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Bekker, Alex Y., Amit Mistry, Arthur A. Ritter, Steven C. Wolk, and Herman Turndorf. "Computer Simulation of Intracranial Pressure Changes During Induction of Anesthesia." Journal of Neurosurgical Anesthesiology 11, no. 2 (April 1999): 69–80. http://dx.doi.org/10.1097/00008506-199904000-00001.
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Syroid, Noah D., James Agutter, Frank A. Drews, Dwayne R. Westenskow, Robert W. Albert, Julio C. Bermudez, David L. Strayer, Hauke Prenzel, Robert G. Loeb, and Matthew B. Weinger. "Development and Evaluation of a Graphical Anesthesia Drug Display." Anesthesiology 96, no. 3 (March 1, 2002): 565–75. http://dx.doi.org/10.1097/00000542-200203000-00010.
Повний текст джерелаАнотація:
Background Usable real-time displays of intravenous anesthetic concentrations and effects could significantly enhance intraoperative clinical decision-making. Pharmacokinetic models are available to estimate past, present, and future drug effect-site concentrations, and pharmacodynamic models are available to predict the drug's associated physiologic effects. Methods An interdisciplinary research team (bioengineering, architecture, anesthesiology, computer engineering, and cognitive psychology) developed a graphic display that presents the real-time effect-site concentrations, normalized to the drugs' EC(95), of intravenous drugs. Graphical metaphors were created to show the drugs' pharmacodynamics. To evaluate the effect of the display on the management of total intravenous anesthesia, 15 anesthesiologists participated in a computer-based simulation study. The participants cared for patients during two experimental conditions: with and without the drug display. Results With the drug display, clinicians administered more bolus doses of remifentanil during anesthesia maintenance. There was a significantly lower variation in the predicted effect-site concentrations for remifentanil and propofol, and effect-site concentrations were maintained closer to the drugs' EC(95). There was no significant difference in the simulated patient heart rate and blood pressure with respect to experimental condition. The perceived performance for the participants was increased with the drug display, whereas mental demand, effort, and frustration level were reduced. In a post-simulation questionnaire, participants rated the display to be a useful addition to anesthesia monitoring. Conclusions The drug display altered simulated clinical practice. These results, which will inform the next iteration of designs and evaluations, suggest promise for this approach to drug data visualization.
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Bekker, Alex, Steven Wolk, Herman Turndorf, David Kristol, and Arthur Ritter. "Computer simulation of cererrovascular circulation: Assessment of intracranial hemodynamics during induction of anesthesia." Journal of Clinical Monitoring 12, no. 6 (November 1996): 433–44. http://dx.doi.org/10.1007/bf02199704.
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Woodworth, Glenn E., Elliza M. Chen, Jean-Louis E. Horn, and Michael F. Aziz. "Efficacy of computer-based video and simulation in ultrasound-guided regional anesthesia training." Journal of Clinical Anesthesia 26, no. 3 (May 2014): 212–21. http://dx.doi.org/10.1016/j.jclinane.2013.10.013.
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Hegedus, Erwin T., Isabela R. Birs, Mihaela Ghita, and Cristina I. Muresan. "Fractional-Order Control Strategy for Anesthesia–Hemodynamic Stabilization in Patients Undergoing Surgical Procedures." Fractal and Fractional 6, no. 10 (October 20, 2022): 614. http://dx.doi.org/10.3390/fractalfract6100614.
Повний текст джерелаАнотація:
Fractional calculus has been opening new doors in terms of better modeling and control of several phenomena and processes. Biomedical engineering has seen a lot of combined attention from clinicians, control engineers and researchers in their attempt to offer individualized treatment. A large number of medical procedures require anesthesia, which in turn requires a closely monitored and controlled level of hypnosis, analgesia and neuromuscular blockade, as well maintenance of hemodynamic variables in a safe range. Computer-controlled anesthesia has been given a tremendous amount of attention lately. Hemodynamic stabilization via computer-based control is also a hot topic. However, very few studies on automatic control of combined anesthesia–hemodynamic systems exist despite the fact that hemodynamics is strongly influenced by hypnotic drugs, while the depth of hypnosis is affected by drugs used in hemodynamic control. The very first multivariable fractional-order controller is developed in this paper for the combined anesthesia–hemodynamic system. Simulation studies on 24 patients show the effectiveness of the proposed approach.
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Aljamaan, Ibrahim, and Ahmed Alenany. "Identification of Wiener Box-Jenkins Model for Anesthesia Using Particle Swarm Optimization." Applied Sciences 12, no. 10 (May 10, 2022): 4817. http://dx.doi.org/10.3390/app12104817.
Повний текст джерелаАнотація:
Anesthesia refers to the process of preventing pain and relieving stress on the patient’s body during medical operations. Due to its vital importance in health care systems, the automation of anesthesia has gained a lot of interest in the past two decades and, for this purpose, several models of anesthesia are proposed in the literature. In this paper, a Wiener Box-Jenkins model, consisting of linear dynamics followed by a static polynomial nonlinearity and additive colored noise, is used to model anesthesia. A set of input–output data is generated using closed-loop simulations of the Pharmacokinetic–Pharmacodynamic nonlinear (PK/PD) model relating the drug infusion rates, in [μgkg−1min−1], to the Depth of Anesthesia (DoA), in [%]. The model parameters are then estimated offline using particle swarm optimization (PSO) technique. Several Monte Carlo simulations and validation tests are conducted to evaluate the performance of the identified model. The simulation showed very promising results with a quick convergence in less than 10 iterations, with a percentage error less than 1.5%.
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Johnson, Chad R., Roger C. Barr, and Stephen M. Klein. "A Computer Model of Electrical Stimulation of Peripheral Nerves in Regional Anesthesia." Anesthesiology 106, no. 2 (February 1, 2007): 323–30. http://dx.doi.org/10.1097/00000542-200702000-00021.
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Background Nerve stimulation for regional anesthesia can be modeled mathematically. The authors present a mathematical framework to model the underlying electrophysiology, the development of software to implement that framework, and examples of simulation results. Methods The mathematical framework includes descriptions of the needle, the resulting potential field, and the active nerve fiber. The latter requires a model of the individual membrane ionic currents. The model geometry is defined by a three-dimensional coordinate system that allows the needle to be manipulated as it is clinically and tracked in relation to the nerve fiber. The skin plane is included as an electrical boundary to current flow. The mathematical framework was implemented in the Matlab (The MathWorks, Natick, MA) computing environment and organized around a graphical user interface. Simulations were performed using an insulated needle or an uninsulated needle inserted perpendicular to the skin with the nerve fiber at a depth of 2 cm. For each needle design, data were obtained with the needle as cathode or anode. Data are presented as current-distance maps that highlight combinations of current amplitude and tip-to-nerve distance that evoked a propagated response. Results With the needle tip positioned 2 mm proximal to the depth of the nerve, an insulated needle required a current greater than 0.457 mA for impulse propagation when attached to the cathode; when attached to the anode, the minimal current was 2.354 mA. In the same position, an uninsulated needle attached to the cathode required a current greater than 2.395 mA to generate a response. However, when an uninsulated needle was attached to the anode, currents up to 7 mA were inadequate to produce a propagated response. Of particular interest were combinations of current amplitude and needle position that activated the fiber but blocked impulse propagation for cathodal stimulation. Conclusions Mathematical modeling of nerve stimulation for regional anesthesia is possible and could be used to investigate new equipment or needle designs, test nerve localization protocols, enhance clinical and experimental data, and ultimately generate new hypotheses.
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OZAKI, M. "Anesthesia and Crisis Management Simulation on the Desktop Computer(Special Issue : Simulators and Medical Education)." JAPANES JOURNAL OF MEDICAL INSTRUMENTATION 69, no. 3 (March 1, 1999): 127–29. http://dx.doi.org/10.4286/ikakikaigaku.69.3_127.
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Bekker, A., I. Osborn, and H. Turndorf. "Computer simulation of cerebrovascular responses during induction of anesthesia: comparison of thiopental, propofol, and etomidate." Journal of Neurosurgical Anesthesiology 10, no. 4 (October 1998): 265. http://dx.doi.org/10.1097/00008506-199810000-00043.
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Bai, Manyun, Renzhong Guo, Qian Zhao, and Yufang Li. "Artificial Intelligence-Based CT Images in Analysis of Postoperative Recovery of Patients Undergoing Laparoscopic Cholecystectomy under Balanced Anesthesia." Scientific Programming 2021 (September 1, 2021): 1–7. http://dx.doi.org/10.1155/2021/1125573.
