Deterioration of previous acute lung injury during neutropenia recovery

[Invasive mechanical ventilation in patients with solid tumor or hematological malignancy]

Invasive mechanical ventilation in onco-hematology patients has become relatively routine, and is now part and parcel of their care pathway. Nevertheless, specific complications and subsequent therapeutic possibilities require discussion. To a greater extent than with regard to other patient populations, cooperation between specialist and ICU physician is mandatory, the objective being to more comprehensively assess a therapeutic project before or during the period of invasive mechanical ventilation. After an overview of recent results concerning ventilated patients in intensive care, this review aims to describe the specific complications and factors associated with mortality in this population.

A scoping review of the pathophysiology of COVID-19

COVID-19 is a highly heterogeneous and complex medical disorder; indeed, severe COVID-19 is probably amongst the most complex of medical conditions known to medical science. While enormous strides have been made in understanding the molecular pathways involved in patients infected with coronaviruses an overarching and comprehensive understanding of the pathogenesis of COVID-19 is lacking. Such an understanding is essential in the formulation of effective prophylactic and treatment strategies. Based on clinical, proteomic, and genomic studies as well as autopsy data severe COVID-19 disease can be considered to be the connection of three basic pathologic processes, namely a pulmonary macrophage activation syndrome with uncontrolled inflammation, a complement-mediated endothelialitis together with a procoagulant state with a thrombotic microangiopathy. In addition, platelet activation with the release of serotonin and the activation and degranulation of mast cells contributes to the hyper-inflammatory state. Auto-antibodies have been demonstrated in a large number of hospitalized patients which adds to the end-organ damage and pro-thrombotic state. This paper provides a clinical overview of the major pathogenetic mechanism leading to severe COVID-19 disease.

Neutrophil Extracellular Traps Are Elevated in Patients with Pneumonia-related Acute Respiratory Distress Syndrome

BACKGROUND

Neutrophil extracellular traps have been associated with tissue damage. Whether these are involved in the pathogenesis of human acute respiratory distress syndrome (ARDS) and could be a potential therapeutic target is unknown. The authors quantified bronchoalveolar and blood neutrophil extracellular traps in patients with pneumonia-related ARDS and assessed their relationship with ventilator-free days.

METHODS

Immunocompetent patients with pneumonia and moderate or severe ARDS (n = 35) and controls (n = 4) were included in a prospective monocentric study. Neutrophil extracellular trap concentrations were quantified (as DNA-myeloperoxidase complexes) in bronchoalveolar lavage fluid and serum by enzyme-linked immunosorbent assay. The relationship between bronchoalveolar lavage neutrophil extracellular trap concentrations and the primary clinical endpoint (i.e., the number of live ventilator-free days at day 28) was assessed using linear regression analyses.

RESULTS

There was no significant relationship between bronchoalveolar lavage neutrophil extracellular trap concentrations and ventilator-free days by multiple regression analysis (β coefficient = 2.40; 95% CI, -2.13 to 6.92; P = 0.288). Neutrophil extracellular trap concentrations were significantly higher in bronchoalveolar lavage than in blood of ARDS patients (median [first to third quartiles]:154 [74 to 1,000] vs. 26 [4 to 68] arbitrary units, difference: -94; 95% CI, -341 to -57; P < 0.0001). Bronchoalveolar concentrations of patients were higher than those of controls (154 [74 to 1,000] vs. 4 [4 to 4] arbitrary units, difference: -150; 95% CI, -996 to -64; P < 0.001) and associated with bronchoalveolar interleukin-8 (Spearman's ρ = 0.42; P = 0.012) and neutrophil concentrations (ρ = 0.57; P < 0.0001). Intensive care unit mortality (12%, n = 2 of 17 vs. 17%, n = 3 of 18; P > 0.99) and the number of ventilator-free days at day 28 (22 [14 to 25] vs. 14 [0 to 21] days; difference: -5; 95% CI, -15 to 0; P = 0.066) did not significantly differ between patients with higher (n = 17) versus lower (n = 18) bronchoalveolar neutrophil extracellular trap concentrations.

CONCLUSIONS

Bronchoalveolar neutrophil extracellular trap concentration was not significantly associated with mechanical ventilation duration in pneumonia-related ARDS.

The Association Between the Neutrophil-to-Lymphocyte Ratio and Mortality in Patients With Acute Respiratory Distress Syndrome: A Retrospective Cohort Study

PURPOSE

Systemic inflammation relates to the initiation and progression of acute respiratory distress syndrome (ARDS). As neutrophil-to-lymphocyte ratio (NLR) has been shown to be a prognostic inflammatory biomarker in various diseases, in this study, we sought to explore whether NLR is a prognostic factor in patients with ARDS.

METHODS

A retrospective study was performed on patients diagnosed as ARDS admitted to the intensive care unit (ICU). We calculated the NLR by dividing the neutrophil count by the lymphocyte count and categorized patients into four groups based on quartile of NLR values. The association of NLR quartiles and 28-day mortality was assessed using multivariable Cox regression. Secondary outcomes included ICU mortality and hospital mortality.

RESULTS

A total of 224 patients were included in the final analysis. The median (interquartile range) NLRs from first quartile to fourth quartile were as follows: 6.88 (4.61-7.94), 13.06 (11.35-14.89), 20.99 (19.09-23.19), and 39.39 (32.63-50.15), respectively. The 28-day mortalities for the same groups were as follows: 10.7%, 19.6%, 41.4%, and 53.6% (P < 0.001). Cox regression analysis showed NLR was a significant risk factor predicting 28-day mortality (first quartile, reference group; second quartile, adjusted hazard ratio [HR]= 1.674, 95% confidence interval [CI], 0.462-6.063, P = 0.432; third quartile, HR = 5.075, 95% CI, 1.554-16.576, P = 0.007; fourth quartile, HR = 5.815, 95% CI, 1.824-18.533, P = 0.003). Similar trends were observed for ICU mortality and hospital mortality.

CONCLUSIONS

High NLR was associated with the poor outcome in critically ill patients with ARDS. The NLR therefore seems to be a prognostic biomarker of outcomes in critically ill patients with ARDS. Further investigation is required to validate this relationship with data collected prospectively.

