Rationality of utilization of antimicrobial agents in medical intensive care unit of a tertiary care hospital

Background: Patients admitted to intensive care unit receive multiple medications of different pharmacological classes due to various life threatening ailments. This study was conducted to assess the patterns of usage of antimicrobial agents in medical ICU of a tertiary care hospital and to suggest necessary modifications in prescribing patterns to achieve rational therapeutic practices.Methods: A cross-sectional observational study was carried out at ICU of the tertiary care hospital for 6 months. From the inpatient case record of ICU relevant data on prescription of each patient was collected. The demographic status, disease data and the utilization of different antimicrobial drug classes and individual drugs were analysed.Results: Of 753 patients admitted in the medical ICU during the study period, 640 consecutive patients were included for analysis. Male to female ratio was 1.45. Mean age was 63.32±17.93 years. Extensive poly-pharmacy (100%) and drugs with non-generic name (73%) noticed among the prescriptions.Average number of drugs per prescription was 12.1±2.13. Penicillins (51.87%) and cephalosporins (45.78%) were most commonly used antimicrobial drug classes. Piperacillin (37.03%), ceftriaxone (33.28%) and levofloxacin (22.5%) were commonly used antimicrobial drugs. A total of 181 prescriptions contained two and 138 contained three antimicrobial drugs. Piperacillin+tazobactam(37.03%) was the most common fixed dose combination noticed.Conclusions: Overall extensive poly-pharmacy and drugs with non-generic name noticed among the prescriptions. Few interventional programs should be aimed at control of infections, rational antimicrobial drug prescription to minimize adverse drug events, emergence of bacterial resistance and attenuating unnecessary cost

Direct electron attachment to fast hydrogen in 10^-9 contrast 10^18 Wcm^-2 intense laser solid target interaction

The interaction of an ultra-short (10^18 Wcm^-2) laser pulse with a solid target is not generally known to produce and accelerate negative ions. The transient accelerating electrostatic-fields are so strong that they ionize any atom or negative ion at the target surface. In spite of what may appear to be unfavourable conditions, here it is reported that H- ions extending up to 80 keV are measured from such an interaction. The H- ion flux is about 0.1 % that of the H+ ions at 20 keV. These measurements employ a recently developed temporally-gated Thomson parabola ion spectrometry diagnostic which significantly improves signal-to-noise ratios. Electrons that co-propagate with the fast protons cause a two-step charge-reduction reaction. The gas phase three-body attachment of electrons to fast neutral hydrogen atoms accounts for the measured H- yield. It is intriguing that such a fundamental gas-phase reaction, involving the attachment of an electron to a hydrogen atom, has not been observed in laboratory experiments previously. Laser-produced plasma offers an alternative environment to the conventional charged particle beam experiments, in which such atomic physics processes can be investigated

Recombination of Protons Accelerated by a High Intensity High Contrast Laser

Short pulse, high contrast, intense laser pulses incident onto a solid target are not known to generate fast neutral atoms. Experiments carried out to study the recombination of accelerated protons show a 200 times higher neutralization than expected. Fast neutral atoms can contribute to 80% of the fast particles at 10 keV, falling rapidly for higher energy. Conventional charge transfer and electron-ion recombination in a high density plasma plume near the target is unable to explain the neutralization. We present a model based on the copropagation of electrons and ions wherein recombination far away from the target surface accounts for the experimental measurements. A novel experimental verification of the model is also presented. This study provides insights into the closely linked dynamics of ions and electrons by which neutral atom formation is enhanced

