. The onset time to maximum blockade was reduced as dose was increased.
CONCLUSIONS
ED50 and ED95 of atracurium in Korean adults were 128microgram/kg, 236microgram/kg, respectively. There was no difference between the effective doses of men and women. Onset time of atracurium was reduced as doses were increased.