Alveolar Macrophage Chemokine Secretion Mediates Neutrophilic Lung Injury in Nox2-Deficient Mice

Acute lung injury (ALI), developing as a component of the systemic inflammatory response syndrome (SIRS), leads to significant morbidity and mortality. Reactive oxygen species (ROS), produced in part by the neutrophil NADPH oxidase 2 (Nox2), have been implicated in the pathogenesis of ALI. Previous studies in our laboratory demonstrated the development of pulmonary inflammation in Nox2-deficient (gp91^phox-/y) mice that was absent in WT mice in a murine model of SIRS. Given this finding, we hypothesized that Nox2 in a resident cell in the lung, specifically the alveolar macrophage, has an essential anti-inflammatory role. Using a murine model of SIRS, we examined whole-lung digests and bronchoalveolar lavage fluid (BALf) from WT and gp91^phox-/y mice. Both genotypes demonstrated neutrophil sequestration in the lung during SIRS, but neutrophil migration into the alveolar space was only present in the gp91^phox-/y mice. Macrophage inflammatory protein (MIP)-1α gene expression and protein secretion were higher in whole-lung digest from uninjected gp91^phox-/y mice compared to the WT mice. Gene expression of MIP-1α, MCP-1, and MIP-2 was upregulated in alveolar macrophages obtained from gp91^phox-/y mice at baseline compared with WT mice. Further, ex vivo analysis of alveolar macrophages, but not bone marrow-derived macrophages or peritoneal macrophages, demonstrated higher gene expression of MIP-1α and MIP-2. Moreover, isolated lung polymorphonuclear neutrophils migrate to BALf obtained from gp91^phox-/y mice, further providing evidence of a cell-specific anti-inflammatory role for Nox2 in alveolar macrophages. We speculate that Nox2 represses the development of inflammatory lung injury by modulating chemokine expression by the alveolar macrophage.

Acute respiratory failure in immunocompromised adults

Acute respiratory failure occurs in up to half of patients with haematological malignancies and 15% of those with solid tumours or solid organ transplantation. Mortality remains high. Factors associated with mortality include a need for invasive mechanical ventilation, organ dysfunction, older age, frailty or poor performance status, delayed intensive care unit admission, and acute respiratory failure due to an invasive fungal infection or unknown cause. In addition to appropriate antibacterial therapy, initial clinical management aims to restore oxygenation and predict the most probable cause based on variables related to the underlying disease, acute respiratory failure characteristics, and radiographic findings. The cause of acute respiratory failure must then be confirmed using the most efficient, least invasive, and safest diagnostic tests. In patients with acute respiratory failure of undetermined cause, a standardised diagnostic investigation should be done immediately at admission before deciding whether to perform more invasive diagnostic procedures or to start empirical treatments. Collaborative and multidisciplinary clinical and research networks are crucial to improve our understanding of disease pathogenesis and causation and to develop less invasive diagnostic strategies and more targeted treatment options.

Early disruption of the alveolar-capillary barrier in a ricin-induced ARDS mouse model: neutrophil-dependent and -independent impairment of junction proteins

Irrespective of its diverse etiologies, acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) leads to increased permeability of the alveolar-capillary barrier, which in turn promotes edema formation and respiratory failure. We investigated the mechanism of ALI/ARDS lung hyperpermeability triggered by pulmonary exposure of mice to the highly toxic plant-derived toxin ricin. One prominent hallmark of ricin-mediated pulmonary intoxication is the rapid and massive influx of neutrophils to the lungs, where they contribute to the developing inflammation yet may also cause tissue damage, thereby promoting ricin-mediated morbidity. Here we show that pulmonary exposure of mice to ricin results in the rapid diminution of the junction proteins VE-cadherin, claudin 5, and connexin 43, belonging, respectively, to the adherens, tight, and gap junction protein families. Depletion of neutrophils in ricin-intoxicated mice attenuated the damage caused to these junction proteins, alleviated pulmonary edema, and significantly postponed the time to death of the intoxicated mice. Inhibition of matrix metalloproteinase (MMP) activity recapitulated the response to neutrophil depletion observed in ricin-intoxicated mice and was associated with decreased insult to the junction proteins and alveolar-capillary barrier. However, neutrophil-mediated MMP activity was not the sole mechanism responsible for pulmonary hyperpermeability, as exemplified by the ricin-mediated disruption of claudin 18, via a neutrophil-independent mechanism involving tyrosine phosphorylation. This in-depth study of the early stage mechanisms governing pulmonary tissue integrity during ALI/ARDS is expected to facilitate the tailoring of novel therapeutic approaches for the treatment of these diseases.

Granulocyte colony-stimulating factor and respiratory status of critically ill neutropenic patients with hematologic malignancies

In patients with hematologic malignancies, respiratory status may deteriorate during neutropenia recovery. This multicenter, observational study aims to evaluate granulocyte colony-stimulating factor (G-CSF) impact on respiratory status in critically ill neutropenic patients. Among 1011 critically ill patients with hematologic malignancies, 288 were neutropenic and included in this study. 201 (70%) did not receive G-CSF at day 1 or 2. After propensity score matching for the probability of receiving G-CSF at day 1 or 2, there was no association between G-CSF and respiratory deterioration at day 14 (OR =1.19; 95%CI (0.57-2.51); p = .64). Additional sensitivity analysis in patients admitted for acute respiratory failure showed similar results (OR =1.34; 95%CI (0.5-3.59); p = .57). Among patients who recovered from neutropenia, 75% experienced respiratory deterioration during neutropenia recovery. This study confirms that neutropenia recovery is a situation at risk of respiratory deterioration. However, whether G-CSF is an aggravating factor cannot be supported by our results.

Factors Predictive of Postoperative Acute Respiratory Failure Following Inpatient Sinus Surgery

OBJECTIVE

The impact of perioperative risk factors on outcomes following outpatient sinus surgery is well defined; however, risk factors and outcomes following inpatient surgery remain poorly understood. We aimed to define risk factors of postoperative acute respiratory failure following inpatient sinus surgery.

METHODS

Utilizing data from the Nationwide Inpatient Sample Database from the years 2010 to 2014, we identified patients (≥18 years of age) with an Internal Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) procedure code of sinus surgery. We used multivariable logistic regression to identify risk factors of postoperative acute respiratory failure.

RESULTS

We identified 4919 patients with a median age of 53 years. The rate of inpatient postoperative acute respiratory failure was 3.35%. Chronic sinusitis (57.7%) was the most common discharge diagnosis. The final multivariable logistic regression analysis suggested that pneumonia, bleeding disorder, alcohol dependence, nutritional deficiency, heart failure, paranasal fungal infections, and chronic kidney disease were associated with increased odds of acute respiratory failure (all P < .05).

