The Changes Of Effect Site Concentration And Sedation Score Of Propofol TCI Induction With Two Pharmacokinetic Models

Objective:During propofol TCI induction with plasma concentration of 5.5μg/ml,compare the effect site concentration(Cep),the difference of correlation of Cep and BIS,Cep and OAAS,OAAS and BIS between Marsh model and Schnider model.When Observer Assessment of Sedation(OAAS) reached 4,3,2,1,0,compare the infusing time,dosage of the propofol of the two groups.Methods:In this prospective,60 selected general anesthesia patients (ASAâ… -â…¡,age 20-40,BMI20—25 Kg/m²) were randomly divided into two groups group M(n=30),received propofol TCI using the Marsh PK/PD model;group S(n=30) received propofol TCI using the Schnider PK/PD model.All the patients were set to the plasma target concentration of 5.5μg/ml within 15 minutes.In the anesthesic recovery room all patients had an intravenous cannula inserted into a peripheral vein.We then established routine monitoring of ECG,pulse oximetry,invasive blood pressure and Bispectral index(BIS).A assistant who was not the investigator connected the propofol TCI pump to the patients,choiced random PK/PD model and set the plasma target concentration of 5.5μg/ml.All this was blamed to the investigators.After infusing Hydroxyethyl Starch 130/0.4 5ml/Kg,a investigator recorded MAP,HR,SPO₂,BIS,Observer Assessment of Sedation(OAAS) and then started propofol TCI pump.Another investigator gave the patients the oxygen and made the sedation score assessed by the OAAS every 30 seconds.The former recorded MAP,HR,SPO₂,BIS,OAAS,the plasma concentration,the effect site concentration(Cep) every 30 seconds.When OAAS reached 4,3,2,1,0 recorded the infusing time,dosage of the propofol and compared the difference between two groups.We compared the Cep,MAP,HR,SPO₂ between two groups at the same induction time,the correlation of Cep and BIS,Cep and OAAS,OAAS and BIS. To find the difference of the time and propofol dosage when reached the same sedation.Results:The effect site concentration(Cep) of grouop M is bigger than group S at the same induction time,Marsh model has better correlation between effect site concentration with the clinical observed effect of propofol,as assessed by the BIS monitoring and OAAS than Schnider model. They are 0.97,0.88 and 0.47,0.31 respectively.But the two groups both have strong correlation between OAAS and BIS(0.87,0.86) and the change of the hemadynamics is small.To achieve a certain level of the sedation,grouop M has the shorter time than group S,but much more propofol is used.Conclusion:When set the plasma target concentration during the propofol induction,Marsh model versus Schnider model:it has faster increase in the effect site concentration,better correlation of the effect site concentration with sedation.At the same sedation level,Marsh model has faster rate and more poropofol infusion dosage.