The utility of clinical predictors of acute lung injury: towards prevention and earlier recognition

Long noncoding RNA MALAT1 inhibition attenuates sepsis-induced acute lung injury through modulating the miR-129-5p/PAX6/ZEB2 axis

This research aimed to investigate the role of the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/microRNA-129-5p (miR-129-5p)/paired box gene 6 (PAX6) axis in sepsis-induced acute lung injury (ALI). MLE-12 cells and C57BL/6 mice were induced by LPS to establish lung injury in in vitro and in vivo models. Cell viability and apoptosis were measured by cell counting kit-8 assay and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining, respectively. Levels of inflammatory cytokines in cell supernatants and bronchoalveolar lavage fluid (BALF) were detected by ELISA. Lung injury was evaluated by lung wet weight-to-dry weight ratio and hematoxylin-eosin staining. MALAT1, PAX6, and zinc finger E-box-binding homeobox 2 (ZEB2) expression was elevated and miR-129-5p expression was reduced in the serum of patients with sepsis-induced ALI, LPS-induced MLE-12 cells, and lung tissues of ALI mice. MALAT1 interference delayed the LPS-induced cell proliferation decrease, apoptosis increase, and inflammatory factor increase. miR-129-5p inhibition could reverse the delaying effect of MALAT1 interference on LPS-induced lung cell injury. PAX6 overexpression (oe) reversed the inhibitory effect of miR-129-5p oe on LPS-induced lung cell injury. Downregulating MALAT1 reduced pulmonary edema, inflammatory cytokine levels, lung injury, and apoptosis in ALI mice. Moreover, miR-129-5p suppression or PAX6 oe reversed the delaying effect of MALAT1 interference on sepsis-induced ALI. MALAT1 aggravates sepsis-induced ALI via the miR-129-5p/PAX6/ZEB2 axis.

CIRCKLHL2 KNOCKDOWN ALLEVIATES SEPSIS-INDUCED ACUTE LUNG INJURY BY REGULATING MIR-29B-3P MEDIATED ROCK1 EXPRESSION DOWN-REGULATION

ABSTRACT

Background: Acute lung injury (ALI) induced by sepsis is distinguished by an inflammatory progression. Herein, we investigated the action of circular RNA kelch like family member 2 (circKlhl2) in sepsis-induced ALI. Methods: The animal or cell model of sepsis ALI was established by LPS stimulation. The contents of circKlhl2, microRNA-29b-3p (miR-29b-3p), rho-associated coiled-coil containing protein kinase 1 (ROCK1), CyclinD1, B-cell lymphoma-2 (Bcl-2), and cleaved-caspase 3 (C-caspase-3) were detected by quantitative real-time polymerase chain reaction and western blot, respectively. Cell viability was assessed by cell counting kit 8 assay. Cell cycle and apoptosis were evaluated by flow cytometry. The abundances of proinflammatory cytokines were detected by enzyme-linked immunosorbent assay. Besides, the targeted relationship between miR-29b-3p and circKlhl2 or ROCK1 was verified by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay. Results: Loss of circKlhl2 mitigated lung injury and proinflammatory cytokine expression in sepsis-ALI mice model and alleviated LPS-induced apoptosis and inflammatory response in microvascular endothelial cell (MPVECs) in vitro . The abundances of circKlhl2 and ROCK1 were boosted, while the miR-29b-3p level was diminished in the animal or cell model of sepsis-ALI. MiR-29b-3p inhibition abrogated circKlhl2 knockdown-mediated effects on MPVECs injury. Moreover, miR-29b-3p overexpression promoted cell proliferation and inhibited apoptosis and inflammation in LPS-treated MPVECs, while ROCK1 enhancement reversed these effects. Conclusion: CircKlhl2 expedited the sepsis-induced ALI by adjusting miR-29b-3p/ROCK1 axis.

