[Establishment of a 3-dimentional finite element system simulating En masse retraction implemented by customized lingual appliances].

PURPOSE: This study was designed to establish a 3-dimentional finite element system to simulate the clinical scenario where labial segment was retracted with sliding mechanism in extraction cases treated by individualized lingual orthodontics. METHODS: A typical clinical case was selected. The subject was diagnosed with Class I malocclusion with alveolar protrusion and treated with extraction of 4 first premolars. The subject was under the treatment stage of frontal retraction by eBrace system, an individualized lingual appliance. The subject was also taken cone-beam CT (CBCT) based on which digital 3D reconstruction of dentition structures was formed with Mimics software. With the aid of software platform Pro/E 4.0, the important anatomical structures were defined, and relevant lingual devices, including lingual brackets, arch-wires, mini-screws and other accessories were formed. With the aids of software platform Geomagic Studio 13.0, the 3-dimentional structural mode, featuring maxillary alveolar, upper dentition, periodontal ligament, miniscrew and lingual applicance, were constructed. With the assistance of Ansys Workbench 15.0, 3D model for finite element system was finalised by conducting model meshing and defining the mechanical properties and the interface relations of the selected materials. RESULTS: Based on the digital information drawn from CBCT image, a 3-dimentional finite element system was successfully created, featuring all the elements mimicking the clinical scenario for En masse retraction. This system enabled an insight study on the effects of various retraction modes controlling the incisal torque and maintaining the dental arch integrity. CONCLUSIONS: The creation of a finite element system in this study is based on the digital data from the CBCT image of a real patient diagnosed with prognathic malocclusion and treated by lingual appliance. The clinical scenario of labial segment retraction via sliding mechanism is simulated in this finite element model.

[Expression of TNFAIP6 in oral verrucous carcinoma and oral squamous cell carcinoma and its relationship with clinicopathology].

PURPOSE: This study was designed to establish a 3-dimentional finite element system to simulate the clinical scenario where labial segment was retracted with sliding mechanism in extraction cases treated by individualized lingual orthodontics. METHODS: A typical clinical case was selected. The subject was diagnosed with Class I malocclusion with alveolar protrusion and treated with extraction of 4 first premolars. The subject was under the treatment stage of frontal retraction by eBrace system, an individualized lingual appliance. The subject was also taken cone-beam CT (CBCT) based on which digital 3D reconstruction of dentition structures was formed with Mimics software. With the aid of software platform Pro/E 4.0, the important anatomical structures were defined, and relevant lingual devices, including lingual brackets, arch-wires, mini-screws and other accessories were formed. With the aids of software platform Geomagic Studio 13.0, the 3-dimentional structural mode, featuring maxillary alveolar, upper dentition, periodontal ligament, miniscrew and lingual applicance, were constructed. With the assistance of Ansys Workbench 15.0, 3D model for finite element system was finalised by conducting model meshing and defining the mechanical properties and the interface relations of the selected materials. RESULTS: Based on the digital information drawn from CBCT image, a 3-dimentional finite element system was successfully created, featuring all the elements mimicking the clinical scenario for En masse retraction. This system enabled an insight study on the effects of various retraction modes controlling the incisal torque and maintaining the dental arch integrity. CONCLUSIONS: The creation of a finite element system in this study is based on the digital data from the CBCT image of a real patient diagnosed with prognathic malocclusion and treated by lingual appliance. The clinical scenario of labial segment retraction via sliding mechanism is simulated in this finite element model.

[Retrospective analysis of 39 child cases of paragonimiasis].

Clinical data of 39 children with paragonimiasis treated in Chongqing Three Gorges Central Hospital during 2008-2010 were retrospectively analyzed. The cases aged from 3 to 10 years old, with 25 cases of polyserositis (64.1%), 14 cases of cerebral paragonimiasis (35.9%). Among the cases of polyserositis, all showed dyspnea,tachypnea and diminished respiration (100%). Other symptoms or signs included purulent pleurisy, orthopnea, restricted activity, distant heart sounds, purulent pericarditis, abdominal distension, and hepatomegaly. In the 14 cases of cerebral paragonimiasis, 10 cases (71.4%) complained headache, 8 cases (57.1%) with vomiting, and other symptoms such as seizures, limb rigidity associated with conscious disturbance. Eight patients were treated with surgery and praziquantel, while others with praziquantel alone. After treatment 25 cases (64.1%) were cured, 13 cases (33.3%) improved, and 1 case (2.6%) showed no change.

