Clinico-radiological related to early brain death factors

OBJECTIVE

To identify clinical and radiological factors associated to early evolution to brain death (BD), defined as occurring within the first 24 h.

DESIGN

A retrospective cohort study was made covering the period 2015-2017.

SETTING

An adult Intensive Care Unit (ICU).

PATIENTS/METHODS

Epidemiological, clinical and imaging (CT scan) parameters upon admission to the ICU in patients evolving to BD.

RESULTS

A total of 166 patients with BD (86 males, mean age 62.7 years) were analyzed. Primary cause: intracerebral hemorrhage 42.8%, subarachnoid hemorrhage 18.7%, traumatic brain injury 17.5%, anoxia 9%, stroke 7.8%, other causes 4.2%. Epidemiological data: arterial hypertension 50%, dyslipidemia 34%, smoking 33%, antiplatelet medication 21%, alcoholism 19%, anticoagulant therapy 15%, diabetes 15%. The Glasgow Coma Score (GCS) upon admission was 3 in 68.8% of the cases in early BD versus in 38.2% of the cases in BD occurring after 24 h (p = 0.0001). Eighty-five patients presented supratentorial hematomas with a volume of 90.9 ml in early BD versus 82.7 ml in BD > 24 h (p = 0.54). The mean midline shift was 10.7 mm in early BD versus 7.8 mm in BD > 24 h (p = 0.045). Ninety-one patients presented ventriculomegaly and 38 additionally ependymal transudation (p = 0.021). Thirty-six patients with early BD versus 24 with BD > 24 h presented complete effacement of basal cisterns (p = 0.005), sulcular effacement (p = 0.013), loss of cortico-subcortical differentiation (p = 0.0001) and effacement of the suprasellar cistern (p = 0.005). The optic nerve sheath measurements showed no significant differences between groups.

CONCLUSIONS

Early BD (>24 h) was associated to GCS < 5, midline shift, effacement of the basal cisterns, cerebral sulci and suprasellar cistern, and ependymal transudation.

Mortality comparison between the first and second/third waves among 3,795 critical COVID-19 patients with pneumonia admitted to the ICU: A multicentre retrospective cohort study

Background

It is unclear whether the changes in critical care throughout the pandemic have improved the outcomes in coronavirus disease 2019 (COVID-19) patients admitted to the intensive care units (ICUs).

Methods

We conducted a retrospective cohort study in adults with COVID-19 pneumonia admitted to 73 ICUs from Spain, Andorra and Ireland between February 2020 and March 2021. The first wave corresponded with the period from February 2020 to June 2020, whereas the second/third waves occurred from July 2020 to March 2021. The primary outcome was ICU mortality between study periods. Mortality predictors and differences in mortality between COVID-19 waves were identified using logistic regression.

Findings

As of March 2021, the participating ICUs had included 3795 COVID-19 pneumonia patients, 2479 (65·3%) and 1316 (34·7%) belonging to the first and second/third waves, respectively. Illness severity scores predicting mortality were lower in the second/third waves compared with the first wave according with the Acute Physiology and Chronic Health Evaluation system (median APACHE II score 12 [IQR 9–16] vs 14 [IQR 10–19]) and the organ failure assessment score (median SOFA 4 [3–6] vs 5 [3–7], p<0·001). The need of invasive mechanical ventilation was high (76·1%) during the whole study period. However, a significant increase in the use of high flow nasal cannula (48·7% vs 18·2%, p<0·001) was found in the second/third waves compared with the first surge. Significant changes on treatments prescribed were also observed, highlighting the remarkable increase on the use of corticosteroids to up to 95.9% in the second/third waves. A significant reduction on the use of tocilizumab was found during the study (first wave 28·9% vs second/third waves 6·2%, p<0·001), and a negligible administration of lopinavir/ritonavir, hydroxychloroquine, and interferon during the second/third waves compared with the first wave. Overall ICU mortality was 30·7% (n = 1166), without significant differences between study periods (first wave 31·7% vs second/third waves 28·8%, p = 0·06). No significant differences were found in ICU mortality between waves according to age subsets except for the subgroup of 61–75 years of age, in whom a reduced unadjusted ICU mortality was observed in the second/third waves (first 38·7% vs second/third 34·0%, p = 0·048). Non-survivors were older, with higher severity of the disease, had more comorbidities, and developed more complications. After adjusting for confounding factors through a multivariable analysis, no significant association was found between the COVID-19 waves and mortality (OR 0·81, 95% CI 0·64–1·03; p = 0·09). Ventilator-associated pneumonia rate increased significantly during the second/third waves and it was independently associated with ICU mortality (OR 1·48, 95% CI 1·19–1·85, p<0·001). Nevertheless, a significant reduction both in the ICU and hospital length of stay in survivors was observed during the second/third waves.