CircEXOC5 facilitates cell pyroptosis via epigenetic suppression of Nrf2 in septic acute lung injury

Acute lung injury (ALI) caused by sepsis is characterized by a destructive high inflammatory response in lungs, which is the ultimate cause of high mortality to patients diagnosed with sepsis. The objective of the present study is to explore the effect and related mechanisms of circEXOC5 on pyroptosis in septic ALI. Sepsis ALI mouse model was induced and established by CLP induction and sepsis MPVEC cell model by LPS. HE staining was used to detect lung tissue pathological changes. ELISA, flow cytometry, and Western blot were utilized to evaluate the release of inflammatory cytokines and cell pyroptosis, and RIP was applied to verify the binding relationship between EZH2 and circEXOC5 or Nrf2. Finally, the interaction between CircEXOC5 and EZH2, H3k27me3, and Nrf2 promoter regions was clarified using ChIP. CircEXOC5 levels were notably ascended in the lung tissues of septic ALI mice. And silencing circEXOC5 inhibited cell pyroptosis and the release of inflammatory cytokines in MPVEC stimulated by LPS. In addition, RIP and ChIP indicated that Nrf2 expression in MPVECs cells could be inhibited by circEXOC5 via recruiting EZH2. In addition, ML385 (a specific inhibitor of Nrf2) reversed the efficacy of Knockdown of circEXOC5 on the Inhibition of pyroptosis and inflammation of MPVEC cells stimulated by LPS. These results indicated that CircEXOC5 could promote cell pyroptosis through epigenetic inhibition of Nrf2 in septic ALI.

Suppression of NOD-like receptor protein 3 inflammasome activation and macrophage M1 polarization by hederagenin contributes to attenuation of sepsis-induced acute lung injury in rats

Acute lung injury (ALI) is a major leading cause of death in sepsis patients. Hederagenin (HG), derived from Hedera helix Linné, has anti-inflammatory effects, while its role in sepsis-induced ALI has not been elucidated. In vivo, rats were subjected to cecal ligation and puncture to induce ALI and then treated with HG (12.5, 25, or 50 mg/kg) by gavage. Administration of HG raised survival rate, ameliorated lung injury, and decreased lung wet/dry ratio and inflammatory cell accumulation in bronchoalveloar lavage fluid (BALF) of ALI rats. HG inhibited macrophage polarization toward the M1 phenotype as evidenced by decreased CD86 expression in rat lung tissues. Moreover, HG decreased the secretion of TNF-α, IL-6 and monocyte chemoattractant protein-1 (MCP-1) in BALF and the levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lung tissues. In vitro, phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 macrophages were stimulated with 100 ng/mL lipopolysaccharide. HG treatment inhibited M1 macrophage polarization and the production of M1-related pro-inflammatory mediators (IL-6, MCP-1, iNOS, and COX-2). Mechanistically, HG inhibited NLRP3 inflammasome activation and subsequent release of IL-18 and IL-1β, and suppressed NF-κB signaling pathway both in vivo and in vitro. Notably, HG treatment further emphasized the inhibitory effect of NF-κB inhibitor BAY11-7082 on NLRP3 inflammasome activation and macrophage M1 polarization. Taken together, HG exerts a protective effect against sepsis-induced ALI by reducing the inflammatory response and macrophage M1 polarization, which may involve NF-κB pathway-modulated NLRP3 inflammasome activation.

miR-942-5p prevents sepsis-induced acute lung injury via targeting TRIM37

MicroRNAs (miRNAs) have been demonstrated to play pivotal roles in the pathogenesis of sepsis-induced acute lung injury (ALI). In this work, we aimed to clarify the potential role and the underlying mechanism of miR-942-5p in a lipopolysaccharide (LPS)-induced A549 cell injury model. The cell injury was evaluated by CCK-8 assay, flow cytometry and enzyme-linked immunosorbent assay (ELISA). The expression levels of miR-942-5p and tripartite motif-containing protein 37 (TRIM37) were measured by real-time PCR and Western blot, and their association was then validated by bioinformatics, luciferase reporter assay and RNA pull-down assay. We found that the expression of miR-942-5p was decreased in LPS-treated A549 cells. Furthermore, LPS treatment suppressed A549 cell viability, promoted apoptosis and increased the levels of inflammatory cytokines. Conversely, overexpression of miR-942-5p increased cell viability, reduced apoptosis and alleviated inflammatory cytokine secretion in the presence of LPS. Moreover, miR-942-5p directly targeted TRIM37 by binding to the 3'-UTR of TRIM37 mRNA. Upregulation of TRIM37 effectively reversed the anti-apoptotic and anti-inflammatory effects of miR-942-5p in LPS-induced A549 cells. Our findings suggested that miR-942-5p protected against LPS-induced cell injury through inhibiting apoptosis and inflammation in A549 cells by negatively regulating TRIM37.

miR-128-3p reduced acute lung injury induced by sepsis via targeting PEL12

Objective

Acute lung injury (ALI) caused by sepsis is clinically a syndrome, which is featured by damage to the alveolar epithelium and endothelium. In this study, we employed mice models of cecal ligation and puncture (CLP) and primary mice pulmonary microvascular endothelial cells (MPVECs) in vitro to investigate the effect of miR-128-3p in ALI caused by sepsis.

