Population pharmacokinetic modeling and evaluation of propofol from multiple centers / 药学学报

In order to successfully develop the effective population pharmacokinetic model to predict the concentration of propofol administrated intravenously, the data including the concentrations across both distribution and elimination phases from five hospitals were analyzed using nonlinear mixed effect model (NONMEM). Three-compartment pharmacokinetic model was applied while the exponential model was used to describe the inter-individual variability and constant coefficient model to the intra-individual variability, accordingly. Covariate effect including the body weight on the parameter CL, V1, Q2, V2, Q3 and V3 were investigated. The performance of final model was assessed by Bootstrapping, goodness-of-fit and visual predictive checking (VPC). The context-sensitive half-times and the infusion rates necessary to maintain the concentration of 1 microg x mL(-1) were simulated to six subpopulations. The results were as follows: the typical value of CL, V1, Q2, V2, Q3 and V3 were 0.965 x (1 + 0.401 x VESS) x (BW/59)(0.578) L x min(-1), 13.4 x (AGE/45)(-0.317) L, 0.659 x (1 + GENDER x 0.385) L x min(-1), 28.8 L, 0.575 x (1 + GENDER x 0.367) x (1 - 0.369 x VESS) L x min(-1) and 196 L respectively. Coefficients of the inter-individual variability of CL, V1, Q2, V2, Q3 and V3 were 29.2%, 46.9%, 35.2%, 40.4%, 67.0% and 49.9% respectively, and the coefficients of residual variability were 24.7%, 16.1% and 22.5%, the final model indicated a positive influence of a body weight on CL, and also that a negative correlation of age with V1. Q2 and Q3 in males were higher than those in females at 38.5% and 36.7%. The CL and Q3 were 40.1% increased and 36.9% decreased in arterial samples compared to those in venous samples. The determination coefficient of observations (DV)-individual predicted value (IPRED) by the final model was 0.91 which could predict the propofol concentration fairly well. The stability and the predictive performance were accepted by Bootstrapping, the goodness-of-fit and VPC. The context-sensitive half-times and infusion rates necessary to maintain the concentration of 1 microg x mL(-1) were different obviously among the 6 sub-populations obviously. The three-compartment model with first-order elimination could describe the pharmacokinetics of propofol fairly well. The involved fixed effects are age, body weight, gender and sampling site. The simulations in 6 subpopulations were available in clinical anesthesia. The propofol anesthesia monitor care could be improved by individualization of pharmacokinetic parameter estimated from the final model.

Changes of hemodynamics and concentrations of nitric oxide, endothelin, prostacyclin, and thromboxane A2 during portal cavity clamping and opening in portal hypertensive canines / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the changes in systemic hemodynamics and their relations to the concentrations of nitric oxide, endothelin, prostacyclin, and thromboxane A2 after portal cavity clamping and opening in portal hypertensive canines.</p><p><b>METHODS</b>Twelve canines were randomly divided into control group and model group, and partial ligation of the portal vein was performed in the model group. Portal cavity clamping and opening was performed 12 weeks later in the two groups. The hemodynamic parameters including cardiac output index (CI), heart rate (HR), mean artery blood pressure (MABP), central venous pressure (CVP), pulmonary arteriole wedge pressure (PAWP), and systemic vascular resistance index (SVRI) were measured during the operation. Samples were obtained from the central vein at 3 time points during the operation for measuring NO, ET, PGI2, and TXA2.</p><p><b>RESULTS</b>Portal vein ligation and portal cavity clamping produced obvious changes in the systemic circulation of the dogs, and the alteration was milder in the control group. After obstruction of the portal vein, the NO levels in systemic circulation in portal hypertensive dogs declined obviously, but gradually recovered the normal level after reperfusion.</p><p><b>CONCLUSION</b>Systemic circulation undergoes significant alterations after portal vein obstruction, but its changes in portal hypertensive dogs are milder than those in the control group, the mechanism of which needs further investigation.</p>

Relationship between the expression of Toll-like receptor 2 and 4 in mononuclear cells and postoperative acute lung injury in orthotopic liver transplantation / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The aim of this study was to investigate the potential relationship between the dynamic expression of Toll-like receptor 2 and 4 (TLR2/4) in peripheral blood mononuclear cells as well as changes in serum concentration of inflammatory factors and acute lung injury (ALI) in patients after orthotopic liver transplantation (OLT).</p><p><b>METHODS</b>The peripheral blood samples of 27 patients (23 men and 4 women with ASA III to IV) who received OLT were collected for measurement of TLR2/4 at T1 (after induction of anesthesia), T2 (25 minutes after anhepatic phase), T3 (3 hours after graft reperfusion) and T4 (24 hours after graft reperfusion). The expression of TLR2/4 in mononuclear cells was measured by flow cytometry. The serum concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-8 were measured by enzyme-linked immunosorbent assay (ELISA). Twenty-seven patients were assigned to ALI group (n = 9) and non-ALI group (n = 18) according to the diagnostic criteria of ALI. The expression of TLR2/4 in the ALI group or non-ALI group was analyzed.</p><p><b>RESULTS</b>Compared to the non-ALI group, the volumes of blood loss, ascites, total output and transfused red blood cells were higher in the ALI group, and the anhepatic phase lasted longer (P < 0.05, P < 0.01). The expression of TLR2/4 in mononuclear cells increased significantly at T3 and T4, and serum concentrations of TNF-alpha, IL-1beta and IL-8 increased significantly too. There was no significant difference in Child-Turcotte-Pugh (CTP) scores between the ALI group and non-ALI group (P > 0.05). The expression of TLR2/4 in mononuclear cells increased significantly at T3 and T4 in the ALI group (P < 0.05, P < 0.01). A positive correlation was noted between the expression of TLR4 in mononuclear cells and the serum concentrations of TNF-alpha, IL-1beta (P = 0.041, P = 0.046) in the ALI group. In the non-ALI group, statistical results showed that the expression level of TLR2/4 in mononuclear cells was not significantly different during the peri-operative period of OLT (besides TLR4 expression at T4). Compared to the non-ALI group, the increasing amplitude of TLR2/4 expression in mononuclear cells was more significant in the ALI group. The patients whose TLR2/4 expression in mononuclear cells exceeded that at T1 by one time were more likely to suffer from ALI (P = 0.013), with a relative risk of 16.</p><p><b>CONCLUSION</b>The expression level of TLR2/4 in mononuclear cells increases significantly in the peri-operative period of OLT, and it may be a high risk factor for occurrence of postoperative ALI.</p>