Why do patients who have acute lung injury/acute respiratory distress syndrome die from multiple organ dysfunction syndrome? Implications for management

Patient Self-Inflicted Lung Injury-A Narrative Review of Pathophysiology, Early Recognition, and Management Options

Patient self-inflicted lung injury (P-SILI) is a life-threatening condition arising from excessive respiratory effort and work of breathing in patients with lung injury. The pathophysiology of P-SILI involves factors related to the underlying lung pathology and vigorous respiratory effort. P-SILI might develop both during spontaneous breathing and mechanical ventilation with preserved spontaneous respiratory activity. In spontaneously breathing patients, clinical signs of increased work of breathing and scales developed for early detection of potentially harmful effort might help clinicians prevent unnecessary intubation, while, on the contrary, identifying patients who would benefit from early intubation. In mechanically ventilated patients, several simple non-invasive methods for assessing the inspiratory effort exerted by the respiratory muscles were correlated with respiratory muscle pressure. In patients with signs of injurious respiratory effort, therapy aimed to minimize this problem has been demonstrated to prevent aggravation of lung injury and, therefore, improve the outcome of such patients. In this narrative review, we accumulated the current information on pathophysiology and early detection of vigorous respiratory effort. In addition, we proposed a simple algorithm for prevention and treatment of P-SILI that is easily applicable in clinical practice.

A 4-Benzene-Indol Derivative Alleviates LPS-Induced Acute Lung Injury Through Inhibiting the NLRP3 Inflammasome

Acute lung injury (ALI) is a common complication of critical illness that could frequently lead to acute respiratory distress syndrome and other serious clinical consequences. Sepsis is one of the major and most common inducements among all causes of ALI. Due to its high incidence and mortality rate and also the complexity in treatment, sepsis-related ALI has become an urgent clinical problem waiting to be solved effectively. At present, only the protective ventilation strategy, restrictive fluid management, and antibiotics application are measures that can improve the prognosis with evidence-based medical proof. No pharmacological treatment is currently available to protect or significantly reverse the prognosis. Seeking for effective interventions measures for sepsis-related ALI is one of the most necessitous research directions. In this research, a conspicuous discovery of treatment-related translational use for a 4-benzene-indol derivative was elaborated by screening a large number of chemical compounds. The results showed that 4-benzene-indol derivative could not only suppress the activation of NLRP3 inflammasome both in vitro and alleviate LPS-induced ALI in vivo but also suppress the NLRP3 inflammasome in human myeloid leukemia mononuclear cells (THP-1) cell lines. Mechanistically, 1,2-diol blocks the NLRP3 inflammasome activation by disrupting NLRP3–NEK7 interaction and the subsequent NLRP3 inflammasome assembly and activation. To summarize, this research indicated that the newly-discovered 4-benzene-indol derivative targets NLRP3 inflammasome signaling, which consequently alleviates sepsis-related ALI. Collectively, the 4-benzene-indol derivative may serve as a potential therapeutic drug and NLRP3 inflammasome signaling would be a novel pharmaceutical target for clinical treatment of sepsis-related ALI.

AUF1 protects against ferroptosis to alleviate sepsis-induced acute lung injury by regulating NRF2 and ATF3

BACKGROUND

The AU-rich element (ARE)-binding factor 1 (AUF1) acts as a switch for septic shock, although its underlying mechanisms remain largely unknown. In this study, we examined the biological significance and potential molecular mechanism of AUF1 in regulating ferroptosis in sepsis-induced acute lung injury (ALI).

METHODS

Alveolar epithelial cells (AECs) challenged with ferroptosis-inducing compounds and cecum ligation and puncture (CLP)-induced ALI were used as the in vitro and in vivo model, respectively. The stability of AUF1 and its degradation by ubiquitin-proteasome pathway were examined by cycloheximide chase analysis and co-immunoprecipitation assay. The regulation of AUF1 on nuclear factor E2-related factor 2 (NRF2) and activation transcription factor 3 (ATF3) was explored by RNA immunoprecipitation (RIP), RNA pull-down, and mRNA stability assays. Functionally, the effects of altering AUF1, NRF2 or ATF3 on ferroptosis in AECs or ALI mice were evaluated by measuring cell viability, lipid peroxidation, iron accumulation, and total glutathione level.

RESULTS

AUF1 was down-regulated in AECs challenged with ferroptosis-inducing compounds, both on mRNA and protein levels. The E3 ubiquitin ligase FBXW7 was responsible for protein degradation of AUF1 during ferroptosis. By up-regulating NRF2 and down-regulating ATF3, AUF1 antagonized ferroptosis in AECs in vitro. In the CLP-induced ALI model, the survival rate of AUF1 knockout mice was significantly reduced and the lung injuries were aggravated, which were related to the enhancement of lung ferroptosis.

CONCLUSIONS

FBXW7 mediates the ubiquitination and degradation of AUF1 in ferroptosis. AUF1 antagonizes ferroptosis by regulating NRF2 and ATF3 oppositely. Activating AUF1 pathway may be beneficial to the treatment of sepsis-induced ALI.

A Nomogram for Predicting the Mortality of Patients with Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is an acute lung injury associated with high morbidity and mortality. This study aimed to establish an accurate prediction model for mortality risk in ARDS. 70% of patients from the Medical Information Mart for Intensive Care Database (MIMIC-III) were selected as the training group, and the remaining 30% as the testing group. Patients from a Chinese hospital were used for external validation. Univariate and multivariate regressions were used to screen the independent predictors. The receiver operating characteristic curve (ROC) analysis, the Hosmer–Lemeshow test, and the calibration curve were used for evaluating the performance of the model. Age, hemoglobin, heart failure, renal failure, Simplified Acute Physiology Score II (SAPS II), immune function impairment, total bilirubin (TBIL), and PaO₂/FiO₂ were identified as independent predictors. The algorithm of the prediction model was: ln (Pr/(1 + Pr)) = −3.147 + 0.037 ∗ age − 0.068 ∗ hemoglobin + 0.522 ∗ heart failure (yes) + 0.487 ∗ renal failure (yes) + 0.029 ∗ SAPS II + 0.697 ∗ immune function impairment (yes) + 0.280 ∗ TBIL (abnormal) − 0.006 ∗ PaO₂/FiO₂ (Pr represents the probability of death occurring). The AUC of the model was 0.791 (0.766–0.816), and the internal and the external validations both confirmed the good performance of the model. A nomogram for predicting the risk of death in ARDS patients was developed and validated. It may help clinicians early identify ARDS patients with high risk of death and thereby help reduce the mortality and improve the survival of ARDS.

