Target Plasma Concentration Of Propofol Research Articles

A Manual Slide Rule for Target-Controlled Infusion of Propofol: Development and Evaluation

We describe the development and evaluation of a simple slide rule that enables the bedside determination of the infusion rate for a particular target plasma concentration of propofol. The infusion rate to reach this target concentration at time (t) is the product of the target concentration, body weight, and a correction factor that depends on the time elapsed from the start of the initial infusion. Our target-controlled infusion (TCI) slide rule, constructed along this principle, performs the multiplications, analogous to the principle of the classical slide rule, as addition of logarithms. We calculated the percentage deviation of the predicted concentration obtained by STANPUMP versus predicted concentrations obtained using the infusion rates determined from the TCI slide rule. The evaluation using STANPUMP simulations showed, for a constant target concentration of 3 μg/mL of propofol, a mean deviation of 4.05% (max, 6.97%) in the first 15 min and a mean deviation of 0.5% (max, 2.03%) between 16 and 300 min. The mean deviation after changing the target from 3 μg/mL to 1, 2, 4, or 5 μg/mL ranged from 1.15% to 17.76%. This pocket-sized TCI slide rule combines the advantages of minimal financial and technical cost with reasonable accuracy.

The Optimal Target Propofol and Alfentanil Concentrations during Plastic Surgery

Background: Propofol and alfentanil are frequently combined to provide total intravenous anesthesia (TIVA). The goals of this study were to determine the target plasma concentration (predicted plasma concentration) of propofol required to provide satisfactory anesthesia in the presence of nitrous oxide over a range of alfentanil infusions for analgesia and to determine the dosing rates required to achieve adequate anesthesia. Methods: Sixty patients undergoing plastic surgery were anesthetized with 50% nitrous oxide, alfentanil (0 [A0 group] or 5g/kg loading followed by 0.12g/kg/min [A5 group] or 10g/kg loading followed by 0.25g/kg/min [A10 group] or 20g/kg loading followed by 0.5g/kg/min [A20 group]) and propofol using a target-controlled infusion (TCI). The mean target concentration and infusion rate of propofol, and induction and recovery time according to changes of the alfentanil regimen were checked. Results: Induction and recovery time were prolonged in the A0 group more than other groups, and recovery time was shortened in the A10 group more than the other three groups (P 0.05). The infusion rate and mean target concentration of propofol had significant impact among the groups (P 0.05). Side effects did not differ among the groups. Conclusions: The optimal target plasma propofol concentrations and infusion rates of alfentanil, both with satisfactory intraoperative anesthetic conditions and speed of recovery, are 3.51, 3.02, 2.35g/ml and 0.12, 0.25, 0.5g/kg/min with 5, 10, 20g/kg loading in plastic surgery patients. We recommand 0.25g/kg infusion with 10g/kg loading of alfentanil combined with 3.02g/ml of target plasma concentration of propofol as the best combination dosage to shorten recovery time.

Target-Controlled Infusion of Alfentanil and Propofol for Total Abdominal Hysterectomy

Background: Alfentanil has been shown to act synergistically if combined with propofol, with or without nitrous oxide, or if combined with potent inhalation anesthetics. The goal of this study was to determine the dosing rate and target plasma concentration of propofol to supplement nitrous oxide in the presence of varying concentrations of alfentanil and to determine the optimal combination of propofol and alfentanil. Methods: Sixty patients undergoing a total abdominal hysterectomy (TAH) were anesthetized with nitrous oxide, and given a target-controlled infusion (TCI) of alfentanil [target plasma concentrations of 0 (A0 group), 50 ng/ml (A50 group), and 100 ng/ml (A100 group)], and propofol at rates varied up and down depending on the bispectal index (BIS). The mean target concentration (Tc) and infusion rate of propofol according to changes of concentrations of alfentanil were determined. Recovery time (from infusion stop to eye opening) and side effects were compared. Results: Induction time and recovery time were shortened in the A50 group and A100 group compared with the A0 group (P 0.05). The infusion rate and mean target concentration of propofol were significantly lower in the A100 group (7.5 mg/kg/h, 3.4g/ml) than the A0 (12.6 mg/kg/h, 4.5g/ml) and A50 (10.2 mg/kg/h, 4.0g/ml) groups (P 0.01). Side effects did not differ among the three groups. Conclusions: The optimal blood propofol and plasma alfentanil concentration, with respect to satisfactory intraoperative anesthetic conditions and speed of recovery, are 4.0g/ml and 50 ng/ml or 3.4g/ ml and 100 ng/ml in TAH patients.