CONCLUSION

To our knowledge, this represents the first study to evaluate potential risk factors of acute respiratory failure following inpatient sinus surgery. Knowledge of these risk factors may be used for risk stratification.

Neutrophils in Tissue Trauma of the Skin, Bone, and Lung: Two Sides of the Same Coin

Following severe tissue injury, patients are exposed to various danger- and microbe-associated molecular patterns, which provoke a strong activation of the neutrophil defense system. Neutrophils trigger and modulate the initial posttraumatic inflammatory response and contribute critically to subsequent repair processes. However, severe trauma can affect central neutrophil functions, including circulation half-life, chemokinesis, phagocytosis, cytokine release, and respiratory burst. Alterations in neutrophil biology may contribute to trauma-associated complications, including immune suppression, sepsis, multiorgan dysfunction, and disturbed tissue regeneration. Furthermore, there is evidence that neutrophil actions depend on the quality of the initial stimulus, including trauma localization and severity, the micromilieu in the affected tissue, and the patient's overall inflammatory status. In the present review, we describe the effects of severe trauma on the neutrophil phenotype and dysfunction and the consequences for tissue repair. We particularly concentrate on the role of neutrophils in wound healing, lung injury, and bone fractures, because these are the most frequently affected tissues in severely injured patients.

Characteristics of early acute respiratory distress syndrome in newly diagnosed acute myeloid leukemia

Acute respiratory complications occur frequently during the early phase of acute myeloid leukemia (AML) but information on the most severe form, acute respiratory distress syndrome (ARDS), is lacking. We retrospectively analyzed 280 patients with newly diagnosed AML in order to describe the incidence, risk factors and early mortality associated with ARDS within 15 d. Univariate and then multivariate analysis were performed. ARDS developed in 9% of patients and was associated with 64% day-30 mortality. White blood cell count on admission was an independent risk factor for ARDS (OR = 1.007, 95% CI = 1.001-1.012, p = .012) with a moderate prediction ability (AUC 0.704, p = .001). Other variables were associated with ARDS in univariate but not in multivariate analysis: body mass index (p = .06), transfusions (p = .001) and sepsis (p < .0001). Leukemia-specific complications and documented infections were the most frequent ARDS etiologies and were sometimes associated, with no clear distinctive temporal pattern.

Respiratory events in ward are associated with later intensive care unit (ICU) admission and hospital mortality in onco-hematology patients not admitted to ICU after a first request

INTRODUCTION

Prognostic impact of delayed intensive care unit(ICU) admission in critically ill cancer patients remains debatable. We determined predictive factors for later ICU admission and mortality in cancer patients initially not admitted after their first ICU request.

METHODS

All cancer patients referred for an emergency ICU admission between 1 January 2012 and 31 August 2013 were included.

RESULTS

Totally, 246(54.8%) patients were immediately admitted. Among 203(45.2%) patients denied at the first request, 54(26.6%) were admitted later. A former ICU stay [OR: 2.75(1.12-6.75)], a request based on a clinical respiratory event[OR: 2.6(1.35-5.02)] and neutropenia[OR: 2.25(1.06-4.8)] were independently associated with later ICU admission. Survival of patients admitted immediately and later did not differ at ICU(78.5% and 70.4%, respectively; p = 0.2) or hospital(74% and 66%, respectively; p = 0.24) discharge. Hospital mortality of patients initially not admitted was 29.7% and independently associated with malignancy progression[OR: 3.15(1.6-6.19)], allogeneic hematopoietic stem cell transplantation[OR: 2.5(1.06-5.89)], a request based on a clinical respiratory event[OR: 2.36(1.22-4.56)] and severe sepsis[OR: 0.27(0.08-0.99)].

CONCLUSION

Compared with immediate ICU admission, later ICU admission was not associated with hospital mortality. Clinical respiratory events were independently associated with both later ICU admission and hospital mortality.

The Intensive Care Medicine research agenda on critically ill oncology and hematology patients

Over the coming years, accelerating progress against cancer will be associated with an increased number of patients who require life-sustaining therapies for infectious or toxic chemotherapy-related events. Major changes include increased number of cancer patients admitted to the ICU with full-code status or for time-limited trials, increased survival and quality of life in ICU survivors, changing prognostic factors, early ICU admission for optimal monitoring, and use of noninvasive diagnostic and therapeutic strategies. In this review, experts in the management of critically ill cancer patients highlight recent changes in the use and the results of intensive care in patients with malignancies. They seek to put forward a standard of care for the management of these patients and highlight important updates that are required to care for them. The research agenda they suggest includes important studies to be conducted in the next few years to increase our understanding of organ dysfunction in this population and to improve our ability to appropriately use life-saving therapies or select new therapeutic approaches that are likely to improve outcomes. This review aims to provide more guidance for the daily management of patients with cancer, in whom outcomes are constantly improving, as is our global ability to fight against what is becoming the leading cause of mortality in industrialized and non-industrialized countries.

Epidemiology of Acute Respiratory Distress Syndrome Following Hematopoietic Stem Cell Transplantation

OBJECTIVES

Pulmonary complications are common following hematopoietic stem cell transplantation. Numerous idiopathic post-transplantation pulmonary syndromes have been described. Patients at the severe end of this spectrum may present with hypoxemic respiratory failure and pulmonary infiltrates, meeting criteria for acute respiratory distress syndrome. The incidence and outcomes of acute respiratory distress syndrome in this setting are poorly characterized.

DESIGN

Retrospective cohort study.

SETTING

Mayo Clinic, Rochester, MN.

PATIENTS

Patients undergoing autologous and allogeneic hematopoietic stem cell transplantation between January 1, 2005, and December 31, 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were screened for acute respiratory distress syndrome development within 1 year of hematopoietic stem cell transplantation. Acute respiratory distress syndrome adjudication was performed in accordance with the 2012 Berlin criteria. In total, 133 cases of acute respiratory distress syndrome developed in 2,635 patients undergoing hematopoietic stem cell transplantation (5.0%). Acute respiratory distress syndrome developed in 75 patients (15.6%) undergoing allogeneic hematopoietic stem cell transplantation and 58 patients (2.7%) undergoing autologous hematopoietic stem cell transplantation. Median time to acute respiratory distress syndrome development was 55.4 days (interquartile range, 15.1-139 d) in allogeneic hematopoietic stem cell transplantation and 14.2 days (interquartile range, 10.5-124 d) in autologous hematopoietic stem cell transplantation. Twenty-eight-day mortality was 46.6%. At 12 months following hematopoietic stem cell transplantation, 89 patients (66.9%) who developed acute respiratory distress syndrome had died. Only 7 of 133 acute respiratory distress syndrome cases met criteria for engraftment syndrome and 15 for diffuse alveolar hemorrhage.

