A novel approach for estimating functions in the multivariate setting based on an adaptive knot selection for B-splines with an application to a chemical system used in geoscience

In this paper, we will outline a novel data-driven method for estimating functions in a multivariate nonparametric regression model based on an adaptive knot selection for B-splines. The underlying idea of our approach for selecting knots is to apply the generalized lasso, since the knots of the B-spline basis can be seen as changes in the derivatives of the function to be estimated. This method was then extended to functions depending on several variables by processing each dimension independently, thus reducing the problem to a univariate setting. The regularization parameters were chosen by means of a criterion based on EBIC. The nonparametric estimator was obtained using a multivariate B-spline regression with the corresponding selected knots. Our procedure was validated through numerical experiments by varying the number of observations and the level of noise to investigate its robustness. The influence of observation sampling was also assessed and our method was applied to a chemical system commonly used in geoscience. For each different framework considered in this paper, our approach performed better than state-of-the-art methods. Our completely data-driven method is implemented in the glober R package which will soon be available on the Comprehensive R Archive Network (CRAN).Comment: 29 pages, 29 figure

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Predicting Distal Aortic Remodeling After Endovascular Repair for Chronic DeBakey III Aortic Dissection.

BACKGROUND: Chronic DeBakey III aortic dissection is typically managed with open aortic reconstruction. Thoracic endovascular aortic grafting (TEVAR) has been attempted in patients with chronic DeBakey III with improved outcomes over medical management, however with frequent failures. This study investigates factors associated with positive aortic remodeling from a large aortic center. METHODS: Three-dimensional reconstructions (M2S, West Lebanon, NH) of computed tomography angiography scans of 48 patients who underwent TEVAR from 2005 to 2015 were analyzed. The dissection was characterized, and measurements were obtained from preoperative and postoperative scans at four time points. Standard univariate Wilcoxon rank sum and Fisher\u27s exact tests were used to analyze continuous and ordinal/nominal data, respectively. Multivariable logistic regression was performed. RESULTS: In a multivariate logistic model, having fewer than two visceral vessels off the true lumen was a negative predictor of total thrombosis (odd ratio [OR] 0.01, 95% confidence interval [CI]: CONCLUSIONS: TEVAR is feasible in chronic dissection but is limited by complex dissection-related anatomy. Increasing number of visceral vessels off the false lumen, maximum preoperative aortic size, and location of the primary tear on the greater curve were associated with poorer remodeling

Law Enforcement Agency Defibrillation (LEA-D): proceedings of the National Center for Early Defibrillation Police AED Issues Forum

Why does LEA-D intervention seem to work in some systems but not others? Panelists agreed that some factors that delay rapid access to treatment, such as long travel distances in rural areas, may represent insurmountable barriers. Other factors, however, may be addressed more readily. These include: absence of a medical response culture, discomfort with the role of medical intervention, insecurity with the use of medical devices, a lack of proactive medical direction, infrequent refresher training, and dependence on EMS intervention. Panelists agreed that successful LEA-D programs possess ten key attributes (Table 6). In the end, the goal remains "early" defibrillation, not "police" defibrillation. It does not matter whether the rescuer wears a blue uniform--or any uniform, for that matter--so long as the defibrillator reaches the victim quickly. If LEA personnel routinely arrive at medical emergencies after other emergency responders or after 8 minutes have elapsed from the time of collapse, an LEA-D program will be unlikely to provide added value. Similarly, if police frequently arrive first, but the department is unwilling or unable to cultivate the attributes of successful LEA-D programs, efforts to improve survival may not be realized. In most communities, however, LEA-D programs have tremendous lifesaving potential and are well worth the investment of time and resources. Law enforcement agencies considering adoption of AED programs should review the frequency with which police arrive first at medical emergencies and LEA response intervals to determine whether AED programs might help improve survival in their communities. It is time for law enforcement agency defibrillation to become the rule, not the exception

Immunocompromised patients with acute respiratory distress syndrome: Secondary analysis of the LUNG SAFE database

Background: The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p &lt; 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p &lt; 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013