Interpretation

Despite substantial changes on supportive care and management, we did not find significant improvement on case-fatality rates among critical COVID-19 pneumonia patients.

Funding

Ricardo Barri Casanovas Foundation (RBCF2020) and SEMICYUC.

Propagative Oscillations in Codirectional Polariton Waveguide Couplers

We report on novel exciton-polariton routing devices created to study and purposely guide light-matter particles in their condensate phase. In a codirectional coupling device, two waveguides are connected by a partially etched section that facilitates tunable coupling of the adjacent channels. This evanescent coupling of the two macroscopic wave functions in each waveguide reveals itself in real space oscillations of the condensate. This Josephson-like oscillation has only been observed in coupled polariton traps so far. Here, we report on a similar coupling behavior in a controllable, propagative waveguide-based design. By controlling the gap width, channel length, or propagation energy, the exit port of the polariton flow can be chosen. This codirectional polariton device is a passive and scalable coupler element that can serve in compact, next generation logic architectures.

Clinico-radiological related to early brain death factors

OBJECTIVE

To identify clinical and radiological factors associated to early evolution to brain death (BD), defined as occurring within the first 24 hours.

DESIGN

A retrospective cohort study was made covering the period 2015-2017.

SETTING

An adult Intensive Care Unit (ICU).

PATIENTS/METHODS

Epidemiological, clinical and imaging (CT scan) parameters upon admission to the ICU in patients evolving to BD.

RESULTS

A total of 166 patients with BD (86 males, mean age 62.7 years) were analyzed. Primary cause: intracerebral hemorrhage 42.8%, subarachnoid hemorrhage 18.7%, traumatic brain injury 17.5%, anoxia 9%, stroke 7.8%, other causes 4.2%. Epidemiological data: arterial hypertension 50%, dyslipidemia 34%, smoking 33%, antiplatelet medication 21%, alcoholism 19%, anticoagulant therapy 15%, diabetes 15%. The Glasgow Coma Score (GCS) upon admission was 3 in 68.8% of the cases in early BD versus in 38.2% of the cases in BD occurring after 24 h (p = 0.0001). Eighty-five patients presented supratentorial hematomas with a volume of 90.9 ml in early BD versus 82.7 ml in BD >24 h (p = 0.54). The mean midline shift was 10.7 mm in early BD versus 7.8 mm in BD >24 h (p = 0.045). Ninety-one patients presented ventriculomegaly and 38 additionally ependymal transudation (p = 0.021). Thirty-six patients with early BD versus 24 with BD >24 h presented complete effacement of basal cisterns (p = 0.005), sulcular effacement (p = 0.013), loss of cortico-subcortical differentiation (p = 0.0001) and effacement of the suprasellar cistern (p = 0.005). The optic nerve sheath measurements showed no significant differences between groups.

CONCLUSIONS

Early BD (>24 h) was associated to GCS < 5, midline shift, effacement of the basal cisterns, cerebral sulci and suprasellar cistern, and ependymal transudation.

Comparative efficacy of linezolid and vancomycin for endotracheal tube MRSA biofilms from ICU patients

PURPOSE

To compare the efficacy of systemic treatment with linezolid (LNZ) versus vancomycin (VAN) on methicillin-resistant Staphylococcus aureus (MRSA) burden and eradication in endotracheal tube (ETT) biofilm and ETT cuff from orotracheally intubated patients with MRSA respiratory infection.

METHODS

Prospective observational clinical study was carried out at four European tertiary hospitals. Plasma and endotracheal aspirate (ETA) levels of LNZ and VAN were determined 72 h after treatment initiation through high-performance liquid chromatography or bioassay. LNZ or VAN concentration in the ETT biofilm and MRSA burden and eradication was determined upon extubation. The minimum inhibitory concentration (MIC) for LNZ and VAN was assessed by E-test strips (Biomerieux®). Scanning electron microscopy images were obtained, and ETT biofilm thickness was compared between groups.