CONCLUSIONS

Acute respiratory distress syndrome is a frequent complication following hematopoietic stem cell transplantation, dramatically influencing patient-important outcomes. Most cases of acute respiratory distress syndrome following hematopoietic stem cell transplantation do not meet criteria for a more specific post-transplantation pulmonary syndrome. These findings highlight the need to better understand the risk factors underlying acute respiratory distress syndrome in this population, thereby facilitating the development of effective prevention strategies.

Inhibition of neutrophil elastase contributes to attenuation of lipopolysaccharide-induced acute lung injury during neutropenia recovery in mice

PURPOSE

Patients in whom neutropenia recovery is complicated by pneumonia have an increased risk of acute lung injury (ALI) and detrimental outcomes. The aim of the present study was to investigate whether inhibition of neutrophil elastase (NE) is effective in lipopolysaccharide (LPS)-induced ALI during neutropenia recovery in a murine model, and whether it upregulates the activation of the MerTK signaling pathway.

METHODS

Cyclophosphamide was given to mice to induce neutropenia. Seven days later, they were administered LPS by intratracheal instillation. Sivelestat, a neutrophil elastase inhibitor, was given by intraperitoneal injection once daily starting on day 0 and continuing until mice were sacrificed on day 5 (preventive group). Alternatively, sivelestat was given after, instead of before, LPS administration on day 2 (therapeutic group).

RESULTS

Sivelestat attenuated the lung edema and histopathological changes associated with LPS-induced lung injury. The accumulation of neutrophils and the concentrations of TNF-α, IL-6, and MPO in bronchoalveolar lavage (BAL) fluids were inhibited effectively by sivelestat. The expression of ICAM-1 and NF-κB p65 was also reduced after sivelestat administration. The protein and gene expression of MerTK tended to increase with sivelestat treatment.

CONCLUSIONS

Sivelestat significantly attenuated LPS-induced ALI during recovery from neutropenia, and this effect was associated with MerTK induction. These findings suggest that NE inhibition could be a promising means of alleviating lung inflammation without increasing susceptibility to infection in ALI/ARDS during neutropenia recovery.

Critical care of patients with cancer

Answer questions and earn CME/CNE The increasing prevalence of patients living with cancer in conjunction with the rapid progress in cancer therapy will lead to a growing number of patients with cancer who will require intensive care treatment. Fortunately, the development of more effective oncologic therapies, advances in critical care, and improvements in patient selection have led to an increased survival of critically ill patients with cancer. As a consequence, critical care has become an important cornerstone in the continuum of modern cancer care. Although, in many aspects, critical care for patients with cancer does not differ from intensive care for other seriously ill patients, there are several challenging issues that are unique to this patient population and require special knowledge and skills. The optimal management of critically ill patients with cancer necessitates expertise in oncology, critical care, and palliative medicine. Cancer specialists therefore have to be familiar with key principles of intensive care for critically ill patients with cancer. This review provides an overview of the state-of-the-art in the individualized management of critically ill patients with cancer. CA Cancer J Clin 2016;66:496-517. © 2016 American Cancer Society.

Management of neutropenic patients in the intensive care unit (NEWBORNS EXCLUDED) recommendations from an expert panel from the French Intensive Care Society (SRLF) with the French Group for Pediatric Intensive Care Emergencies (GFRUP), the French Society of Anesthesia and Intensive Care (SFAR), the French Society of Hematology (SFH), the French Society for Hospital Hygiene (SF2H), and the French Infectious Diseases Society (SPILF)

Neutropenia is defined by either an absolute or functional defect (acute myeloid leukemia or myelodysplastic syndrome) of polymorphonuclear neutrophils and is associated with high risk of specific complications that may require intensive care unit (ICU) admission. Specificities in the management of critically ill neutropenic patients prompted the establishment of guidelines dedicated to intensivists. These recommendations were drawn up by a panel of experts brought together by the French Intensive Care Society in collaboration with the French Group for Pediatric Intensive Care Emergencies, the French Society of Anesthesia and Intensive Care, the French Society of Hematology, the French Society for Hospital Hygiene, and the French Infectious Diseases Society. Literature review and formulation of recommendations were performed using the Grading of Recommendations Assessment, Development and Evaluation system. Each recommendation was then evaluated and rated by each expert using a methodology derived from the RAND/UCLA Appropriateness Method. Six fields are covered by the provided recommendations: (1) ICU admission and prognosis, (2) protective isolation and prophylaxis, (3) management of acute respiratory failure, (4) organ failure and organ support, (5) antibiotic management and source control, and (6) hematological management. Most of the provided recommendations are obtained from low levels of evidence, however, suggesting a need for additional studies. Seven recommendations were, however, associated with high level of evidences and are related to protective isolation, diagnostic workup of acute respiratory failure, medical management, and timing surgery in patients with typhlitis.

Neutropenic sepsis is associated with distinct clinical and biological characteristics: a cohort study of severe sepsis

Background

Immunocompromised patients who develop sepsis while neutropenic are at high risk for morbidity and mortality; however, it is unknown if neutropenic sepsis is associated with distinct clinical and biological characteristics.

Methods

We conducted a prospective cohort study of patients admitted to the medical intensive care unit of an academic medical center with severe sepsis. Patients were followed for the development of acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality. Plasma proteins, representing the host inflammatory response, anti-inflammatory response, and endothelial leak were measured in 30 % of subjects. Clinical characteristics and plasma protein concentrations of patients with neutropenia at enrollment were compared to patients without neutropenia.

Results

Of 797 subjects enrolled, 103 (13 %) were neutropenic at ICU admission. The neutropenic subjects were more often in shock, admitted from the hospital ward, had higher APACHE III scores, and more likely bacteremic. Neutropenia was an independent risk factor for AKI (RR 1.28; 95 % CI 1.04, 1.57; p = 0.03), but not ARDS (RR 0.90; 95 % CI 0.70, 1.17; p = 0.42) or 30-day mortality (RR 1.05; 95 % CI 0.85, 1.31; p = 0.65). Neutropenic subjects had higher plasma interleukin (IL)-6 (457 vs. 249 pg/ml; p = 0.03), IL-8 (581 vs. 94 pg/ml; p <0.001), and granulocyte colony-stimulating factor (G-CSF) (3624 vs. 99 pg/ml; p <0.001). Angiopoietin-2 and IL-1 receptor antagonist concentrations did not differ between groups.