The significance of disseminated intravascular coagulation on multiple organ dysfunction during the early stage of acute respiratory distress syndrome

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is a predominant cause of death in acute respiratory distress syndrome (ARDS). Disseminated intravascular coagulation (DIC) is recognized as a syndrome that frequently develops MODS. To test the hypothesis that DIC scores are useful for predicting MODS development and that DIC is associated with MODS, we retrospectively analyzed the data of a prospective, multicenter study on ARDS.

METHODS

Patients who met the Berlin definition of ARDS were included. DIC scores as well as the disease severity and the development of MODS on the day of the diagnosis of ARDS (day 0) and day 3 were evaluated. The primary and secondary outcomes were the development of MODS and the hospital mortality.

RESULTS

In the 129 eligible patients, the prevalence of DIC was 45.7% (59/129). DIC patients were more seriously ill and exhibited a higher prevalence of MODS on days 0 and 3 than non-DIC patients. The DIC scores on day 0 detected the development of MODS with good area under the receiver operating characteristic curve (0.714, p<.001). DIC on day 0 was significantly associated with MODS on days 0 and 3 (odds ratio 1.53 and 1.34, respectively). Patients with persistent DIC from days 0 to 3 had higher rates of both MODS on day 3 (p=.035) and hospital mortality (p=.031) than the other patients.

CONCLUSIONS

DIC scores were able to predict MODS, and DIC was associated with MODS during the early stage of ARDS. Persistent DIC may also have role in this association.

Acute Respiratory Distress Syndrome as an Organ Phenotype of Vascular Microthrombotic Disease: Based on Hemostatic Theory and Endothelial Molecular Pathogenesis

Acute respiratory distress syndrome (ARDS) is a life-threatening noncardiogenic circulatory disorder of the lungs associated with critical illnesses such as sepsis, trauma, and immune and collagen vascular disease. Its mortality rate is marginally improved with the best supportive care. The demise occurs due to progressive pulmonary hypoxia and multi-organ dysfunction syndrome (MODS) with severe inflammation. Complement activation is a part of immune response against pathogen or insult in which membrane attack complex (MAC) is formed and eliminates microbes. If complement regulatory protein such as endothelial CD59 is underexpressed, MAC may also cause pulmonary vascular injury to the innocent bystander endothelial cell of host and provokes endotheliopathy that causes inflammation and pulmonary vascular microthrombosis, leading to ARDS. Its pathogenesis is based on a novel "two-path unifying theory" of hemostasis and "two-activation theory of the endothelium" promoting molecular pathogenesis. Endotheliopathy activates two independent molecular pathways: inflammatory and microthrombotic. The former triggers the release inflammatory cytokines and the latter promotes exocytosis of unusually large von Willebrand factor multimers (ULVWF) and platelet activation. Inflammatory pathway initiates inflammation, but microthrombotic pathway more seriously produces "microthrombi strings" composed of platelet-ULVWF complexes, which become anchored on the injured endothelial cells, and causes disseminated intravascular microthrombosis (DIT). DIT is a hemostatic disease due to lone activation of ULVWF path without activated tissue factor path. It leads to endotheliopathy-associated vascular microthrombotic disease (EA-VMTD), which orchestrates consumptive thrombocytopenia, microangiopathic hemolytic anemia, and MODS. Thrombotic thrombocytopenic purpura (TTP)-like syndrome is the hematologic phenotype of EA-VMTD. ARDS is one of organ phenotypes among MODS associated with TTP-like syndrome. The most effective treatment of ARDS can be achieved by counteracting the activated microthrombotic pathway based on two novel hemostatic theories.

Risk factors affecting post-traumatic acute respiratory distress syndrome development in thoracic trauma patients

Background

This study aims to investigate the risk factors affecting post-traumatic acute respiratory distress syndrome development in thoracic trauma patients.

Methods

This two-centered, retrospective study included 3,080 thoracic trauma patients (2,562 males, 518 females; mean age 33.9±19.4 years; range, 2 months to 91 years) treated between January 2005 and January 2019. Demographic characteristics, mechanisms of injury, traumatic injuries, injury severity score and new injury severity score results, treatments, comorbidities, complications, morbidity and mortality rates, and durations of hospital stay were collected. Data were used to predict the risk factors for development of post-traumatic acute respiratory distress syndrome by univariate and multivariate statistical analysis.

Results

Acute respiratory distress syndrome was detected in 81 patients. In multivariate logistic regression analysis; age, pulmonary contusion, intracranial hemorrhage, rib fracture (unilateral and four-five pieces), femur and tibia fracture, diabetes mellitus, chronic obstructive pulmonary disease, blood transfusion (≥3 units), high white blood cell count at admission, sepsis, and hepatic injury were detected as independent risk factors (p<0.05). Optimal cutoff points (sensitivity/specificity ratios) for acute respiratory distress syndrome development risk were ≥16 (79%/68%) for injury severity score, ≥27 (90%/68.7%) for new injury severity score, and ≥16,000 (75.3%/71.6%) for admission white blood cell count. New injury severity score was superior than injury severity score to predict the development of acute respiratory distress syndrome.

Conclusion

Acute respiratory distress syndrome causes significant mortality and morbidity in trauma patients. In addition to the well-known risk factors, diabetes mellitus and chronic obstructive pulmonary disease were independent risk factors. We defined a cutoff value for new injury severity score to predict post-traumatic acute respiratory distress syndrome.

Blocking of gastric acid induced histopathological alterations, enhancing of DNA content and proliferation of goblet cells in the acute lung injury mice models by nano-fenugreek oral administration

This current study aimed at detecting the potential protective role of nano-fenugreek seed on acute lung injury (ALI) induced by instillation gastric acid in male Swiss albino mice using histological and histochemical studies. Forty animals were grouped as follows: control group, HCl-treated group, low nano-fenugreek + HCl treated group, and high nano-fenugreek + HCl treated group. Pretreatment with nano-fenugreek in animal model of ALI resulted in marked ameliorations of the lung histological lesions and injury induced by HCL instillation in a dose dependent manner. It also caused inhibition in the increase of the DNA content and prevented proliferation of goblet cells induced by HCl instillation alone. In conclusion, pretreatment with Nano-fenugreek prior induction ALI could be suppress the aggregations of inflammatory cells, enhancing of DNA content, and proliferation of goblet cells induced by gastric acid in a dose dependent manner. We suggest that Nano-fenugreek may be useful in combating lung injury.

