Shock Fluid Research Articles

Anesthesia Trauma Guidelines: A Systematic Review of Global Accessibility and Quality.

This systematic review describes the available clinical practice guidelines (CPGs) for the anesthetic management of trauma and appraises the accessibility and quality of these resources. This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A search was conducted across 8 databases (MEDLINE, Embase, Web of Science, CABI Digital Library, Global Index Medicus, SciELO, Google Scholar, and National Institute for Health and Care Excellence) for guidelines from 2010 to 2023. Two independent reviewers assessed guideline eligibility and extracted data, which were audited by a third reviewer. Data regarding author demographics, accessibility, clinical topics, and quality were collected. The quality of guidelines was evaluated according to the National Guideline Clearinghouse Extent Adherence to Trustworthy Standards (NEATS) Instrument. A total of 2426 articles were identified, of which 165 met eligibility criteria and were included. Guidelines were developed by 122 professional societies and authors from 51 countries. By region, Europe contributed with the most authors (61%), while Africa had the fewest (4%). Most CPGs were developed by authors from high-income countries (HIC) and only 12% had a first or last author from low- and middle-income countries (LMIC). The United States was the country with the most guideline authors. While 70% were open access, the average cost for paid access was US$36.61. Among the 8 languages identified, English was the most common. The most common topics were blood and fluid management, shock, and airway management. The overall quality of included guidelines was considered moderately high, with an average NEATS score of 3.13 of 5. Quality scores were lowest for involvement of patient perspectives, plans for updating, and presence of a methodologist. On logistic regression analysis, the involvement of a methodological expert was the only predictor of having a high-quality NEATS score, with no association observed with open accessibility, English language, society endorsement, first author from a HIC, or a multidisciplinary group composition. Though many countries and societies have contributed to the development of anesthesia CPGs for trauma, there has been a disproportionate lack of representation from LMICs, where the burden of trauma mortality is highest. In this study, we identify barriers to accessibility and areas for improving future guideline quality. We recommend ongoing efforts to incorporate perspectives from diverse settings and to increase the availability of high-quality, open-access guidelines to improve worldwide health outcomes in trauma.

Dextrose 5% versus normal saline as maintenance fluid therapy in patients with septic shock (DEMANDS): a randomized controlled trial

ABSTRACT Objective To determine the effects of Dextrose 5% for maintenance and creep fluids on cumulative fluid balance (CFB) for septic shock concerning adult people. Design An open-label randomized clinical trial with a single center and parallel groups. Setting ICUs of a tertiary care academic medical center. Patients Adult individuals who have developed septic shock as described by the Sepsis 3 criteria. Interventions Dextrose 5% (n = 50) versus Saline 0.9% (n = 50) for maintenance and creep fluid for 72 hours. Main variables of interest The primary outcome measured was the CFB at 72 hours. Secondary outcomes assessed included mortality within 28 days, the number of days patients were free from (coma and delirium, ICU, mechanical ventilation, vasopressors), the occurrence of acute kidney injury, and disturbances in electrolyte levels. Results The CFB was significantly lower in Dextrose group vs Saline group (4.46 versus 6.75 L, median difference; −2.06 L; 95% CI, −2.63 to −1.35; p = P < 0.001). No significant difference mortality within 28 days (32% in the Dextrose vs 42% in the saline group; hazard ratio, 0.7; 95% CI, 0.36 to 1.34, p = 0.28). The proportions of patients with hyponatremia were higher in the Dextrose than the Saline group (31% versus 0%, p < 0.001). Conclusions Particularly in cases of septic shock, maintenance and creep fluids with Dextrose 5% as compared to Saline 0.9% resulted in a significantly lower CFB at 72 hours.