[Effect of remifentanil on propofol pharmacokinetics with target controlled infusion in elderly patients].

OBJECTIVE: To investigate the effects of remifentanil administered by target-controlled infusion (TCI) with different plasma concentration and time on pharmacokinetics of propofol in elderly patients. METHODS: Thirty-two ASA I-II patients (65-82 years old) undergoing elective lower abdominal operations were divided into 4 groups randomly: TCI propofol combined with epidural block (group A, n=8); TCI remifentanil with plasma concentration 4 µg/L and propofol (group B, n=8); TCI remifentanil with plasma concentration 7 µg/L and propofol (group C, n=8); and TCI propofol and remifentanil (plasma concentration 4 µg/L) with infusion time longer than 4 hours (group D, n=8). Propofol was infused by target-controlled infusion with plasma concentration 3 mg/L in the 4 groups. bispetral index (BIS), heart rate (HR), blood pressure (BP) were recorded during operation. Blood samples were collection from radial arterial catheter. Samples of 2 mL of arterial blood were taken at 0, 1, 3, 5, 10, 15, 30 min and then every 30 min after the start of the infusion of propofol, and at 0, 2, 4, 6, 8, 10, 15, 30, 45, 60, 120, 240, 360, 480, 720, 1440 min after the termination of the infusion of propofol. Propofol concentrations in blood were measured by reversed-phase high-performance liquid chromatography (HPLC). The pharmacokinetics analyses were performed using the nonlinear mixed-effects model approach implemented in NONMEM computer program. After obtaining the best NONMEM model with covariates, the influence of coadministered remifentanil on the model was examined. RESULTS: In all the patients, the depth of anesthesia was enough (BIS value=40-60), and the circulatory system function was stable during operation. The final model of propofol pharmacokinetics in the three groups (A+B, A+C, and A+D groups) was best described by a three-compartment mammillary model. The values of objective function (OFV) were -810.1, -714.4, and -896.4. Addition of remifentanil covariate effects to the final model resulted in no improvement in the objective function. CONCLUSION: target-controlled infusion of propofol combined with different plasma concentration of remifentanil or remifentanil infusing more than 4 hours had no effect on pharmacokinetics of propofol in elderly patients.

Two-stage analysis of pharmacokinetics of sufentanil administered by target-controlled infusion in Chinese patients.

BACKGROUND: Sufentanil is a suitable choice for target-controlled infusion (TCI) because of its shorter context-sensitive half-time. The current study was to estimate the pharmacokinetics of sufentanil TCI in Chinese patients using the two-stage analysis. METHODS: Twelve adult patients with American Society of Anesthesiologists (ASA) physical status I or II undergoing elective surgery under general anesthesia were included. Anesthesia was induced with propofol, rocuronium and sufentanil administered by TCI lasting for 30 minutes, with target effect-site concentration of sufentanil 4 or 6 ng/ml. Frequent arterial blood samples (1.5 ml) were taken during and up to 24 hours after sufentanil TCI. Before the end of surgery, another arterial blood sample (1.0 ml) was drawn for the blood-gas analysis. Plasma sufentanil concentrations were determined by liquid chromatography-tandem mass spectrometry (limit of quantitation was 5 pg/ml). The data were analyzed with the two-stage approach, linear regression and correlation analysis. RESULTS: The pharmacokinetics of sufentanil TCI were adequately described by a three-compartment model. The variables were derived as follows: the volume of central compartment (V(1)) was 5.4 L, volume of distribution at steady-state (Vdss) was 222.6 L, metabolic clearance (Cl(1)) was 0.84 L/min and elimination half-life (t(1/2Y)) was 389 minutes. Patients' age, gender and PaCO2 correlated significantly with the pharmacokinetic parameters. The Vdss, volume of slowly equilibrating compartment (V(3)) and t(1/2Y) increased, and rapid distribution clearance (Cl(2)) decreased with increasing patient age. Male patients had larger values of Vdss, volume of rapidly equilibrating compartment (V(2)) and V(3) than female patients. The Vdss and V(3) increased with higher PaCO2 values. There were no significant correlations between the pharmacokinetic variables and body weight, height, lean body mass, plasma albumin, sufentanil dose, duration of surgery, pH or base excess of blood (BE-B). CONCLUSIONS: The pharmacokinetics of sufentanil TCI in Chinese patients can be optimally described by a three-compartment model. The pharmacokinetic analysis technique may affect the pharmacokinetic parameters and correlations.