Methods

miR-128-3p agomir or randomized control were injected into adult male C57BL/6 mice 1 week before the CLP surgery. We used miR-128-3p agomir or scrambled control to transfect MPVECs and then employed lipopolysaccharide (LPS) stimulation on the cells. Pellino homolog 2 (PELI2) was predicted to be a direct target of miR-128-3p via luciferase reporter assay. MPVECs were cotransfected with lentiviral vector that expressed PELI2 (or empty vector) as well as miR-128-3p-mimics 1 day before LPS stimulation in rescue experiment. Transcriptional activity of caspase-3, cell apoptosis rate, and the expression levels of miR-128-3p, interleukin-1β (IL-1β), interleukin-6 (IL-6), and PELI2 were analyzed.

Results

Compared with the sham group, the lung of mice in the CLP group showed pulmonary morphological abnormalities, and the expression of IL-6 and IL-1β, caspase-3 activity, and apoptosis rate were significantly upregulated in the CLP group. Inflammatory factor levels and apoptosis rate were also significantly induced by LPS stimulation on MPVECs. Upregulation of miR-128-3p effectively inhibited sepsis-induced ALI, apoptosis as well as inflammation. miR-128-3p also played a role in antiapoptosis and anti-inflammation in MPVECs with LPS treatment. PEL12 upregulation in MPVECs alleviated miR-128-3p-induced caspase-3 activity inhibition and pro-inflammatory factor production.

Conclusions

miR-128-3p enabled to alleviate sepsis-induced ALI by inhibiting PEL12 expression, indicating a novel treatment strategy of miR-128-3p for sepsis-induced ALI.

Long non-coding RNA NEAT1 promotes lipopolysaccharide-induced acute lung injury by regulating miR-424-5p/MAPK14 axis

BACKGROUND

Many long non-coding RNAs (lncRNAs) have been suggested to play critical roles in acute lung injury (ALI) pathogenesis, including lncRNA nuclear enriched abundant transcript 1 (NEAT1).

OBJECTIVE

We aimed to further elucidate the functions and molecular mechanism of NEAT1 in ALI.

METHODS

Human pulmonary alveolar epithelial cells (HPAEpiCs) stimulated by lipopolysaccharide (LPS) were served as a cellular model of ALI. Cell viability and cell apoptosis were determined by cell counting kit-8 (CCK-8) assay and flow cytometry, respectively. The expression of NEAT1, microRNA-424-5p (miR-424-5p), and mitogen-activated protein kinase 14 (MAPK14) was measured by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot analysis. Caspase activity was determined by caspase activity kit. The inflammatory responses were evaluated using enzyme-linked immunosorbent assay (ELISA). The oxidative stress factors were analyzed by corresponding kits.

RESULTS

NEAT1 was upregulated in LPS-stimulated HPAEpiCs. NEAT1 knockdown weakened LPS-induced injury by inhibiting apoptosis, inflammation and oxidative stress in HPAEpiCs. Moreover, miR-424-5p was a direct target of NEAT1, and its knockdown reversed the effects caused by NEAT1 knockdown in LPS-induced HPAEpiCs. Furthermore, MAPK14 was a downstream target of miR-424-5p, and its overexpression attenuated the effects of miR-424-5p on reduction of LPS-induced injury in HPAEpiCs. Besides, NEAT1 acted as a sponge of miR-424-5p to regulate MAPK14 expression.

CONCLUSION

NEAT1 knockdown alleviated LPS-induced injury of HPAEpiCs by regulating miR-424-5p/MAPK14 axis, which provided a potential therapeutic target for the treatment of ALI.