Simulations on perturbation growth and mixing of a shocked light fluid layer with two different interfaces

The Richtmyer–Meshkov instability of a light fluid layer with two different interface modes is studied numerically. By fixing the wavelength of the second interface (I2) while varying that of the first interface (I1), we examine distinct cases with identical wavelengths at both interfaces, as well as smaller or larger wavelengths at I1, to explore the effects of initial layer configurations on instability development. The larger wavelength interface significantly transmits modes to the smaller wavelength interface, whereas mode transmission in the reverse direction is limited. This results in two primary consequences: (i) the smaller wavelength interface and the overall mixing layer evolve periodically with the larger wavelength; (ii) compared to the identical wavelength case, the linear amplitude growth duration of I2 is slightly extended for the smaller I1 wavelength case, but significantly prolonged for the larger I1 wavelength case. The linear amplitude growth rate of I2 for all cases can be predicted by the model of Jacobs et al. [J. Fluid Mech., vol. 195, 23–42 (1995)]. For cases with identical wavelengths and larger I1 wavelengths, the collisions of finger structures at both interfaces occur earlier, suppressing the growth of mixing width at early times while enhancing the mixed mass. In the later stages, the overall mixing efficiency in these cases significantly declines, despite continuous increases in both mixing width and mixed mass. This decline is attributed to severe deformation of the mixing layer due to interactions between finger structures, confining intense mixing to localized regions.

An improved efficient adaptive method for large-scale multi-explosives explosion simulations

Shock wave caused by a sudden release of high-energy, such as explosion and blast, usually affects a significant range of areas. The utilization of a uniform fine mesh to capture sharp shock wave and to obtain precise results is inefficient in terms of computational resource. This is particularly evident when large-scale fluid field simulations are conducted with significant differences in computational domain size. In this work, a variable-domain-size adaptive mesh enlargement (vAME) method is developed based on the proposed adaptive mesh enlargement (AME) method for modeling multi-explosives explosion problems. The vAME method reduces the division of numerous empty areas or unnecessary computational domains by adaptively suspending enlargement operation in one or two directions, rather than in all directions as in AME method. A series of numerical tests via AME and vAME with varying nonintegral enlargement ratios and different mesh numbers are simulated to verify the efficiency and order of accuracy. An estimate of speedup ratio is analyzed for further efficiency comparison. Several large-scale near-ground explosion experiments with single/multiple explosives are performed to analyze the shock wave superposition formed by the incident wave, reflected wave, and Mach wave. Additionally, the vAME method is employed to validate the accuracy, as well as to investigate the performance of the fluid field and shock wave propagation, considering explosive quantities ranging from 1 to 5 while maintaining a constant total mass. The results show a satisfactory correlation between the overpressure versus time curves for experiments and numerical simulations. The vAME method yields a competitive efficiency, increasing the computational speed to 3.0 and approximately 120,000 times in comparison to AME and the fully fine mesh method, respectively. It indicates that the vAME method reduces the computational cost with minimal impact on the results for such large-scale high-energy release problems with significant differences in computational domain size.

Major Publications in the Critical Care Pharmacotherapy Literature: 2023.

We aimed to summarize the most significant and impactful publications describing the pharmacotherapeutic care of critically ill patients in 2023. PubMed/MEDLINE and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update. Randomized controlled trials and prospective studies of adult critically ill patients assessing a pharmacotherapeutic intervention and reporting clinical endpoints published between January 1, 2023, and December 31, 2023, were eligible for inclusion in this article. Articles from a systematic search and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update were included. An a priori defined three-round modified Delphi process was employed to achieve consensus on the most impactful publications based on the following considerations: 1) overall contribution to scientific knowledge and 2) novelty to the literature. The systematic search and Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update returned a total of 1202 articles, of which 1164 were excluded. The remaining 38 articles underwent a three-round modified Delphi process. In each round, articles were independently scored based on overall contribution to scientific knowledge and novelty to the literature. Included articles are summarized and their impact discussed. Article topics included hydrocortisone for severe community-acquired pneumonia, inhaled amikacin for prevention of ventilator-associated pneumonia, methylene blue for septic shock, restrictive vs. liberal fluid management for sepsis-induced hypotension, andexanet alfa for major bleeding associated with factor Xa inhibitors, and early administration of four-factor prothrombin complex concentrate in patients with trauma at risk for massive transfusion. This review provides a summary and perspective on the potential impact of the most relevant articles in 2023 describing advances in the pharmacotherapeutic care of critically ill patients.