Titration of Effect Site Concentration of Propofol for Conscious Sedation in Elderly Patients

Background: Propofol is used for sedation during local and regional anesthesia. In order to evaluate the depth of sedation the bispectral index (BIS) and observer's sedation scoring (OAA/S) are widely used. However, there are few studies focused on elderly surgical patients during propofol-induced sedation for regional anesthesia. The goal of this study was to examine the effect site concentration of propofol for conscious sedation using the bispectral index (BIS) and hemodynamic changes in elderly patients. Methods: Sixteen patients aged 65 yrs or older presenting for elective surgery requiring regional anesthesia were studied. After performing spinal anesthesia, target plasma concentration of propofol was set at 2.5/ml. Effect site concentration was titrated by increasing and decreasing the target plasma concentration to maintain a BIS of 75-80. Effect site concentration, the OAA/S score, mean arterial pressure (MAP) and heart rate were measured for 1 hour every 5 minutes. Statistical analysis was performed using repeated measurement of ANOVA and correlation analysis. Results: The mean effect site concentrations was 1.3 0.2/ml and OAA/S score was 2.8 0.5 when the BIS was maintained between 75-80. The correlation coefficient for the effect site concentration versus the BIS was r = - 0.79. The MAP significantly decreased with an effect site concentration of propofol 1.0 and 1.2/ml and the heart rate significantly decreased at 1.2/ml. MAP decreased significantly at the level of conscious sedation. Conclusions: The mean effect site concentration of propofol was 1.3 0.2/ml when the BIS was 75-80. There were significant correlation between the effect site concentration and BIS.

Clinical assessment of target-controlled infusion of propofol during monitored anesthesia care.

To determine the plasma concentrations of propofol required to achieve different levels of sedation during monitored anesthesia care. Sixty ASA I-II, 18-65 yr-old patients, received a target-controlled continuous iv infusion of propofol. The target plasma concentration of propofol (Cpt) was initially set at 0.4 microg x ml(-1). Two minutes after calculated equilibrium between plasma and effect-site concentrations, the Cpt of propofol was increased by 0.2 microg x ml(-1) steps until the patient showed no reaction to squeezing the trapezius. The level of sedation was assessed immediately before each increase in propofol Cpt using the Observer's Assessment of Alertness/Sedation (OAA/S) scale. The Cpt of propofol required to induce lethargic response to name was 1.3 microg x ml(-1) (5 degrees and 95 degrees percentiles: 1.0 - 1.8 microg x ml(-1)), to obtain response after loud and repeated calling name was 1.7 microg x ml(-1) (1.2 - 2.2 microg x ml(-1)), to obtain response after prodding or shaking was 2.0 microg x ml(-1) (1.6 - 2.6 microg x ml(-1)), to obtain response after squeezing the trapezius was 2.4 microg x ml(-1) (1.8 - 3.0 microg x ml(-1)). Patients showed no response after squeezing the trapezius at 2.8 microg x ml(-1) (2.0 - 3.6 microg x ml(-1)). Correlation between Cpt propofol and sedation scores were r = 0.76, P < 0.0001. Target-controlled infusion of propofol provided easy and safe management of intraoperative sedation, allowing fast and predictable deepening in the level of sedation, while minimizing systemic side effects of intravenous sedation due to the minimal risk of overdosing the drug.