Consumptive coagulopathy is associated with organ dysfunction during PICS

Patients who survive the acute phase of sepsis can progress to persistent inflammation, immunosuppression, and catabolism syndrome (PICS). Although sepsis is characterized by early hypercoagulability and delayed hypocoagulability, coagulopathy during chronic critical illness is not fully understood. The objective of this study was to determine whether sepsis-induced PICS is associated with coagulation abnormalities. Using our previously described murine PICS model, outbred mice underwent cecal ligation and puncture, and coagulability was characterized after 8 days. We found that during PICS the spleen became markedly enlarged with increased splenocytes and splenic megakaryocytes without a concomitant increase in circulating platelets. Microscopy revealed a nearly sevenfold increase in pulmonary microvascular thrombi in PICS mice, along with significantly decreased pulmonary tidal volumes and inspiratory times and with significantly increased respiratory rates. Thromboelastometry showed that PICS mice had significantly delayed clot initiation time but increased clot firmness. Finally, PICS mice displayed delayed thrombin production and decreased overall thrombin concentrations. All together, these data demonstrate a general dysregulation of coagulation resulting in microthrombus formation and compromised lung function. On the basis of these findings, we propose that consumptive coagulopathy constitutes another cardinal feature of PICS and may contribute to the ongoing tissue damage and multiple organ failure that can occur in chronic critical illness.

Optimising experimental research in respiratory diseases: an ERS statement

Experimental models are critical for the understanding of lung health and disease and are indispensable for drug development. However, the pathogenetic and clinical relevance of the models is often unclear. Further, the use of animals in biomedical research is controversial from an ethical perspective.The objective of this task force was to issue a statement with research recommendations about lung disease models by facilitating in-depth discussions between respiratory scientists, and to provide an overview of the literature on the available models. Focus was put on their specific benefits and limitations. This will result in more efficient use of resources and greater reduction in the numbers of animals employed, thereby enhancing the ethical standards and translational capacity of experimental research.The task force statement addresses general issues of experimental research (ethics, species, sex, age, ex vivo and in vitro models, gene editing). The statement also includes research recommendations on modelling asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, lung infections, acute lung injury and pulmonary hypertension.The task force stressed the importance of using multiple models to strengthen validity of results, the need to increase the availability of human tissues and the importance of standard operating procedures and data quality.

Corticosteroids in ARDS: The Never-Ending Story

This feature examines the impact of pharmacologic interventions on the treatment of the critically ill patient — an area of health care that has become increasingly complex. Recent advances in drug therapy (including evolving and controversial data) for adult intensive-care-unit patients will be reviewed and assessed in terms of clinical, humanistic, and economic outcomes.

The Effect of ARDS on Survival: Do Patients Die From ARDS or With ARDS?

OBJECTIVE:

To investigate the contribution of acute respiratory distress syndrome (ARDS) in of itself to mortality among ventilated patients.

DESIGN AND SETTING:

A longitudinal retrospective study of ventilated intensive care unit (ICU) patients.

PATIENTS:

The analysis included patients ventilated for more than 48 hours. Patients were classified as having ARDS on admission (early-onset ARDS), late-onset ARDS (ARDS not present during the first 24 hours of admission), or no ARDS. Primary outcomes were mortality at 28 days, and secondary outcomes were 2-year mortality rate from ICU admission.

RESULTS:

A total of 1411 ventilated patients were enrolled: 41% had ARDS on admission, 28.5% developed ARDS during their ICU stay, and 30.5% did not meet the ARDS criteria prior to ICU discharge or death. The non-ARDS group was used as the control. We also divided the cohort based on the severity of ARDS. After adjusting for covariates, mortality risk at 28 days was not significantly different among the different groups. Both early- and late-onset ARDS as well as the severity of ARDS were found to be significant risk factors for 2 years from ICU survival.

CONCLUSION:

Among patients who were ventilated on ICU admission, neither the presence, the severity, or the timing of ARDS contribute independently to the short-term mortality risk. However, acute respiratory distress syndrome does contribute significantly to 2-year mortality risk. This suggests that patients may not die acutely from ARDS itself but rather from the primary disease, and during the acute phase of ARDS, clinicians should focus on improving treatment strategies for the diseases that led to ARDS.

Biomarkers for patients with trauma associated acute respiratory distress syndrome

Trauma is a major factor that contributes to the risk for acute respiratory distress syndrome (ARDS). Biomarkers that predict the risk, diagnosis, treatment response and prognosis of ARDS after trauma have been widely investigated. In addition to their applications in clinical diagnosis and treatment, these biomarkers provide important insights into our understanding of the pathogenesis of ARDS. This review begins with a brief introduction regarding the incidence and pathogenesis of trauma-associated ARDS. Then, we focus on reviewing the clinical trials that have been designed to investigate the value of biomarkers in ARDS after trauma. Biomarkers with a confirmed value in ARDS have been organized on the basis of key pathogenic processes that are central to ARDS and are described in detail. Among these, angiopoietin 2 (Ang-2), L-selectin, Clara cell protein 16 (CC16), soluable receptor for advanced glycation end products (sRAGE), Surfactant protein D (SP-D), histones, mtDNAs and some biomarker panels had a certain association with the diagnosis and prognosis of trauma-related ARDS. Further investigations are needed regarding the design of trials, the best sampling approaches and the optimal combinations of the biomarker panels.

Prophylactic antibiotics are associated with a lower incidence of pneumonia in cardiac arrest survivors treated with targeted temperature management

INTRODUCTION

Prophylactic antibiotics (PRO) reduce the incidence of early-onset pneumonia in comatose patients with structural brain injury, but have not been examined in cardiac arrest survivors undergoing targeted temperature management (TTM). We investigated the effect of PRO on the development of pneumonia in that population.

METHODS

We conducted a retrospective cohort study comparing patients treated with PRO to those not receiving PRO (no-PRO) using Northern Hypothermia Network registry data. Cardiac arrest survivors ≥ 18 years of age with a GCS<8 at hospital admission and treated with TTM at 32-34 °C were enrolled in the registry. Differences were analyzed in univariate analyses and with logistic regression models to evaluate independent associations of clinical factors with incidence of pneumonia and good functional outcome.

RESULTS

416 of 1240 patients (33.5%) received PRO. Groups were similar in age, gender, arrest location, initial rhythm, and time from collapse to return of spontaneous circulation. PRO patients had less pneumonia (12.6% vs. 54.9%, p < 0.001) and less sepsis (1.2 vs. 5.7%, p < 0.001) compared to no-PRO patients. ICU length of stay (98 vs. 100 h, p = 0.2) and incidence of a good functional outcome (41.1 vs. 36.6%, p = 0.19) were similar between groups. Backwards stepwise logistic regression demonstrated PRO were independently associated with a lower incidence of pneumonia (OR 0.09, 95% 0.06-0.14, p < 0.001) and a similar incidence of good functional outcome.