Numerical simulation study on the effect of ignition position on premixed hydrogen deflagration characteristics in tunnels

To analyze the influence of different ignition positions on the propagation of deflagration characteristics and the disaster mechanism in the hydrogen deflagration process in the tunnel, this study compares and verifies the experimental data of tunnel model deflagration based on the CFD code GASFLOW-MPI. A combustion velocity model based on the accelerated separation effect is used, and the effect of heat transfer on the consequences of deflagration is considered. The propagation laws of pressure waves, fluid velocity and temperature in the tunnel are analyzed, and it is found that the changing trends of shock waves and fluid velocity in the tunnel are consistent, but completely opposite in the tunnel outside. The effects of different ignition positions on the hydrogen deflagration characteristics are compared and analyzed. The results show that when ignition occurs at different heights of the center of the premixed region, the impact on the deflagration characteristics is relatively small, while when ignition occurs at different horizontal distances in the premixed region, the impact on the deflagration characteristics is relatively large; the peak overpressure of side ignition is far lower than the case where ignition occurs in the center of the premixed region, but the maximum flow velocity is much higher than the center ignition. The impact on temperature is the smallest. In general, in areas close to the hydrogen/air premixed zone, side ignition results in more severe consequences, whereas in areas far from the premixed zone and outside the tunnel, central ignition leads to more severe consequences. This study provides theoretical support for understanding the disaster-causing mechanisms of hydrogen/air premixed gas deflagration in tunnels under different ignition positions.

Going beyond an old shockwave conjecture for improving upon Navier-Stokes.

Nonequilibrium molecular dynamics (NEMD) computer simulations of steady shockwaves in dense fluids and rarefied gases produce detailed shockwave profiles of mechanical and thermal properties. The Boltzmann equation, under the assumption of local thermodynamic equilibrium (LTE), leads to the first-order (linear) continuum theory of hydrodynamic flow: Navier-Stokes-Fourier (NSF). (Expansion of the LTE Boltzmann equationin higher powers of gradients yields so-called Burnett second-order terms, etc.) NEMD simulations of strong shockwaves with high gradients are not well modeled by NSF theory. Many years ago, a conjecture for going "beyond Navier-Stokes" was proposed, applying the empirical observation of anisotropic thermal enhancement in the shock front to the temperature dependence of the NSF transport coefficients, whose dissipation determines the slope at the center of the shock profile: for weak shocks, the actual coefficients in NEMD simulations appear to be smaller than in NSF predictions, leading to steeper gradients being observed, while for strong shocks, the NEMD coefficients appear to be larger, leading to less steep shock rises than predicted by NSF calculations. In this paper, we show that adding significant Burnett nonlinearity into an LTE continuum theory reproduces the early shock rise and slope of NEMD profiles, for both weak and strong shocks in dense fluids, as well as strong shockwaves in the ideal gas. Moreover, we show that "Holian's conjecture" incorporates significant Burnett nonlinearity, but like all the other LTE continuum theories, it fails to describe the slow NEMD return to equilibrium beyond the shock front. We show that Maxwell relaxation has to be applied to the hydrodynamic variables themselves (rather than attempting indirect relaxation of their gradients) in order to more accurately model the entire shockwave profile. Non-LTE Maxwell relaxation is the only way to bring the entire profile into agreement with NEMD, most noticeably for strong shockwaves.

JWST Reveals Powerful Feedback from Radio Jets in a Massive Galaxy at z = 4.1

We report observations of a powerful ionized gas outflow in the z = 4.1 luminous radio galaxy TNJ1338-1942 hosting an obscured quasar using the Near Infrared Spectrograph (NIRSpec) on board JWST. We spatially resolve a large-scale (∼15 kpc) outflow and measure outflow rates. The outflowing gas shows velocities exceeding 900 km s−1 and broad line profiles with widths exceeding 1200 km s−1 located at an ∼10 kpc projected distance from the central nucleus. The outflowing nebula spatially overlaps with the brightest radio lobe, indicating that the powerful radio jets are responsible for the outflow kinematics. The gas is possibly ionized by the obscured quasar with a contribution from shocks induced by the jets. The mass outflow rate map shows that the region with the broadest line profiles exhibits the strongest outflow rates. The total mass outflow rate is ∼500 M ⊙ yr−1, and the mass loading factor is ∼1, indicating that a significant part of the gas is displaced outwards by the outflow. Our hypothesis is that the overpressured shocked jet fluid expands laterally to create an expanding ellipsoidal “cocoon” that causes the surrounding gas to accelerate outwards. The total kinetic energy injected by the radio jet is about 3 orders of magnitude larger than the energy in the outflowing ionized gas. This implies that kinetic energy must be transferred inefficiently from the jets to the gas. The bulk of the deposited energy possibly lies in the form of hot X-ray-emitting gas.

