Adesão à ventilação mecânica protetora e seu impacto na mortalidade de pacientes com Síndrome do Desconforto Respiratório Agudo por Covid-19

Background: Most COVID-19 patients who need invasive ventilatory support meet the diagnostic criteria for acute respiratory distress syndrome (ARDS). Despite being essential for the maintenance of life of these individuals, mechanical ventilation (MV) may worsen the already existing lung inflammatory injury, a phenomenon known as ventilator-induced lung injury (VILI). Studies with ARDS of other etiologies have shown an association between ventilatory parameters, such as tidal volume (VT), plateau pressure (Pplat) and driving pressure (∆P), and mortality. Thus, in addition to correcting hypoxemia, ventilatory support in ARDS should prevent the occurrence of VILI, a strategy known as protective MV. Objectives: To evaluate the association between ∆P and VT/kg predicted weight (PBW) with in-hospital mortality in a cohort of COVID-19 ARDS patients. In addition, to identify adherence to protective MV in this cohort compared to a cohort of patients with ARDS of other etiologies. Results: 231 individuals were included in the COVID-19 cohort. Hospital mortality was 51.9%. The ∆P was independently associated with in-hospital mortality (OR= 1.21; CI95%, 1.04-1.41, p=0.01), a fact not observed with VT/kg PBW (OR= 0.75; CI-95%, 0.55-1.04, p=0.09). Based on the double stratification analysis, it was found that, for the same level of VT/kg PBW, the risk of hospital mortality increased significantly with increasing ∆P. However, increments in VT/kg PBW were not associated with increased mortality when ∆P was held constant. In the second study, we found that adherence to protective MV was higher in the COVID-19 cohort than in the non-COVID-19 ARDS cohort (65.8% vs. 50.0%, p=0.005), mainly because of the higher proportion of patients being ventilated at levels considered protective of ∆P (75.0% vs. 62.4%, p=0.02). Multivariate logistic regression analysis showed that belonging to the COVID-19 cohort was independently associated with greater adherence to protective MV. Conclusions: In COVID-19 ARDS patients, exposure to higher ∆P was associated with higher in-hospital mortality, a fact not observed with exposure to higher VT/kg PBW. We observed increased adherence to protective MV in COVID-19 ARDS patients compared to patients with ARDS due to other etiologies ventilated before the pandemic. These results suggest that ∆P might be a better target to pursue during MV in ARDS and that its incorporation into MV practice increased during the pandemic.Introdução: A maioria dos pacientes com COVID-19 que evoluem com necessidade de ventilação mecânica (VM) preenchem os critérios diagnósticos da síndrome do desconforto respiratório agudo (SDRA). Apesar de ser essencial para a manutenção da vida desses indivíduos, a VM pode agravar a lesão inflamatória pulmonar já existente, fenômeno conhecido como VILI (ventilator-induced lung injury). Estudos com SDRA de outras etiologias mostraram associação entre parâmetros ventilatórios, como volume corrente (VT), pressão de platô (Pplat) e driving pressure (∆P), e mortalidade. Assim, além da correção da hipoxemia, o suporte ventilatório na SDRA deve evitar a ocorrência da VILI, estratégia conhecida como VM protetora. Objetivos: Avaliar a associação entre ∆P e VT/kg peso predito (PBW) com mortalidade hospitalar em uma coorte de pacientes com SDRA por COVID-19. Além disso, identificar a adesão à VM protetora nessa coorte, em comparação com uma coorte de pacientes com SDRA de outras etiologias. Métodos: Foram conduzidos dois estudos observacionais. No primeiro, avaliou-se uma coorte prospectiva com adultos com diagnóstico de SDRA por COVID-19 e submetidos a VM, internados em duas unidades de terapia intensiva (UTI). Foram coletados dados demográficos, clínicos e calculados os escores de gravidade na admissão na UTI. Os parâmetros ventilatórios e gasométricos foram coletados no dia da intubação traqueal (D0) e nos dois dias subsequentes de VM (D1 e D2). Realizaram-se análises multivariadas para determinar se ∆P e VT/kg PBW no primeiro dia de VM associam-se à mortalidade hospitalar. No segundo estudo, essa mesma coorte de pacientes com SDRA por COVID-19 foi comparada com outra coorte, composta de pacientes com SDRA por outras etiologias, admitidos em 37 UTIs brasileiras durante um período de 30 dias, em 2016. Comparou- se a adesão à VM protetora (VT <8 ml/kg PBW, Pplat <30 cm H2O e ∆P <15 cm H2O) e a adesão a cada um de seus componentes individuais, nas duas coortes. Resultados: 231 indivíduos foram incluídos na coorte COVID-19. A mortalidade hospitalar foi de 51,9%. A ∆P associou-se de forma independente com a mortalidade hospitalar (OR= 1,21; IC-95%, 1,04-1,41; p=0,01), fato não observado com o VT/kg PBW (OR= 0,75; IC-95%, 0,55-1,04; p=0,09). Com base na análise de dupla estratificação, encontrou-se que, para um mesmo nível de VT/kg PBW, o risco de óbito hospitalar aumentou significativamente com o aumento da ∆P. No entanto, incrementos no VT/kg PBW não se associaram com aumento da mortalidade quando a ∆P era mantida constante. No segundo estudo, observou-se que a adesão à VM protetora foi maior na coorte de COVID-19 do que na coorte de SDRA por outras etiologias (65,8% vs. 50,0%, p=0,005), principalmente pela maior proporção de pacientes sendo ventilados em níveis considerados protetores de ∆P (75,0% vs. 62,4%, p=0,02). Análise multivariada de regressão logística mostrou que pertencer à coorte COVID-19 associou-se de forma independente com maior adesão à VM protetora. Conclusões: Em pacientes com SDRA por COVID-19, a exposição a altas ∆P associou-se a maior mortalidade hospitalar, fato não observado com a exposição a altos VT/kg PBW. Observamos maior adesão à VM protetora em pacientes com SDRA por COVID-19, em comparação com pacientes com SDRA por outras etiologias ventilados antes da pandemia. Esses resultados sugerem a ∆P como um melhor alvo a ser buscado durante a VM na SDRA e que sua incorporação à prática da VM aumentou durante a pandemia