Повний текст джерелаАнотація:
To explore whether preoperative processing can promote the recovery of gastrointestinal function after laparoscopic cholecystectomy (LC) surgery, in the study, an artificial intelligence-based algorithm was used to segment the CT images to assist doctors in decision making. The patients were divided into observation group (balanced anesthesia) and control group (general anesthesia) with SPSS. The observation group received balanced anesthesia half a day before the operation. The method of balanced anesthesia was to induce 0.2 mg/kg midazolam, 3 mg/kg propofol, 2 μg/kg remifentanil, 0.2 mg/kg vecuronium, 4∼5 mg/(kg·h) propofol, and 9∼11 μg/(kg·h) remifentanil continuous intravenous infusion to maintain anesthesia, and it was stopped once the patient defecated; the control group had general anesthesia in the afternoon after the operation, and it was stopped once the patient defecated. The time before the first exhaust and defecation after the surgery as well as the recovery time of bowel sound was recorded, and the degree of abdominal pain, abdominal distension, and gastrointestinal adverse reactions was evaluated at 22 hours, 46 hours, and 70 hours after the surgery. It was found that the accuracy of the artificial intelligence-based segmentation algorithm was 81%. The reconstruction accuracy of multidimensional liver could be observed at any angle, and the reconstruction accuracy was not lower than the resolution of original input CT. The calculation error was less than 9%, and the volume of whole liver, liver segment, preresection liver, and residual liver was less than 9%. The simulation accuracy of virtual liver surgery was not lower than the resolution of original input CT. The time before the first exhaust and defecation was shorter in the observation group versus the control group ( P < 0.05). The recovery time of bowel sound in the observation group was shorter than that in the control group ( P < 0.05). There was a significant difference in the scores of abdominal distension between the two groups at 22 h and 46 h after surgery ( P < 0.05). It suggested that both the observation group and the control group could improve the symptoms of gastrointestinal adverse reactions after surgery. Nevertheless, balanced anesthesia can shorten the time before the first exhaust and defecation after surgery and promote the recovery of postoperative bowel sound. Furthermore, balanced anesthesia can alleviate abdominal distension, abdominal pain, and gastrointestinal adverse reactions, which should be promoted in clinic.
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Caiado, Daniela V., João M. Lemos, and Bertinho A. Costa. "Robust control of depth of anesthesia based on H∞ design." Archives of Control Sciences 23, no. 1 (March 1, 2013): 41–59. http://dx.doi.org/10.2478/v10170-011-0041-z.
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Abstract This paper presents a case study on the design of a robust controller for the depth of anesthesia (DoA) induced by the drug propofol. This process is represented by a linear model together with a non-parametric uncertainty description that is evaluated using a patient model bank with 20 patients undergoing sedation. By using H∞ methods, the controller is aimed to comply with robust stability and performance specifications for the class of patient models considered. A minimization problem of sensitivity and complementary sensitivity is made to design the controller. The controller that results from this procedure is approximated by a controller with a lower order, that in turn is redesigned in discrete time for computer control application. The resulting controller is evaluated in simulations using a realistic nonlinear model of DoA.
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McNeer, Richard R., Danielle Bodzin Horn, Christopher L. Bennett, Judy Reed Edworthy, and Roman Dudaryk. "Auditory Icon Alarms Are More Accurately and Quickly Identified than Current Standard Melodic Alarms in a Simulated Clinical Setting." Anesthesiology 129, no. 1 (July 1, 2018): 58–66. http://dx.doi.org/10.1097/aln.0000000000002234.
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Abstract Background Current standard audible medical alarms are difficult to learn and distinguish from one another. Auditory icons represent a new type of alarm that has been shown to be easier to learn and identify in laboratory settings by lay subjects. In this study, we test the hypothesis that icon alarms are easier to learn and identify than standard alarms by anesthesia providers in a simulated clinical setting. Methods Twenty anesthesia providers were assigned to standard or icon groups. Experiments were conducted in a simulated intensive care unit. After a brief group-specific alarm orientation, subjects identified patient-associated alarm sounds during the simulation and logged responses via a tablet computer. Each subject participated in the simulation twice and was exposed to 32 alarm annunciations. Primary outcome measures were response accuracy and response times. Secondary outcomes included assessments of perceived fatigue and task load. Results Overall accuracy rate in the standard alarm group was 43% (mean) and in the icon group was 88% (mean). Subjects in the icon group were 26.1 (odds ratio [98.75% CI, 8.4 to 81.5; P < 0.001]) times more likely to correctly identify an alarm. Response times in the icon group were shorter than in the standard alarm group (12 vs. 15 s, difference 3 s [98.75% CI ,1 to 5; P < 0.001]). Conclusions Under our simulated conditions, anesthesia providers more correctly and quickly identified icon alarms than standard alarms. Subjects were more likely to perceive higher fatigue and task load when using current standard alarms than icon alarms.
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Jang, Won-Seok, Soo-Hwan Byun, Seoung-Won Cho, In-Young Park, Sang-Min Yi, Jong-Cheol Kim, and Byoung-Eun Yang. "Correction of Condylar Displacement of the Mandible Using Early Screw Removal following Patient-Customized Orthognathic Surgery." Journal of Clinical Medicine 10, no. 8 (April 9, 2021): 1597. http://dx.doi.org/10.3390/jcm10081597.
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Objective: Orthognathic surgery (OGS) is a surgical intervention that corrects dentofacial deformities through the movement of maxillary and mandibular segments to achieve adequate masticatory function, joint health, and facial harmony. However, some patients present with occlusal discrepancies, condylar sag, and/or temporomandibular disorders after OGS. Various methods have been employed to solve these problems after surgery. This study aimed to evaluate the effectiveness of early screw removal in patients with occlusal discrepancies after OGS using three-dimensional cone-beam computed tomography (CBCT). Methods: In 44 patients with dentofacial deformities, patient-customized OGSs with customized plates were performed to correct facial deformities using customized guides with computer-aided surgical simulation. Of the 44 patients, eight patients complained of occlusal discrepancies and temporomandibular disorders after OGS. These eight patients underwent screw removal under local anesthesia around four weeks. The temporomandibular joint spaces at three time points (pre-surgical, post-surgical, and after screw removal) in the sagittal and coronal planes were compared using CBCT. Results: Eight patients showed an increase in joint space on CBCT images immediately after surgery (T1), but after early screw removal (T2), these spaces almost returned to their pre-surgical state, and the temporomandibular joint problem disappeared. Conclusions: The removal of screws located in the distal segment under local anesthesia between three and four weeks post-surgically may be a treatment option for patients with post-OGS occlusal discrepancies, condylar sag, and/or temporomandibular disorder.
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Manyam, Sandeep C., Dhanesh K. Gupta, Ken B. Johnson, Julia L. White, Nathan L. Pace, Dwayne R. Westenskow, and Talmage D. Egan. "Opioid–Volatile Anesthetic Synergy." Anesthesiology 105, no. 2 (August 1, 2006): 267–78. http://dx.doi.org/10.1097/00000542-200608000-00009.
Повний текст джерелаАнотація:
Background Combining a hypnotic and an analgesic to produce sedation, analgesia, and surgical immobility required for clinical anesthesia is more common than administration of a volatile anesthetic alone. The aim of this study was to apply response surface methods to characterize the interactions between remifentanil and sevoflurane. Methods Sixteen adult volunteers received a target-controlled infusion of remifentanil (0-15 ng/ml) and inhaled sevoflurane (0-6 vol%) at various target concentration pairs. After reaching pseudo-steady state drug levels, the Observer's Assessment of Alertness/Sedation score and response to a series of randomly applied experimental pain stimuli (pressure algometry, electrical tetany, and thermal stimulation) were observed for each target concentration pair. Response surface pharmacodynamic interaction models were built using the pooled data for sedation and analgesic endpoints. Using computer simulation, the pharmacodynamic interaction models were combined with previously reported pharmacokinetic models to identify the combination of remifentanil and sevoflurane that yielded the fastest recovery (Observer's Assessment of Alertness/Sedation score > or = 4) for anesthetics lasting 30-900 min. Results Remifentanil synergistically decreased the amount of sevoflurane necessary to produce sedation and analgesia. Simulations revealed that as the duration of the procedure increased, faster recovery was produced by concentration target pairs containing higher amounts of remifentanil. This trend plateaued at a combination of 0.75 vol% sevoflurane and 6.2 ng/ml remifentanil. Conclusion Response surface analyses demonstrate a synergistic interaction between remifentanil and sevoflurane for sedation and all analgesic endpoints.
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Li, Sean, Libby Copeland-Halperin, Alexander Kaminsky, Jihui Li, Fahad Lodhi, and Reza Miraliakbari. "Computer-Aided Surgical Simulation in Head and Neck Reconstruction: A Cost Comparison among Traditional, In-House, and Commercial Options." Journal of Reconstructive Microsurgery 34, no. 05 (February 20, 2018): 341–47. http://dx.doi.org/10.1055/s-0037-1621735.
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Background Computer-aided surgical simulation (CASS) has redefined surgery, improved precision and reduced the reliance on intraoperative trial-and-error manipulations. CASS is provided by third-party services; however, it may be cost-effective for some hospitals to develop in-house programs. This study provides the first cost analysis comparison among traditional (no CASS), commercial CASS, and in-house CASS for head and neck reconstruction. Methods The costs of three-dimensional (3D) pre-operative planning for mandibular and maxillary reconstructions were obtained from an in-house CASS program at our large tertiary care hospital in Northern Virginia, as well as a commercial provider (Synthes, Paoli, PA). A cost comparison was performed among these modalities and extrapolated in-house CASS costs were derived. The calculations were based on estimated CASS use with cost structures similar to our institution and sunk costs were amortized over 10 years. Results Average operating room time was estimated at 10 hours, with an average of 2 hours saved with CASS. The hourly cost to the hospital for the operating room (including anesthesia and other ancillary costs) was estimated at $4,614/hour. Per case, traditional cases were $46,140, commercial CASS cases were $40,951, and in-house CASS cases were $38,212. Annual in-house CASS costs were $39,590. Conclusions CASS reduced operating room time, likely due to improved efficiency and accuracy. Our data demonstrate that hospitals with similar cost structure as ours, performing greater than 27 cases of 3D head and neck reconstructions per year can see a financial benefit from developing an in-house CASS program.
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Lee, Seung Jun, Ho Yeong Kil, Sung Mi Hwang, and Dae Woo Kim. "Comparison of Context-Sensitive Half-Time from PK-SIM Computer Simulation with Duration of Propofol Infusion and Awakening after Propofol-N2O-O2 Anesthesia." Korean Journal of Anesthesiology 36, no. 4 (1999): 584. http://dx.doi.org/10.4097/kjae.1999.36.4.584.