Solitonic solutions and stability analysis of Benjamin Bona Mahony Burger equation using two versatile techniques

This study aims to explore the precise resolution of the nonlinear Benjamin Bona Mahony Burgers (BBMB) equation, which finds application in a variety of nonlinear scientific disciplines including fluid dynamics, shock generation, wave transmission, and soliton theory. Within this paper, we employ two versatile methodologies, specifically the extended exp(-Ψ(χ))\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\exp (-\\Psi (\\chi ))$$\\end{document} expansion technique and the novel Kudryashov method, to identify the exact soliton solutions of the nonlinear BBMB equation. The solutions we discovered involve trigonometric functions, hyperbolic functions, and rational functions. The uniqueness of this research lies in uncovering the bright soliton, kink wave solution, and periodic wave solution, and conducting stability analysis. Furthermore, the solutions’ graphical characteristics were explored through the utilization of the mathematical software Maple 2022 (https://maplesoft.com/downloads/selectplatform.aspx?hash=61ab59890f2313b2241fde3423fd975e). The system’s physical interpretation is defined through various types of graphs, including contour graphs, 3D-surface graphs, and line graphs, which use appropriate parameter values. These recommended techniques hold significant importance and are applicable in diverse nonlinear evolutionary equations found in the field of nonlinear sciences for illustrating nonlinear physical models.

The nonlinear stability of (n + 1)-dimensional FLRW spacetimes

We prove nonlinear Lyapunov stability of a family of “([Formula: see text])”-dimensional cosmological models of general relativity locally isometric to the Friedman–Lemaître–Robertson–Walker (FLRW) spacetimes including a positive cosmological constant. In particular, we show that the perturbed solutions to the Einstein–Euler field equations around a class of spatially compact FLRW metrics (for which the spatial slices are compact negative Einstein spaces in general and hyperbolic for the physically relevant [Formula: see text] case) arising from regular Cauchy data remain uniformly bounded and decay to a family of metrics with constant negative spatial scalar curvature. To accomplish this result, we employ an energy method for the coupled Einstein–Euler field equations in constant mean extrinsic curvature spatial harmonic (CMCSH) gauge. In order to handle Euler’s equations, we construct energy from a current that is similar to the one derived by Christodoulou [The Formation of Shocks in 3-dimensional Fluids, EMS Monographs in Mathematics, Vol. 2 (European Mathematical Society, 2007)] (and which coincides with Christodoulou’s current on the Minkowski space) and show that this energy controls the desired norm of the fluid degrees of freedom. The use of a fluid energy current together with the CMCSH gauge condition casts the Einstein–Euler field equations into a coupled elliptic–hyperbolic system. Utilizing the estimates derived from the elliptic equations, we first show that the gravity-fluid energy functional remains uniformly bounded in the expanding direction. Using this uniform boundedness property, we later obtain sharp decay estimates if a positive cosmological constant [Formula: see text] is included, which confirms that the accelerated expansion of the physical universe that is induced by the positive cosmological constant is sufficient to control the nonlinearities in the case of small data. A few physical consequences of this stability result are discussed.

Freeze-out of perturbation growth for shocked heavy fluid layers by eliminating reverberating waves

The shock wave accelerating a heavy fluid layer can induce reverberating waves that continuously interact with the first and second interfaces. In order to manipulate the perturbation growths at fluid-layer interfaces, we present a theoretical framework to eliminate the reverberating waves. A model is established to predict the individual freeze-out (i.e. stagnation of perturbation growth) for the first and second interfaces under specific flow conditions determined based on the shock dynamics theory. The theoretical model quantifies the controllable parameters required for freeze-out, including the initial amplitudes of the first and second interfaces, the interface coupling strength and the maximum initial layer thickness preventing the second interface's phase reversal. The effectiveness of the model in predicting individual freeze-out for the first and second interfaces is validated numerically over a wide range of initial conditions. The upper and lower limits of initial amplitudes for the freeze-out of the whole fluid-layer width growth are further predicted. Within this amplitude range, a slightly higher initial amplitude for the second interface is specified, effectively arresting the growth of the entire fluid-layer width before the phase reversal of the second interface.

