Matthay, Michael A.

Neutrophil accumulation is a key feature of ARDS, but their contribution to the pathogenesis is still uncertain. We investigated the effect of reducing neutrophils in a clinically relevant mouse model of pneumococcal pneumonia treated with antibiotics. When appropriate antibiotics were administered, neutrophil reduction with Ly6G antibody markedly attenuated lung injury and improved oxygenation. In the early phase of bacterial pneumonia, neutrophils contribute to the severity of lung injury, although they also participate in host defense.

Abstract Background: Streptococcus pneumoniae is the most common bacterial cause of community acquired pneumonia and the acute respiratory distress syndrome (ARDS). Some clinical trials have demonstrated a beneficial effect of corticosteroid therapy in community acquired pneumonia, COVID-19, and ARDS, but the mechanisms of this benefit remain unclear. The objective of this study was to investigate the effects of corticosteroids on the pulmonary biology of pneumococcal pneumonia in an observational cohort of mechanically ventilated patients and in a mouse model of bacterial pneumonia with Streptococcus pneumoniae. Methods: We studied gene expression with lower respiratory tract transcriptomes from a cohort of mechanically ventilated patients and in mice. We also carried out comprehensive physiologic, biochemical, and histological analyses in mice to identify the mechanisms of lung injury in Streptococcus pneumoniae with and without adjunctive steroid therapy. Results: Transcriptomic analysis identified pleiotropic effects of steroid therapy on the lower respiratory tract in critically ill patients with pneumococcal pneumonia, findings that were reproducible in mice. In mice with pneumonia, dexamethasone in combination with ceftriaxone reduced (1) pulmonary edema formation, (2) alveolar protein permeability, (3) proinflammatory cytokine release, (4) histopathologic lung injury score, and (5) hypoxemia but did not increase bacterial burden. Conclusions: The gene expression studies in patients and in the mice support the clinical relevance of the mouse studies, which replicate several features of pneumococcal pneumonia and steroid therapy in humans. In combination with appropriate antibiotic therapy in mice, treatment of pneumococcal pneumonia with steroid therapy reduced hypoxemia, pulmonary edema, lung permeability, and histologic criteria of lung injury, and also altered inflammatory responses at the protein and gene expression level. The results from these studies provide evidence for the mechanisms that may explain the beneficial effects of glucocorticoid therapy in patients with community acquired pneumonia from Streptococcus Pneumoniae.

Abstract Patients hospitalized for pneumonia are at high risk for mortality. Effective therapies are therefore needed. Recent randomized clinical trials suggest that systemic steroids can reduce the length of hospital stays among patients hospitalized for pneumonia. Furthermore, preliminary findings from a feasibility study demonstrated that early treatment with a combination of an inhaled corticosteroid and a bronchodilator can improve oxygenation and reduce risk of respiratory failure in patients at risk of acute respiratory distress syndrome. Whether such a combination administered early is effective in reducing acute respiratory failure (ARF) among patients hospitalized with pneumonia is unknown. Here we describe the ARREST Pneumonia (Arrest Respiratory Failure due to Pneumonia) trial designed to address this question. ARREST Pneumonia is a two-arm, randomized, double-blinded, placebo-controlled trial designed to test the efficacy of a combination of an inhaled corticosteroid and a β-agonist compared with placebo for the prevention of ARF in hospitalized participants with severe pneumonia. The primary outcome is ARF within 7 days of randomization, defined as a composite endpoint of intubation and mechanical ventilation; need for high-flow nasal cannula oxygen therapy or noninvasive ventilation for >36 hours (each alone or combined); or death within 36 hours of being placed on respiratory support. The planned enrollment is 600 adult participants at 10 academic medical centers. In addition, we will measure selected plasma biomarkers to better understand mechanisms of action. The trial is funded by the U.S. National Heart Lung and Blood Institute. Clinical trial registered with www.clinicaltrials.gov (NCT 04193878).