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Leiva, Jorge, Pau Fonseca i Casas, and Jordi Ocaña. "Modeling anesthesia and pavilion surgical units in a Chilean hospital with Specification and Description Language." SIMULATION 89, no. 8 (July 11, 2013): 1020–35. http://dx.doi.org/10.1177/0037549713495742.
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Zafar, Sobia, Kristina Mladenovic, Sakher AlQahtani, Chaitanya Puranik, and Rasa Mladenovic. "Assessing the Pedological Impact of Local Anesthesia Dental Simulator as Serious Game." Applied Sciences 12, no. 7 (March 23, 2022): 3285. http://dx.doi.org/10.3390/app12073285.
Повний текст джерелаАнотація:
The aim of our study was to determine the effectiveness of a mobile 3D augmented reality (AR) simulator for local anesthesia training as a serious game. We present a mobile simulator which has three modes for learning: study, 3D simulation, and AR reality. Both pre- and post-training surveys contained open-ended and Likert-scale questions (comprising five response options) on demographics and students’ experiences. The response rate was 90.1%. Of the total participants, 37 subjects were female and 27 were male. The mean age was 20 years. The results of the pre-training survey showed that over 80% of dental students from both universities agreed that they were excited about using the mobile simulator. The results from the post training survey showed that 78.7–88.2% of participants felt comfortable using the mobile application, over 72% agreed that it was user friendly, and over 82.3% of participants agreed that it looked realistic. It was also found that 76.6–88.2% of participants agreed that the 3D anatomical structures improved their understanding of LA administration. A serious game for learning local anesthesia can be a very interesting and valuable learning tool for dental students.
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Adamus, Milan, and Radim Belohlavek. "Fuzzy control of neuromuscular block during general anesthesia—system design, development and implementation." International Journal of General Systems 36, no. 6 (December 2007): 733–43. http://dx.doi.org/10.1080/03081070601058687.
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Schild, Stefanie, Julian Gruendner, Christian Gulden, Hans-Ulrich Prokosch, Michael St Pierre, and Martin Sedlmayr. "Data Model Requirements for a Digital Cognitive Aid for Anesthesia to Support Intraoperative Crisis Management." Applied Clinical Informatics 11, no. 01 (January 2020): 190–99. http://dx.doi.org/10.1055/s-0040-1703015.
Повний текст джерелаАнотація:
Abstract Objective The aim of this study is to define data model requirements supporting the development of a digital cognitive aid (CA) for intraoperative crisis management in anesthesia, including medical emergency text modules (text elements) and branches or loops within emergency instructions (control structures) as well as their properties, data types, and value ranges. Methods The analysis process comprised three steps: reviewing the structure of paper-based CAs to identify common text elements and control structures, identifying requirements derived from content, design, and purpose of a digital CA, and validating requirements by loading exemplary emergency checklist data into the resulting prototype data model. Results The analysis of paper-based CAs identified 19 general text elements and two control structures. Aggregating these elements and analyzing the content, design and purpose of a digital CA revealed 20 relevant data model requirements. These included checklist tags to enable different search options, structured checklist action steps (items) in groups and subgroups, and additional information on each item. Checklist and Item were identified as two main classes of the prototype data model. A data object built according to this model was successfully integrated into a digital CA prototype. Conclusion To enable consistent design and interactivity with the content, presentation of critical medical information in a digital CA for crisis management requires a uniform structure. So far it has not been investigated which requirements need to be met by a data model for this purpose. The results of this study define the requirements and structure that enable the presentation of critical medical information. Further research is needed to develop a comprehensive data model for a digital CA for crisis management in anesthesia, including supplementation of requirements resulting from simulation studies and feasibility analyses regarding existing data models. This model may also be a useful template for developing data models for CAs in other medical domains.
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Pawłowski, Andrzej, Michele Schiavo, Nicola Latronico, Massimiliano Paltenghi, and Antonio Visioli. "Model predictive control using MISO approach for drug co-administration in anesthesia." Journal of Process Control 117 (September 2022): 98–111. http://dx.doi.org/10.1016/j.jprocont.2022.07.007.
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Schiavo, Michele, Fabrizio Padula, Nicola Latronico, Massimiliano Paltenghi, and Antonio Visioli. "Individualized PID tuning for maintenance of general anesthesia with propofol and remifentanil coadministration." Journal of Process Control 109 (January 2022): 74–82. http://dx.doi.org/10.1016/j.jprocont.2021.12.004.
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Klyuchareva, S. V., Igor V. Ponomarev, and A. E. Pushkareva. "Numerical Modeling and Clinical Evaluation of Pulsed Dye Laser and Copper Vapor Laser in Skin Vascular Lesions Treatment." Journal of Lasers in Medical Sciences 10, no. 1 (December 18, 2018): 44–49. http://dx.doi.org/10.15171/jlms.2019.07.
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Introduction: Different yellow lasers have been successfully used for the treatment of vascular lesions. This study is aimed to ascertain the role and efficiency of copper vapor lasers (CVLs) and pulsed dye lasers (PDLs) for the treatment of vascular lesions using numerical modeling and to compare results with our clinical experience. In this study we aimed to develop criteria for the choice of more efficient laser exposure mode, investigate more relevant modes of laser irradiation to ensure selective photothermolysis of target vessels, and compare the CVL and PDL efficiency in the course of patients with skin vascular lesions (SVL) treatment. Methods: We performed numerical simulation of the processes of heating a vessel with CVL and PDL to temperatures at which its coagulation could occur. Calculated fluencies were compared with clinical results of laser therapy performed on 1242 patients with skin hemangiomas and vascular malformations (SHVM), including 635 patients treated with CVL and 607 patients treated with PDL. PDL and CVL provided excellent results in 40 and ten days after treatment. The treatment was not painful. Patients did not need anesthesia. Postoperative crusts were greater with PDL than with CVL. Results: Results of computer simulation of a selective vessel heating using PDL and CVL radiation are presented. By results obtained, depth of the location and sizes of vessels that could be selectively heated to more than 75°C are determined. Conclusion: Based on calculated and clinical data, the heating mode for dysplastic vessels using a series of CVL micropulses could be regarded to be safer and more efficient than the mode of a PDL short, powerful pulse.
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AHMADI, BEHZAD, BAHAREH ZAGHARI, RASSOUL AMIRFATTAHI, and MOJTABA MANSOURI. "QUANTIFICATION OF DEPTH OF ANESTHESIA BY MEANS OF ADAPTIVE CALCULATION OF CORRELATION DIMENSION PARAMETERS." Fractals 17, no. 04 (December 2009): 473–83. http://dx.doi.org/10.1142/s0218348x09004594.
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This paper proposes an approach for quantifying Depth of Anesthesia (DOA) based on correlation dimension (D2) of electroencephalogram (EEG). The single-channel EEG data was captured in both ICU and operating room while different anesthetic drugs, including propofol and isoflurane, were used. Correlation dimension was computed using various optimized parameters in order to achieve the maximum sensitivity to anesthetic drug effects and to enable real time computation. For better analysis, application of adaptive segmentation on EEG signal for estimating DOA was evaluated and compared to fixed segmentation, too. Prediction probability (PK) was used as a measure of correlation between the predictors and BIS index to evaluate the proposed methods. Appropriate correlation between DOA and correlation dimension is achieved while choosing (D2) parameters adaptively in comparison to fixed parameters due to the nonstationary nature of EEG signal.
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Koubi, Laure, Mounir Tarek, Sanjoy Bandyopadhyay, Michael L. Klein, and Daphna Scharf. "Effects of the Nonimmobilizer Hexafluroethane on the Model Membrane Dimyristoylphosphatidylcholine." Anesthesiology 97, no. 4 (October 1, 2002): 848–55. http://dx.doi.org/10.1097/00000542-200210000-00016.
Повний текст джерелаАнотація:
Background Nonimmobilizers are agents that lack anesthetic properties, although their chemical structure is very similar to known anesthetics. The primary action site of both agents, whether at the membrane or target protein level, is still a matter of debate. However, increasing evidence points to the distinct modifications of the membrane physical properties that such agents induce. Such modification may play a role in the mechanism of anesthesia, and may therefore be related to the differences in their clinical behavior. Methods Molecular dynamics (MD) computer simulations have been used to investigate the distribution of a nonimmobilizer, hexafluroethane (HFE, C(2)F(6)), in a lipid membrane. The biologically relevant liquid-crystal phase of a hydrated dimyristoyl phosphatidyl choline (DMPC) bilayer was used as a membrane model. Two MD simulations corresponding to HFE mole fractions of 6% and 25% have been performed at room temperature and constant ambient pressure, for a duration of 2 nanoseconds each. Results The equilibrium configurations of HFE in the bilayer show that the nonimmobilizer molecules are evenly distributed along the lipid hydrocarbon chains with a slight preference for the bilayer center. This partitioning induces an expansion of the bilayer thickness and a lateral contraction of the membrane (decrease of the area per lipid). The presence of HFE has essentially no effect on the lipid acyl chain conformations in agreement with nuclear magnetic resonance (NMR) measurements of the chain order parameters. The partitioning of the nonimmobilizer does not influence the orientation of the lipid head-group dipole moment. Conclusions The modifications induced by the presence of the nonimmobilizer HFE on a model membrane are distinct from those previously found for halothane (CF(3)CHBrCl), its anesthetic analogue, and appear to result from different distributions in the lipid bilayer. The results of the MD simulations show that (1) the changes in the average area per lipid and in the membrane thickness are opposite for the two agents and (2) HFE induces no change in the lipid head-group orientation, in contrast to halothane. These different effects (1) on the physical properties of the lipid bilayer and (2) on the electrostatic properties of the membrane-water interface may be linked to different clinical effects, and thus might contribute to the mechanism of general anesthesia.