CONCLUSIONS

Prophylactic antibiotics were associated with a reduced incidence of pneumonia but a similar rate of good functional outcome.

Glucocorticoid receptor function is decreased in neutrophils during endotoxic shock

OBJECTIVES

It remains unclear whether glucocorticoid treatment can improve the outcome of sepsis. The aim of the present study was to investigate if glucocorticoid receptor (GR) expression and function is impaired in lipopolysaccharide (LPS) induced shock, and whether the time point for start of glucocorticoid treatment affects the outcome.

METHODS

Male C57BL/6J mice were administered LPS i.p. and GR expression and binding ability in blood and spleen leukocytes were analysed by flow cytometry. GR translocation was analysed using Image Stream technique. The effect of dexamethasone treatment started 2 h before or 2, 12 or 36 h after LPS administration on survival was studied.

RESULTS

Despite increased GR expression in neutrophils after LPS administration, the GR binding capacity was reduced. In addition, GR translocation was decreased in neutrophils and T lymphocytes from endotoxic mice at 12 h compared to control animals. Dexamethasone treatment improved survival only when started early (2 h) after LPS administration.

CONCLUSION

The decreased glucocorticoid responsiveness displayed by neutrophils, in combination with their increased numbers, may explain why survival is increased only when dexamethasone treatment is given early during LPS induced shock.

Mechanical ventilation worsens abdominal edema and inflammation in porcine endotoxemia

INTRODUCTION

We hypothesized that mechanical ventilation per se increases abdominal edema and inflammation in sepsis and tested this in experimental endotoxemia.

METHODS

Thirty anesthetized piglets were allocated to one of five groups: healthy control pigs breathing spontaneously with continuous positive pressure of 5 cm H2O or mechanically ventilated with positive end-expiratory pressure of 5 cm H2O, and endotoxemic piglets during mechanical ventilation for 2.5 hours and then continued on mechanical ventilation with positive end-expiratory pressure of either 5 or 15 cm H2O or switched to spontaneous breathing with continuous positive pressure of 5 cm H2O for another 2.5 hours. Abdominal edema formation was estimated by isotope technique, and inflammatory markers were measured in liver, intestine, lung, and plasma.

RESULTS

Healthy controls: 5 hours of spontaneous breathing did not increase abdominal fluid, whereas mechanical ventilation did (Normalized Index increased from 1.0 to 1.6; 1 to 3.3 (median and range, P<0.05)). Endotoxemic animals: Normalized Index increased almost sixfold after 5 hours of mechanical ventilation (5.9; 4.9 to 6.9; P<0.05) with twofold increase from 2.5 to 5 hours whether positive end-expiratory pressure was 5 or 15, but only by 40% with spontaneous breathing (P<0.05 versus positive end-expiratory pressure of 5 or 15 cm H2O). Tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 in intestine and liver were 2 to 3 times higher with mechanical ventilation than during spontaneous breathing (P<0.05) but similar in plasma and lung. Abdominal edema formation and TNF-α in intestine correlated inversely with abdominal perfusion pressure.

CONCLUSIONS

Mechanical ventilation with positive end-expiratory pressure increases abdominal edema and inflammation in intestine and liver in experimental endotoxemia by increasing systemic capillary leakage and impeding abdominal lymph drainage.

Predictors of pulmonary failure following severe trauma: a trauma registry-based analysis

BACKGROUND

The incidence of pulmonary failure in trauma patients is considered to be influenced by several factors such as liver injury. We intended to assess the association of various potential predictors of pulmonary failure following thoracic trauma and liver injury.

METHODS

Records of 12,585 trauma patients documented in the TraumaRegister DGU® of the German Trauma Society were analyzed regarding the potential impact of concomitant liver injury on the incidence of pulmonary failure using uni- and multivariate analyses. Pulmonary failure was defined as pulmonary failure of ≥ 3 SOFA-score points for at least two days. Patients were subdivided according to their injury pattern into four groups: group 1: AIS thorax < 3; AIS liver < 3; group 2: AIS thorax ≥ 3; AIS liver < 3; group 3: AIS thorax < 3; AIS liver ≥ 3 and group 4: AIS thorax ≥ 3; AIS liver ≥ 3.

RESULTS

Overall, 2643 (21%) developed pulmonary failure, 12% (n= 642) in group 1, 26% (n= 697) in group 2, 16% (n= 30) in group 3, and 36% (n= 188) in group 4. Factors independently associated with pulmonary failure included relevant lung injury, pre-existing medical conditions (PMC), sex, transfusion of more than 10 units of packed red blood cells (PRBC), Glasgow Coma Scale (GCS) ≤ 8, and the ISS. However, liver injury was not associated with an increased risk of pulmonary failure following severe trauma in our setting.

CONCLUSIONS

Specific factors, but not liver injury, were associated with an increased risk of pulmonary failure following trauma. Trauma surgeons should be aware of these factors for optimized intensive care treatment.

Strategies to reduce ventilator-associated lung injury (VALI)

Optimal management of the acute respiratory distress syndrome (ARDS) requires prompt recognition, treatment of the underlying cause and the prevention of secondary injury. Ventilator-associated lung injury (VALI) is one of the several iatrogenic factors that can exacerbate lung injury and ARDS. Reduction of VALI by protective low tidal volume ventilation is one of the only interventions with a proven survival benefit in ARDS. There are, however, several factors inhibiting the widespread use of this technique in patients with established lung injury. Prevention of ARDS and VALI by detecting at-risk patients and implementing protective ventilation early is a feasible strategy. Detection of injurious ventilation itself is possible, and potential biological markers of VALI have been investigated. Finally, facilitation of protective ventilation, including techniques such as extracorporeal support, can mitigate VALI.

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.

Acute lung injury and the acute respiratory distress syndrome in the injured patient

Acute lung injury and acute respiratory distress syndrome are clinical entities of multi-factorial origin frequently seen in traumatically injured patients requiring intensive care. We performed an unsystematic search using PubMed and the Cochrane Database of Systematic Reviews up to January 2012. The purpose of this article is to review recent evidence for the pathophysiology and the management of acute lung injury/acute respiratory distress syndrome in the critically injured patient. Lung protective ventilation remains the most beneficial therapy. Future trials should compare intervention groups to controls receiving lung protective ventilation, and focus on relevant outcome measures such as duration of mechanical ventilation, length of intensive care unit stay, and mortality.