AbstractBackgroundConsensus definitions for transfusion‐related acute lung injury (TRALI) and transfusion‐associated circulatory overload (TACO) have recently been revised; however, pulmonary transfusion reactions remain difficult to diagnose. We hypothesized that N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) levels could have utility in the identification and classification of pulmonary transfusion reactions.Study design and methodsWe performed a secondary analysis of a case‐control study of pulmonary transfusion reactions at four academic hospitals. We evaluated clinical data and measured NT‐proBNP levels prior to and following transfusion in patients with TACO (n = 160), transfused acute respiratory distress syndrome (ARDS) [n = 51], TRALI [n = 12], TACO/TRALI [n = 7], and controls [n = 335]. We used Wilcoxon Rank‐Sum tests to compare NT‐proBNP levels, and classification and regression tree (CART) algorithms to produce a ranking of covariates in order of relative importance for differentiating TACO from transfused controls.ResultsPre‐transfusion NT‐proBNP levels were elevated in cases of transfused ARDS and TACO (both P < .001) but not TRALI (P = .31) or TACO/TRALI (P = .23) compared to transfused controls. Pre‐transfusion NT‐proBNP levels were higher in cases of transfused ARDS or TRALI with a diagnosis of sepsis compared to those without (P < .05 for both). CART analyses resulted in similar differentiation of patients with TACO from transfused controls for models utilizing either NT‐proBNP levels (AUC 0.83) or echocardiogram results (AUC 0.80).ConclusionsNT‐proBNP levels may have utility in the classification of pulmonary transfusion reactions. Prospective studies are needed to test the predictive utility of pre‐transfusion NT‐proBNP in conjunction with other clinical factors in identifying patients at risk of pulmonary transfusion reactions.

Objectives: Transfusion-associated circulatory overload is characterized by hydrostatic pulmonary edema following blood transfusion. Restrictive transfusion practice may affect the occurrence and severity of transfusion-associated circulatory overload in critically ill patients. We sought to examine contemporary risk factors and outcomes for transfusion-associated circulatory overload. Design: Case-control study. Setting: Four tertiary care hospitals. Patients: We prospectively enrolled 200 patients with transfusion-associated circulatory overload identified by active surveillance and 405 controls matched by transfusion intensity. Interventions: None. Measurements and Main Results: Among 20,845 transfused patients who received 128,263 blood components from May 2015 until July 2016, transfusion-associated circulatory overload incidence was one case per 100 transfused patients. In addition to cardiovascular comorbidities, multivariable analysis identified the following independent predictors of transfusion-associated circulatory overload: acute kidney injury, emergency surgery, pretransfusion diuretic use, and plasma transfusion—the latter especially in females. Compared with matched controls, transfusion-associated circulatory overload cases were more likely to require mechanical ventilation (71% vs 49%; p < 0.001), experienced longer intensive care and hospital lengths of stay following transfusion, and had higher mortality (21% vs 11%; p = 0.02) even after adjustment for other potentially confounding variables. Conclusions: Despite restrictive transfusion practice, transfusion-associated circulatory overload remains a frequent complication of transfusion and is an independent risk factor for in-hospital morbidity and mortality. In addition to cardiovascular and renal risk factors, plasma transfusion was associated with transfusion-associated circulatory overload after controlling for other covariates. Additional research is needed to examine the benefit of reduced erythrocyte or plasma exposure in patients at high risk for transfusion-associated circulatory overload.

BACKGROUNDIt is increasingly recognized that recipient risk factors play a prominent role in possible transfusion‐related acute lung injury (pTRALI) and transfusion‐associated circulatory overload (TACO). We hypothesized that both transfusion and recipient factors including natriuretic peptides could be used to distinguish TRALI from TACO and pTRALI.STUDY DESIGN AND METHODSWe performed a post hoc analysis of a case‐control study of pulmonary transfusion reactions conducted at the University of California at San Francisco and Mayo Clinic, Rochester. We evaluated clinical data and brain natriuretic peptides (BNP) levels drawn after transfusion in patients with TRALI (n = 21), pTRALI (n = 26), TACO (n = 22), and controls (n = 24). Logistic regression and receiver operating characteristics curve analyses were used to determine the accuracy of clinical and biomarker predictors in differentiating TRALI from TACO and pTRALI.RESULTSWe found that pTRALI and TACO were associated with older age, higher fluid balance, and elevated BNP levels relative to those of controls and TRALI. The following variables were useful in distinguishing cases of pTRALI and TACO from TRALI: age more than 70 years, BNP levels more than 1000 pg/mL, 24‐hour fluid balance of more than 3 L, and a lower number of transfused blood components. Using the above variables, our logistic model had a 91% negative predictive value in the differential diagnosis of TRALI.CONCLUSIONSModels incorporating readily available clinical and biomarker data can be used to differentiate transfusion‐related respiratory complications. Additional studies examining recipient risk factors and the likelihood of TRALI may be useful in decision making regarding donor white blood cell antibody testing.

