Comparison between pharmacokinetics of propofol in the elderly and young patients during induction / 中华麻醉学杂志

ABSTRACT

Objective To compare the pharmacokinetic profile of propofol after a single intravenous dose during induction in the elderly and young patients. Methods Eighteen ASA I-II patients undergoing elective gastro-intestinal and intracranial surgery were studied. Patients with abnormal liver and/or kidney function were excluded. The patients were premedicated with intramuscular phenobarbital 100mg and scopolamine 0.3mg 1h before operation. The patients were divided into two groups according to their age; the young and middle-aged group, aged between 31-57, on average 46. 5yr (A, n=6); the elderly group, aged between 67-81 yr, on average 74.6 yr(E, n = 12) . Group E was further divided into two subgroups: E1 aged between 67-73 yr, on average 69 .3 yr (n = 6); E2 aged between 76-81 yr,on average 78. 7 yr ( n=6 ) . In group A anesthesia was induced with propofol 1 . 5rng kg-1 , midazolam 0.03-0.06mg kg-1 , fentanyl 3-5ugkg-1 and vecuronium 0. 1 mgkg-1 . In group E propofol 1.0 mgkg-1 was given but the doses of the other three drugs for induction were the same as in group A. Anesthesia was maintained with isoflurane 0.5%-2.0% supplemented with intermittent iv boluses of fentanyl, vecuronium and midazolam. ECG, BP, SpO2 , PET CO2 , CVP and urine output were continuously monitored during anesthesia. Propofol was given in bolus through the vein in the forearm slowly over 30-45 s, and blood samples were taken from internal jugular vein before propofol injection and 1 ,2,4 ,6,10,15,30,45,60,75, 90,120 ,150 ,180,240 ,300,360min after the end of propofol injection for measurement of plasma propofolconcentration by HPLC with fluorescence detection. Results The pharmacokinetics of propofol in the 18 patients were best described by a three compartment pharmacokinetic model. The dose-corrected mean plasma concentrations of propofol in group A were lower at 1,2,4,6,10 min after the end of propofol injection (P