Evaluating abdominal oedema during experimental sepsis using an isotope technique

PURPOSE

Abdominal oedema is common in sepsis. A technique for the study of such oedema may guide in the fluid regime of these patients.

PROCEDURES

We modified a double-isotope technique to evaluate abdominal organ oedema and fluid extravasation in 24 healthy or endotoxin-exposed ('septic') piglets. Two different markers were used: red blood cells (RBC) labelled with Technetium-99m ((99m)Tc) and Transferrin labelled with Indium111 ((111)In). Images were acquired on a dual-head gamma camera. Microscopic evaluation of tissue biopsies was performed to compare data with the isotope technique.

RESULTS

No (99m)Tc activity was measured in the plasma fraction in blood sampled after labelling. Similarly, after molecular size gel chromatography, (111)In activity was exclusively found in the high molecular fraction of the plasma. Extravasation of transferrin, indicating the degree of abdominal oedema, was 4·06 times higher in the LPS group compared to the healthy controls (P<0·0001). Abdominal free fluid, studied in 3 animals, had as high (111)In activity as in plasma, but no (99m)Tc activity. Intestinal lymphatic vessel size was higher in LPS (3·7 ± 1·1 μm) compared to control animals (0·6 + 0·2 μm; P<0·001) and oedema correlated to villus diameter (R(2) = 0·918) and lymphatic diameter (R(2) = 0·758). A correlation between a normalized index of oedema formation (NI) and intra-abdominal pressure (IAP) was also found: NI = 0·46*IAP-3·3 (R(2) = 0·56).

CONCLUSIONS

The technique enables almost continuous recording of abdominal oedema formation and may be a valuable tool in experimental research, with the potential to be applied in the clinic.

Vaporized Perfluorocarbon Confers Protection against Acute Lung Injury by Inhibiting MMP-9 Expression without Protective Effects in other Organs

OBJECTIVE: Vaporized perfluorocarbon (PFC) is a treatment for lung injury; this study investigated its mode of action and potential protective effects on other organs, which are unclear. METHODS: Acute lung injury was induced by lung lavage with artificial seawater in 32 female New Zealand White rabbits. Animals received either conventional mechanical ventilation (CMV), positive end-expiratory pressure under CMV (PEEP), vaporized PFC ventilation, or positive end-expiratory pressure with vaporized PFC ventilation (PEEP + PFC). Histopathology of the lung, small intestine, liver and kidney were investigated. Matrix metalloproteinase (MMP)-9 mRNA levels in the lung were analysed. RESULTS: Pathological injury of the lung was significantly alleviated in the PEEP, PFC and PEEP + PFC groups compared with the CMV group. Tissue damage in the liver, kidney and small intestine was similar between all groups. MMP-9 mRNA levels in the PEEP, PFC and PEEP + PFC groups were significantly lower than those in the CMV group. CONCLUSIONS: Vaporized PFC ventilation can significantly alleviate lung injury but has no significant protective effect on other organs. Alleviation of lung injury may be associated with MMP-9 inhibition.

Mechanical ventilation during acute lung injury: current recommendations and new concepts

Despite a very large body of investigations, no effective pharmacological therapies have been found to cure acute lung injury. Hence, supportive care with mechanical ventilation remains the cornerstone of treatment. However, several experimental and clinical studies showed that mechanical ventilation, especially at high tidal volumes and pressures, can cause or aggravate ALI. Therefore, current clinical recommendations are developed with the aim of avoiding ventilator-induced lung injury (VILI) by limiting tidal volume and distending ventilatory pressure according to the results of the ARDS Network trial, which has been to date the only intervention that has showed success in decreasing mortality in patients with ALI/ARDS. In the past decade, a very large body of investigations has determined significant achievements on the pathophysiological knowledge of VILI. Therefore, new perspectives, which will be reviewed in this article, have been defined in terms of the efficiency and efficacy of recognizing, monitoring and treating VILI, which will eventually lead to further significant improvement of outcome in patients with ARDS.

Intestinal epithelium is more susceptible to cytopathic injury and altered permeability than the lung epithelium in the context of acute sepsis

Mitochondrial morphology and function are altered in intestinal epithelia during endotoxemia. However, it is unclear whether mitochondrial abnormalities occur in lung epithelial cells during acute sepsis or whether mitochondrial dysfunction corresponds with altered epithelial barrier function. Thus, we hypothesized that the intestinal epithelium is more susceptible to mitochondrial injury than the lung epithelium during acute sepsis and that mitochondrial dysfunction precedes impaired barrier function. Using a resuscitated feline model of Escherichia coli-induced sepsis, lung and ileal tissues were harvested after 6 h for histological and mitochondrial ultrastructural analyses in septic (n = 6) and time-matched controls (n = 6). Human lung epithelial cells (HLEC) and Caco-2 monolayers (n = 5) were exposed to 'cytomix' (TNFα: 40 ng/ml, IL-1β: 20 ng/ml, IFNγ: 10 ng/ml) for 24-72 h, and measurements of transepithelial electrical resistance (TER), epithelial permeability and mitochondrial membrane potential (ΔΨ) were taken. Lung epithelial morphology, mitochondrial ultrastructure and pulmonary gas exchange were unaltered in septic animals compared to matching controls. While histologically intact, ileal epithelia demonstrated marked mitochondrial ultrastructural damage during sepsis. Caco-2 monolayers treated with cytomix showed a significant decrease in mitochondrial ΔΨ within 24 h, which was associated with a progressive reduction in TER and increased epithelial permeability over the subsequent 48 h. In contrast, mitochondrial ΔΨ and epithelial barrier functions were preserved in HLEC following cytomix. These findings indicate that intestinal epithelium is more susceptible to mitochondrial damage and dysfunction than the lung epithelium in the context of sepsis. Early alterations in mitochondrial function portend subsequent epithelial barrier dysfunction.

Nutrition support for the acute lung injury/adult respiratory distress syndrome patient: a review

Support for Acute Lung Injury (ALI) and Adult Respiratory Distress Syndrome (ARDS) in many ways represents the summation of all intensive care unit nutrition modalities. Basic tenets of management are based on those established for the general population of mechanically ventilated patients. As a marker of critical illness however, patients with ALI/ARDS suffer from other organ dysfunctions that require advanced support. Specific issues to be considered in this population include carbon dioxide production, prevention of aspiration, and modulation of the inflammatory response. These particular areas, with special attention paid to the role of lipids in ALI/ARDS, will be reviewed.