RESULTS

Twenty-five patients, 15 treated with LNZ and 10 with VAN, were included in the study. LNZ presented a significantly higher concentration (μg/mL) than VAN in ETT biofilm (72.8 [1.3-127.1] vs 0.4 [0.4-1.3], p < 0.001), although both drugs achieved therapeutic plasma levels 72 h after treatment initiation. Systemic treatment with LNZ achieved lower ETT cuff MRSA burdens than systemic treatment with VAN. Indeed, LNZ increased the MRSA eradication rate in ETT cuff compared with VAN (LNZ 75%, VAN 20%, p = 0.031).

CONCLUSIONS

In ICU patients with MRSA respiratory infection intubated for long periods, systemic treatment with LNZ obtains a greater beneficial effect than VAN in limiting MRSA burden in ETT cuff.

[Meningitis/Encephalitis diagnosis in ICU using Multiplex PCR system: Is it time of change?]

OBJECTIVE

To evaluate the clinical impact of Meningitis/Encephalitis FilmArray® panel for the diagnosis of cerebral nervous system infection and to compare the results (including time for diagnosis) with those obtained by conventional microbiological techniques.

METHODS

A prospective observational study in an Intensive Care Unit of adults from a tertiary hospital was carried out. Cerebrospinal fluid from all patients was taken by lumbar puncture and assessed by the meningitis/encephalitis FilmArray® panel ME, cytochemical study, Gram, and conventional microbiological cultures.

RESULTS

A total of 21 patients admitted with suspicion of Meningitis/Encephalitis. Median age of patients was 58.4 years (RIQ 38.1-67.3), median APACHE II 18 (RIQ 12-24). Median stay in ICU and median hospital stay was 4 (RIQ 2-6) and 17 days (RIQ 14-28), respectively. The overall mortality was 14.3%. A final clinical diagnosis of meningitis or encephalitis was established in 16 patients, obtaining the etiological diagnosis in 12 of them (75%). The most frequent etiology was Streptococcus pneumoniae (8 cases). FilmArray® allowed etiological diagnosis in 3 cases in which the culture had been negative, and the results led to changes in the empirical antimicrobial therapy in 7 of 16 cases (43.8%). FilmArray® yielded a global sensitivity and specificity of 100% and 90%, respectively. The median time to obtain results from the latter and conventional culture (including antibiogram) was 2.9 hours (RIQ 2.1-3.8) and 45.1 hours (RIQ 38.9-58.7), respectively.

CONCLUSIONS

The Meningitis/Encephalitis FilmArray® panel was able to establish the etiologic diagnosis faster than conventional methods. Also, it achieved a better sensitivity and led to prompt targeted antimicrobial therapy.

Infectious complications related to external ventricular shunt. Incidence and risk factors

OBJECTIVE

Infectious complications related to external ventricular shunt (ICREVS) are a main problem in neurocritical intensive care units (ICU). The aim of the review is to assess the incidence of ICREVS and to analyse factors involved.

METHODS

Retrospective analysis, adult polyvalent ICU in a third level reference hospital. Patients carrying external ventricular shunt (DVE) were included. Those patients with central nervous system infection diagnosed prior DVE placement were excluded.

RESULTS

87 patients were included with 106 DVE. Most common admittance diagnosis was subarachnoid haemorrhage (49.4%). 31 patients with 32 DVE developed an ICREVS. Infection rate is 19.5 per 1000 days of shunt for ICREVS and 14 per 1000 days for ventriculitis. 31.6% of the patients developed ICREVS and 25.3% ventriculitis. Patients who developed ICREVS presented higher shunt manipulations (2.0 ± 0.6 vs. 3.26 ± 1.02, p=0.02), shunt repositioning (0.1 ± 0.1 vs. 0.2 ± 0.1) and ICU and hospital stay (29.8 ± 4.9 vs 49.8 ± 5.2, p<0.01 y 67.4 ± 18.8 vs. 108.9 ± 30.2, p=0.02. Those DVE with ICREVS were placed for longer not only at infection diagnosis but also at removal (12.6 ± 2.1 vs. 18.3 ± 3.6 and 12.6 ± 2.1 vs. 30.4 ± 7.3 days, p<0.01). No difference in mortality was found.

CONCLUSIONS

One out of three patients with a DVE develops an infection. The risk factors are the number of manipulations, repositioning and the permanency days. Patients with ICREVS had a longer ICU and hospital average stay without an increase in mortality.

[Visitation policy, design and comfort in Spanish intensive care units]

OBJECTIVE

To determine the design and comfort in the Intensive Care Units (ICUs), by analysing visiting hours, information, and family participation in patient care.

DESIGN

Descriptive, multicentre study.

SETTING

Spanish ICUs.