Conclusions

Neutropenic sepsis is associated with a higher AKI risk and concentrations of inflammatory mediators IL-6, IL-8, and G-CSF relative to non-neutropenic patients. These differences may have implications for future therapies targeting neutropenic sepsis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1398-y) contains supplementary material, which is available to authorized users.

Intensive care for cancer patients: An interdisciplinary challenge for cancer specialists and intensive care physicians

Every sixth to eighth European intensive care unit patient suffers from an underlying malignant disease. A large proportion of these patients present with cancer-related complications. This review explains why the prognosis of critically ill cancer patients has improved substantially over the last decades and which risk factors are of prognostic importance. Furthermore, the main reasons for intensive care unit admission – acute respiratory failure and septic complications – are discussed with regard to diagnostic and therapeutic specifics. In addition, we discuss potential intensive care unit admission criteria with respect to cancer prognosis. The successful management of critically ill cancer patients requires a close collaboration of intensivists with hematologists, oncologists and colleagues from other disciplines, such as infectious disease specialists, microbiologists, radiologists, surgeons, pharmacists, and others.

Recombinant human brain natriuretic peptide attenuates trauma-/haemorrhagic shock-induced acute lung injury through inhibiting oxidative stress and the NF-κB-dependent inflammatory/MMP-9 pathway

Acute lung injury (ALI) is one of the most serious complications in traumatic patients and is an important part of multiple organ dysfunction syndrome (MODS). Recombinant human brain natriuretic peptide (rhBNP) is a peptide with a wide range of biological activity. In this study, we investigated local changes in oxidative stress and the NF-κB-dependent matrix metalloproteinase-9 (MMP-9) pathway in rats with trauma/haemorrhagic shock (TH/S)-induced ALI and evaluated the effects of pretreatment with rhBNP. Forty-eight rats were randomly divided into four groups: sham operation group, model group, low-dosage rhBNP group and high-dosage rhBNP group (n = 12 for each group). Oxidative stress and MPO activity were measured by ELISA kits. MMP-9 activity was detected by zymography analysis. NF-κB activity was determined using Western blot assay. With rhBNP pretreatment, TH/S-induced protein leakage, increased MPO activity, lipid peroxidation and metalloproteinase (MMP)-9 activity were inhibited. Activation of antioxidative enzymes was reversed. The phosphorylation of NF-κB and the degradation of its inhibitor IκB were suppressed. The results suggested that the protection mechanism of rhBNP is possibly mediated through upregulation of anti-oxidative enzymes and inhibition of NF-κB activation. More studies are needed to further evaluate whether rhBNP is a suitable candidate as an effective inhaling drug to reduce the incidence of TH/S-induced ALI.

Rosiglitazone dampens pulmonary inflammation in a porcine model of acute lung injury

The hallmarks of acute lung injury (ALI) are the compromised alveolar-capillary barrier and the extravasation of leukocytes into the alveolar space. Given the fact that the peroxisome proliferator-activated receptor-γ agonist rosiglitazone holds significant anti-inflammatory properties, we aimed to evaluate whether rosiglitazone could dampen these hallmarks of local pulmonary inflammation in a porcine model of lung injury. For this purpose, we used a model of lipopolysaccharide (LPS, 50 μg/kg)-induced ALI. One hundred twenty minutes following the infusion of LPS, we started the exposure to rosiglitazone through inhalation or infusion. We found that intravenous rosiglitazone significantly controlled local pulmonary inflammation as determined through the expression of cytokines within the alveolar compartment. Furthermore, we found a significant reduction of the protein concentration and neutrophil activity within the alveolar space. In summary, we therefore conclude that the treatment with rosiglitazone might dampen local pulmonary inflammation during the initial stages of ALI.

Diagnostic Radiology in Hematological Patients with Febrile Neutropenia

Radiologists have a special role in the management of neutropenic patients. The appropriate investigational technique, specific differential diagnoses, and particular risks of these patients need to be understood by referring physicians as well as by radiologists. Thus, communication and cooperation, also including other clinical disciplines such as pulmonology, are required.

Early detection of an infectious focus is the major goal in febrile neutropenic patients. As pneumonia is the most common focus, chest imaging is a special radiological task. The sensitivity of chest x-ray, especially in supine position, is low. Therefore, the very sensitive thin-section multislice CT became a gold standard in neutropenic hosts and might be cost effective in comparison to antibiotic treatment. CT-based localization can be used to guide invasive procedures in order to obtain samples for microbiological workup. Furthermore, the radiological characterization of infiltrates gives a first and rapid hint to discriminate between infectious (viral, typical bacterial, atypical bacterial, fungal) and noninfectious etiologies. Radiological follow-up has to take into account aspects according to disease, immune recovery, and treatment modalities. Due to a high incidence of fungal-related lung infiltrates, interpretation of follow-up findings must include further parameters besides lesion size.

Apart from the lungs, also other organ systems such as the brain, liver, and paranasal sinuses need attention and are to be imaged with the appropriate technique.

How to treat severe infections in critically ill neutropenic patients?

Severe infections in neutropenic patient often progress rapidly leading to life-threatening organ dysfunction requiring admission to the Intensive Care Unit. Management strategies include early adequate appropriate empirical antimicrobial, early admission to ICU to avoid any delay in the diagnostic and therapeutic management of organ dysfunction. This review discusses the main clinical situations encountered in critically ill neutropenic patients. Specific diagnostic and therapeutic approaches have been proposed for acute respiratory failure, shock, neutropenic enterocolitis, catheter-related infections, cellulitis and primary bacteriemia. Non anti-infectious agents and recent advances will also be discussed. At present, most of large-scale studies and recommendations in neutropenic patients stem from hematological patients and will need further validation in ICU patients.

Silencing Bruton's tyrosine kinase in alveolar neutrophils protects mice from LPS/immune complex-induced acute lung injury

Previous observations made by our laboratory indicate that Bruton's tyrosine kinase (Btk) may play an important role in the pathophysiology of local inflammation in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). We have shown that there is cross talk between FcγRIIa and TLR4 in alveolar neutrophils from patients with ALI/ARDS and that Btk mediates the molecular cooperation between these two receptors. To study the function of Btk in vivo we have developed a unique two-hit model of ALI: LPS/immune complex (IC)-induced ALI. Furthermore, we conjugated F(ab)2 fragments of anti-neutrophil antibodies (Ly6G1A8) with specific siRNA for Btk to silence Btk specifically in alveolar neutrophils. It should be stressed that we are the first group to perform noninvasive transfections of neutrophils, both in vitro and in vivo. Importantly, our present findings indicate that silencing Btk in alveolar neutrophils has a dramatic protective effect in mice with LPS/IC-induced ALI, and that Btk regulates neutrophil survival and clearance of apoptotic neutrophils in this model. In conclusion, we put forward a hypothesis that Btk-targeted neutrophil specific therapy is a valid goal of research geared toward restoring homeostasis in lungs of patients with ALI/ARDS.