Pathogenesis of indirect (secondary) acute lung injury

At present, therapeutic interventions to treat acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) remain largely limited to lung-protective strategies, as no real molecular-pathophysiologic-driven therapeutic intervention has yet become available. This is in part the result of the heterogeneous nature of the etiological processes that contribute to the state of ALI/ARDS. This article sets out to understand the development of ALI resulting from indirect pulmonary insults, such as extrapulmonary sepsis and trauma, shock, burn injury or mass transfusion, as opposed to direct pulmonary challenges, such as pneumonia, aspiration or lung contusion. Here, we consider not only the experimental and clinical data concerning the roles of various immune (neutrophil, macrophage, lymphocyte and dendritic) as well as nonimmune (epithelial and endothelial) cells in orchestrating the development of ALI resulting from indirect pulmonary stimuli, but also how these cell populations might be targeted therapeutically.

Early enteral nutrition reduces mortality in trauma patients requiring intensive care: a meta-analysis of randomised controlled trials

INTRODUCTION

To determine whether the provision of early standard enteral nutrition (EN) confers treatment benefits to adult trauma patients who require intensive care.

MATERIALS AND METHODS

MEDLINE and EMBASE were searched. Hand citation review of retrieved guidelines and systematic reviews was undertaken and academic and industry experts were contacted. Methodologically sound randomised controlled trials (RCTs) conducted in adult trauma patients requiring intensive care that compared the delivery of standard EN, provided within 24 h of injury, to standard care were included.The primary analysis was conducted on clinically meaningful patient-oriented outcomes, which included mortality, functional status and quality of life. Secondary analyses considered vomiting/regurgitation, pneumonia, bacteraemia, sepsis and multiple organ dysfunction syndrome. Meta-analysis was conducted using an analytical method known to minimise bias in the presence of sparse events. The impact of heterogeneity was assessed using the I2 metric.

RESULTS

Three RCTs with 126 participants were found to be free from major flaws and were included in the primary analysis. The provision of early EN was associated with a significant reduction in mortality(OR = 0.20, 95% confidence interval 0.04–0.91, I2 = 0). No other outcomes could be pooled. A sensitivity analysis and a confirmatory analysis conducted using a different analytical method confirmed the presence of a mortality reduction.

CONCLUSION

Although the detection of a statistically significant reduction in mortality is promising,overall trial quality was low and trial size was small. The results of this meta-analysis should be confirmed by the conduct of a large multi-center trial.

Erythropoetin as a novel agent with pleiotropic effects against acute lung injury

Current pharmacotherapy for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is not optimal, and the biological and physiological complexity of these severe lung injury syndromes requires consideration of combined-agent treatments or agents with pleiotropic action. In this regard, exogenous erythropoietin (EPO) represents a possible candidate since a number of preclinical studies have revealed beneficial effects of EPO administration in various experimental models of ALI. Taken together, this treatment strategy is not a single mediator approach, but it rather provides protection by modulating multiple levels of early signaling pathways involved in apoptosis, inflammation, and peroxidation, potentially restoring overall homeostasis. Furthermore, EPO appears to confer vascular protection by promoting angiogenesis. However, only preliminary studies exist and more experimental and clinical studies are necessary to clarify the efficacy and potentially cytoprotective mechanisms of EPO action. In addition to the attempts to optimize the dose and timing of EPO administration, it would be of great value to minimize any potential toxicity, which is essential for EPO to fulfill its role as a potential candidate for the treatment of ALI in routine clinical practice. The present article reviews recent advances that have elucidated biological and biochemical activities of EPO that may be potentially applicable for ALI/ARDS management.

Methyl-beta-cyclodextrin restores the structure and function of pulmonary surfactant films impaired by cholesterol

Pulmonary surfactant, a defined mixture of lipids and proteins, imparts very low surface tension to the lung-air interface by forming an incompressible film. In acute respiratory distress syndrome and other respiratory conditions, this function is impaired by a number of factors, among which is an increase of cholesterol in surfactant. The current study shows in vitro that cholesterol can be extracted from surfactant and function subsequently restored to dysfunctional surfactant films in a dose-dependent manner by methyl-beta-cyclodextrin (MbetaCD). Bovine lipid extract surfactant was supplemented with cholesterol to serve as a model of dysfunctional surfactant. Likewise, when cholesterol in a complex with MbetaCD ("water-soluble cholesterol") was added in aqueous solution, surfactant films were rendered dysfunctional. Atomic force microscopy showed recovery of function by MbetaCD is accompanied by the re-establishment of the native film structure of a lipid monolayer with scattered areas of lipid bilayer stacks, whereas dysfunctional films lacked bilayers. The current study expands upon a recent perspective of surfactant inactivation in disease and suggests a potential treatment.

Early enteral nutrition, provided within 24 h of injury or intensive care unit admission, significantly reduces mortality in critically ill patients: a meta-analysis of randomised controlled trials

PURPOSE

To determine whether the provision of early standard enteral nutrition (EN) confers treatment benefits to critically ill patients.

METHODS

Medline and EMBASE were searched. Hand citation review of retrieved guidelines and systematic reviews were undertaken, and academic and industry experts were contacted. Methodologically sound randomised controlled trials (RCTs) conducted in critically ill patient populations that compared the delivery of standard EN, provided within 24 h of intensive care unit (ICU) admission or injury, to standard care were included. The primary analysis was conducted on clinically meaningful patient-oriented outcomes. Secondary analyses considered vomiting/regurgitation, pneumonia, bacteraemia, sepsis and multiple organ dysfunction syndrome. Meta-analyses were conducted using the odds ratio (OR) metric and a fixed effects model. The impact of heterogeneity was assessed using the I (2) metric.

RESULTS

Six RCTs with 234 participants were analysed. The provision of early EN was associated with a significant reduction in mortality [OR = 0.34, 95% confidence interval (CI) 0.14-0.85] and pneumonia (OR = 0.31, 95% CI 0.12-0.78). There were no other significant differences in outcomes. A sensitivity analysis and a simulation exercise confirmed the presence of a mortality reduction.

CONCLUSION

Although the detection of a statistically significant reduction in mortality is promising, overall trial quality was low, trial size was small, and the findings may be restricted to the patient groups enrolled into included trials. The results of this meta-analysis should be confirmed by the conduct of a large multi-centre trial enrolling diverse critically ill patient groups.