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Sandstrom, David J. "Isoflurane Reduces Excitability of Drosophila Larval Motoneurons by Activating a Hyperpolarizing Leak Conductance." Anesthesiology 108, no. 3 (March 1, 2008): 434–46. http://dx.doi.org/10.1097/aln.0b013e318164cfda.
Повний текст джерелаАнотація:
Background Mechanisms of anesthetic-mediated presynaptic inhibition are incompletely understood. Isoflurane reduces presynaptic excitability at the larval Drosophila neuromuscular junction, slowing conduction velocity and depressing glutamate release. Mutations in the Para voltage-gated Na channel enhance anesthetic sensitivity of adult flies. Here, the author examines the role of para in anesthetic sensitivity and seeks to identify the conductance underlying presynaptic inhibition at this synapse. Methods Neuromuscular transmission was studied using a two-electrode voltage clamp, with isoflurane applied in physiologic saline. The relation between ionic conductances and presynaptic function was modeled in the Neuron Simulation Environment. Motoneuron ionic currents were monitored via whole cell recordings. Results Presynaptic inhibition by isoflurane was enhanced significantly in para mutants. Computer simulations of presynaptic actions of anesthetics indicated that each candidate target conductance would have diagnostic effects on the relation between latency and amplitude of synaptic currents. The experimental latency-amplitude relation for isoflurane most closely resembled activation of a simulated hyperpolarizing leak. Simulations indicated that increased isoflurane potency in para axons resulted from reduced excitability of mutant axons. In whole cell recordings, isoflurane activated a hyperpolarizing leak current. The effects of isoflurane at the neuromuscular junction were insensitive to low pH. Conclusions The effects of isoflurane on presynaptic excitability are mediated via an acid-insensitive inhibitory leak conductance. para mutations enhance the sensitivity of this anesthetic-modulated neural pathway by reducing axonal excitability. This work provides a link between anesthetic-sensitive leak currents and presynaptic function and has generated new tools for analysis of the function of this synapse.
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Lambden, Simon, and Bruce Martin. "The Use of Computers for Perioperative Simulation in Anesthesia, Critical Care, and Pain Medicine." Anesthesiology Clinics 29, no. 3 (September 2011): 521–31. http://dx.doi.org/10.1016/j.anclin.2011.05.006.
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Yıldırım, İlknur, Ayça İ Çelik, Sema B Bay, Özge Pasin, and Ayşe Ç. Tütüncü. "Propofol-based balanced anesthesia is safer in pediatric radiotherapy." Journal of Oncology Pharmacy Practice 25, no. 8 (January 30, 2019): 1891–96. http://dx.doi.org/10.1177/1078155218825296.
Повний текст джерелаАнотація:
Backround and purpose To investigate the incidence of complications related to propofol-based anesthesia and the factors associated with complications in children with radiotherapy. Materials and methods Patients who underwent anesthesia for external beam radiotherapy between May 2013 and November 2017 were included in the study. We assessed the age/weight, sex, oncologic diagnosis, type of radiotherapy procedure, duration of anesthesia, applied agents, and complications related to anesthesia. Complications were evaluated between group I (only propofol group) and group II (propofol plus adjuvant drugs) as respiratory and cardiac. Results In 130 patients, sedation was given for 1376 radiotherapy procedures. Of these, 1274 (1140 radiation treatment sessions and 134 computed tomography simulations) in 126 patients were propofol-based and were included in the analysis. Although respiratory complications are the most common in both groups, there were no episodes of laryngospasm, broncospasm, and no use of advanced airway intervention. The rate of complication was significantly higher in only propofol anesthesia group than in patients treated with propofol plus adjuvant drugs. In the multivariate analysis, we found three factors that were significantly associated with the risk of complications: total dose of propofol (mg/kg) (p < 0.001), anesthesia with propofol alone (as compared to propofol plus adjunct agents) (p = 0.001), and diagnosis of neuroblastoma (as compared to other diagnosis) (p = 0.043). Conclusion Propofol-based anesthesia is preferred in order to minimize the rate of complications in radiotherapy anesthesia applications. The use of non-opioid adjuvants in combination with propofol to achieve a balanced anesthesia will also reduce the complications that may be encountered.
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Vermeulen, P. M., J. G. C. Lerou, R. Dirksen, L. H. D. J. Booij, and G. F. Borm. "A System Model for Halothane Closed-Circuit Anesthesia." Anesthesiology 83, no. 3 (September 1, 1995): 515–27. http://dx.doi.org/10.1097/00000542-199509000-00010.
Повний текст джерелаАнотація:
Background Previously, the authors described a physiologic model for closed-circuit inhalational anesthesia. The basic version of this system model was clinically validated for isoflurane. An extended version adopted nonpulmonary elimination causing a constant fraction of anesthetic to be irreversibly lost. This version improved the accuracy of the model for enflurane. The model's performance for other inhalational anesthetics that are not biochemically inert, such as halothane, remained to be evaluated. Methods The current study quantified the predictive performance of four versions of the model by comparison of the predicted and measured alveolar halothane concentration-time profiles in 53 patients. Version A did not incorporate nonpulmonary elimination, whereas version D adopted a nonlinear hepatic nonpulmonary elimination following Michaelis-Menten kinetics. A and D used fixed partition coefficients. Their counterparts, A' and D', were formulated to examine the impact of age-adjusted partition coefficients on the accuracy of our model. Each concentration measured by mass spectrometry was compared to four predicted concentrations calculated by four computer simulations (one per version). For each patient, the authors calculated the root mean squared error (rmse; typical error size), bias (systematic component), and scatter of the prediction errors. Results Fifty-three patients were anesthetized with 330 ml of liquid halothane via 426 bolus injections during more than 61 h; 21,890 alveolar concentrations (average 0.6 vol%) were measured. Version D' showed the best overall performance with an rmse of 19.6 +/- 7.2%, a bias of 0.5 +/- 15.9%, and a scatter of 13.2 +/- 3.5% (mean +/- SD). Conclusions The model incorporating nonpulmonary elimination and age-adjusted partition coefficients (D') is sufficiently reliable and accurate to represent halothane closed-circuit anesthesia. This system model, with its various versions, is a valuable tool to predict the dynamics of isoflurane, enflurane, and halothane for clinical, educational, and research purposes.
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Wei, Yueguang, Jianxun Liu, and Xuhai Gong. "Painless Gastrointestinal Endoscopy Assisted with Computed Tomography Image Information Data Monitoring in Postoperative Neurocognitive Dysfunction in Patients with Combined Anesthesia of Propofol and Butorphanol Tartrate under Electronic Health." Computational and Mathematical Methods in Medicine 2022 (June 20, 2022): 1–8. http://dx.doi.org/10.1155/2022/7086472.
Повний текст джерелаАнотація:
The aim of this study was to explore the value of computed tomography (CT) images based on electronic health (E-health) combined with painless gastrointestinal endoscopy (PGE) in the diagnosis of neurocognitive function in patients with combined anesthesia of propofol and butorphanol tartrate. 126 patients undergoing PGE were selected as the research objects, and all were performed with CT perfusion imaging before and after anesthesia to obtain the cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP). The Montreal Cognitive Assessment (MoCA) was adopted to evaluate the cognitive function of patients. The results showed that after anesthesia, the levels of CBF and CBV in the left and right thalami, frontal lobe, and temporal lobe of the patients were lower than those before anesthesia, while TTP and MTT were higher than those before anesthesia ( P < 0.05 ). The MoCA score after anesthesia was lower than that before anesthesia ( P < 0.05 ). After anesthesia, the CBF, CBV, TTP, and MTT values of the left and right frontal lobes and left and right temporal lobes were significantly positively correlated with MoCA ( P < 0.05 ). In conclusion, the brain CT image parameters based on E-health can clearly display the blood perfusion in the lesion area of the patient, which was beneficial to the PGE-assisted judgment of cognitive dysfunction in patients with propofol tartrate and butorphanol tartrate anesthesia. Therefore, CT-assisted PGE examination based on E-health had a certain clinical value in evaluating the neurocognitive function of patients.
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Sneyd, J. Robert, Chao Dong, Christopher D. Reeve, and Emmanuel C. Ifeachor. "Using Simulations in the Design of an Anesthesia System." Simulation & Gaming 32, no. 2 (June 2001): 205–14. http://dx.doi.org/10.1177/104687810103200208.
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Dexter, Franklin, and John H. Tinker. "Analysis of Strategies to Decrease Postanesthesia Care Unit Costs." Anesthesiology 82, no. 1 (January 1, 1995): 94–101. http://dx.doi.org/10.1097/00000542-199501000-00013.
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Background The goal of this study was to identify interventions that anesthesiologists can make to decrease total costs of a postanesthesia care unit (PACU). Methods Data were collected retrospectively from patients who underwent ambulatory surgery at our tertiary care center. Results Supplies and medications accounted for only 2% of PACU charges. Personnel costs, which depend on the peak number of patients in the PACU, accounted for almost all PACU costs. If nausea and vomiting could have been eliminated in each patient who suffered this complication, without causing sedation, the total time to discharge for all patients would have been decreased by less than 4.8% (95% confidence interval < 7.3%). Arrival rates to and times to discharge from the PACU followed triangular and log-normal distributions, respectively. Computer simulations, using published times to discharge for drugs with "faster recovery," such as propofol, showed that the use of these drugs would only decrease PACU costs if operating rooms were consistently scheduled to run later each day. Such earlier discharge also might be beneficial if used at night, but only if the PACU could close after a single patient leaves. However, reasonably achievable decreases in the times to discharge for all patients undergoing general anesthesia are unlikely to substantively decrease PACU costs. In contrast, arranging an operating room schedule to optimize admission rates would greatly affect the number of PACU nurses needed. Conclusions Anesthesiologists have little control over PACU economics via choice of anesthetic drugs. The major determinant of PACU costs is the distribution of admissions.