Does Point-of-Care Ultrasound Affect Fluid Resuscitation Volume in Patients with Septic Shock: A Retrospective Review.

Fixed, large volume resuscitation with intravenous fluids (IVFs) in septic shock can cause inadvertent hypervolemia, increased medical interventions, and death when unguided by point-of-care ultrasound (POCUS). The primary study objective was to evaluate whether total IVF volume differs for emergency department (ED) septic shock patients receiving POCUS versus no POCUS. We conducted a retrospective observational cohort study from 7/1/2018 to 8/31/2021 of atraumatic adult ED patients with septic shock. We agreed upon a priori variables and defined septic shock as lactate ≥4 and hypotension (SBP <90 or MAP <65). A sample size of 300 patients would provide 85% power to detect an IVF difference of 500 milliliters between POCUS and non-POCUS cohorts. Data are reported as frequencies, median (IQR), and associations from bivariate logistic models. 304 patients met criteria and 26% (78/304) underwent POCUS. Cardiac POCUS demonstrated reduced ejection fraction in 15.4% of patients. Lung ultrasound showed normal findings in 53% of patients. The POCUS vs. non-POCUS cohorts had statistically significant differences for the following variables: higher median lactate (6.7 [IQR 5.2-8.7] vs. 5.6], p = 0.003), lower systolic blood pressure (77.5 [IQR 61-86] vs. 85.0, p < 0.001), more vasopressor use (51% vs. 34%, p = 0.006), and more positive pressure ventilation (38% vs. 24%, p = 0.017). However, there were no statistically significant differences between POCUS and non-POCUS cohorts in total IVF volume ml/kg (33.02 vs. 32.1, p = 0.47), new oxygen requirement (68% vs. 59%, p = 0.16), ED death (3% vs. 4%, p = 0.15), or hospital death (31% vs. 27%, p = 0.48). There were similar distributions of lactate, total fluids, and vasopressors in patients with CHF and severe renal failure. Among ED patients with septic shock, POCUS was more likely to be used in sicker patients. Patients who had POCUS were given similar volume of crystalloids although these patients were more critically ill. There were no differences in new oxygen requirement or mortality in the POCUS group compared to the non-POCUS group.

Effects of compressibility on Richtmyer–Meshkov instability of heavy/light interface

Experimental and numerical studies on the evolution of shock-accelerated SF6/air interface with small initial amplitude are conducted. The effect of compressibility on the early development of perturbation is highlighted by varying shock intensity and fluid properties. The startup process is analyzed when rarefaction waves are reflected and the characteristic time of the startup process is provided. The relationship between the phase inversion process and the startup process under different incident shock strengths is clarified. According to the startup time, a new start point for normalization is given, which can better normalize the amplitude growth at the early stage. In addition, the effects of incident shock strength and physical properties of fluids on the linear growth rate are highlighted through numerical simulations. The incompressible linear model loses validity when the incident shock is strong, and the existing rotational model is verified to provide excellent predictions under any shock strengths. The decrease in adiabatic exponent of the heavy fluid or the increase in adiabatic exponent of the light fluid can reduce the linear growth rate. As the absolute value of Atwood number increases, the adiabatic exponent of the heavy fluid has a more significant effect on the linear growth than that of the light fluid.

Maser flares driven by isothermal shock waves

ABSTRACT We use 3D computer modelling to investigate the time-scales and radiative output from maser flares generated by the impact of shock waves on astronomical unit-scale clouds in interstellar and star-forming regions, and in circumstellar regions in some circumstances. Physical conditions are derived from simple models of isothermal hydrodynamic (single-fluid) and C-type (ionic and neutral fluid) shock waves, and based on the ortho-H2O 22-GHz transition. Maser saturation is comprehensively included, and we find that the most saturated maser inversions are found predominantly in the shocked material. We study the effect on the intensity, flux density, and duration of flares of the following parameters: the pre-shock level of saturation, the observer’s viewpoint, and the shock speed. Our models are able to reproduce observed flare rise times of a few times 10 d, specific intensities of up to 105 times the saturation intensity and flux densities of order 100(R/d)2 Jy from a source of radius R astronomical units at a distance of d kiloparsec. We found that flares from C-type shocks are approximately five times more likely to be seen by a randomly placed observer than flares from hydrodynamically shocked clouds of similar dimensions. We computed intrinsic beaming patterns of the maser emission, finding substantial extension of the pattern parallel to the shock front in the hydrodynamic models. Beaming solid angles for hydrodynamic models can be as small as 1.3 × 10−5 sr, but are an order of magnitude larger for C-type models.