Reciprocal backcross mice confirm major loci linked to hyperoxic acute lung injury survival time

Morbidity and mortality associated with acute lung injury (ALI) and acute respiratory distress syndrome remain substantial. Although many candidate genes have been tested, a clear understanding of the pathogenesis is lacking, as is our ability to predict individual outcome. Because ALI is a complex disease, single gene approaches cannot easily identify effectors that must be treated concurrently. We employed a strategy to help identify critical genes and gene combinations involved in ALI mortality. Using hyperoxia to induce ALI, a mouse model for genetic analyses of ALI survival time was identified: C57BL/6J (B) mice are sensitive (i.e., die early), whereas 129X1/SvJ (S) mice are significantly more resistant, but with low penetrance. Segregation analysis of reciprocal F(2) mice generated from B and S strains revealed significant sex, cross, and parent of origin effects. Quantitative trait locus (QTL) analysis identified five chromosomal regions significantly linked to hyperoxic ALI survival time (named Shali1-Shali5). Further analyses demonstrated that both parental strains contribute resistance alleles to their offspring and that the phenotype demonstrated parent of origin effects. To validate earlier findings, we generated and tested mice from all eight possible B-S-derived backcrosses. Results from segregation and QTL analyses of 935 backcrosses, alone and combined with the previous 840 B-S-derived F(2) population, further supported the highly significant QTLs on chromosomes 1 (Shali1) and 4 (Shali2) and confirmed that the sex, cross, and parent of origin all contribute to survival time with hyperoxic ALI.

American College of Surgeons trauma centre designation and mechanical ventilation outcomes

OBJECTIVE

The association between hospital volume and outcomes following mechanical ventilation has been previously examined in diverse patient populations. The American College of Surgeons (ACS) Committee on Trauma has outlined criteria for trauma centre level designations with specific requirements for both specialty capabilities and hospital volume. Our objective is to determine the relationship between ACS centre designation and outcomes for trauma patients undergoing mechanical ventilation.

METHODS

We conducted a retrospective cohort study using the National Trauma Databank (NTDB), identifying 13,933 adult (age>or=18) trauma patients receiving mechanical ventilation for greater than 48 h from 2000 to 2004 who were admitted to either an ACS Level I or Level II trauma centre. The primary endpoints examined were mortality, pneumonia and Acute Respiratory Distress Syndrome (ARDS). Univariate analysis defined differences between those patients admitted to ACS Level I and Level II facilities. Logistic regression analysis was used to identify if ACS level designation was an independent risk factor for the goal outcomes.

RESULTS

Patients admitted to a Level I facility and mechanically ventilated for greater than 48 h were more commonly greater than age 55 (71.3% vs. 67.9%, p<0.01), hypotensive (SBP<90) (16.1% vs. 12.8%, p<0.01), and likely to have sustained injury due to penetrating mechanism (11.1% vs. 5.1%, p<0.01). On univariate analysis, mortality and the incidence of pneumonia did not differ between the two groups. Level I admission was, however, less commonly associated with the development of ARDS (5.8% vs. 7.7%, p<0.01) and patients admitted to Level I facilities were significantly more likely to be discharged to home than Level II counterparts (29.7% vs. 22.9%, p<0.01). Logistic regression revealed that, while ACS Level designation was not a predictive factor for mortality or the development of pneumonia, admission to an ACS Level II facility was an independent predictor for the development of ARDS [p<0.01, odds ratio, 95% CI: 1.35 (1.18-1.59)].

CONCLUSION

For trauma patients requiring mechanical ventilation for >48 h, ACS trauma centre designation had no effect on overall mortality or the incidence of pneumonia. Compared to Level I counterparts, however, patients admitted to an ACS Level II facility were significantly more likely to develop ARDS following trauma. This finding needs further investigation in a large, prospective analysis.

Intensive care unit hypoglycemia predicts depression during early recovery from acute lung injury

OBJECTIVE

To evaluate the association between intensive care unit blood glucose levels and depression after acute lung injury.

DESIGN

Prospective cohort study.

SETTING

Twelve intensive care units in four hospitals in Baltimore, MD.

PATIENTS

Consecutive acute lung injury survivors (n = 104) monitored during 1717 intensive care unit patient-days and screened for depression at 3 months after acute lung injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The prevalence of a positive screening test for depression (Hospital Anxiety and Depression subscale score > or = 8) at follow-up was 28%. After adjustment for confounders, patients with a mean daily minimum intensive care unit glucose level < 100 mg/dL had significant increases in mean depression score (2.1 points, 95% confidence interval 0.6-3.7) and in the likelihood of a positive depression screening test (relative risk 2.6, 95% confidence interval 1.2-4.2). Patients with documented hypoglycemia < 60 mg/dL during their intensive care unit stay also had greater symptoms of depression (2.0 points, 95% confidence interval 0.5-3.5; relative risk 3.6, 95% confidence interval 1.8-5.1). Other factors independently associated with a positive depression screening test included body mass index > 40 kg/m2 (relative risk 3.3, 95% confidence interval 1.2-4.2), baseline depression/anxiety (relative risk 3.9, 95% confidence interval 1.5-6.5), and mean daily intensive care unit benzodiazepine dose > 100 mg of midazolam-equivalent agent (relative risk 2.4, 95% confidence interval 1.1-3.8).

CONCLUSIONS

Hypoglycemia in the intensive care unit is associated with an increased risk of positive screening for depression during early recovery from acute lung injury. Baseline depressive symptoms, morbid obesity, and intensive care unit benzodiazepine dose were also associated with postacute lung injury depressive symptoms. These findings warrant increased glucose monitoring for intensive care unit patients at risk for hypoglycemia and further research on how patient and intensive care unit management factors may contribute to postintensive care unit depression.

Epithelial cell apoptosis and neutrophil recruitment in acute lung injury-a unifying hypothesis? What we have learned from small interfering RNAs

In spite of protective ventilatory strategies, Acute Lung Injury (ALI) remains associated with high morbidity and mortality. One reason for the lack of therapeutic options might be that ALI is a co-morbid event associated with a diverse family of diseases and, thus, may be the result of distinct pathological processes. Among them, activated neutrophil- (PMN-) induced tissue injury and epithelial cell apoptosis mediated lung damage represent two potentially important candidate pathomechanisms that have been put forward. Several approaches have been undertaken to test these hypotheses, with substantial success in the treatment of experimental forms of ALI. With this in mind, we will summarize these two current hypotheses of ALI briefly, emphasizing the role of apoptosis in regulating PMN and/or lung epithelial cell responses. In addition, the contribution that Fas-mediated inflammation may play as a potential biological link between lung cell apoptosis and PMN recruitment will be considered, as well as the in vivo application of small interfering RNA (siRNA) as a novel approach to the inhibition of ALI and its therapeutic implications.