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Tian, Pinghua, Shuhong Zhang, and Linling Guo. "Reconstruction Algorithm-Based Ultrasonic and Spiral CT Images in Evaluating the Effects of Dexmedetomidine Anesthesia for Acute Abdomen." Computational and Mathematical Methods in Medicine 2021 (December 28, 2021): 1–10. http://dx.doi.org/10.1155/2021/3712701.
Повний текст джерелаАнотація:
Objective. The study focused on the application value of iteration reconstruction algorithm-based ultrasound and spiral computed tomography (CT) examinations, and the safety of dexmedetomidine anesthesia in acute abdominal surgery. Methods. 80 cases having the acute abdomen surgery were selected as the research subjects. They were divided into group A (40 cases) and group B (40 cases) according to the anesthetic drugs used in the later period. The experimental group was injected with propofol, remifentanil, and atracurium combined with dexmedetomidine; the control group was injected with propofol, remifentanil, and atracurium only. After the operation, the patient was for observed for the pain, agitation, adverse reactions, heart rate (HR), and blood pressure. All patients received ultrasound and spiral CT examinations, and based on the characteristics of the back-projection algorithm, an accelerated algorithm was established and used to process the image, and according to which, the patient’s condition and curative effects were evaluated. Results. After image reconstruction, the ultrasound and spiral CT images were clearer with less noise and more prominent lesions than before reconstruction. Before image reconstruction, the accuracy rates of ultrasound and spiral CT in diagnosing acute abdomen were 92.3% and 91.1%, respectively. After reconstruction, the corresponding numbers were 96.3% and 98.1%, respectively. After reconstruction, the accuracy of the two methods in diagnosing acute abdomen was significantly improved compared with that before reconstruction, and the difference was statistically significant ( P < 0.05 ). The Ramsay score of the experimental group was significantly higher than that of the control group at each time period, P < 0.05 ; the agitation score and visual analogue scale (VAS) score of the experimental group were significantly lower than the control group at each time period after waking up, P < 0.05 . Conclusion. Reconstruction algorithm-based ultrasound and spiral CT images have high application value in the diagnosis of patients with acute abdomen, and dexmedetomidine has good safety in anesthesia surgery.
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Navarro-Guerrero, Gerardo, and Yu Tang. "Fractional-Order Closed-Loop Model Reference Adaptive Control for Anesthesia." Algorithms 11, no. 7 (July 14, 2018): 106. http://dx.doi.org/10.3390/a11070106.
Повний текст джерелаАнотація:
The design of a fractional-order closed-loop model reference adaptive control (FOCMRAC) for anesthesia based on a fractional-order model (FOM) is proposed in the paper. This proposed model gets around many difficulties, namely, unknown parameters, lack of state measurement, inter and intra-patient variability, and variable time-delay, encountered in controller designs based on the PK/PD model commonly used for control of anesthesia, and allows to design a simple adaptive controller based on the Lyapunov analysis. Simulations illustrate the effectiveness and robustness of the proposed control.
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Ljubenovic, Arsène, Sadiq Said, Julia Braun, Bastian Grande, Michaela Kolbe, Donat R. Spahn, Christoph B. Nöthiger, David W. Tscholl, and Tadzio R. Roche. "Visual Attention of Anesthesia Providers in Simulated Anesthesia Emergencies Using Conventional Number-Based and Avatar-Based Patient Monitoring: Prospective Eye-Tracking Study." JMIR Serious Games 10, no. 1 (March 22, 2022): e35642. http://dx.doi.org/10.2196/35642.
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Background Inadequate situational awareness accounts for two-thirds of preventable complications in anesthesia. An essential tool for situational awareness in the perioperative setting is the patient monitor. However, the conventional monitor has several weaknesses. Avatar-based patient monitoring may address these shortcomings and promote situation awareness, a prerequisite for good decision making. Objective The spatial distribution of visual attention is a fundamental process for achieving adequate situation awareness and thus a potential quantifiable surrogate for situation awareness. Moreover, measuring visual attention with a head-mounted eye-tracker may provide insights into usage and acceptance of the new avatar-based patient monitoring modality. Methods This prospective eye-tracking study compared anesthesia providers' visual attention on conventional and avatar-based patient monitors during simulated critical anesthesia events. We defined visual attention, measured as fixation count and dwell time, as our primary outcome. We correlated visual attention with the potential confounders: performance in managing simulated critical anesthesia events (task performance), work experience, and profession. We used mixed linear models to analyze the results. Results Fifty-two teams performed 156 simulations. After a manual quality check of the eye-tracking footage, we excluded 57 simulations due to technical problems and quality issues. Participants had a median of 198 (IQR 92.5-317.5) fixations on the patient monitor with a median dwell time of 30.2 (IQR 14.9-51.3) seconds. We found no significant difference in participants' visual attention when using avatar-based patient monitoring or conventional patient monitoring. However, we found that with each percentage point of better task performance, the number of fixations decreased by about 1.39 (coefficient –1.39; 95% CI –2.44 to –0.34; P=.02), and the dwell time diminished by 0.23 seconds (coefficient –0.23; 95% CI: –0.4 to –0.06; P=.01). Conclusions Using eye tracking, we found no significant difference in visual attention when anesthesia providers used avatar-based monitoring or conventional patient monitoring in simulated critical anesthesia events. However, we identified visual attention in conjunction with task performance as a surrogate for situational awareness.
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Wada, D. Russell, Sven Bjorkman, William F. Ebling, Hideyoshi Harashima, Sandra R. Harapat, and Donald R. Stanski. "Computer Simulation of the Effects of Alterations in Blood Flows and Body Composition on Thiopental Pharmacokinetics in Humans." Anesthesiology 87, no. 4 (October 1, 1997): 884–99. http://dx.doi.org/10.1097/00000542-199710000-00024.
Повний текст джерелаАнотація:
Background Understanding the influence of physiological variables on thiopental pharmacokinetics would enhance the scientific basis for the clinical usage of this anesthetic. Methods A physiological pharmacokinetic model for thiopental previously developed in rats was scaled to humans by substituting human values for tissue blood flows, tissue masses, and elimination clearance in place of respective rat values. The model was validated with published serum concentration data from 64 subjects. The model was simulated after intravenous thiopental administration, 250 mg, over 1 min, to predict arterial plasma concentrations under conditions of different cardiac outputs, degrees of obesity, gender, or age. Results The human pharmacokinetic model is characterized by a steady state volume of distribution of 2.2 l/kg, an elimination clearance of 0.22 l/min, and a terminal half-life of 9 h. Measured thiopental concentrations are predicted with an accuracy of 6 +/- 37% (SD). Greater peak arterial concentrations are predicted in subjects with a low versus a high cardiac output (3.1 and 9.4 l/min), and in subjects who are lean versus obese (56 and 135 kg). Acutely, obesity influences concentrations because it affects cardiac output. Prolonged changes are due to differences in fat mass. Changes with gender and age are relatively minor. Conclusions The physiological pharmacokinetic model developed in rats predicts thiopental pharmacokinetics in humans. Differences in basal cardiac output may explain much of the variability in early thiopental disposition between subjects.
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Versichelen, Linda F. M., Georges Rolly, Marie-Paule L. A. Bouche, Jan F. P. Van Bocxlaer, Michel M. R. F. Struys, Catherine Van der herten, André P. De Leenheer, and Eric P. Mortier. "In Vitro Compound A Formation in a Computer-controlled Closed-circuit Anesthetic Apparatus." Anesthesiology 93, no. 4 (October 1, 2000): 1064–68. http://dx.doi.org/10.1097/00000542-200010000-00030.
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Background Few data exist on compound A during sevoflurane anesthesia when using closed-circuit conditions and sodalime with modern computer-controlled liquid injection. Methods A PhysioFlex apparatus (Dräger, Lübeck, Germany) was connected to an artificial test lung (inflow approximately 160 ml/min carbon dioxide, outflow approximately 200 ml/min, simulating oxygen consumption). Ventilation was set to obtain an end-tidal carbon dioxide partial pressure (Petco2) approximately 40 mmHg. Canister inflow (T degrees in) and outflow (T degrees out) temperatures were measured. Fresh sodalime and charcoal were used. After baseline analysis, sevoflurane concentration was set at 2.1% end-tidal for 120 min. At baseline and at regular intervals thereafter, Petco2, end-tidal sevoflurane, T degrees in, and T degrees out were measured. For inspiratory and expiratory compound A determination, samples of 2-ml gas were taken. These data were compared with those of a classical valve-containing closed-circuit machine. Ten runs were performed in each set-up. Results Inspired compound A concentrations increased from undetectable to peak at 6.0 (SD 1.3) and 14.3 (SD 2.5) ppm (P < 0.05), and maximal temperature in the upper outflow part of the absorbent canister was 24.3 degrees C (SD 3.6) and 39.8 degrees C (SD 1.2) (P < 0.05) in the PhysioFlex and valve circuit machines, respectively. Differences between the two machines in compound A concentrations and absorbent canister temperature at the inflow and outflow regions were significantly different (P < 0.05) at all times after 5 min. Conclusion Compound A concentrations in the high-flow (70 l/min), closed-circuit PhysioFlex machine were significantly lower than in conventional, valve-based machines during closed-circuit conditions. Lower absorbent temperatures, resulting from the high flow, appear to account for the lower compound A formation.