Study on dynamic characteristics of cavitation in underwater explosion with large charge

Underwater explosions (UNDEX) generate shock waves that interact with the air–water interface and structures, leading to the occurrence of rarefaction waves and inducing cavitation phenomena. In deep-water explosions, complex coupling relationships exist between shock wave propagation, bubble motion, and cavitation evolution. The shock wave initiates the formation of cavitation, and their growth and collapse are influenced by the pressure field. The collapsing bubbles generate additional shock waves and fluid motion, affecting subsequent shock wave propagation and bubble behavior. This intricate interaction significantly impacts the hydrodynamic characteristics of deep-water explosions, including pressure distribution, density, and phase changes in the surrounding fluid. In this paper, we utilize a two-fluid phase transition model to capture the evolution of cavitation in deep-water explosions. Our numerical results demonstrate that the introduction of a two-phase vapor–liquid phase change model is necessary to accurately capture scenarios involving prominent evaporation or condensation phenomena. Furthermore, we find that the cavitation produced by the same charge under different explosion depths exhibits significant differences, as does the peak value of cavitation collapse pressure. Similarly, the cavitation produced by different charge quantities under the same explosion depth varies, and the relationship between cavitation volume and charge quantity is not a simple linear increase. The research methods and results presented in this paper provide an important reference for studying the dynamic characteristics of deep-water explosions.

A perturbation approach to study the shock wave propagation in a non-ideal magnetogasdynamics under isothermal condition

The main goal of this paper is to obtain a global solution to the problem of imploding strong cylindrical shock waves (SWs) collapsing at the axis of symmetry in a non-ideal gas under the influence of an axial magnetic field using the perturbation series technique. This global solution is valid for the entire flow field up to the instant of collapse. Guderley's asymptotic solution, which is only applicable in the neighborhood of the axis of implosion, is properly reproduced by this global solution. Guderley's local self-similar solution allows for the determination of the first dominant similarity exponent only; however, this approach also enables the identification of additional, less dominant similarity exponents along with the corresponding amplitudes. Additionally, the computed values of the similarity exponents have been compared with the results drawn from Guderley's approach. The profiles of fluid variables and shock trajectory are shown graphically for different values of the non-ideal parameter, adiabatic index, and shock Cowling number. The “Mathematica” software has been used to do all numerical computations.

A numerical study of relativistic oblique shock reflection

Shocks are ubiquitous in astrophysical sources, many of which involve relativistic bulk motions, leading to the formation of relativistic shocks. Such relativistic shocks have so far been studied mainly in one dimension, for simplicity, but the complex nature of the relevant astrophysical flows often requires higher-dimensional studies. Here, we study the two-dimensional problem of the reflection of a planer shock off of a wall for a general incidence angle and a cold unshocked medium. We use primarily relativistic hydrodynamic numerical simulations and elaborately compare the results to an analytic treatment. The simulations are performed both in the rest frame S of the unshocked fluid, where the dimensionless proper speed of the singly shocked fluid is u1=Γ1β1 and the shock incidence angle is α1, and in the rest frame S′ of the point P of intersection of the incident shock and the wall for regular reflection (RR). Good agreement is obtained between the simulations in these two frames and with the analytic solution. The establishment of a steady flow in frame S′ is explored, along with the transition between the strong and weak shock RR solutions. The transition line between RR and Mach reflection is studied numerically in the u1 − α1 plane and found to coincide with the analytic detachment/sonic line. The flow properties along the sonic line are investigated in detail focusing on how they vary between the Newtonian and relativistic limits.

