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9 result(s) for "Stevanovic, Predrag D."
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Physiological and Oxidative Stress in General and Spinal Anesthesia for Elective Cesarean Section in Women: Is There Any Difference?
This study evaluates the influence of general anesthesia (GA) and spinal anesthesia (SA) on physiological and oxidative stress in parturients undergoing elective cesarean section, one of the most frequently performed surgical procedures worldwide. A total of 101 pregnant women were included, categorized into GA (n = 51) and SA (n = 50) groups. Blood samples were collected at three time points: one hour before surgery (Measurement 1), at umbilical cord clamping (Measurement 2), and two hours post-surgery (Measurement 3). Biomarkers of oxidative stress, complete blood count, and levels of biochemical parameters were measured. In second and/or third measurement, biochemical blood analysis showed increased prolactin and cortisol levels, followed by spike of glucose and insulin in the GA group. However, levels of tri-iodothyronine were reduced in both groups in the third measurement. Glutathione S-transferase (GST) activity was increased in both groups in third measurement. The results showed increased concentrations of total SH groups and decreased concentrations of non-protein SH groups in the GA group during Measurement 2. Lymphocyte count was found to be predictor of GST levels. The results indicate more a pronounced endocrine response in GA group and speak in favor of spinal anesthesia. Both kinds of anesthesia are equally safe in terms of the oxidative status of the tissue.
Low fresh gas flow balanced anesthesia versus target controlled intravenous infusion anesthesia in laparoscopic cholecystectomy: A cost-minimization analysis
Background: Laparoscopic surgery is widely recognized as a well-tolerated and effective method for cholecystectomy. It is also considered cost saving because it has been associated with a decreased hospital length of stay. Variables that might lead to increased costs in laparoscopic surgery are the technique and drugs used in anesthesia. Objective: The goal of this study was to compare the costs of 2 anesthetic techniques used in laparoscopic cholecystectomy (LC)—balanced versus IV anesthesia—from the standpoint of an outpatient surgical department, with a time horizon of 1 year. Methods: Patients scheduled to undergo elective LC were enrolled in this prospective case study. Patients were randomly allocated to receive balanced anesthesia, administered as low fresh gas flow (LFGF) with inhalational sevoflurane and IV sufentanil in a target controlled infusion (LFGF SS group), or IV anesthesia, administered as IV propofol/sufentanil in a target controlled infusion (TCI group). We used a microcosting procedure to measure health care resource utilization in individual patients to detect treatment differences. The costs of medications used for the induction and maintenance of anesthesia during surgery were considered for LFGF SS and TCI. Other end points included duration of anesthesia; mean times to early emergence, tracheal extubation, orientation, and postanesthesia discharge (PAD); pain intensity before first analgesia; number of analgesics required in the first 24 hours after surgery; and prevalences of nausea, vomiting, and agitation. Results: A total of 60 patients were included in this analysis (male/female ratios in the LFGF SS and TCI groups: 11/19 and 12/18, respectively; mean [SD] ages, 48 [7.9] and 47 [8.6] years; and mean [SD] body mass indexes, 26 [2.0] and 26 [3.0] kg/m 2). The costs of anesthetics were significantly lower with LFGF SS compared with TCI (€17.40 [€2.66] vs €22.01 [€2.50] [2006 euros]). Times to early emergence and tracheal extubation were significantly shorter with LFGF SS than TCI (5.97 [1.16] vs 7.73 [1.48] minutes and 7.57 [1.07] vs 8.87 [1.45] minutes, respectively). There were no significant between-group differences in mean duration of anesthesia; times to orientation and PAD; pain intensity before first analgesia; number of analgesics required in the first 24 hours; or prevalences of nausea, vomiting, and agitation. Because no clinically significant differences in the anesthetic results were observed, a cost-minimization analysis was conducted and found that using LFGF SS, the outpatient surgical department could realize a budget savings of €454 per 100 patients. For the nearly 1000 expected patients per year, the savings for the department was calculated as €4540. Conclusion: The results from this cost analysis in these patients who underwent elective LC suggest that the use of sevoflurane through the LFGF technique would be cost saving in this outpatient surgical department.