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Lécuyer, Anatole. "Simulating Haptic Feedback Using Vision: A Survey of Research and Applications of Pseudo-Haptic Feedback." Presence: Teleoperators and Virtual Environments 18, no. 1 (February 1, 2009): 39–53. http://dx.doi.org/10.1162/pres.18.1.39.
Повний текст джерелаАнотація:
This paper presents a survey of the main results obtained in the field of “pseudo-haptic feedback”: a technique meant to simulate haptic sensations in virtual environments using visual feedback and properties of human visuo-haptic perception. Pseudo-haptic feedback uses vision to distort haptic perception and verges on haptic illusions. Pseudo-haptic feedback has been used to simulate various haptic properties such as the stiffness of a virtual spring, the texture of an image, or the mass of a virtual object. This paper describes the several experiments in which these haptic properties were simulated. It assesses the definition and the properties of pseudo-haptic feedback. It also describes several virtual reality applications in which pseudo-haptic feedback has been successfully implemented, such as a virtual environment for vocational training of milling machine operations, or a medical simulator for training in regional anesthesia procedures.
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Sultanova, N. N., and M. S. Alieva. "Orbital proportion indices and microlipografting for correction of secondary post-traumatic enophthalmos." Kazan medical journal 101, no. 1 (February 11, 2020): 139–44. http://dx.doi.org/10.17816/kmj2020-139.
Повний текст джерелаАнотація:
Aim. Aesthetic rehabilitation of patients with secondary post-traumatic enophthalmos.
Methods. From 2013 to 2018, 14 patients with secondary post-traumatic enophthalmos were treated at the maxillofacial surgery clinic of the Azerbaijan Medical University. All patients underwent reconstruction of the damaged orbital wall, so its bone volume was restored. However, in the postoperative period, a deficiency of the orbital soft tissue was noted. In preparation for the surgery, all patients underwent the following types of examination: three-dimensional computed tomography, photographic, anthropometric measurements with the determination of proportional indices and computer simulation. Based on the data obtained, the orbital proportion indices were calculated: intercanthal index (en-en)100/(ex-ex); orbital protrusion index (ex-ex)100/(ex-en,rl)+(en-en); orbital width index (ex-en,l)100/(en-en); eye fissure (palpebral) index (ps-pi, l)100/(ex-en,l); orbital index (os-or,l)100/(ex-en,l); eyebrow orbital height index (os-or,l)100/(sci-or,l); index of vertical orbital contour (os-or,l)100/(ps-os+pi-or)+(ps-pi); eyelid height index (pi-or,l)100/(ps-os,l). Microlipografting was performed according to the Coleman method with modification by T. Marten. Fat aspiration was performed with a blunt cannula with a diameter of 2.12.4 mm and a 10 ml syringe, without anesthetic administration. Prior to microlipografting, fibrotic cords between the skin and underlying tissues were dissected using a sharp needle and a V-shaped cannula. Microlipografting was performed using microcannulas of 0.71.1 mm. The fat microtransplant was introduced in two layers: under the circular muscle of the eye and subperiostally in the orbit.
Results. In 11 cases, with an unexpressed form of secondary post-traumatic enophthalmos, a good aesthetic result was recorded. In 3 patients with a pronounced form of enophthalmos, a satisfactory aesthetic result was obtained; in these cases, repeated microlipografting was carried out.
Conclusion. Microlipografting based on the calculation of the orbit proportions indices during rehabilitation of patients with secondary post-traumatic enophthalmos is a minimally invasive and effective procedure.
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I. Bon, Lizaveta, and Maksimovich N.Yе. "Neurological Deficit and Corrective Effect of Omega-3 Polyunsaturated Fatty Acids in Cerebral Ischemia in Rats: A case-control study." Biotechnology and Bioprocessing 2, no. 8 (October 28, 2021): 01–06. http://dx.doi.org/10.31579/2766-2314/050.
Повний текст джерелаАнотація:
Objectives: It was to assess vasoprotective effects of ω-3 polyunsaturated fatty acids in cerebral ischemia. Materials and methods: The experiments were carried out on 42 male outbred white rats weighing 260 ± 20 g. modeling of cerebral ischemia was carried out under conditions of intravenous thiopental anesthesia (40-50 mg / kg). The studies used models of subtotal, partial and stepwise subtotal cerebral ischemia. The table shows the experimental groups and the number of animals in them. Subtotal cerebral ischemia (SCI) was modeled by simultaneous ligation of both common carotid arteries (CCA). Partial cerebral ischemia (PCI) was modeled by ligating one CCA on the right. Stepwise subtotal CI (SSCI) was performed by sequential ligation of both CCA with an interval of 1 day (subgroup 1), 3 days (subgroup 2), or 7 days (subgroup 3). To study the effects of omega-3 polyunsaturated fatty acids (ω-3 PUFA), animals with CI were injected intragastrically with the drug "Omegamed" (SCI+ω-3 PUFA) at a dose of 5 g / kg body weight for a week. The control group consisted of sham-operated rats of the same sex and weight. Neurological deficits were assessed in the "muscle strength", "swimming test" and "open field" tests after 5-6 hours of the ischemic period. The study was carried out 6 hours after the simulation of the CI. Quantitative continuous data were obtained, which were processed using the licensed computer program Statistica 10.0 for Windows (StatSoft, Inc., USA). Since the experiment used small samples that had an abnormal distribution, the analysis was carried out by methods of nonparametric statistics. Data are presented as Me (LQ; UQ), where Me is the median, LQ is the value of the lower quartile; UQ is the upper quartile value. Differences between groups were considered significant at p <0.05 (Regression Model). Results: With a stepwise bilateral ligation of both common carotid arteries with an interval of 1 day, neurological disorders were most pronounced, which indicates an aggravation of neurological deficit with a reduction in the time between CCA dressings. In rats with SCI, the changes were more pronounced than with PCI, but less than with SCI. The least pronounced changes were noted in the 3rd subgroup (the interval between CCA dressings was 7 days). Studies have shown the dependence of the severity of brain damage in SSCI on the interval between the cessation of blood flow in both CCA. At a 7-day interval between CCA dressings, compensatory mechanisms were activated, which prevented the development of morphological changes and neurological deficits. When CCA was ligated with an interval of 1 day, the degree of neurological deficit was maximal, which indicates insufficient implementation of compensatory mechanisms. Compared with the control group, the rats of the "SCI+ω3-PUFA" group retained neurological deficit, the muscle strength indicator was 86% less (p<0.05), the swimming duration - by 63% (p<0.05), the number of crossed squares - by 55% (p<0.05), the number of washes - by 62% (p<0.05), the number of racks - by 62.5% (p<0.05) and the number of bowel movements - by 60% (p<0.05). However, in comparison with the SCI group, the neurological deficit was less pronounced. There was an increase in muscle strength by 67% (p<0.05), swimming duration by 37.5% (p<0.05) and the number of squares crossed in the open field test by 31% (p<0.05), which indicates the presence of a corrective action in the ω-3 polyunsaturated fatty acids preparation. Conclusion: The introduction of the preparation of ω-3 polyunsaturated fatty acids has a corrective effect in conditions of subtotal cerebral ischemia, contributing to a lesser severity of manifestations of neurological deficit (an increase in muscle strength, duration of swimming and the number of squares crossed in the open field test).
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Yang, Elaine, Daniele Granata, Roderic G. Eckenhoff, Vincenzo Carnevale, and Manuel Covarrubias. "Propofol inhibits prokaryotic voltage-gated Na+ channels by promoting activation-coupled inactivation." Journal of General Physiology 150, no. 9 (July 17, 2018): 1299–316. http://dx.doi.org/10.1085/jgp.201711924.
Повний текст джерелаАнотація:
Propofol is widely used in the clinic for the induction and maintenance of general anesthesia. As with most general anesthetics, however, our understanding of its mechanism of action remains incomplete. Local and general anesthetics largely inhibit voltage-gated Na+ channels (Navs) by inducing an apparent stabilization of the inactivated state, associated in some instances with pore block. To determine the biophysical and molecular basis of propofol action in Navs, we investigated NaChBac and NavMs, two prokaryotic Navs with distinct voltage dependencies and gating kinetics, by whole-cell patch clamp electrophysiology in the absence and presence of propofol at clinically relevant concentrations (2–10 µM). In both Navs, propofol induced a hyperpolarizing shift of the pre-pulse inactivation curve without any significant effects on recovery from inactivation at strongly hyperpolarized voltages, demonstrating that propofol does not stabilize the inactivated state. Moreover, there was no evidence of fast or slow pore block by propofol in a non-inactivating NaChBac mutant (T220A). Propofol also induced hyperpolarizing shifts of the conductance-voltage relationships with negligible effects on the time constants of deactivation at hyperpolarized voltages, indicating that propofol does not stabilize the open state. Instead, propofol decreases the time constants of macroscopic activation and inactivation. Adopting a kinetic scheme of Nav gating that assumes preferential closed-state recovery from inactivation, a 1.7-fold acceleration of the rate constant of activation and a 1.4-fold acceleration of the rate constant of inactivation were sufficient to reproduce experimental observations with computer simulations. In addition, molecular dynamics simulations and molecular docking suggest that propofol binding involves interactions with gating machinery in the S4–S5 linker and external pore regions. Our findings show that propofol is primarily a positive gating modulator of prokaryotic Navs, which ultimately inhibits the channels by promoting activation-coupled inactivation.