Objectives: Effective pharmacologic treatments directly targeting lung injury in patients with the acute respiratory distress syndrome are lacking. Early treatment with inhaled corticosteroids and beta agonists may reduce progression to acute respiratory distress syndrome by reducing lung inflammation and enhancing alveolar fluid clearance. Design: Double-blind, randomized clinical trial (ClinicalTrials.gov: NCT01783821). The primary outcome was longitudinal change in oxygen saturation divided by the F io 2 (S/F) through day 5. We also analyzed categorical change in S/F by greater than 20%. Other outcomes included need for mechanical ventilation and development of acute respiratory distress syndrome. Setting: Five academic centers in the United States. Patients: Adult patients admitted through the emergency department at risk for acute respiratory distress syndrome. Interventions: Aerosolized budesonide/formoterol versus placebo bid for up to 5 days. Measurements and Main Results: Sixty-one patients were enrolled from September 3, 2013, to June 9, 2015. Median time from presentation to first study drug was less than 9 hours. More patients in the control group had shock at enrollment (14 vs 3 patients). The longitudinal increase in S/F was greater in the treatment group ( p = 0.02) and independent of shock ( p = 0.04). Categorical change in S/F improved ( p = 0.01) but not after adjustment for shock ( p = 0.15). More patients in the placebo group developed acute respiratory distress syndrome (7 vs 0) and required mechanical ventilation (53% vs 21%). Conclusions: Early treatment with inhaled budesonide/formoterol in patients at risk for acute respiratory distress syndrome is feasible and improved oxygenation as assessed by S/F. These results support further study to test the efficacy of inhaled corticosteroids and beta agonists for prevention of acute respiratory distress syndrome.

BackgroundThe concordance of haemovigilance criteria developed for surveillance of transfusion‐associated circulatory overload (TACO) with its clinical diagnosis has not been assessed. In a pilot study to evaluate an electronic screening algorithm, we sought to examine TACO incidence and application of haemovigilance criteria in patients with post‐transfusion pulmonary oedema.Study Design and MethodsFrom June to September 2014, all transfused adult inpatients at four academic hospitals were screened with an algorithm identifying chest radiographs ordered within 12 h of blood component release. Patients with post‐transfusion pulmonary oedema underwent case adjudication by an expert panel. TACO incidence was calculated, and clinical characteristics were compared with other causes of post‐transfusion pulmonary oedema.ResultsAmong 4932 transfused patients, there were 3412 algorithm alerts, 50 cases of TACO and 47 other causes of pulmonary oedema. TACO incidence was 1 case per 100 patients transfused. TACO classification based on two sets of haemovigilance criteria (National Healthcare Safety Network and proposed revised International Society for Blood Transfusion) was concordant with expert panel diagnosis in 57% and 54% of reviewed cases, respectively. Although the majority of clinical parameters did not differentiate expert panel adjudicated TACO from other cases, improved oxygenation within 24 h of transfusion did (P = 0·01).ConclusionsThe incidence of TACO was similar to that observed in prior studies utilizing active surveillance. Case classification by haemovigilance criteria was frequently discordant with clinical diagnoses of TACO in patients with post‐transfusion pulmonary oedema. Improvements in oxygenation within 24 h of transfusion merit further evaluation in the diagnosis of TACO.

A lung-protective ventilator strategy significantly reduces mortality in patients with acute lung injury. Substantial progress has been made in understanding how mechanical stress can injure the lung, both in terms of alterations in barrier properties of the pulmonary endothelium and epithelium as well as in stimulating proinflammatory responses of macrophages and neutrophils.

BACKGROUND Pulmonary transfusion reactions are important complications of blood transfusion, yet differentiating these clinical syndromes is diagnostically challenging. We hypothesized that biologic markers of inflammation could be used in conjunction with clinical predictors to distinguish transfusion‐related acute lung injury (TRALI), transfusion‐associated circulatory overload (TACO), and possible TRALI. STUDY DESIGN AND METHODS In a nested case‐control study performed at the University of California at San Francisco and Mayo Clinic, Rochester, we evaluated clinical data and blood samples drawn before and after transfusion in patients with TRALI (n = 70), possible TRALI (n = 48), TACO (n = 29), and controls (n = 147). Cytokines measured included granulocyte‐macrophage–colony‐stimulating factor, interleukin (IL)‐6, IL‐8, IL‐10, and tumor necrosis factor‐α. Logistic regression and receiver operating characteristics curve analyses were used to determine the accuracy of clinical predictors and laboratory markers in differentiating TACO, TRALI, and possible TRALI. RESULTS Before and after transfusion, IL‐6 and IL‐8 were elevated in patients with TRALI and possible TRALI relative to controls, and IL‐10 was elevated in patients with TACO and possible TRALI relative to that of TRALI and controls. For all pulmonary transfusion reactions, the combination of clinical variables and cytokine measurements displayed optimal diagnostic performance, and the model comparing TACO and TRALI correctly classified 92% of cases relative to expert panel diagnoses. CONCLUSIONS Before transfusion, there is evidence of systemic inflammation in patients who develop TRALI and possible TRALI but not TACO. A predictive model incorporating readily available clinical and cytokine data effectively differentiated transfusion‐related respiratory complications such as TRALI and TACO.