Two- and Three-Dimensional Speckle Tracking Analysis of the Relation Between Myocardial Deformation and Functional Capacity in Patients With Systemic Hypertension
The purpose of this study was to investigate left ventricular (LV) mechanics in hypertensive patients by 2- and 3-dimensional (3D) speckle tracking imaging, and determine the relation between the LV mechanics and functional capacity in this population. This cross-sectional study included 51 recently diagnosed, untreated, hypertensive patients, 49 treated subjects with well-controlled arterial hypertension, 52 treated participants with uncontrolled hypertension, and 50 controls adjusted by gender and age. All the subjects underwent 24-hour blood pressure monitoring, complete 2-dimensional and 3D examination, and cardiopulmonary exercise testing. 3D global longitudinal, circumferential, radial, and area strains were similar between the control group and well-controlled hypertensive patients but significantly decreased in comparison with patients with untreated or inadequately controlled hypertension. Similar findings were obtained for LV torsion and twist rate, whereas LV untwisting rate significantly deteriorated from the controls, across the well-controlled group, to the patients with untreated or uncontrolled hypertension. Peak oxygen uptake was significantly lower in the patients with untreated and uncontrolled hypertension than in the controls and the well-treated hypertensive patients. Peak oxygen uptake was independently associated with LV untwisting rate (β = 0.28, p = 0.03), 3D LV ejection fraction (β = 0.31, p = 0.024), and 3D global longitudinal strain (β = 0.26, p = 0.037) in the whole hypertensive population in our study. In conclusion, LV mechanics and functional capacity are significantly impaired in the patients with uncontrolled and untreated hypertension in comparison with the controls and the well-controlled hypertensive patients. Functional capacity is independently associated with 3D global longitudinal strain, LV untwisting rate, and 3D LV ejection fraction.
Correlation Between Morphology and Crystal Structure of Electrolytically Produced Zinc Dendritic Particles
The correlation between the morphology and crystal structure of zinc dendritic particles produced by electrolysis from the alkaline electrolyte has been established. Morphology and crystal structure of Zn particles electrodeposited by the potentiostatic regime of electrolysis at overpotentials inside (−100 and −160 mV) and outside (−220, −280, and −340 mV) the plateau of the limiting diffusion current density were characterized by scanning electron microscope (SEM) and by X-ray diffraction (XRD), respectively. The particle size distribution (PSD) was performed in order to determine the dependency of the size of dendritic particles on applied electrolysis overpotential. With increasing the overpotential of electrolysis, the shape of particles changed from irregular forms denoted as precursors of dendrites to various forms of dendrites, while the size of the particles simultaneously decreased. All types of Zn dendrites exhibited the strong (002) preferred orientation, while the precursors of dendrites exhibited (101)(002) preferred orientation. The development of strong (002) preferred orientation was explained and discussed by making an analogy with the electrolytic production of lead dendrites from the concentrated nitrate electrolyte. Although zinc and lead belong to different types of crystal lattice (Pb-face-centered cubic type and Zn-hexagonal close-packed type), they have a common characteristic that is manifested by the strong preferred orientation in the crystal plane with the lowest surface energy.
Relationship between the kinetic parameters and morphology of electrochemically deposited lead
The processes of lead electrodeposition from electrolytes of various concentrations of sodium nitrate as the supporting electrolyte have been examined by chronoamperometry and by the scanning electron microscopic (SEM) analysis of deposits obtained in the potentiostatic regime of electrolysis. The good agreement between the diffusion coefficents determined by Cottrell equation and non-linear fitting method was observed. For the first time, the transition from the mixed ohmic-diffusion to the full diffusion control was defined from the analysis of Cottrell equation. The parameters, such as the number density of active sites and the nucleation rate constant, obtained by non-linear fitting method were discussed in accordance with the fact that lead belongs to the group of metals characterized by the high values of the exchange current density. The data obtained by the chronoamperometric analysis were succesfully correlated with morphologies of electrodeposited lead obtained in the different types of electrodeposition control.
Self-Powered Wearable Breath-Monitoring Sensor Enabled by Electromagnetic Harvesting Based on Nano-Structured Electrochemically Active Aluminum
Self-powered sensors are gaining a lot of attention in recent years due to their possible application in the Internet of Things, medical implants and wireless and wearable devices. Human breath detection has applications in diagnostics, medical therapy and metabolism monitoring. One possible approach for breath monitoring is detecting the humidity in exhaled air. Here, we present an extremely sensitive, self-powered sensor for breath humidity monitoring. As a power source, the sensor uses electromagnetic energy harvested from the environment. Even electromagnetic energy harvested from the human body is enough for the operation of this sensor. The signal obtained using the human body as a source was up to 100 mV with an estimated power of 1 nW. The relatively low amount of energy that could be harvested in this way was producing a signal that was modulated by an interdigitated capacitor made out of electrochemically activated aluminum. The signal obtained in this way was rectified by a set of Schottky diodes and measured by a voltmeter. The sensor was capable of following a variety of different respiration patterns during normal breathing, exercise and rest, at the same time powered only by electromagnetic energy harvested from the human body. Everything happened in the normal environment used for everyday work and life, without any additional sources, and at a safe level of electromagnetic radiation.