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Hirota, Koki, Junko Fujimura, Masahiro Wakasugi, and Yusuke Ito. "Isoflurane and Sevoflurane Modulate Inactivation Kinetics of Calcium sup 2+ Currents in Single Bullfrog Atrial Myocytes." Anesthesiology 84, no. 2 (February 1, 1996): 377–83. http://dx.doi.org/10.1097/00000542-199602000-00016.
Повний текст джерелаАнотація:
Background To clarify the mechanism(s) of anesthetic depression of myocardial Ca2+ currents, the effects of isoflurane and sevoflurane on the inactivation kinetics of Ca2+ current in single bullfrog atrial myocytes were studied. Methods Freshly isolated bullfrog atrial myocytes were obtained with an enzymatic dispersion procedure. Ca2+ currents were recorded with a whole-cell voltage-clamp technique. Results Both isoflurane (1.25, 2.5, 5.0 vol%) and sevoflurane (2.5, 5.0 vol%) decreased the peak amplitude of Ca2+ current ICa with a minimal change in the time to peak and the reversal potential. The inactivation kinetics studies revealed that (1) isoflurane (2.5 vol%) and sevoflurane (5.0 vol%) markedly reduced the time constant of inactivation in ICa to 55% and 75% of control, respectively; (2) isoflurane (2.5 vol%) shifted the midpoint (V1/2) of steady-state inactivation curve of ICa toward negative by 2.3 mV; and (3) isoflurane (2.5 vol%) delayed the reactivation time constant of ICa to 119% of control. The further computer-simulation study demonstrated that the observed decrease of time constant by isoflurane (1.25, 2.5 vol%) and sevoflurane (2.5 vol%) can explain the reduction in amplitude of ICa. Conclusions The depression of ICa by lower concentration of isoflurane (1.25, 2.5 vol%) and sevoflurane (2.5 vol%) mainly is due to the decrease of time constant and, at higher concentration, isoflurane and sevoflurane may affect the other membrane components.
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Fuentealba, Pablo, Igor Timofeev, Maxim Bazhenov, Terrence J. Sejnowski, and Mircea Steriade. "Membrane Bistability in Thalamic Reticular Neurons During Spindle Oscillations." Journal of Neurophysiology 93, no. 1 (January 2005): 294–304. http://dx.doi.org/10.1152/jn.00552.2004.
Повний текст джерелаАнотація:
The thalamic reticular (RE) nucleus is a major source of inhibition in the thalamus. It plays a crucial role in regulating the excitability of thalamocortical networks and in generating some sleep rhythms. Current-clamp intracellular recordings of RE neurons in cats under barbiturate anesthesia revealed the presence of membrane bistability in ∼20% of neurons. Bistability consisted of two alternate membrane potentials, separated by ∼17–20 mV. While non-bistable (common) RE neurons fired rhythmic spike-bursts during spindles, bistable RE neurons fired tonically, with burst modulation, throughout spindle sequences. Bistability was strongly voltage dependent and only expressed under resting conditions (i.e. no current injection). The transition from the silent to the active state was a regenerative event that could be activated by brief depolarization, whereas brief hyperpolarizations could switch the membrane potential from the active to the silent state. These effects outlasted the current pulses. Corticothalamic stimulation could also switch the membrane potential from silent to active states. Addition of QX-314 in the recording micropipette either abolished or disrupted membrane bistability, suggesting INa(p) to be responsible for its generation. Thalamocortical cells presented various patterns of spindling that reflected the membrane bistability in RE neurons. Finally, experimental data and computer simulations predicted a role for RE neurons' membrane bistability in inducing various patterns of spindling in target thalamocortical cells. We conclude that membrane bistability of RE neurons is an intrinsic property, likely generated by INa(p) and modulated by cortical influences, as well as a factor that determines different patterns of spindle rhythms in thalamocortical neurons.
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Zanderigo, Eleonora, Valentina Sartori, Gorazd Sveticic, Thomas Bouillon, Peter Schumacher, Manfred Morari, and Michele Curatolo. "The Well-being Model." Anesthesiology 104, no. 4 (April 1, 2006): 742–53. http://dx.doi.org/10.1097/00000542-200604000-00019.
Повний текст джерелаАнотація:
Background Drugs are routinely combined in anesthesia and pain management to obtain an enhancement of the desired effects. However, a parallel enhancement of the undesired effects might take place as well, resulting in a limited therapeutic usefulness. Therefore, when addressing the question of optimal drug combinations, side effects must be taken into account. Methods By extension of a previously published interaction model, the authors propose a method to study drug interactions considering also their side effects. A general outcome parameter identified as patient's well-being is defined by superposition of positive and negative effects. Well-being response surfaces are computed and analyzed for varying drugs pharmacodynamics and interaction types. In particular, the existence of multiple maxima and of optimal drug combinations is investigated for the combination of two drugs. Results Both drug pharmacodynamics and interaction type affect the well-being surface and the deriving optimal combinations. The effect of the interaction parameters can be explained in terms of synergy and antagonism and remains unchanged for varying pharmacodynamics. For all simulations performed for the combination of two drugs, the presence of more than one maximum was never observed. Conclusions The model is consistent with clinical knowledge and supports previously published experimental results on optimal drug combinations. This new framework improves understanding of the characteristics of drug combinations used in clinical practice and can be used in clinical research to identify optimal drug dosing.
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Mikuni, Ikuomi, Carlos G. Torres, Tania Bakshi, Akihito Tampo, Brian E. Carlson, Martin W. Bienengraeber, and Wai-Meng Kwok. "Enhanced Effects of Isoflurane on the Long QT Syndrome 1–associated A341V Mutant." Anesthesiology 122, no. 4 (April 1, 2015): 806–20. http://dx.doi.org/10.1097/aln.0000000000000583.
Повний текст джерелаАнотація:
Abstract Background: The impact of volatile anesthetics on patients with inherited long QT syndrome (LQTS) is not well understood. This is further complicated by the different genotypes underlying LQTS. No studies have reported on the direct effects of volatile anesthetics on specific LQTS-associated mutations. We investigated the effects of isoflurane on a common LQTS type 1 mutation, A341V, with an unusually severe phenotype. Methods: Whole cell potassium currents (IKs) were recorded from HEK293 and HL-1 cells transiently expressing/coexpressing wild-type KCNQ1 (α-subunit), mutant KCNQ1, wild-type KCNE1 (β-subunit), and fusion KCNQ1 + KCNE1. Current was monitored in the absence and presence of clinically relevant concentration of isoflurane (0.54 ± 0.05 mM, 1.14 vol %). Computer simulations determined the resulting impact on the cardiac action potential. Results: Isoflurane had significantly greater inhibitory effect on A341V + KCNE1 (62.2 ± 3.4%, n = 8) than on wild-type KCNQ1 + KCNE1 (40.7 ± 4.5%; n = 9) in transfected HEK293 cells. Under heterozygous conditions, isoflurane inhibited A341V + KCNQ1 + KCNE1 by 65.2 ± 3.0% (n = 13) and wild-type KCNQ1 + KCNE1 (2:1 ratio) by 32.0 ± 4.5% (n = 11). A341V exerted a dominant negative effect on IKs. Similar differential effects of isoflurane were also observed in experiments using the cardiac HL-1 cells. Mutations of the neighboring F340 residue significantly attenuated the effects of isoflurane, and fusion proteins revealed the modulatory effect of KCNE1. Action potential simulations revealed a stimulation frequency–dependent effect of A341V. Conclusions: The LQTS-associated A341V mutation rendered the IKs channel more sensitive to the inhibitory effects of isoflurane compared to wild-type IKs in transfected cell lines; F340 is a key residue for anesthetic action.
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Dolgalev, A., I. Rzhepakovsky, A. Danaev, V. Avanisyan, G. Shulga, and A. Korobkeev. "RESULTS of MORPHOLOGICAL ANALYSIS of ANIMAL HARD TISSUES IN NORMAL AND SIMULATED OSTEOPOROSIS USING A NON-INVASIVE COMPUTED MICROTOMOGRAPHY TECHNIQUE." International journal of Innovative Medicine, no. 2 (September 8, 2022): 17–21. http://dx.doi.org/10.33667/2782-4101-2022-2-17-21.
Повний текст джерелаАнотація:
Introduction. X-ray microtomography is a non-destructive method of microstructural analysis, which has a high level of detail and allows the possibility of assessing the internal architecture of organs and tissues using 3D-analysis[1]. The specifics of working with such equipment can be divided into in vivo and in vitro, i.e. working with live laboratory animals (mice, rats, rabbits) under anesthesia or studying organs and tissues separated from the animal [2].The aim of the work was to study the microstructure of sheep bone tissues in normal and simulated osteoporosis using computed microtomography.Materials and methods. We performed microCT analysis of different sheep bones in normal and experimental osteoporosis. Bone tissue of the jaw, iliac and femur, and teeth were collected from control and experimental animals. Bone tissue samples were fixed in 10% buffered formalin. X-ray microCT scanner Skyscan 1176 (BrukermicroCT, Belgium) and software Skyscan 1176 control program (10.0.0.0), Nrecon (1.7.4.2), DataViewer (1.5.6.2), CT-analyser (1.18.4.0), CTvox (3.3.0r1403) were used to scan and process materials.Results. MicroCT examination and 3D-imaging confirmed the elimination of trabeculae in the metaphyseal region of the femur in sheep with experimental osteoporosis from the centre to the periphery; in addition, 3D-analysis showed a 15.1% decrease in bone percentage, a 7.8% decrease in bone mineral density, and an increase in Tb. Sp. (trabecular separation), Tb. Pf. (trabecular pattern factor) and SMI (structure model index) by 30.2%, 20.8% and 23.6%, respectively, and a decrease in Tb.N. (trabecular number) index by 18.6%, indicating calcium washout, decreased trabecular connectivity and a transition from a lamellar to a rod-like architecture. Similar changes were found in the 3D-analysis of the jaw bone tissue. Thus, a decrease of 18.9% in mineral density was found, as well as a significant increase of 11.58 and 2.21 in the indices, particularly Tb. Pf. and SMI. 3D-analysis of iliac microtomography also indicates a simulation of osteoporosis, as evidenced by a significant increase in the main indices characterising the development of this pathology.Conclusions. The obtained results not only objectively testify to the development of osteoporosis in the experimental animals, but also indicate signs of the adaptation-compensatory reactions of the body, characterized by appearance of large single trabeculae in the metaphysis of the femur as well as by not expressed reduction of bone mineral density and bone tissue area.
