Quiz Ref ID Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury, associated with increased pulmonary vascular permeability, increased lung weight, and loss of aerated lung tissue.¹ Although prior epidemiologic studies have provided substantial insights into ARDS,^2-5 there remains limited information about the epidemiology, recognition, management, and outcomes of patients with the ARDS, especially in the era of the current Berlin Definition.¹ This definition was constructed empirically and validated using retrospective cohorts¹; however, prospective studies of the Berlin Definition have been limited to small numbers of centers and patients.^6,7

Research from JAMA — Anemia and Blood Transfusion in Critically Ill Patients — ContextAnemia is a common problem in critically ill patients admitted to intensive care units (ICUs), but the consequences of anemia on morbidity and mortality in the critically ill is poorly defined.ObjectivesTo prospectively define the incidence of anemia and use of red blood cell (RBC) transfusions in critically ill patients and to explore the potential benefits and risks associated with transfusion in the ICU.DesignProspective observational study conducted November 1999, with 2 components: a blood sampling study and an anemia and blood transfusion study.Setting and PatientsThe blood sampling study included 1136 patients from 145 western European ICUs, and the anemia and blood transfusion study included 3534 patients from 146 western European ICUs. Patients were followed up for 28 days or until hospital discharge, interinstitutional transfer, or death.Main Outcome MeasuresFrequency of blood drawing and associated volume of blood drawn, collected over a 24-hour period; hemoglobin levels, transfusion rate, organ dysfunction (assessed using the Sequential Organ Failure Assessment score), and mortality, collected throughout a 2-week period.ResultsThe mean (SD) volume per blood draw was 10.3 (6.6) mL, with an average total volume of 41.1 (39.7) mL during the 24-hour period. There was a positive correlation between organ dysfunction and the number of blood draws (r = 0.34; P<.001) and total volume drawn (r = 0.28; P<.001). The mean hemoglobin concentration at ICU admission was 11.3 (2.3) g/dL, with 29% (963/3295) having a concentration of less than 10 g/dL. The transfusion rate during the ICU period was 37.0% (1307/3534). Older patients and those with a longer ICU length of stay were more commonly transfused. Both ICU and overall mortality rates were significantly higher in patients who had vs had not received a transfusion (ICU rates: 18.5% vs 10.1%, respectively; χ2 = 50.1; P<.001; overall rates: 29.0% vs 14.9%, respectively; χ2 = 88.1; P<.001). For similar degrees of organ dysfunction, patients who had a transfusion had a higher mortality rate. For matched patients in the propensity analysis, the 28-day mortality was 22.7% among patients with transfusions and 17.1% among those without (P = .02); the Kaplan-Meier log-rank test confirmed this difference.ConclusionsThis multicenter observational study reveals the common occurrence of anemia and the large use of blood transfusion in critically ill patients. Additionally, this epidemiologic study provides evidence of an association between transfusions and diminished organ function as well as between transfusions and mortality.

Background: This document provides evidence-based clinical practice guidelines on the use of mechanical ventilation in adult patients with acute respiratory distress syndrome (ARDS). Methods: A multidisciplinary panel conducted systematic reviews and metaanalyses of the relevant research and applied Grading of Recommendations, Assessment, Development, and Evaluation methodology for clinical recommendations. Results: For all patients with ARDS, the recommendation is strong for mechanical ventilation using lower tidal volumes (4–8 ml/kg predicted body weight) and lower inspiratory pressures (plateau pressure < 30 cm H₂O) (moderate confidence in effect estimates). For patients with severe ARDS, the recommendation is strong for prone positioning for more than 12 h/d (moderate confidence in effect estimates). For patients with moderate or severe ARDS, the recommendation is strong against routine use of high-frequency oscillatory ventilation (high confidence in effect estimates) and conditional for higher positive end-expiratory pressure (moderate confidence in effect estimates) and recruitment maneuvers (low confidence in effect estimates). Additional evidence is necessary to make a definitive recommendation for or against the use of extracorporeal membrane oxygenation in patients with severe ARDS. Conclusions: The panel formulated and provided the rationale for recommendations on selected ventilatory interventions for adult patients with ARDS. Clinicians managing patients with ARDS should personalize decisions for their patients, particularly regarding the conditional recommendations in this guideline.

In the acute respiratory distress syndrome (ARDS), positive end-expiratory pressure (PEEP) may decrease ventilator-induced lung injury by keeping lung regions open that otherwise would be collapsed. Since the effects of PEEP probably depend on the recruitability of lung tissue, we conducted a study to examine the relationship between the percentage of potentially recruitable lung, as indicated by computed tomography (CT), and the clinical and physiological effects of PEEP.