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| &lt; 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Search for Physics beyond the Standard Model in Events with Overlapping Photons and Jets

Results are reported from a search for new particles that decay into a photon and two gluons, in events with jets. Novel jet substructure techniques are developed that allow photons to be identified in an environment densely populated with hadrons. The analyzed proton-proton collision data were collected by the CMS experiment at the LHC, in 2016 at root s = 13 TeV, and correspond to an integrated luminosity of 35.9 fb(-1). The spectra of total transverse hadronic energy of candidate events are examined for deviations from the standard model predictions. No statistically significant excess is observed over the expected background. The first cross section limits on new physics processes resulting in such events are set. The results are interpreted as upper limits on the rate of gluino pair production, utilizing a simplified stealth supersymmetry model. The excluded gluino masses extend up to 1.7 TeV, for a neutralino mass of 200 GeV and exceed previous mass constraints set by analyses targeting events with isolated photons.Peer reviewe

Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

Bose-Einstein correlations of charged hadrons in proton-proton collisions at s\sqrt s = 13 TeV

Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s}$ = 7 TeV, as well as with theoretical predictions.[graphic not available: see fulltext]Bose-Einstein correlations of charged hadrons are measured over a broad multiplicity range, from a few particles up to about 250 reconstructed charged hadrons in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The results are based on data collected using the CMS detector at the LHC during runs with a special low-pileup configuration. Three analysis techniques with different degrees of dependence on simulations are used to remove the non-Bose-Einstein background from the correlation functions. All three methods give consistent results. The measured lengths of homogeneity are studied as functions of particle multiplicity as well as average pair transverse momentum and mass. The results are compared with data from both CMS and ATLAS at $\sqrt{s} =$ 7 TeV, as well as with theoretical predictions

Search for dark matter in events with a leptoquark and missing transverse momentum in proton-proton collisions at 13 TeV

A search is presented for dark matter in proton-proton collisions at a center-of-mass energy of root s= 13 TeV using events with at least one high transverse momentum (p(T)) muon, at least one high-p(T) jet, and large missing transverse momentum. The data were collected with the CMS detector at the CERN LHC in 2016 and 2017, and correspond to an integrated luminosity of 77.4 fb(-1). In the examined scenario, a pair of scalar leptoquarks is assumed to be produced. One leptoquark decays to a muon and a jet while the other decays to dark matter and low-p(T) standard model particles. The signature for signal events would be significant missing transverse momentum from the dark matter in conjunction with a peak at the leptoquark mass in the invariant mass distribution of the highest p(T) muon and jet. The data are observed to be consistent with the background predicted by the standard model. For the first benchmark scenario considered, dark matter masses up to 500 GeV are excluded for leptoquark masses m(LQ) approximate to 1400 GeV, and up to 300 GeV for m(LQ) approximate to 1500 GeV. For the second benchmark scenario, dark matter masses up to 600 GeV are excluded for m(LQ) approximate to 1400 GeV. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe