Daily Ards Research Analysis

BACKGROUND: Despite the widespread adoption of lung-protective ventilation strategies, mortality among patients receiving invasive mechanical ventilation (IMV) remains high. Mechanical power (MP) integrates various variables responsible for ventilator-induced lung injury and has been associated with mortality in patients with ARDS. However, the impact of MP on ICU mortality in the larger group of patients with acute hypoxemic respiratory failure (AHRF) has not been well established, and previous studies have reported inconsistent thresholds for predicting outcomes. RESEARCH QUESTION: Is high MP (> 17 J/min) within the first 24 hours of IMV, calculated using dynamic driving pressure, associated with ICU mortality in patients with AHRF? Additionally, does a threshold exist below which IMV is considered safe? STUDY DESIGN AND METHODS: In this multicenter cohort study, we included adult patients with AHRF who received IMV. Patients were excluded if they received IMV for > 24 hours before inclusion or were receiving extracorporeal life support. We applied multivariable logistic regression models with inverse probability of treatment weighting and used change-point regression models with restricted cubic splines. RESULTS: Of the 21,714 patients in our registry, 9,031 patients (42%) met the inclusion criteria. After adjusting for baseline characteristics, high MP was associated with increased ICU mortality (OR, 1.58; 95% CI, 1.44-1.72), with a nonlinear dose-response relationship. No consistent safe MP threshold was identified. High MP also was associated with lower extubation rates and fewer ventilator-free days. INTERPRETATION: In this study, exposure to high MP within the first 24 hours of IMV was associated with increased ICU mortality in patients with AHRF. The absence of a consistent safe threshold suggests that reducing MP at IMV initiation may be a strategy to improve outcomes, warranting exploration in clinical trials.

BACKGROUND: Prone positioning (PP) has been shown to improve oxygenation in patients with acute respiratory distress syndrome (ARDS); with a focus on its early physiological effects. However, the time-dependent effects of PP on ventilation-perfusion (V/Q) matching have not been fully investigated. In this study we aimed to investigate the longitudinal effects of PP on regional V/Q matching and the distribution of ventilation and perfusion in patients with coronavirus disease 2019 (COVID-19)-associated ARDS. METHODS: This study analyzed patients with COVID-19 ARDS who were mechanically ventilated and underwent their first PP treatment. V/Q mismatching was assessed using electrical impedance tomography (EIT). At five intervals during the initial PP session PaO RESULTS: In this study eighteen COVID-19 ARDS patients were enrolled. In comparison with SP, PP led to significant improvements in oxygenation, with PaO CONCLUSIONS: In COVID-19-induced ARDS patients, prone positioning initially improves oxygenation and V/Q matching by enhancing ventilation distribution and decreasing low V/Q (%). Over time, perfusion changes further improve V/Q matching, but these benefits diminish once the patient returns to the supine position, leading to increased V/Q mismatch. Trial registration Clinical Trials.gov, NCT04725227. Registered 25 January 2021, https://clinicaltrials.gov/study/NCT04725227?cond=NCT04725227&rank=1.

BACKGROUND: Critically ill patients who receive circulatory or respiratory assist using extracorporeal membrane oxygenation (ECMO) may develop hemolysis, which can complicate the delivery of supportive care and be a potential risk factor for increased morbidity and mortality. Clinically, hemolysis is often identified using laboratory markers such as cell-free hemoglobin (CFH) and haptoglobin (Hp). However, such measurements require photometry or enzyme-linked immunosorbent assay (ELISA) and are labor intensive. In contrast, metabolic downstream products of CFH, such as carboxyhemoglobin (CO-Hb) and methemoglobin (Met-Hb), can be regularly monitored via arterial blood gas analyses in the intensive care unit (ICU). We hypothesized that CO-Hb and Met-Hb values measured during ECMO would correlate with the presence of hemolytic events as measured by CFH values exceeding 50mg/dl. We further hypothesized that CO-Hb and Met-Hb levels would correlate with peri-ECMO mortality. METHODS: Retrospective analysis of 435 patients with acute respiratory distress syndrome (ARDS) and veno-venous ECMO admitted to a tertiary ARDS referral center. Plasma concentrations of CO-Hb and Met-Hb were correlated with hemolytic events. Cutoff values of mean CO-Hb (mCO-Hb) and mean Met-Hb (mMet-Hb) associated with increased ICU mortality were calculated with recursive binary partitioning. Single and multivariable regression models for HE and ICU mortality were trained and compared. RESULTS: Simple and multivariable models including potential confounders identified associations between Met-Hb and hemolytic events (adj. odds ratio [OR] 2.99 [95% confidence interval {CI}, 2.19-4.10], P < .001). A cutoff value with 90% specificity of a hemolytic event was estimated for Met-Hb (1.55%). Both, mean CO-Hb (OR 2.03 [95% CI, 1.60-2.61], P < .001) and Met-Hb (2.78 [1.59-5.09], P < .001) were associated with ICU mortality. Cutoff values for mortality were 2% for mean CO-Hb and 1.25% for mean Met-Hb. The multivariable regression model for mortality including the continuous markers mCO-Hb and mMet-Hb produced an area under the curve (AUC) of 0.803. CONCLUSIONS: In patients with ARDS and ECMO, Met-Hb plasma concentrations were independently associated with hemolytic events. Both, mean CO-Hb and Met-Hb levels were associated with ICU mortality. These markers and their associated cutoff values might serve as a risk indicator in clinical practice.