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3 results on '"Ultra short"'

1. The concomitant use of ultra short beta-blockers with vasopressors and inotropes in critically ill patients with septic shock: A systematic review and meta-analysis of randomized controlled trials

Author

Khalid Al Sulaiman, Hadeel A. Alkofide, Mashael E. AlFaifi, Sarah S. Aljohani, Abdullah F. Al Harthi, Rahaf A. Alqahtani, Ashwaq M. Alanazi, Lama H. Nazer, Abdulrahman I. Al Shaya, and Ohoud Aljuhani

Subjects
Ultra short, Beta-blockers, Meta-Analyses, Concomitant use, Inotropes, Vasopressors, Therapeutics. Pharmacology, RM1-950
Abstract

Background: Septic shock is associated with systemic inflammatory response, hemodynamic instability, impaired sympathetic control, and the development of multiorgan dysfunction that requires vasopressor or inotropic support. The regulation of immune function in sepsis is complex and varies over time. However, activating Beta-2 receptors and blocking Beta-1 receptors reduces the proinflammatory response by influencing cytokine production. Evidence that supports the concomitant use of ultra short beta-blockers with inotropes and vasopressors in patients with septic shock is still limited. This study aimed to evaluate the use of ultra short beta-blockers and its impact on the ICU related outcomes such as mortality, length of stay, heart rate control, shock resolution, and vasopressors/inotropes requirements. Methods: A systematic review and meta-analysis of randomized controlled trials including critically ill patients with septic shock who received inotropes and vasopressors. Patients who received either epinephrine or norepinephrine without beta-blockers “control group” were compared to patients who received ultra short beta-blockers concomitantly with either epinephrine or norepinephrine “Intervention group”. MEDLINE and Embase databases were utilized to systematically search for studies investigating the use of ultra short beta-blockers in critically ill patients on either epinephrine or norepinephrine from inception to October 10, 2023. The primary outcome was the 28-day mortality. While, length of stay, heart rate control, and inotropes/ vasopressors requirements were considered secondary outcomes. Results: Among 47 potentially relevant studies, nine were included in the analysis. The 28-day mortality risk was lower in patients with septic shock who used ultra short beta-blockers concomitantly with either epinephrine or norepinephrine compared with the control group (RR (95%CI): 0.69 (0.53, 0.89), I2=26%; P=0.24). In addition, heart rate was statistically significantly lower with a standardized mean difference (SMD) of -22.39 (95% CI: -24.71, –20.06) among the beta-blockers group than the control group. The SMD for hospital length of stay and the inotropes requirement were not statistically different between the two groups (SMD (95%CI): -0.57 (-2.77, 1.64), and SMD (95%CI): 0.08 (-0.02, 0.19), respectively). Conclusion: The use of ultra short beta-blockers concomitantly with either epinephrine or norepinephrine in critically ill patients with septic shock was associated with better heart rate control and survival benefits without increment in the inotropes and vasopressors requirement.

Published
2024
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2. The concomitant use of ultra short beta-blockers with vasopressors and inotropes in critically ill patients with septic shock: A systematic review and meta-analysis of randomized controlled trials.

Author

Al Sulaiman, Khalid, Alkofide, Hadeel A., AlFaifi, Mashael E., Aljohani, Sarah S., Al Harthi, Abdullah F., Alqahtani, Rahaf A., Alanazi, Ashwaq M., Nazer, Lama H., Al Shaya, Abdulrahman I., and Aljuhani, Ohoud

Abstract

Septic shock is associated with systemic inflammatory response, hemodynamic instability, impaired sympathetic control, and the development of multiorgan dysfunction that requires vasopressor or inotropic support. The regulation of immune function in sepsis is complex and varies over time. However, activating Beta-2 receptors and blocking Beta-1 receptors reduces the proinflammatory response by influencing cytokine production. Evidence that supports the concomitant use of ultra short beta-blockers with inotropes and vasopressors in patients with septic shock is still limited. This study aimed to evaluate the use of ultra short beta-blockers and its impact on the ICU related outcomes such as mortality, length of stay, heart rate control, shock resolution, and vasopressors/inotropes requirements. A systematic review and meta-analysis of randomized controlled trials including critically ill patients with septic shock who received inotropes and vasopressors. Patients who received either epinephrine or norepinephrine without beta-blockers "control group" were compared to patients who received ultra short beta-blockers concomitantly with either epinephrine or norepinephrine "Intervention group". MEDLINE and Embase databases were utilized to systematically search for studies investigating the use of ultra short beta-blockers in critically ill patients on either epinephrine or norepinephrine from inception to October 10, 2023. The primary outcome was the 28-day mortality. While, length of stay, heart rate control, and inotropes/ vasopressors requirements were considered secondary outcomes. Among 47 potentially relevant studies, nine were included in the analysis. The 28-day mortality risk was lower in patients with septic shock who used ultra short beta-blockers concomitantly with either epinephrine or norepinephrine compared with the control group (RR (95%CI): 0.69 (0.53, 0.89), I 2=26%; P =0.24). In addition, heart rate was statistically significantly lower with a standardized mean difference (SMD) of -22.39 (95% CI: -24.71, –20.06) among the beta-blockers group than the control group. The SMD for hospital length of stay and the inotropes requirement were not statistically different between the two groups (SMD (95%CI): -0.57 (-2.77, 1.64), and SMD (95%CI): 0.08 (-0.02, 0.19), respectively). The use of ultra short beta-blockers concomitantly with either epinephrine or norepinephrine in critically ill patients with septic shock was associated with better heart rate control and survival benefits without increment in the inotropes and vasopressors requirement. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Novel Pump-Probe Particle-In-Cell Simulations of Relativistic Transparency and Birefringence