CircC3P1 attenuated pro-inflammatory cytokine production and cell apoptosis in acute lung injury induced by sepsis through modulating miR-21

Acute lung injury (ALI) induced by sepsis is characterized by an inflammatory process related to the up‐regulation of inflammatory cytokines and chemokines. In the present study, we explored the role of circC3P1 in sepsis‐induced ALI in vitro and in vivo. The caecal ligation and puncture (CLP)‐induced sepsis model was established through CLP surgery. Forty adult male C57BL/6 mice were randomly assigned into sham, CLP, CLP + vector and CLP + circC3P1 (each n = 10). Primary murine pulmonary microvascular endothelial cells (MPVECs) were transfected with circC3P1 or empty vector 24 hours prior to LPS treatment via Lipofectamine 2000. The expressions of circC3P1, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6) and IL‐1β were evaluated after 6‐h LPS treatment. Cell apoptosis was evaluated via flow cytometry. The CLP group demonstrated pulmonary morphological abnormalities, increased concentrations of TNF‐α, IL‐6 and IL‐1β in the lung tissue, compared with the sham group. MPVECs treated with LPS significantly elevated TNF‐α, IL‐6 and IL‐1β levels and increased cell apoptosis than that in the control group. The circC3P1 overexpression in sepsis‐induced ALI mice attenuated pulmonary injury, inflammation and apoptosis. Besides, circC3P1 revealed anti‐inflammatory and anti‐apoptotic effect in MPVEC‐treated LPS. CircC3P1 overexpression reduced cell apoptosis and pro‐inflammatory cytokines levels via down‐regulating miR‐21. CircC3P1 attenuated pro‐inflammatory cytokine production and cell apoptosis in ALI induced by sepsis through modulating miR‐21, indicating that circC3P1 is a promising therapeutic biomarker for sepsis‐induced ALI.

LncRNA TUG1 alleviates sepsis-induced acute lung injury by targeting miR-34b-5p/GAB1

Background

Sepsis-induced acute lung injury (ALI) is a clinical syndrome characterized by the injury of alveolar epithelium and pulmonary endothelial cells. This study aimed to investigate the regulation of long noncoding RNA (lncRNA) taurine up-regulated gene 1 (TUG1) in a murine ALI model and in primary murine pulmonary microvascular endothelial cells (PMVECs) stimulated with lipopolysaccharide (LPS).

Methods

Adult C57BL/6 mice were intravenously injected with or without TUG1-expressiong adenoviral vector or control vector 1 week before the establishment of ALI model. PMVECs were transfected with TUG1-expressiong or control vectors followed by LPS stimulation. MiR-34b-5p was confirmed as a target of TUG1 using dual-luciferase reporter assay. GRB2 associated binding protein 1 (GAB1) was confirmed as a downstream target of miR-34b-5p using the same method. In the rescue experiment, PMVECs were co-transfected with TUG1-expressing vector and miR-34b-5p mimics (or control mimics) 24 h before LPS treatment.

Results

ALI mice showed reduced levels of TUG1, pulmonary injury, and induced apoptosis and inflammation compared to the control group. The overexpression of TUG1 in ALI mice ameliorated sepsis-induced pulmonary injury, apoptosis and inflammation. TUG1 also showed protective effect in LPS-treated PMVECs. The expression of MiR-34b-5p was negatively correlated with the level of TUG1. TUG1-supressed apoptosis and inflammation in LPS-stimulated PMVECs were restored by miR-34b-5p overexpression. GAB1 was inversely regulated by miR-34b-5p but was positively correlated with TUG1 expression.

Conclusion

TUG1 alleviated sepsis-induced inflammation and apoptosis via targeting miR-34b-5p and GAB1. These findings suggested that TUG1 might be served as a therapeutic potential for the treatment of sepsis-induced ALI.

Timing of Intubation and Clinical Outcomes in Adults With Acute Respiratory Distress Syndrome

OBJECTIVE

The prevalence, clinical characteristics, and outcomes of critically ill, nonintubated patients with evidence of the acute respiratory distress syndrome remain inadequately characterized.

DESIGN

Secondary analysis of a prospective observational cohort study.

SETTING

Vanderbilt University Medical Center.