Clinical evaluation of target controlled infusion system for sufentanil administration.

BACKGROUND: Sufentanil target controlled infusion (TCI) provides stable analgesia, better hemodynamic control than a bolus injection of intravenous anesthetics, anticipated recovery and improved quality of anesthesia during perioperative period. This study evaluated the accuracy and feasibility of TCI system for sufentanil at high concentrations in Chinese surgical patients. METHODS: Twelve low risk adult patients undergoing elective surgery under general anesthesia were included in this study. Sufentanil was administered with a specific TCI system incorporating the population pharmacokinetic data of sufentanil previously reported, using a target effect-site concentration of sufentanil 4 or 6 ng/ml. Sufentanil TCI duration was 30 minutes. Frequent arterial blood samples were taken during and up to 24 hours after sufentanil TCI for determination of plasma sufentanil concentrations by liquid chromatography-mass spectrometry/mass spectrometry. The changes of circulatory system function during the procedure, recovery profile and adverse effects were recorded. Measured plasma sufentanil concentrations were compared with the values predicted by the TCI system. The bias (median performance error, MDPE), precision (median absolute performance error, MDAPE) and wobble (variability of performance error) of the sufentanil TCI system were determined. RESULTS: All patients had stable cardiovascular variables during induction and maintenance of anesthesia. Time to eye opening and extubation were (5.6 + or - 1.7) minutes when TCI set to 4 ng/ml and (7.2 + or - 2.3) minutes when set to 6 ng/ml. There was no episode of agitation, muscle rigidity or intraoperative awareness. The bias (MDPE), precision (MDAPE) and wobble of the sufentanil TCI system were -3.7%, 18.9% and 19.6% respectively during TCI, and the MDPE, MDAPE and wobble were -29.1%, 31.7% and 15.0% respectively after TCI (up to 8 hours). CONCLUSIONS: The TCI system programmed for sufentanil at 4 or 6 ng/ml was considered acceptable for clinical use in low risk Chinese surgical patients. But the relatively larger MDPE and MDAPE after TCI suggest improvements of the pharmacokinetic model are needed.

[Target-controlled infusions of remifentanil and propofol in elderly patients].

OBJECTIVE: To investigate the clinical reliability and feasibility of target-controlled infusion (TCI) with different plasma concentration remifentanil and propofol. METHODS: Thirty ASA I-II patients, > or =65 years old, undergoing selective lower abdominal operation were divided into 3 groups, group A with anesthesia using propofol combined with epidural block, group B with anesthesia using propofol and remifentanil (plasma concentration 4 microg/L), group C with anesthesia using propofol and remifentanil (plasma concentration 7 microg/L). BIS value, heart rate, blood pressure, heart rate variability and so on, were recorded during anesthesia and operation. Radial arterial blood samples for analysis of plasma concentration of propofol were taken during operation. RESULTS: (1) The intubation response of groups B and C was lower than that of group A . (2) The depth of anesthesia was enough during operation (BIS value=45-60). (3) TCI propofol combined with remifentanil didn't lengthen the awaking time of patients; (4) MDPE of target-controlled infusion using propofol with Marsh parameters was 11.17%, MDAPE was 12.16% in Chinese elderly patients. CONCLUSION: Remifentanil with plasma concentration of 4 and 7 microg/L combined with propofol could be safely used during clinical anesthesia of old patient, but monitoring must be strengthened during induction when plasma concentration of remifentanil was 7 microg/L. TCI propofol with Marsh parameters could be applied to Chinese elderly patients safely and efficiently.

[Elimination half-life of propofol in effect-site of mice].

OBJECTIVE: To study the elimination half-life of propofol in mouse brain. METHODS: One hundred and forty mice were injected with propofol 32 mg/kg through caudal vein. The mice were divided into 14 groups with different time points, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9 , 10, 15, 30, 45, and 60 min, with 10 mice in each group. The mice were killed to obtain arterial blood by picking off their eyeballs, and their brains by cutting off their heads. The concentrations of propofol in serum and brain were measured by high performance liquid chromatography. The parameters of elimination half-life were calculated by software 3P97. RESULTS: Time to peak concentration of propofol in serum was about 1 min, and time to peak concentration of propofol in brain was about 3 min. The elimination half-life of propofol in brain were (9.6+/-0.5) mins. CONCLUSION: The peak concentrations of propofol in brain was later than it in serum. There is correlation between the concentrations of propofol in blood and in brain. The metabolism of propofol in effect site could be measured accurately by the elimination half-life in brain.