METHODS

A questionnaire e-mailed to members of the Spanish Society of Intensive Care Medicine, Critical and Coronary Units (SEMICYUC), subscribers of the Electronic Journal Intensive Care Medicine, and disseminated through the blog Proyecto HU-CI.

RESULTS

A total of 135 questionnaires from 131 hospitals were analysed. Visiting hours: 3.8% open 24h, 9.8% open daytime, and 67.7% have 2 visits a day. Information: given only by the doctor in 75.2% of the cases, doctor and nurse together in 4.5%, with a frequency of once a day in 79.7%. During weekends, information is given in 95.5% of the cases. Information given over the phone 74.4%. Family participation in patient care: hygiene 11%, feeding 80.5%, physiotherapy 17%. Personal objects allowed: mobile phone 41%, computer 55%, sound system 77%, and television 30%. Architecture and comfort: all individual cubicles 60.2%, natural light 54.9%, television 7.5%, ambient music 12%, clock in the cubicle 15.8%, environmental noise meter 3.8%, and a waiting room near the ICU 68.4%.

CONCLUSIONS

Visiting policy is restrictive, with a closed ICU being the predominating culture. On average, technological communication devices are not allowed. Family participation in patient care is low. The ICU design does not guarantee privacy or provide a desirable level of comfort.

Build up of off-diagonal long-range order in microcavity exciton-polaritons across the parametric threshold

We report an experimental study of the spontaneous spatial and temporal coherence of polariton condensates generated in the optical parametric oscillator configuration, below and at the parametric threshold, and as a function of condensate area. Above the threshold we obtain very long coherence times (up to 3 ns) and a spatial coherence extending over the entire condensate (40 μm). The very long coherence time and its dependence on condensate area and pump power reflect the suppression of polariton-polariton interactions by an effect equivalent to motional narrowing.

Motion of spin polariton bullets in semiconductor microcavities

The dynamics of optical switching in semiconductor microcavities in the strong coupling regime is studied by using time- and spatially resolved spectroscopy. The switching is triggered by polarized short pulses which create spin bullets of high polariton density. The spin packets travel with speeds of the order of 10(6)  m/s due to the ballistic propagation and drift of exciton polaritons from high to low density areas. The speed is controlled by the angle of incidence of the excitation beams, which changes the polariton group velocity.

Onset and dynamics of vortex-antivortex pairs in polariton optical parametric oscillator superfluids

We study, both theoretically and experimentally, the occurrence of topological defects in polariton superfluids in the optical parametric oscillator (OPO) regime. We explain in terms of local supercurrents the deterministic behavior of both the onset and dynamics of vortex-antivortex pairs generated by perturbing the system with a pulsed probe. Using a generalized Gross-Pitaevskii equation, including photonic disorder, pumping and decay, we elucidate the reason why topological defects form in couples and can be detected by direct visualizations in multishot OPO experiments.

Polariton condensates put in motion

We present several examples of the interesting phenomenology shown by a moving polariton condensate in semiconductor microcavities. The superfluid behavior is probed by colliding the polariton condensate against physical obstacles in the form of natural defects of the sample, demonstrating a clear suppression of scattering when the speed of the flow lies below the critical velocity. At higher velocities Cerenkov-like shock waves around the defect and disruption of the condensate are also observed.

Dynamics of the formation and decay of coherence in a polariton condensate

We study the dynamics of the formation and decay of a condensate of microcavity polaritons. We investigate the relationship among the number of particles, the emission linewidth, and its degree of linear polarization, which serves as the order parameter. Tracking the condensate formation, we show that coherence is not determined only by occupation of the ground state, bringing new insights into the determining factors for Bose-Einstein condensation.

Observation of long-lived polariton states in semiconductor microcavities across the parametric threshold

The excitation spectrum around the pump-only stationary state of a polariton optical parametric oscillator in semiconductor microcavities is investigated by time-resolved photoluminescence. The response to a weak pulsed perturbation in the vicinity of the idler mode is directly related to the lifetime of the elementary excitations. A dramatic increase of the lifetime is observed for a pump intensity approaching and exceeding the optical parametric oscillator threshold. The observations can be explained in terms of a critical slowing down of the dynamics upon approaching the threshold and the following appearance of a soft Goldstone mode in the spectrum.

Observation of resonant behavior in the energy velocity of diffused light

In this Letter we demonstrate Mie resonances mediated transport of light in randomly arranged, monodisperse dielectric spheres packed at high filling fractions. By means of both static and dynamic optical experiments we show resonant behavior in the key transport parameters and, in particular, we find that the energy transport velocity, which is lower than the group velocity, also displays a resonant behavior.