Internal shocks hydrodynamics: the collision of two cold shells in detail

ABSTRACT Emission in many astrophysical transients originates from a shocked fluid. A central engine typically produces an outflow with varying speeds, leading to internal collisions within the outflow at finite distances from the source. Each such collision produces a pair of forward and reverse shocks with the two shocked regions separated by a contact discontinuity (CD). As a useful approximation, we consider the head-on collision between two cold and uniform shells (a slower leading shell and a faster trailing shell) of finite radial width, and study the dynamics of shock propagation in planar geometry. We find significant differences between the forward and reverse shocks, in terms of their strength, internal energy production efficiency, and the time it takes for the shocks to sweep through the respective shells. We consider the subsequent propagation of rarefaction waves in the shocked regions and explore the cases where these waves can catch up with the shock fronts and thereby limit the internal energy dissipation. We demonstrate the importance of energy transfer from the trailing to leading shell through pdV work across the CD. We outline the parameter space regions relevant for models of different transients,e.g. Gamma-ray burst internal shock model, fast radio burst blast wave model, Giant flare due to magnetars, and superluminous supernovae ejecta. We find that the reverse shock likely dominates the internal energy production for many astrophysical transients.

Major Publications in the Critical Care Pharmacotherapy Literature: 2022.

A number of trials related to critical care pharmacotherapy were published in 2022. We aimed to summarize the most influential publications related to the pharmacotherapeutic care of critically ill patients in 2022. PubMed/Medical Literature Analysis and Retrieval System Online and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update. Randomized controlled trials, prospective studies, or systematic review/meta-analyses of adult critically ill patients assessing a pharmacotherapeutic intervention and reporting clinical endpoints published between January 1, 2022, and December 31, 2022, were included in this article. Articles from a systematic search and the Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update were included and stratified into clinical domains based upon consistent themes. Consensus was obtained on the most influential publication within each clinical domain utilizing an a priori defined three-round modified Delphi process with the following considerations: 1) overall contribution to scientific knowledge and 2) novelty to the literature. The systematic search and Clinical Pharmacy and Pharmacology Pharmacotherapy Literature Update yielded a total of 704 articles, of which 660 were excluded. The remaining 44 articles were stratified into the following clinical domains: emergency/neurology, cardiovascular, gastroenterology/fluids/nutrition, hematology, infectious diseases/immunomodulation, and endocrine/metabolic. The final article selected from each clinical domain was summarized following a three-round modified Delphi process and included three randomized controlled trials and three systematic review/meta-analyses. Article topics summarized included dexmedetomidine versus other sedatives during mechanical ventilation, beta-blocker treatment in the critically ill, restriction of IV fluids in septic shock, venous thromboembolism prophylaxis in critically ill adults, duration of antibiotic therapy for Pseudomonas aeruginosa ventilator-associated pneumonia, and low-dose methylprednisolone treatment in severe community-acquired pneumonia. This concise review provides a perspective on articles published in 2022 that are relevant to the pharmacotherapeutic care of critically ill patients and their potential impact on clinical practice.

Fluid Resuscitation in Patients With Traumatic Brain Injury: A Comprehensive Review.

Patients with traumatic brain injury (TBI) or head trauma present challenges for emergency physicians and neurosurgeons. Traumatic brain injury is currently a community health issue. For the best possible care, it is crucial to understand the various helpful therapy techniques in the pre-operative and pre-hospital phases. The initial rapid infusion of large volumes of mannitol and a hypertonic crystalloid solution to restore blood pressure and blood volume is the current standard of care for people with combined hemorrhagic shock (HS) and traumatic brain injury. The selection and administration of fluids to trauma and traumatic brain injury patients may be especially helpful in preventing subsequent ischemic brain damage because of the hemodynamic stabilizing effects of these fluids in hypovolemic shock. Traumatic brain injury is an essential factor that may lead to disability and death in a patient. Traumatic brain damage can develop either as a direct result of the trauma or as a result of the initial harm. Significant neurologic problems, such as cranial nerve damage, dementia, seizures, and Alzheimer's disease, can develop after a traumatic brain injury. The comorbidity of the victims may also be significantly increased by additional psychiatric problems such as psychological diseases and other behavioral and cognitive sequels. We review the history of modern fluid therapy, complications after traumatic brain injury, and the use of fluid treatment for decompressive craniectomy and traumatic brain injury.