Electron acceleration by a transient intense-laser-plasma electrode

Rapid strides in the technology of laser plasma-based acceleration of charged particles leading to high brightness, tunable, monochromatic energetic beams of electrons and ions has been driven by potential multidisciplinary applications in cancer therapy, isotope preparation, radiography and thermonuclear fusion. Hitherto laser plasma acceleration schemes were confined to large-scale facilities generating a few tens of terawatt to petawatt laser pulses at repetition rates of 10 Hz or less. However, the need to make viable systems using high-repetition-rate femtosecond lasers has impelled recent research into novel targetry [1,2]. Of contemporary importance is the generation of supra thermal electrons, beyond those predicted by the scaling relation, reflected in both theoretical and computational work [3,4]. In this work we present evidence of generation of relativistic electrons (temperature >200 keV, maximum energies >1 MeV) at intensities that are two orders of magnitude lower than the relativistic intensity threshold. The novel targets [6] are 15 micron sized crystals suspended as aerosols in a gas interacting with a kHz, few-mJ femtosecond laser focussed to intensities of 10 PW/cm2. A pre-pulse with 1-5% of the intensity of the main pulse, arriving 4 ns early, is critical for hot electron generation. In addition to this unprecedented energy enhancement, we also characterize the dependence of X-ray spectra on the background gas of the aerosol. Intriguingly, easier the gas is to ionise, greater is the number of hot electrons observed, while the electron temperature remains the same. 2-D Radiation hydrodynamics and Particle-in-cell (PIC) simulations explain both the experimentally observed electron emission and the role of the low-density plasma in yield enhancement. We observe a two-temperature electron spectrum with about 50 and 240 keV temperatures consistent with the measurements made in the experiments. The simulations show that the following features contribute to the high-energy electron emission. The pre-pulse generates a hemispherical plasma-profile that enhances the coupling of the laser light. Overdense plasma is generated about the hemispherical cavity on the particle due to the main pulse interaction. The gradient in the plasma density in and around the cavity serves as a reservoir of low energy electrons to be injected into the particle potential and enables the hot electron generation observed in the experiments. Higher energy electron emission is dominantly from the edges of the hemispherical cavitation. The increase in total X-ray yield observed in the experiments scales with the number of electrons generated in the low density neighborhood surrounding the particle. In a simple-man picture, the laser interacts with the particle and ejects electrons from the particle. The particle acquires a strong positive potential that can only be brought down by ion expansion that occurs over 10's of picoseconds. The particle with strong positive potential acts as an 'accelerating electrode' for the electrons ionized in the low-density gas neighborhood. These results assume importance in the context of applications such as fast fuel ignition [6] or in medical applications of laser plasmas [7] where high irradiance of energetic electrons is of consequence. 1. D. Gustas et al., Phys. Rev. Accel. Beams, 21, 013401 (2018). 2. S. Feister et al , Opt. Express, 25, 18736 (2017). 3. B. S. Paradkar, S. I. Krasheninnikov, and F. N. Beg, Physics of Plasmas, 19, 060703 (2012). 4. A. P. L. Robinson, A. V. Areev, and D. Neely, Phys. Rev. Lett., 111, 065002 (2013). 5. R. Gopal, et al., Review of Scientific Instruments, 88, 023301 (2017). 6. M. Tabak et al., Physics of Plasmas, 1, 1626 (1994). 7. A. Sjogren, M. Harbst, C.-G. Wahlstrom, S. Svanberg, and C. Olsson, Review of Scientific Instruments, 74, 2300 (2003)

Shaped liquid drops generate MeV temperature electron beams with millijoule class laser

MeV temperature electrons are typically generated at laser intensities of 1018 W cm−2. Their generation at non-relativistic intensities (~1016 W cm−2) with high repetition rate lasers is cardinal for the realization of compact, ultra-fast electron sources. Here we report a technique of dynamic target structuring of micro-droplets using a 1 kHz, 25 fs, millijoule class laser, that uses two collinear laser pulses; the first to create a concave surface in the liquid drop and the second, to dynamically-drive electrostatic plasma waves that accelerate electrons to MeV energies. The acceleration mechanism, identified as two plasmon decay instability, is shown to generate two beams of electrons with hot electron temperature components of 200 keV and 1 MeV, respectively, at an intensity of 4 × 1016 Wcm−2, only. The electron beams are demonstrated to be ideal for single shot high resolution (tens of μm) electron radiography

Shaped liquid drops generate MeV temperature electron beams with millijoule class laser

MeV temperature electrons are typically generated at laser intensities of 1018 W cm−2. Their generation at non-relativistic intensities (~1016 W cm−2) with high repetition rate lasers is cardinal for the realization of compact, ultra-fast electron sources. Here we report a technique of dynamic target structuring of micro-droplets using a 1 kHz, 25 fs, millijoule class laser, that uses two collinear laser pulses; the first to create a concave surface in the liquid drop and the second, to dynamically-drive electrostatic plasma waves that accelerate electrons to MeV energies. The acceleration mechanism, identified as two plasmon decay instability, is shown to generate two beams of electrons with hot electron temperature components of 200 keV and 1 MeV, respectively, at an intensity of 4 × 1016 Wcm−2, only. The electron beams are demonstrated to be ideal for single shot high resolution (tens of μm) electron radiography

Laser structured micro-targets generate MeV electron temperature at 4 x10^16 W/cm^2

Relativistic temperature electrons higher than 0.5 MeV are generated typically with laser intensities of about 10^18 W/cm^2. Their generation with high repetition rate lasers that operate at non-relativistic intensities (~10^16W/cm^2) is cardinal for the realization of compact, ultra-short, bench-top electron sources. New strategies, capable of exploiting different aspects of laser-plasma interaction, are necessary for reducing the required intensity. We report here, a novel technique of dynamic target structuring of microdroplets, capable of generating 200 keV and 1 MeV electron temperatures at 1/100th of the intensity required by ponderomotive scaling(10^18 W/cm^2) to generate relativistic electron temperature. Combining the concepts of pre-plasma tailoring, optimized scale length and micro-optics, this method achieves two-plasmon decay boosted electron acceleration with "non-ideal" ultrashort (25 fs) pulses at 4 x10^16 W/cm^2 only. With shot repeatability at kHz, this precise in-situ targetry produces directed, imaging quality beam-like electron emission up to 6 MeV with milli-joule class lasers, that can be transformational for time-resolved, microscopic studies in all fields of science