Polariton and spin dynamics in semiconductor microcavities under non-resonant excitation

Semiconductor microcavities offer an ideal scenario to study strong radiation-matter interactions. In this paper we review the temporal dynamics of polaritons in II-VI and III-V based microcavities under non-resonant excitation conditions. We present evidence of final-state stimulated scattering and discuss the spin-dependent emission, which exhibits a remarkably rich behaviour.

Polarization control of the nonlinear emission of semiconductor microcavities

The degree of circular polarization ( Weierstrass p ) of the nonlinear emission in semiconductor microcavities is controlled by changing the exciton-cavity detuning. The polariton relaxation towards K approximately 0 cavitylike states is governed by final-state stimulated scattering. The helicity of the emission is selected due to the lifting of the degeneracy of the +/-1 spin levels at K approximately 0. At short times after a pulsed excitation Weierstrass p reaches very large values, either positive or negative, as a result of stimulated scattering to the spin level of lowest energy (+1/-1 spin for positive/negative detuning).

B-cell epitope mapping of the Neisseria meningitidis P64k protein using overlapping peptides

A common meningococcal antigen designated P64k has been identified, cloned and expressed in Escherichia coli. The recombinant antigen is highly immunogenic in several animal species and its immunogenicity in healthy human volunteers is under investigation. Recently, P64k has been used as an immunological carrier for weak immunogens. To characterize the B-cell epitopes on P64k, recognized by immune sera obtained from mice, rabbits and monkeys, multiple overlapping peptides were synthesized and screened for antibody binding. Peptides covering the complete sequence of the P64k protein, 59 in all, of 20 amino acids each (overlapped by 10 residues), were synthesized. A number of continuous epitopes were detected with all sera, when immune and pre-immune bleeds were compared. For mouse and monkey sera, a few major antigenic peptides were identified, while the recognition of the rabbit serum was much more heterogeneous. Despite variation in the exact location of continuous epitopes defined by different anti-P64k sera, we found an immunogenic core region within the molecule, composed of amino acids Asp(524)-Gly(533). Consistently, in this protein segment there was an amino acid stretch located in a beta-hairpin loop, which is exposed to the solvent in the previously determined three-dimensional structure of the protein. This region is protruding and accessible to a sphere with a radius of 9 A.

P64k meningococcal protein as immunological carrier for weak immunogens

Previously, the P64k meningococcal protein, an antigen of 64 kDa expressed in Escherichia coli, has been extensively characterized. We have successfully conjugated several synthetic peptides and meningococcal group C polysaccharide to P64k. In three out of four model peptides, the murine humoral immune response against the homologous peptide, evaluated after three doses of conjugate, was higher in the animals immunized with the coupled peptide than in those that received free peptide. The fourth and largest was immunogenic by itself. Similarly, the antigroup C polysaccharide levels reached by conjugated polysaccharide were significantly higher than those produced against unconjugated polysaccharide. As a carrier for one of the peptides, P64k was compared with bovine serum albumin (BSA) and tetanus toxoid (TT), being able to induce slightly higher or similar antipeptide antibody levels than these well-establish protein carriers. Our results suggest that recombinant P64k protein could be a readily available immunological carrier, as efficient as other commonly used large carrier molecules.

Influence of several adjuvants on the immune response against a recombinant meningococcal high molecular weight antigen

Studying outer membrane proteins as vaccine candidates, our group has previously isolated, cloned, and expressed in Escherichia coli the gene encoding for a high molecular weight protein (P64k), common to many meningococcal strains. To continue the characterisation of this meningococcal antigen, we have evaluated its immunogenicity in mice alone or combined with several commercially-available adjuvants. We used as an adjuvant aluminium hydroxide (Alhydrogel and Rehydragel), aluminium phosphate, Algammulin, crude saponin, the saponin Quil A, dimethyl-dioctadecyl ammonium bromide (DDA), Freund's adjuvant, and Montanide 888. The antibody titres against the recombinant protein and whole meningococci elicited with these adjuvants were compared. We found that Quil A produced the highest titres against the recombinant P64k. Algammulin and the quaternary ammonium compound DDA induced the highest levels of antibodies against meningococci. We analysed the recognition of a set of linear peptides by antisera prepared against the protein combined with some of the adjuvants. The responses depended on the adjuvant used and the results have been confirmed by epitope mapping using overlapping peptides synthesised on pins.