Author

Pozderac, Preston

Subjects
Physics, Plasma Physics, relativistic transparency, relativistic birefringence, ultra intense, ultra short, laser, plasma, relativistic plasma, particle in cell, pump probe
Abstract

In this work we investigate the important phenomenon of relativistic transparency (RT) and the related effect of relativistic birefringence (RB) in the field of ultra-intense laser-plasma interactions. RT occurs when a highly intense laser (exceeding 1018 W/cm2) is incident on a classically opaque plasma. As the electrons are driven to relativistic speeds, there is an effective relativistic mass increase that can lead to a relativistically transparent plasma. Furthermore, the electrons are driven more in the polarization direction of the laser leading to a nonuniform dielectric tensor and a relativistically birefringent plasma. These two fundamental phenomena are present, to some degree, in all ultra-intense laser target interactions and can significantly influence applications of high power lasers. RT is a major contributor to the enhancement of laser-driven ion acceleration schemes and the utilization of plasmas as optical devices like mirrors, apertures, or polarizers.We present a computational study into RT and RB using a novel optical pump optical probe setup and the particle-in-cell (PIC) method. The framework is based on an experimental study at the Scarlet laser facility providing one of the few extant direct measurements of RT and the first experimental observation of RB. A high intensity 1021 W/cm2 pump was obliquely incident on an ultra-thin 20 nm 8CB liquid crystal (LC) target, exciting a relativistic plasma. A lower intensity 1018 W/cm2 probe was near normally incident with a varying polarization and delay time, relative to the pump, in order to diagnose the dynamics of RT and RB. In the simulations described here, the plasma target has its thickness and electron density proportionally scaled to simulate different pre-expanded targets with a constant areal density across all of them.Simulation diagnostics are utilized to assess the primary experimental diagnostics: the transmission and polarization state of each laser individually as a function of probe delay and target thickness. The transmission is derived from each polarization component intensity leaving the simulation boundary in a relevant collection region. The polarization state is measured by calculating the Stokes parameters from the electric fields within the same collection region.Due to the issue of signal-to-noise ratio between the strong pump and relatively weak probe, background removal techniques are implemented to appropriately isolate the probe signal. A simulation without the probe present provides removal of the bulk pump signal and the probe is further isolated by applying a band-pass filter on a proxy probe shifted by 200 nm in wavelength (from 800 nm to 1000 nm).In addition, the plasma conditions are studied as a function of time to determine the effect the electron density, relativistic factor &#947, and momentum distributions have on the interaction. The theory states that the ratio of the electron density and &#947 indicates if the target is relativistically transparent and that anisotropy in the momentum leads to a relativistically birefringent plasma.Our simulation results corroborate the experimental results, including a return to opacity after RT is achieved. Based on the measured pump transmission, an estimation of pre-expansion due to the experimental pre-pulse is found to expand the initial 20 nm thin target to 2 &#956m. We find that the temporal dynamics of RT exhibits a rapid turn on in the presence of the pump and an equally rapid return to classical opacity from novel dynamical high-density structures in the target. A relativistic hole can be directly viewed by plotting a normalized relativistic electron density and persists on the duration and spatial size relative to the pump duration and spot size, 30 fs and 1.2 &#956m at FWHM respectively.Moreover, there is a clear anisotropy in the electron momentum distribution present during RT. This anisotropy generates a large positive induced ellipticity change to the mixed polarization probe laser in both simulation, Δχ ≥ 10°, and experiment, Δχ = 7.8°, that cannot be due to magnetic effects. As a culmination of this work, our framework is extended beyond the initial experiment to observe universal behavior of RT across nearly two orders of magnitude in pump intensity, from ∼1020-22 W/cm2, when the electron density is scaled appropriately. We observe the plasma conditions and laser transmission undergo the same temporal dynamics of sharp turn on and off with the pump and a constant ∼15% pump transmission. This work has produced a substantial collection of results to describe RT and RB behavior, and is well situated to diagnose a variety of experimental setups at different laser facilities along with the applications of relativistic plasmas.

Published
2022

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