PATIENTS

Among adult patients enrolled in a large, multi-ICU prospective cohort study between the years of 2006 and 2011, we studied intubated and nonintubated patients with acute respiratory distress syndrome as defined by acute hypoxemia (PaO2/FIO2 ≤ 300 or SpO2/FIO2 ≤ 315) and bilateral radiographic opacities not explained by cardiac failure. We excluded patients not committed to full respiratory support.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 457 patients with acute respiratory distress syndrome, 106 (23%) were not intubated at the time of meeting all other acute respiratory distress syndrome criteria. Nonintubated patients had lower morbidity and severity of illness than intubated patients; however, mortality at 60 days was the same (36%) in both groups (p = 0.91). Of the 106 nonintubated patients, 36 (34%) required intubation within the subsequent 3 days of follow-up; this late-intubation subgroup had significantly higher 60-day mortality (56%) when compared with the both early intubation group (36%, P<0.03) and patients never requiring intubation (26%; p = 0.002). Increased mortality in the late intubation group persisted at 2-year follow-up. Adjustment for baseline clinical and demographic differences did not change the results.

CONCLUSIONS

A substantial proportion of critically ill adults with acute respiratory distress syndrome were not intubated in their initial days of intensive care, and many were never intubated. Late intubation was associated with increased mortality. Criteria defining the acute respiratory distress syndrome prior to need for positive pressure ventilation are required so that these patients can be enrolled in clinical studies and to facilitate early recognition and treatment of acute respiratory distress syndrome.

Corticosteroids in treatment of aspiration-related acute respiratory distress syndrome: results of a retrospective cohort study

Background

Acute stroke patients suffering from aspiration may present with acute respiratory distress syndrome (ARDS). There is still a lack of convincing data about the efficacy of corticosteroids in the treatment of aspiration-related ARDS. Therefore, we evaluated the clinical impact of corticosteroids on aspiration-related ARDS.

Methods

Between 2012 and 2014, we conducted a retrospective study among acute stroke patients diagnosed with aspiration-related ARDS. The data analyzed included demographic characteristics, clinical manifestations, laboratory examinations, chest imaging, and hospital discharge status.

Results

Seventy-three acute stroke patients were diagnosed with aspiration-related ARDS. The hospital mortality rate was 39.7 %. Corticosteroids were administered in 47 patients (64.4 %). The mean dosage was 1.14 (standard deviation [SD] 0.47) mg/kg daily of methylprednisolone (or an equivalent) by intravenous infusion for a period of 7.3 (SD 3.8) days. Ground glass opacities in chest computed tomography images were resolved when corticosteroids were administered. The admission National Institute of Health Stroke Scale score (odds ratio [OR] 5.17, 95 % confidence interval [CI] 1.27–10.64) and Acute Physiology and Chronic Health Evaluation II score (OR 2.00, 95 % CI 1.12–3.56) were associated with an increased risk of hospital mortality, while albumin (OR 0.81, 95 % CI 0.64–0.92) and corticosteroids therapy (OR 0.50, 95 % CI 0.35–0.70) were associated with a decreased risk.

Conclusions

Low-dose and short-term corticosteroid therapy may have an impact on survival in aspiration-related ARDS. The presence of ground glass opacities on the chest computed tomography, performed to rule out aspiration-related ARDS, could be translated into an increased possibility of positive response to corticosteroid therapy.

Evolving epidemiology and definitions of the acute respiratory distress syndrome and early acute lung injury

This article reviews the evolving definitions and epidemiology of the acute respiratory distress syndrome (ARDS) and highlights current efforts to improve identification of high-risk patients, thus to target prevention and early treatment before progression to ARDS. This information will be important for general practitioners and intensivists interested in improving the care of patients at risk for ARDS, and clinical researchers interested in designing clinical trials targeting the prevention and early treatment of acute lung injury.

Hyperoxia increases the elastic modulus of alveolar epithelial cells through Rho kinase

Patients with acute lung injury are administered high concentrations of oxygen during mechanical ventilation, and while both hyperoxia and mechanical ventilation are necessary, each can independently cause additional injury. However, the precise mechanisms that lead to injury are not well understood. We hypothesized that alveolar epithelial cells may be more susceptible to injury caused by mechanical ventilation because hyperoxia causes cells to be stiffer due to increased filamentous actin (f-actin) formation via the GTPase RhoA and its effecter Rho kinase (ROCK). We examined cytoskeletal structures in cultured murine lung alveolar epithelial cells (MLE-12) under normoxic and hyperoxic (48 h) conditions. We also measured cell elasticity (E) using an atomic force microscope in the indenter mode. Hyperoxia caused increased f-actin stress fibers and bundle formation, an increase in g- and f-actin, an increase in nuclear area and a decrease in nuclear height, and cells became stiffer (higher E). Treatment with an inhibitor (Y-27632) of ROCK significantly decreased E and prevented the cytoskeletal changes, while it did not influence the nuclear height and area. Pre-exposure of cells to hyperoxia promoted detachment when cells were subsequently stretched cyclically, but the ROCK inhibitor prevented this effect. Hyperoxia caused thickening of vinculin focal adhesion plaques, and inhibition of ROCK reduced the formation of distinct focal adhesion plaques. Phosphorylation of focal adhesion kinase was significantly reduced by both hyperoxia and treatment with Y-27632. Hyperoxia caused increased cell stiffness and promoted cell detachment during stretch. These effects were ameliorated by inhibition of ROCK.