Acute respiratory distress syndrome in patients with malignancies

PURPOSE

Little attention has been given to ARDS in cancer patients, despite their high risk for pulmonary complications. We sought to describe outcomes in cancer patients with ARDS meeting the Berlin definition.

METHODS

Data from a cohort of patients admitted to 14 ICUs between 1990 and 2011 were used for a multivariable analysis of risk factors for hospital mortality.

RESULTS

Of 1,004 included patients (86 % with hematological malignancies and 14 % with solid tumors), 444 (44.2 %) had neutropenia. Admission SOFA score was 12 (10-13). Etiological categories were primary infection-related ARDS (n = 662, 65.9 %; 385 bacterial infections, 213 invasive aspergillosis, 64 Pneumocystis pneumonia); extrapulmonary septic shock-related ARDS (n = 225, 22.4 %; 33 % candidemia); noninfectious ARDS (n = 76, 7.6 %); and undetermined cause (n = 41, 4.1 %). Of 387 (38.6 %) patients given noninvasive ventilation (NIV), 276 (71 %) subsequently required endotracheal ventilation. Hospital mortality was 64 % overall. According to the Berlin definition, 252 (25.1 %) patients had mild, 426 (42.4 %) moderate and 326 (32.5 %) severe ARDS; mortality was 59, 63 and 68.5 %, respectively (p = 0.06). Mortality dropped from 89 % in 1990-1995 to 52 % in 2006-2011 (p < 0.0001). Solid tumors, primary ARDS, and later admission period were associated with lower mortality. Risk factors for higher mortality were allogeneic bone-marrow transplantation, modified SOFA, NIV failure, severe ARDS, and invasive fungal infection.

CONCLUSIONS

In cancer patients, 90 % of ARDS cases are infection-related, including one-third due to invasive fungal infections. Mortality has decreased over time. NIV failure is associated with increased mortality. The high mortality associated with invasive fungal infections warrants specific studies of early treatment strategies.

Management of sepsis in neutropenic patients: 2014 updated guidelines from the Infectious Diseases Working Party of the German Society of Hematology and Medical Oncology (AGIHO)

Sepsis is a major cause of mortality during the neutropenic phase after intensive cytotoxic therapies for malignancies. Improved management of sepsis during neutropenia may reduce the mortality of cancer therapies. Clinical guidelines on sepsis treatment have been published by others. However, optimal management may differ between neutropenic and non-neutropenic patients. Our aim is to give evidence-based recommendations for haematologist, oncologists and intensive care physicians on how to manage adult patients with neutropenia and sepsis.

Intravenous infusion of mesenteric lymph from severe intraperitoneal infection rats causes lung injury in healthy rats

AIM: To investigate whether mesenteric lymph from rats with severe intraperitoneal infection (SII) induces lung injury in healthy rats.

METHODS: Twenty adult male specific pathogen-free Wistar rats were divided into two groups. Animals in the SII group received intraperitoneal injection of Escherichia coli (E. coli) at a dose of 0.3 mL/100 g. Control rats underwent the same procedure, but were injected with normal saline rather than E. coli. We ligated and drained the mesenteric lymphatic vessels and collected the mesenteric lymph. Mesenteric lymph collected from SII or control rats was infused intravenously into male healthy rats at a rate of 1 mL/h for 4 h. At the end of the infusion, all rats were sacrificed. Lungs were removed and examined histologically, and wet-to-dry weight (W/D) ratio and myeloperoxidase (MPO) activity were determined. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the levels of the proinflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6. We performed Western blot to investigate the activation of Toll-like receptor (TLR)-4, and nuclear factor (NF)-κB p65.

RESULTS: Compared with the control infusion group, there were obvious pathological changes in the SII group. The W/D ratio was significantly increased in the SII compared to control infusion group (5.86 ± 0.06 vs 5.37 ± 0.06, P < 0.01). MPO activity significantly increased in the SII infusion rats with a mean level of 0.86 ± 0.02 U/g compared to 0.18 ± 0.05 U/g in the control group (P < 0.01). The concentrations of TNF-α and IL-6 were significantly increased in the SII infusion group. The concentration of TNF-α was significantly increased in the SII infusion rats compared to control infusion rats (2104.46 ± 245.91 vs 1475.13 ± 137.82 pg/mL, P < 0.01). The concentration of IL-6 was significantly increased in the SII infusion rats with a mean level of 50.56 ± 2.85 pg/mL compared to 43.29 ± 2.02 pg/mL (P < 0.01). The expression levels of TLR-4 (7496.68 ± 376.43 vs 4589.02 ± 233.16, P < 0.01) and NF-κB (8722.19 ± 323.96 vs 6498.91 ± 338.76, P < 0.01) were significantly increased in the SII infusion group compared to the control infusion group. The infusion of SII lymph, but not control lymph, caused lung injury.

CONCLUSION: The results indicate that SII lymph is sufficient to induce acute lung injury.

[Neutropenia and sepsis]

The clinical management of neutropenic infections represents a great diagnostic and therapeutic challenge. Established sepsis criteria only partially reflect the neutropenic setting. Diagnostic procedures are frequently impaired by thrombocytopenia and progressive respiratory insufficiency. Increased tendency to bleed, engraftment, and fulminant progression represent major therapeutic challenges. Thus, crucial for the diagnosis and therapy of neutropenic sepsis are clear and well-communicated algorithms, rapid action, and close collaboration between oncologists and intensivists.

Instilled air promotes lipopolysaccharide-induced acute lung injury

Optimization of intratracheal instillation is necessary to establish an ideal animal model of acute lung injury (ALI) in order to further reveal the cellular and molecular pathogenesis of ALI. It is possible that instilling air from a prefilled syringe may promote the delivery of reagents into the alveolar spaces, resulting in different pulmonary responses. In the present study, the influence of instilling air by trans-tracheal intratracheal instillation in a lipopolysaccharide (LPS)-induced mouse model of ALI was investigated. The bronchoalveolar lavage (BAL) fluid biochemical index, BAL fluid differential cell counts, lung wet/dry weight ratio, lung histology and BAL fluid interleukin-8 (IL-8) levels were assessed 24 h subsequent to intratracheal instillation. Instilled air promoted LPS-induced ALI, as indicated by the severity of acute pulmonary inflammation and increased IL-8 release. In conclusion, this study indicates that instilled air may be used to improve the intratracheal instillation procedure and to establish a more reliable animal model of ALI.

