Pathophysiology of Hypoxemia in COVID-19 Lung Disease.

As the pandemic has progressed, our understanding of hypoxemia in coronavirus disease 2019 (COVID-19) lung disease has become more nuanced, although much remains to be understood. In this article, we review ventilation-perfusion mismatching in COVID-19 and the evidence to support various biologic theories offered in explanation. In addition, the relationship between hypoxemia and other features of severe COVID-19 lung disease such as respiratory symptoms, radiographic abnormalities, and pulmonary mechanics is explored.

A Prospective Observational Study on Short and Long-Term Outcomes of COVID-19 Patients with Acute Hypoxic Respiratory Failure Treated with High-Flow Nasal Cannula.

(1) The use of high-flow nasal cannula (HFNC) combined with frequent respiratory monitoring in patients with acute hypoxic respiratory failure due to COVID-19 has been shown to reduce intubation and mechanical ventilation. (2) This prospective, single-center, observational study included consecutive adult patients with COVID-19 pneumonia treated with a high-flow nasal cannula. Hemodynamic parameters, respiratory rate, inspiratory fraction of oxygen (FO), saturation of oxygen (SO), and the ratio of oxygen saturation to respiratory rate (ROX) were recorded prior to treatment initiation and every 2 h for 24 h.

Of Climate Change and Competing Risks.

Of Climate Change and Competing Risks This Stats, STAT! animated video explores the concept of competing risks - and discusses why it is so important for investigators to consider whether the occurrence of one event can prevent or change the likelihood of the occurrence of another.

Threats to Blinding.

Blinding is a critical strategy used to limit certain types of bias in randomized controlled trials. This animated video explores the rationale and examines potential threats to keeping group allocation concealed - from study participants and investigators.

Subgroup Analyses: Subpar or Sublime?

Subgroup Analyses: Subpar or Sublime?This animated video explores some of the potential pitfalls of performing subgroup analyses in randomized controlled trials and explains how to approach potential findings with caution.

The Problem of Multiple Comparisons.

The Problem of Multiple Comparisons This animated video reviews the problem of multiple comparisons in research studies and explains how performing multiple statistical hypothesis tests can produce associations simply by chance.

Vasculopathy and Increased Vascular Congestion in Fatal COVID-19 and Acute Respiratory Distress Syndrome.

The leading cause of death in coronavirus disease 2019 (COVID-19) is severe pneumonia, with many patients developing acute respiratory distress syndrome (ARDS) and diffuse alveolar damage (DAD). Whether DAD in fatal COVID-19 is distinct from other causes of DAD remains unknown. To compare lung parenchymal and vascular alterations between patients with fatal COVID-19 pneumonia and other DAD-causing etiologies using a multidimensional approach.

The Case of the Missing Data.

The Case of the Missing DataThis animated video explores how investigators approach missing data in clinical trials.

Is Noninferior Not Inferior?

Is Noninferior Not Inferior? What is a non-inferiority trial margin? To answer this, ask whether you have ever weighed a tradeoff between the best version of something and an acceptable alternative. Restated, in a choice between two decisions, is one option not inferior to the other? Watch an animated video that explores the basis for non-inferiority trials, the meaning of non-inferiority margins, and the interpretation of a non-inferiority trial's results.

Feasibility and Consistency of Results with Deployment of an In-Line Filter for Exercise-Based Evaluations of Patients With Heart Failure During the Novel Coronavirus Disease-2019 Pandemic.

Background: Exercise testing plays an important role in evaluating heart failure prognosis and selecting patients for advanced therapeutic interventions. However, concern for severe acute respiratory syndrome novel coronavirus-2 transmission during exercise testing has markedly curtailed performance of exercise testing during the novel coronavirus disease-2019 pandemic.

Methods And Results: To examine the feasibility to conducting exercise testing with an in-line filter, 2 healthy volunteer subjects each completed 2 incremental exercise tests, one with discrete stages of increasing resistance and one with a continuous ramp.

An organosynthetic soft robotic respiratory simulator.

In this work, we describe a benchtop model that recreates the motion and function of the diaphragm using a combination of advanced robotic and organic tissue. First, we build a high-fidelity anthropomorphic model of the diaphragm using thermoplastic and elastomeric material based on clinical imaging data. We then attach pneumatic artificial muscles to this elastomeric diaphragm, pre-programmed to move in a clinically relevant manner when pressurized.

Impaired Exercise Tolerance in Heart Failure With Preserved Ejection Fraction: Quantification of Multiorgan System Reserve Capacity.

Exercise intolerance is a principal feature of heart failure with preserved ejection fraction (HFpEF), whether or not there is evidence of congestion at rest. The degree of functional limitation observed in HFpEF is comparable to patients with advanced heart failure and reduced ejection fraction. Exercise intolerance in HFpEF is characterized by impairments in the physiological reserve capacity of multiple organ systems, but the relative cardiac and extracardiac deficits vary among individuals.

A portable single-sided magnet system for remote NMR measurements of pulmonary function.

In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung.

Cell elasticity determines macrophage function.

Macrophages serve to maintain organ homeostasis in response to challenges from injury, inflammation, malignancy, particulate exposure, or infection. Until now, receptor ligation has been understood as being the central mechanism that regulates macrophage function. Using macrophages of different origins and species, we report that macrophage elasticity is a major determinant of innate macrophage function.

Air Force expeditionary medical support unit at the Houston floods: use of a military model in civilian disaster response.

From June 6 to 10, 2001, Tropical Storm Allison delivered 40 inches of rain to the city of Houston, Texas. Nine of the city's hospitals were closed or severely curtailed services as a result of the flooding. All area hospitals were full to capacity, intensive care unit beds were unavailable, and patient wait times for emergency department care were 18 to 21 hours.

Extraction of information on the buildup and consumption of reactive intermediates from quadruplex DNA assembly time courses.

A method was developed to detect the time course of the overall presence of intermediate species during K+-induced DNA quadruplex assembly from single-stranded d(TG4) oligonucleotides in experiments in which only the combined circular dichroisms (CD) of all species present could be measured directly. The presence of intermediate species is determined unambiguously but quantitative estimates can be made only to the extent that the CD characteristics of all intermediates are known. The method consists of (i) obtaining CD spectra of known concentrations of initial and final species to determine their molar ellipticity coefficients, (ii) carrying out CD measurements of the kinetics of quadruplex assembly reactions at two different wavelengths, chosen to give optimal differentiation between the initial and final species, and (iii) using the results of (ii) to detect discrepancies between the rates of consumption of single strands and the generation of quadruplex to infer the presence of intermediate species.

Effect of sulfated polysaccharides on heat-induced structural changes in beta-lactoglobulin.

The mechanism that leads to a decreased aggregation of beta-lactoglobulin in the presence of dextran sulfate and lambda-carrageenan was investigated by assessing changes in the denaturation thermodynamics and protein structure. Differential scanning calorimetry results showed that the denaturation temperature (Tp) was about 4.6 degrees C higher in the presence of dextran sulfate, as compared with beta-lactoglobulin alone, whereas in the presence of lambda-carrageenan the difference in Tp was about 1.