A randomized controlled trial of peripheral blood mononuclear cell depletion in experimental human lung inflammation

RATIONALE

Depletion of monocytes reduces LPS-induced lung inflammation in mice, suggesting monocytes as potential therapeutic targets in acute lung injury.

OBJECTIVES

To investigate whether depletion of circulating blood monocytes has beneficial effects on markers of systemic and pulmonary inflammation in a human model of acute lung inflammation.

METHODS

A total of 30 healthy volunteers were enrolled in a randomized controlled trial. Volunteers inhaled LPS at baseline, and were randomized to receive active mononuclear cell depletion by leukapheresis, or sham leukapheresis, in a double-blind fashion (15 volunteers per group). Serial blood counts were measured, bronchoalveolar lavage (BAL) was performed at 9 hours, and [(18)F]fluorodeoxyglucose positron emission tomography at 24 hours. The primary endpoint was the increment in circulating neutrophils at 8 hours.

MEASUREMENTS AND MAIN RESULTS

As expected, inhalation of LPS induced neutrophilia and an up-regulation of inflammatory mediators in the blood and lungs of all volunteers. There was no significant difference between the depletion and sham groups in the mean increment in blood neutrophil count at 8 hours (6.16 × 10(9)/L and 6.15 × 10(9)/L, respectively; P = 1.00). Furthermore, there were no significant differences in BAL neutrophils or protein, positron emission tomography-derived measures of global lung inflammation, or cytokine levels in plasma or BAL supernatant between the study groups. No serious adverse events occurred, and no symptoms were significantly different between the groups.

CONCLUSIONS

These findings do not support a role for circulating human monocytes in the early recruitment of neutrophils during LPS-mediated acute lung inflammation in humans.

Prospective and management: acute nonimmunologic inhalation injuries

The Occupational Medicine Forum is prepared by the ACOEM Occupational and Environmental Medical Practice Committee and does not necessarily represent an official ACOEM position. The Forum is intended for health professionals and is not intended to provide medical or legal advice, including illness prevention, diagnosis or treatment, or regulatory compliance. Such advice should be obtained directly from a physician and/or attorney.

Preoperative and intraoperative predictors of postoperative acute respiratory distress syndrome in a general surgical population

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a devastating condition with an estimated mortality exceeding 30%. There are data suggesting risk factors for ARDS development in high-risk populations, but few data are available in lower incidence populations. Using risk-matched analysis and a combination of clinical and research data sets, we determined the incidence and risk factors for the development of ARDS in this general surgical population.

METHODS

We conducted a review of common adult surgical procedures completed between June 1, 2004 and May 31, 2009 using an anesthesia information system. This data set was merged with an ARDS registry and an institutional death registry. Preoperative variables were subjected to multivariate analysis. Matching and multivariate regression was used to determine intraoperative factors associated with ARDS development.

RESULTS

In total, 50,367 separate patient admissions were identified, and 93 (0.2%) of these patients developed ARDS. Preoperative risk factors for ARDS development included American Society of Anesthesiologist status 3-5 (odds ratio [OR] 18.96), emergent surgery (OR 9.34), renal failure (OR 2.19), chronic obstructive pulmonary disease (OR 2.16), number of anesthetics during the admission (OR 1.37), and male sex (OR 1.65). After matching, intraoperative risk factors included drive pressure (OR 1.17), fraction inspired oxygen (OR 1.02), crystalloid administration in liters (1.43), and erythrocyte transfusion (OR 5.36).