Histopathological evaluation of the diversity of cells susceptible to H5N1 virulent avian influenza virus

Patients infected with highly pathogenic avian influenza A H5N1 viruses (H5N1 HPAIV) show diffuse alveolar damage. However, the temporal progression of tissue damage and repair after viral infection remains poorly defined. Therefore, we assessed the sequential histopathological characteristics of mouse lung after intranasal infection with H5N1 HPAIV or H1N1 2009 pandemic influenza virus (H1N1 pdm). We determined the amount and localization of virus in the lung through IHC staining and in situ hybridization. IHC used antibodies raised against the virus protein and antibodies specific for macrophages, type II pneumocytes, or proliferating cell nuclear antigen. In situ hybridization used RNA probes against both viral RNA and mRNA encoding the nucleoprotein and the hemagglutinin protein. H5N1 HPAIV infection and replication were observed in multiple lung cell types and might result in rapid progression of lung injury. Both type II pneumocytes and macrophages proliferated after H5N1 HPAIV infection. However, the abundant macrophages failed to block the viral attack, and proliferation of type II pneumocytes failed to restore the damaged alveoli. In contrast, mice infected with H1N1 pdm exhibited modest proliferation of type II pneumocytes and macrophages and slight alveolar damage. These results suggest that the virulence of H5N1 HPAIV results from the wide range of cell tropism of the virus, excessive virus replication, and rapid development of diffuse alveolar damage.

Sauchinone, a lignan from Saururus chinensis, attenuates neutrophil pro-inflammatory activity and acute lung injury

Previous studies have shown that sauchinone modulates the expression of inflammatory mediators through mitogen-activated protein kinase (MAPK) pathways in various cell types. However, little information exists about the effect of sauchinone on neutrophils, which play a crucial role in inflammatory process such as acute lung injury (ALI). We found that sauchinone decreased the phosphorylation of p38 MAPK in lipopolysaccharide (LPS)-stimulated murine bone marrow neutrophils, but not ERK1/2 and JNK. Exposure of LPS-stimulated neutrophils to sauchinone or SB203580, a p38 inhibitor, diminished production of tumor necrosis factor (TNF)-α and macrophage inflammatory protein (MIP)-2 compared to neutrophils cultured with LPS. Treatment with sauchinone decreased the level of phosphorylated ribosomal protein S6 (rpS6) in LPS-stimulated neutrophils. Systemic administration of sauchinone to mice led to reduced levels of phosphorylation of p38 and rpS6 in mice lungs given LPS, decreased TNF-α and MIP-2 production in bronchoalveolar lavage fluid, and also diminished the severity of LPS-induced lung injury, as determined by reduced neutrophil accumulation in the lungs, wet/dry weight ratio, and histological analysis. These results suggest that sauchinone diminishes LPS-induced neutrophil activation and ALI.

Detrimental role of the airway mucin Muc5ac during ventilator-induced lung injury

Acute lung injury (ALI) is associated with high morbidity and mortality in critically ill patients. At present, the functional contribution of airway mucins to ALI is unknown. We hypothesized that excessive mucus production could be detrimental during lung injury. Initial transcriptional profiling of airway mucins revealed a selective and robust induction of MUC5AC upon cyclic mechanical stretch exposure of pulmonary epithelia (Calu-3). Additional studies confirmed time- and stretch-dose-dependent induction of MUC5AC transcript or protein during cyclic mechanical stretch exposure in vitro or during ventilator-induced lung injury in vivo. Patients suffering from ALI showed a 58-fold increase in MUC5AC protein in their bronchoalveolar lavage. Studies of the MUC5AC promoter implicated nuclear factor κB in Muc5ac induction during ALI. Moreover, mice with gene-targeted deletion of Muc5ac⁻/⁻ experience attenuated lung inflammation and pulmonary edema during injurious ventilation. We observed that neutrophil trafficking into the lungs of Muc5ac⁻/⁻ mice was selectively attenuated. This implicates that endogenous Muc5ac production enhances pulmonary neutrophil trafficking during lung injury. Together, these studies reveal a detrimental role for endogenous Muc5ac production during ALI and suggest pharmacological strategies to dampen mucin production in the treatment of lung injury.

Effect of tyrosine kinase inhibitors, imatinib and nilotinib, in murine lipopolysaccharide-induced acute lung injury during neutropenia recovery

Introduction

Neutrophil recovery has been implicated in deterioration of oxygenation and exacerbation of preexisting acute lung injury (ALI). The aim of this study was to investigate whether imatinib or nilotinib was effective on lipopolysaccharide (LPS)-induced ALI during neutropenia recovery in mice.

Methods

Mice were rendered neutropenic with cyclophosphamide prior to the intratracheal instillation of LPS. Imatinib or nilotinib was administrated by oral gavage during neutropenia recovery. In order to study the effects of drugs, mice were killed on day 5 and blood, bronchoalveolar lavage (BAL) fluid and lung tissue samples were obtained. The lung wet/dry weight ratio and protein levels in the BAL fluid or lung tissue were determined.

Results

Treatment with imatinib or nilotinib significantly attenuated the LPS-induced pulmonary edema, and this result was supported by the histopathological examination. The concentrations of tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and myeloperoxidase in BAL fluid were significantly inhibited by imatinib or nilotinib in mice of ALI during neutropenia recovery. The mRNA expressions of platelet-derived growth factor receptor-β and c-KIT in imatinib or nilotinib group were significantly lower than LPS group.

Conclusions

Our data indicated that imatinib or nilotinib effectively attenuated LPS-induced ALI during neutropenia recovery. These results provide evidence for the therapeutic potential of imatinib and nilotinib in ALI during neutropenia recovery.

Plasma glutamate-modulated interaction of A2AR and mGluR5 on BMDCs aggravates traumatic brain injury-induced acute lung injury

Activation of adenosine A_2A receptor aggravates lung damage in a neurogenic mouse model of acute lung injury (ALI) but protects against nonneurogenic ALI.