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Short, Timothy G., Tam Yuk Ho, Charles F. Minto, Thomas W. Schnider, and Steven L. Shafer. "Efficient Trial Design for Eliciting a Pharmacokinetic– Pharmacodynamic Model–based Response Surface Describing the Interaction between Two Intravenous Anesthetic Drugs." Anesthesiology 96, no. 2 (February 1, 2002): 400–408. http://dx.doi.org/10.1097/00000542-200202000-00027.
Повний текст джерелаАнотація:
Background The authors published a pharmacokinetic- pharmacodynamic model for two drugs based on response surface methodology. Because of the complexity of the model, they performed a simulation study to answer two questions about use of the model: (1) which study design would be most satisfactory; and (2) how many patients would need to be studied to adequately describe an entire response surface. Methods Data were simulated using realistic variability for two hypothetical intravenous anesthetic drugs that interact synergistically and that could be given by computer-controlled infusion. Three trial designs were simulated, one that made a series of parallel slices of the response surface, one that crisscrossed the response surface, and one that made a series of radial slices across the surface. Series of 5, 10, 20, and 40 "subjects" were simulated. A pooled data approach was used to assess the ability of the various trial designs and numbers of subjects to adequately identify the interaction response surface and estimate the original response surface. Results The crisscross design was shown to be the most robust in terms of its ability to both discriminate the correct order of the interaction term and to discriminate the original response surface using the least number of patients. Twenty subjects would be required to adequately define a surface using the crisscross study design, and 40 subjects would be required using the other trial designs. Conclusions The results showed that a number of trial designs would be viable, but a design that crossed the surface in a crisscross fashion would give the most robust result with the least patients.
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Gan, T. J., P. S. A. Glass, S. T. Howell, A. T. Canada, A. P. Grant, and B. Ginsberg. "Determination of Plasma Concentrations of Propofol Associated with 50% Reduction in Postoperative Nausea." Anesthesiology 87, no. 4 (October 1, 1997): 779–84. http://dx.doi.org/10.1097/00000542-199710000-00010.
Повний текст джерелаАнотація:
Background Subhypnotic doses of propofol possess direct antiemetic properties. The authors sought to determine the plasma concentration of propofol needed to effectively manage postoperative nausea and vomiting. Methods Patients aged 18-70 yr who were classified as American Society of Anesthesiologists physical status 1 or 2 and had surgery during general anesthesia were approached for the study. Only patients who had nausea (verbal rating score > 5 on a 0- to 10-point scale), retching, or vomiting in the postanesthetic care unit participated. Propofol was administered to these patients to achieve target plasma concentrations of 100, 200, 400, and 800 ng/ml using a computer-assisted continuous infusion device. Target concentrations were increased every 15 min until patients described at least a 50% reduction in symptoms on the verbal rating score. An arterial blood sample was obtained at each step. The measured plasma propofol concentrations were used to analyze data. Blood pressure, heart and respiratory rates, arterial blood saturation, sedation score, and overall satisfaction with treatment were recorded. Results Of the 89 patients who consented to the study, 15 patients met entry criteria and were enrolled. Five of these patients also had retching or vomiting when they entered the study. Fourteen patients responded successfully to treatment. One patient did not achieve the required response at plasma concentrations of 830 ng/ml. Hence the success rate for the treatment of postoperative nausea and vomiting was 93%. Among patients who responded, the median plasma concentration associated with an antiemetic response was 343 ng/ml. There was no difference in sedation scores from baseline and no episodes of desaturation. Hemodynamic parameters were stable during the study. Conclusions Propofol is generally efficacious in treating postoperative nausea and vomiting at plasma concentrations that do not produce increased sedation. Simulations indicate that to achieve antiemetic plasma propofol concentrations of 343 ng/ml, a bolus dose of 10 mg followed by an infusion of approximately 10 microg x kg(-1) x min(-1) are necessary.
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Chon, Deokiee, Kenneth C. Beck, Brett A. Simon, Hidenori Shikata, Osama I. Saba, and Eric A. Hoffman. "Effect of low-xenon and krypton supplementation on signal/noise of regional CT-based ventilation measurements." Journal of Applied Physiology 102, no. 4 (April 2007): 1535–44. http://dx.doi.org/10.1152/japplphysiol.01235.2005.
Повний текст джерелаАнотація:
Xenon computed tomography (Xe-CT) is used to estimate regional ventilation by measuring regional attenuation changes over multiple breaths while rebreathing a constant Xe concentration ([Xe]). Xe-CT has potential human applications, although anesthetic properties limit [Xe] to ≤35%. We investigate effects of lower [Xe], including a low [Xe]-krypton (Kr) combination, on time constant (TC) determination. Six anesthetized sheep were scanned prone and supine using multidetector row CT. Lungs were imaged by respiratory gating during washin of a 30%, 40%, 55% Xe, and a 30% Xe/30% Kr mixture. Using Kr avoids unwanted effects of Xe. Mean TCs, coefficients of variation (CV), and half confidence intervals (CI)/mean served as indexes of sensitivity to noise. Mean supine and prone TCs of three [Xe] values were not significantly different. Average CVs of TCs increased from 57% (55% Xe), 58% (40% Xe), and 73% (30% Xe) ( P < 0.05: paired t-tests; 30% Xe vs. higher [Xe]). Monte Carlo simulation indicated a CV based on inherent image noise was 8% for 55% Xe and 17% for 30% Xe ( P < 0.05). Adding 30% Kr to 30% Xe gave a washin signal equivalent to 40% Xe. Half CI/mean using the 30% Xe/30% Kr mixture was not significantly different from 55 and 40% Xe. Although average TCs were not affected by changes in [Xe], the higher CV and half CI/mean suggested reduced signal-to-noise ratio at the 30% [Xe]. The 30% Xe/30% Kr mixture was comparable to that of 40% Xe, providing an important agent for CT-based assessment of regional ventilation in humans.
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Yamauchi, Y., Y. Izumi, N. Tsukada, K. Asakura, M. Inoue, H. Yashiro, S. Nakatsuka, and M. Kawamura. "Assessment of the safety and efficacy of percutaneous cryoablation for lung tumors." Journal of Clinical Oncology 27, no. 15_suppl (May 20, 2009): 7592. http://dx.doi.org/10.1200/jco.2009.27.15_suppl.7592.
Повний текст джерелаАнотація:
7592 Background: Percutaneous cryoablation using high resolution fluoroscopic CT guidance under local anesthesia offers a potential tool for local control of lung tumors in combination with systemic treatments. In this study, we retrospectively analyzed the safety, and efficacy of percutaneous cryoablation for lung tumors (PCLT). Methods: This study was approved by the institutional review board. From October 2002, PCLT was performed in patients who either did not oncologically fulfill the indications for resection, or refused resection. CT scan was examined every 3 months after PCLT. >20% increase in the treated lesion size was diagnosed as local failure. Survival analysis was done by Kaplan-Meier. Results: There were 147 patients (95 male, 52 female, mean age 60, 20 primary lung cancer, metastases; 29 of lung cancer, 35 of colorectal cancer, 63 of other sites). 251 sessions were done for 462 tumors. Mean tumor diameter was 18.3mm. PCLT was well tolerated in most patients. In 1 case, broncho-thoracic fistula occurred in the treated region which lead to empyema. Other complications were pneumothorax (153 sessions, 61%, chest tube required in 23 sessions), pleural effusion (160 sessions, 64%), and transient hemoptysis (82 sessions, 33%). Overall one- and two-year local control rates were 81.0% and 59.1%, respectively. Overall one- and two-year survival rates were 80.0% and 54.5%, respectively. In the 1–20 mm sized (n=362) vs. over 21mm sized (n=100) lesions, the local control rates at one year were 84% vs. 56% (p=0.0007), and at two years were 63% vs. 35% (p=0.017), respectively. There were no differences in local control between primary and metastatic tumors, carcinomas and sarcomas. Survival of patients whose lesions were limited to 1–20mm (n=89) was prolonged vs. those who had at least one over 21mm lesion (n=58) (p=0.01). However, one, and two-year survival rates did not differ significantly between these groups (one-year; 85.5% vs. 71.7% (p=0.07), two-year; 60.7% vs. 46.5% (p=0.16)). Conclusions: PCLT was minimally invasive and safe. 1–20mm tumors were good candidates. Contribution of PCLT to survival was not clear in this mixed patient population. To improve local control in over 20 mm tumors, we are computer simulating freezing kinetics to optimize the number and the positioning of the probes. No significant financial relationships to disclose.