CONCLUSIONS

ARDS is a rare condition postoperatively in the general surgical population and is exceptionally uncommon in low American Society of Anesthesiologists status patients undergoing scheduled surgery. Analysis after matching suggests that ARDS development is associated with median drive pressure, fraction inspired oxygen, crystalloid volume, and transfusion.

Preventing the acute respiratory distress syndrome

Laudable supportive advances have been made to improve the care of patients with the Acute Respiratory Distress Syndrome (ARDS) but no pharmacologic interventions are known to reduce the high mortality of this disorder once it is established. This commentary discusses some of the challenges that arise in preventing ARDS in at-risk individuals and the likely dependence of this approach on biomarker panels that can be done in real time.

Intraoperative ventilation: incidence and risk factors for receiving large tidal volumes during general anesthesia

Background

There is a growing concern of the potential injurious role of ventilatory over-distention in patients without lung injury. No formal guidelines exist for intraoperative ventilation settings, but the use of tidal volumes (V_T) under 10 mL/kg predicted body weight (PBW) has been recommended in healthy patients. We explored the incidence and risk factors for receiving large tidal volumes (V_T > 10 mL/kg PBW).

Methods

We performed a cross-sectional analysis of our prospectively collected perioperative electronic database for current intraoperative ventilation practices and risk factors for receiving large tidal volumes (V_T > 10 mL/kg PBW). We included all adults undergoing prolonged (≥ 4 h) elective abdominal surgery and collected demographic, preoperative (comorbidities), intraoperative (i.e. ventilatory settings, fluid administration) and postoperative (outcomes) information. We compared patients receiving exhaled tidal volumes > 10 mL/kg PBW with those that received 8-10 or < 8 mL/kg PBW with univariate and logistic regression analyses.

Results

Ventilatory settings were non-uniform in the 429 adults included in the analysis. 17.5% of all patients received V_T > 10 mL/kg PBW. 34.0% of all obese patients (body mass index, BMI, ≥ 30), 51% of all patients with a height < 165 cm, and 34.6% of all female patients received V_T > 10 mL/kg PBW.

Conclusions

Ventilation with V_T > 10 mL/kg PBW is still common, although poor correlation with PBW suggests it may be unintentional. BMI ≥ 30, female gender and height < 165 cm may predispose to receive large tidal volumes during general anesthesia. Further awareness of patients' height and PBW is needed to improve intraoperative ventilation practices. The impact on clinical outcome needs confirmation.

Immunodetection of occult eosinophils in lung tissue biopsies may help predict survival in acute lung injury

BACKGROUND

Acute lung injury (ALI) is a serious respiratory disorder for which therapy is primarily supportive once infection is excluded. Surgical lung biopsy may rule out other diagnoses, but has not been generally useful for therapy decisions or prognosis in this setting. Importantly, tissue and peripheral blood eosinophilia, the hallmarks of steroid-responsive acute eosinophilic pneumonia, are not commonly linked with ALI. We hypothesized that occult eosinophilic pneumonia may explain better outcomes for some patients with ALI.

METHODS

Immunohistochemistry using a novel monoclonal antibody recognizing eosinophil peroxidase (EPX-mAb) was used to assess intrapulmonary eosinophil accumulation/degranulation. Lung biopsies from ALI patients (n = 20) were identified following review of a pathology database; 45% of which (i.e., 9/20) displayed classical diffuse alveolar damage (ALI-DAD). Controls were obtained from uninvolved tissue in patients undergoing lobectomy for lung cancer (n = 10). Serial biopsy sections were stained with hematoxylin and eosin (H&E) and subjected to EPX-mAb immunohistochemistry.

RESULTS

EPX-mAb immunohistochemistry provided a >40-fold increased sensitivity to detect eosinophils in the lung relative to H&E stained sections. This increased sensitivity led to the identification of higher numbers of eosinophils in ALI patients compared with controls; differences using H&E staining alone were not significant. Clinical assessments showed that lung infiltrating eosinophil numbers were higher in ALI patients that survived hospitalization compared with non-survivors. A similar conclusion was reached quantifying eosinophil degranulation in each biopsy.

CONCLUSION

The enhanced sensitivity of EPX-mAb immunohistochemistry uniquely identified eosinophil accumulation/degranulation in patients with ALI relative to controls. More importantly, this method was a prognostic indicator of patient survival. These observations suggest that EPX-mAb immunohistochemistry may represent a diagnostic biomarker identifying a subset of ALI patients with improved clinical outcomes.