Effect of acute hypervolemic hemodilution on pharmacokinetics of propofol in patients undergoing total hip replacement / 中华麻醉学杂志

ABSTRACT

Objective To investigate the influence of acute hypervolemic hemodilution(HHD)on pharmacokinetics of propofol.Methods Sixteen ASA Ⅰ or Ⅱ patients aged 20-55 yrs undergoing elective surgery under general anesthesia combined with epidural analgesia were randomly allocated into 2 groups(n=8 each);Ⅰ control group and Ⅱ HHD group.The patients were premedicated with intramuscular phenobarbital 0.1 g and scopolamine 0.3 mg.Right internal jugular vein was cannulated for CVP monitoring and blood sampling.Radial artery was cannulated for BP monitoring.All patients in both groups received lactated Ringer's solution(0.7 ml?kg~(-1)? number of hours of fasting before operation)before induction of general anesthesia.In HHD group 4% gelofusine 20 ml?kg~(-1) was infused at the rate of 20 ml?kg~(-1)?h~(-1).Anesthesia was induced with midazolam 0.04 mg?kg~(-1),fentanyl 4 ?g?kg~(-1) and propofol 1.5 mg?kg~(-1).Tracheal intubation was facilitated by succinylcholine 2 mg?kg~(-1).Anesthesia was maintained with isoflurane,fentanyl,vecuronium and epidural analgesia.ECG,BP, SpO_2,P_(ET)CO_2 and CVP were continuously monitored.Blood samples were taken at 1,2,4,6,10,15,30,45, 60,75,90,120,150,180,240,300 and 360 min after propofol was given Ⅳ for determination of plasma concentration of propofol(HPLC).Pharmacokinetic data were analyzed by 3P97 pharmacokinetic software.Results The two groups were comparable with respect to demographic data.Blood propofol concentrations were significantly lower in HHD group than in control group at 1,2,4,6,10 min after propofol injection(P＜0.01), thereafter there was no significant difference in plasma propofol concentration between the two groups(P＞0.05). The pharmacokinetic profile of propofol was well described by a standard three-compartment model.In HHD group V_C was significantly increased,K_(10) and Cl were significantly decreased and T_(1/2?) was significantly prolonged as compared with control group.Conclusion Acute HHD increases V_C,prolongs the T_(1/2?) and decreases K_(10) and Cl, suggesting that the effect of propofol may be potentiated by acute HHD.