The bone marrow–derived cell (BMDC)–associated inflammatory response plays a key role in the development of acute lung injury (ALI). Activation of adenosine A_2A receptor (A_2AR) is generally considered to be antiinflammatory, inhibiting BMDC activities to protect against ALI. However, in the present study, we found that in a mouse model of neurogenic ALI induced by severe traumatic brain injury (TBI), BMDC A_2AR exerted a proinflammatory effect, aggravating lung damage. This is in contrast to the antiinflammatory effect observed in the mouse oleic acid–induced ALI model (a nonneurogenic ALI model.) Moreover, the A_2AR agonist CGS21680 aggravated, whereas the antagonist ZM241385 attenuated, the severe TBI-induced lung inflammatory damage in mice. Further investigation of white blood cells isolated from patients or mouse TBI models and of cultured human or mouse neutrophils demonstrated that elevated plasma glutamate after severe TBI induced interaction between A_2AR and the metabotropic glutamate receptor 5 (mGluR5) to increase phospholipase C–protein kinase C signaling, which mediated the proinflammatory effect of A_2AR. These results are in striking contrast to the well-known antiinflammatory and protective role of A_2AR in nonneurogenic ALI and indicate different therapeutic strategies should be used for nonneurogenic and neurogenic ALI treatment when targeting A_2AR.

Outcome and predictors of mortality in patients requiring invasive mechanical ventilation due to acute respiratory failure while undergoing ambulatory chemotherapy for solid cancers

PURPOSE

Acute respiratory failure that requires invasive mechanical ventilation is a leading cause of death in critically ill cancer patients. The aim of this study was to evaluate the outcome and prognostic factors of patients requiring invasive mechanical ventilator for acute respiratory failure, within 1 month of ambulatory chemotherapy for solid cancer.

METHODS

A retrospective observational study of patients who underwent ambulatory chemotherapy at Samsung Medical Center, between January of 2007 and April of 2009, was employed for this study.

RESULTS

A total of 51 patients met the inclusion criteria and were included in the study. The median age was 65 years (25-87) and the majority of the patients were male (n = 38, 74.5%). There were 42 patients (82.3%) with lung cancer. The most common cause of acute respiratory failure was pneumonia (n = 24, 47.1%), followed by acute respiratory failure due to extra-pulmonary infection, drug-induced pneumonitis, alveolar hemorrhage, and cancer progression. The intensive care unit (ICU) mortality was 68.6% and the most common cause of death in the ICU was uncorrected cause of acute respiratory failure. Before adjustment for others factors, prechemotherapy Eastern Cooperative Oncology Group (ECOG) Performance Scale (PS) (P = 0.03), Sequential Organ Failure Assessment score (P = 0.01), and anemia (P = 0.04) were significantly associated with ICU mortality. However, when adjusted for age, sex, and Acute Physiologic and Chronic Health Evaluation II score, only poor ECOG PS (≥2) was significantly associated with ICU mortality [OR 6.36 (95% CI (1.02-39.5))].

CONCLUSIONS

The outcome of patients with acute respiratory failure needing invasive mechanical ventilation during ambulatory chemotherapy for solid cancer is poor. Prechemotherapy performance status is an independent predictor of mortality.

Role of activated neutrophils in chest trauma-induced septic acute lung injury

More than 50% of severely injured patients have chest trauma. Second insults frequently result in acute lung injury (ALI), with sepsis being the main underlying condition. We aimed to develop a standardized, reproducible, and clinically relevant double-hit mouse model of ALI induced by chest trauma and polymicrobial sepsis and to investigate the pathophysiologic role of activated neutrophils. Lung contusion was applied to C57Bl/6 mice via a focused blast wave. Twenty-four hours later, sepsis was induced by cecal ligation and puncture. For polymorphonuclear leukocyte (PMN) depletion, animals received intravenous injections of PMN-depleting antibody. In response to blunt chest trauma followed by sepsis as well as after sepsis alone, a significant local and systemic inflammatory response with increased cytokine/chemokine levels in lung and plasma was observed. In contrast, lung apoptosis was markedly elevated only after a double hit. Intra-alveolar neutrophils and total bronchoalveolar lavage protein concentrations were markedly increased following isolated chest trauma or the combined insult, but not after sepsis alone. Lung myeloperoxidase activity was enhanced only in response to the double hit accompanied by histological disruption of the alveolar architecture, lung congestion, and marked cellular infiltrates. Neutrophil depletion significantly diminished lung interleukin 1β and interleukin 6 concentrations and reduced the degree of septic ALI. Here we have established a novel and highly reproducible mouse model of chest trauma-induced septic ALI characterizing a clinical relevant double-hit scenario. In particular, the depletion of neutrophils substantially mitigated the extent of lung injury, indicating a pathomechanistic role for neutrophils in chest trauma-induced septic ALI.

Models and mechanisms of acute lung injury caused by direct insults

Acute lung injury (ALI) and its more severe form acute respiratory distress syndrome (ARDS) are life-threatening diseases that are characterized by acute onset, pulmonary inflammation, oedema due to increased vascular permeability and severe hypoxemia. Clinically, ARDS can be divided into ARDS due to direct causes such as pneumonia, aspiration or injurious ventilation, and due to extrapulmonary indirect causes such as sepsis, severe burns or pancreatitis. In order to identify potential therapeutic targets, we asked here whether common molecular mechanisms can be identified that are relevant in different models of the direct form of ALI/ARDS. To this end, we reviewed three widely used models: (a) one based on a biological insult, i.e. instillation of bacterial endotoxins; (b) one based on a chemical insult, i.e. instillation of acid; and (c) one based on a mechanical insult, i.e. injurious ventilation. Studies were included only if the mediator or mechanism of interest was studied in at least two of the three animal models listed above. As endpoints, we selected neutrophil sequestration, permeability, hypoxemia (physiological dysfunction) and survival. Our analysis showed that most studies have focused on mechanisms of pulmonary neutrophil sequestration and models with moderate forms of oedema. The underlying mechanisms that involve canonical inflammatory pathways such as MAP kinases, CXCR2 chemokines, PAF, leukotrienes, adhesions molecules (CD18, ICAM-1) and elastase have been defined relatively well. Further mechanisms including TNF, DARC, HMGB1, PARP, GADD45 and collagenase are under investigation. Such mechanisms that are shared between the three ALI models may represent viable therapeutic targets. However, only few studies have linked these pathways to hypoxemia, the most important clinical aspect of ALI/ARDS. Since moderate oedema does not necessarily lead to hypoxemia, we suggest that the clinical relevance of experimental studies can be further improved by putting greater emphasis on gas exchange.