Rationality of utilization of antimicrobial agents in medical intensive care unit of a tertiary care hospital

Background: Patients admitted to intensive care unit receive multiple medications of different pharmacological classes due to various life threatening ailments. This study was conducted to assess the patterns of usage of antimicrobial agents in medical ICU of a tertiary care hospital and to suggest necessary modifications in prescribing patterns to achieve rational therapeutic practices.Methods: A cross-sectional observational study was carried out at ICU of the tertiary care hospital for 6 months. From the inpatient case record of ICU relevant data on prescription of each patient was collected. The demographic status, disease data and the utilization of different antimicrobial drug classes and individual drugs were analysed.Results: Of 753 patients admitted in the medical ICU during the study period, 640 consecutive patients were included for analysis. Male to female ratio was 1.45. Mean age was 63.32±17.93 years. Extensive poly-pharmacy (100%) and drugs with non-generic name (73%) noticed among the prescriptions.Average number of drugs per prescription was 12.1±2.13. Penicillins (51.87%) and cephalosporins (45.78%) were most commonly used antimicrobial drug classes. Piperacillin (37.03%), ceftriaxone (33.28%) and levofloxacin (22.5%) were commonly used antimicrobial drugs. A total of 181 prescriptions contained two and 138 contained three antimicrobial drugs. Piperacillin+tazobactam(37.03%) was the most common fixed dose combination noticed.Conclusions: Overall extensive poly-pharmacy and drugs with non-generic name noticed among the prescriptions. Few interventional programs should be aimed at control of infections, rational antimicrobial drug prescription to minimize adverse drug events, emergence of bacterial resistance and attenuating unnecessary cost

Uncertainty-Aware Convolutional Neural Network for Identifying Bilateral Opacities on Chest X-rays: A Tool to Aid Diagnosis of Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome (ARDS) is a severe lung injury with high mortality, primarily characterized by bilateral pulmonary opacities on chest radiographs and hypoxemia. In this work, we trained a convolutional neural network (CNN) model that can reliably identify bilateral opacities on routine chest X-ray images of critically ill patients. We propose this model as a tool to generate predictive alerts for possible ARDS cases, enabling early diagnosis. Our team created a unique dataset of 7800 single-view chest-X-ray images labeled for the presence of bilateral or unilateral pulmonary opacities, or ‘equivocal’ images, by three blinded clinicians. We used a novel training technique that enables the CNN to explicitly predict the ‘equivocal’ class using an uncertainty-aware label smoothing loss. We achieved an Area under the Receiver Operating Characteristic Curve (AUROC) of 0.82 (95% CI: 0.80, 0.85), a precision of 0.75 (95% CI: 0.73, 0.78), and a sensitivity of 0.76 (95% CI: 0.73, 0.78) on the internal test set while achieving an (AUROC) of 0.84 (95% CI: 0.81, 0.86), a precision of 0.73 (95% CI: 0.63, 0.69), and a sensitivity of 0.73 (95% CI: 0.70, 0.75) on an external validation set. Further, our results show that this approach improves the model calibration and diagnostic odds ratio of the hypothesized alert tool, making it ideal for clinical decision support systems

High-harmonic spectroscopy of low-energy electron-scattering dynamics in liquids

High-harmonic spectroscopy is an all-optical nonlinear technique with inherent attosecond temporal resolution. It has been applied to a variety of systems in the gas phase and solid state. Here we extend its use to liquid samples. By studying high-harmonic generation over a broad range of wavelengths and intensities, we show that the cut-off energy is independent of the wavelength beyond a threshold intensity and that it is a characteristic property of the studied liquid. We explain these observations with a semi-classical model based on electron trajectories that are limited by the electron scattering. This is further confirmed by measurements performed with elliptically polarized light and with ab-initio time-dependent density functional theory calculations. Our results propose high-harmonic spectroscopy as an all-optical approach for determining the effective mean free paths of slow electrons in liquids. This regime is extremely difficult to access with other methodologies, but is critical for understanding radiation damage to living tissues. Our work also indicates the possibility of resolving subfemtosecond electron dynamics in liquids offering an all-optical approach to attosecond spectroscopy of chemical processes in their native liquid environment.ISSN:1745-2473ISSN:1745-248