Influence of age on hypnotic target plasma concentration of dexmedetomidine administered by TCI / 中华麻醉学杂志

ABSTRACT

ObjectiveTo investigate the influence of age on hypnotic target plasma concentration (CT) of dexmedetomidine (Dex) administered by TCI.MethodsSixty ASA Ⅰ - Ⅱ patients aged 18-85 yr undergoing lower abdominal or extremity operation under combined spinal-epidural anesthesia were divided into 2 age groups ( n =30each)18 yr＜groupⅠ＜55 yr (Y) and 65 yr＜group Ⅱ＜85 yr (E).Each group was further divided into 5subgroups (n =6 each) receiving Dex administered by TCI at CT of 0.54,0.64,0.76,0.90,1.07 ng/ml in group Y and 0.36,0.42,0.51,0.60,0.71 ng/ml in group E respectively.Hypnosis was defined as no response to verbal command (OAA/S score ≤2) and loss of eyelash reflex.A quantal response model (probit analysis) was used to calculate the concentration-effect curve and predict plasma EC50 and EC95 (95％CI) of Dex.ResultsEC50 (95％CI) was 0.478(0.424-0.536) ng/ml and EC95(95％CI) 0.641 (0.567-0.816) ng/ml in group E,significantly lower than EC50 (95 ％ CI) 0.738 (0.657-0.827) ng/ml and EC95 (95％CI) 0.990 (0.874-1.267 ) ng/ml in group Y.ConclusionThe EC50 and EC95 of dexmedetomidine for hypnosis were significantly lower in the elderly than in younger patients.