CFD simulations of thermal comfort in naturally ventilated primary school classrooms
The purpose of Thermal Comfort is to specify the combinations of indoor space environment and personal factors that will produce thermal environment conditions acceptable to 80% or more of the occupants within a space. Naturally ventilated indoors has a very complex air movement, which depends on numerous variables such as: outdoor interaction, intensity of infiltration, the number of openings, the thermal inertia of walls, occupant behaviors, etc. The most important mechanism for naturally ventilated indoors is the intensity of infiltration and thermal buoyancy mechanism. In this study the objective was to determine indicators of thermal comfort for children, by the CFD model based on experimental measurements with modification on turbulent and radiant heat transfer mathematical model. The case study was selected on school children aged 8 and 9 years in primary school ?France Presern?, Belgrade. The purpose was to evaluate the relationships between the indoor environment and the subjective responses. Also there was analysis of infiltration and stack effect based on meterological data on site. The main parameters that were investigated are: operative temperature, radiant temperature, concentration of CO2 and air velocity. The new correction of turbulence and radiative heat transfer models has been validated by comparison with experimental data using additional statistical indicators. It was found that both turbulence model correct and the new radiative model of nontransparent media have a significant influence on CFD data set accuracy. nema
Slow Positive End-Expiratory Pressure Titration During General Anesthesia with Muscle Paralysis Improves Lung Function Without Compromising Hemodynamic Stability in Preschool Children: A Randomized Control Clinical Trial
Background: Mechanical ventilation impairs oxygenation and increases intrapulmonary shunt. Positive end-expiratory pressure (PEEP) slows derecruitment, improves lung function but can compromise hemodynamics. Objectives: To asses slow PEEP titration effect on intrapulmonary shunt, oxygenation and hemodynamics in preschool children on mechanical ventilation under general anesthesia. Methods: This was a single tertiary care center an open-label, randomized parallel group controlled clinical trial. Study included 70 children, 3 - 7 years, ASA I and II, under general anesthesia for non-cardiothoracic surgery. Children were randomly allocated either to receive PEEP titration 5 - 11 cmH2O 20 minutes before the end of anesthesia (intervention group) or to be ventilated until the end of anesthesia with constant positive end-expiratory pressure of 3 cmH2O (control group). Main outcome measures were changes in oxygenation index (PaO2/FiO2) and alveolar-arterial gradient (P(A-a)O2) between and within groups and changes in systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) in interventional group during PEEP trial. Results: Seventy children were recruited and analyzed. P(A-a)O2 and PaO2/FiO2 improved in interventional group comparing to control as consequence of PEEP titration (ΔPaO2/FiO2 -30.3 vs. 0.52; P < 0.001; ΔP(A-a)O2 6.7 vs. -1.0; P < 0.001) and within interventional group before and after PEEP titration (PaO2/FiO2 522.0 vs. 552.3; P < 0.01; P(A-a)O2 20.1 vs. 13.3; P < 0.001). Hypotension and bradycardia were not documented. Conclusions: Slow PEEP titration up to 11 cmH2O improves oxygenation, reduces intrapulmonary shunt without causing hemodynamic instability in preschool children during general anesthesia.
Mapping the potential for decentralized energy generation based on RES in Western Balkans
Although the countries of the Western Balkans are mostly electrified, there are still regions which do not have access to the electricity network or where the network capacity is insufficient. For the most part such areas are under special care of the state (i. e. underdeveloped, devastated by war, depopulated), on islands or in mountainous regions. Since the decentralized energy generation covers a broad range of technologies, including many renewable energy technologies that provide small-scale power at sites close to the users, such concept could be of interest for these locations. This paper identifies the areas in Western Balkans where such systems could be applied. Consideration is given to geographical locations as well as possible applications. Wind, hydro, solar photovoltaic, and biomass conversion systems were taken into consideration. Since the renewable energy sources data for Western Balkans region are rather scarce, the intention was to give a survey of the present situation and an estimate of future potential for decentralized energy generation based on renewable energy sources. The decentralized energy generation based on renewable energy sources in Western Balkans will find its niche easier for the users that will produce electricity for their own needs and for the users located in remote rural areas (off-grid applications).