Endothelial pathomechanisms in acute lung injury

Acute lung injury (ALI) and its most severe extreme the acute respiratory distress syndrome (ARDS) refer to increased-permeability pulmonary edema caused by a variety of pulmonary or systemic insults. ALI and in particular ARDS, are usually accompanied by refractory hypoxemia and the need for mechanical ventilation. In most cases, an exaggerated inflammatory and pro-thrombotic reaction to an initial stimulus, such as systemic infection, elicits disruption of the alveolo-capillary membrane and vascular fluid leak. The pulmonary endothelium is a major metabolic organ promoting adequate pulmonary and systemic vascular homeostasis, and a main target of circulating cells and humoral mediators under injury; pulmonary endothelium is therefore critically involved in the pathogenesis of ALI. In this review we will discuss mechanisms of pulmonary endothelial dysfunction and edema generation in the lung with special emphasis on the interplay between the endothelium, the immune and hemostatic systems, and highlight how these principles apply in the context of defined disorders and specific insults implicated in ALI pathogenesis.

Impact of preexisting organ dysfunction on extracorporeal life support for non-postcardiotomy cardiopulmonary failure

BACKGROUND

Extracorporeal life support (ECLS) is associated with a high mortality rate in patients with preexisting multiple organ failure. To achieve better outcomes of ECLS in this high risk group, an understanding of the real impact of preexisting organ dysfunction on ECLS-associated mortality is necessary.

METHODS

From January 2003 to March 2007, a total of 45 patients (mean age: 48 years) were placed on ECLS for acute cardiopulmonary failure and survived longer than 24h. The medical records of these 45 patients were retrospectively reviewed. The indications for ECLS were acute respiratory distress syndrome (n=23), acute myocarditis (n=10) and acute myocardial infarction (n=12). Organ failure was assessed based on the Sequential Organ Failure Assessment (SOFA) score, which was calculated daily until ECLS termination. The demographic variables, SOFA score variables, and ECLS-related complications, including renal dialysis, severe brain damage and limb ischemia, were analysed.

RESULTS

Twenty-seven patients (60%) were weaned from ECLS and 21 (47%) survived to discharge. Multivariate analysis revealed that the necessity of renal dialysis was an independent risk factor associated with failure to wean and non-survival, and the necessity of cardiopulmonary resuscitation (CPR) before ECLS was an independent risk factor for non-survival. Preexisting organ dysfunction, quantified by the pre-ECLS SOFA score, was predictive of survival to discharge. A pre-ECLS SOFA score greater than 14 predicted mortality in this study.

CONCLUSIONS

SOFA score is a practical assessment tool and is predictive of ECLS-associated mortality in non-postcardiotomy patients. Patients having cardiac arrest requiring CPR or acute renal failure requiring dialysis before ECLS may have inferior ECLS outcomes.

Secondary necrosis in multicellular animals: an outcome of apoptosis with pathogenic implications

In metazoans apoptosis is a major physiological process of cell elimination during development and in tissue homeostasis and can be involved in pathological situations. In vitro, apoptosis proceeds through an execution phase during which cell dismantling is initiated, with or without fragmentation into apoptotic bodies, but with maintenance of a near-to-intact cytoplasmic membrane, followed by a transition to a necrotic cell elimination traditionally called “secondary necrosis”. Secondary necrosis involves activation of self-hydrolytic enzymes, and swelling of the cell or of the apoptotic bodies, generalized and irreparable damage to the cytoplasmic membrane, and culminates with cell disruption. In vivo, under normal conditions, the elimination of apoptosing cells or apoptotic bodies is by removal through engulfment by scavengers prompted by the exposure of engulfment signals during the execution phase of apoptosis; if this removal fails progression to secondary necrosis ensues as in the in vitro situation. In vivo secondary necrosis occurs when massive apoptosis overwhelms the available scavenging capacity, or when the scavenger mechanism is directly impaired, and may result in leakage of the cell contents with induction of tissue injury and inflammatory and autoimmune responses. Several disorders where secondary necrosis has been implicated as a pathogenic mechanism will be reviewed.

Treatment of sepsis-induced acquired protein C deficiency reverses Angiotensin-converting enzyme-2 inhibition and decreases pulmonary inflammatory response

The protein C (PC) pathway plays an important role in vascular and immune function, and acquired deficiency during sepsis is associated with increased mortality in both animal models and in clinical studies. However, the association of acquired PC deficiency with the pathophysiology of lung injury is unclear. We hypothesized that low PC induced by sepsis would associate with increased pulmonary injury and that replacement with activated protein C (APC) would reverse the activation of pathways associated with injury. Using a cecal ligation and puncture (CLP) model of polymicrobial sepsis, we examined the role of acquired PC deficiency on acute lung injury assessed by analyzing changes in pulmonary pathology, chemokine response, inducible nitric-oxide synthase (iNOS), and the angiotensin pathway. Acquired PC deficiency was strongly associated with an increase in lung inflammation and drivers of pulmonary injury, including angiotensin (Ang) II, thymus and activation-regulated chemokine, plasminogen activator inhibitor (PAI)-1, and iNOS. In contrast, the protective factor angiotensin-converting enzyme (ACE)-2 was significantly suppressed in animals with acquired PC deficiency. The endothelial protein C receptor, required for the cytoprotective signaling of APC, was significantly increased post-CLP, suggesting a compensatory up-regulation of the signaling receptor. Treatment of septic animals with APC reduced pulmonary pathology, suppressed the macrophage inflammatory protein family chemokine response, iNOS expression, and PAI-1 activity and up-regulated ACE-2 expression with concomitant reduction in AngII peptide. These data demonstrate a clear link between acquired PC deficiency and pulmonary inflammatory response in the rat sepsis model and provide support for the concept of APC as a replacement therapy in acute lung injury associated with acquired PC deficiency.

Impact of the method of initial stabilization for femoral shaft fractures in patients with multiple injuries at risk for complications (borderline patients)

OBJECTIVES

The timing of definitive fixation for major fractures in patients with multiple injuries is controversial. To address this gap, we randomized patients with blunt multiple injuries to either initial definitive stabilization of the femur shaft with an intramedullary nail or an external fixateur with later conversion to an intermedullary nail and documented the postoperative clinical condition.

METHODS

Multiply injured patients with femoral shaft fractures were randomized to either initial (<24 hours) intramedullary femoral nailing or external fixation and later conversion to an intramedullary nail. Inclusion: New Injury Severity Score >16 points, or 3 fractures and Abbreviated Injury Scale score > or =2 points and another injury (Abbreviated Injury Scale score > or =2 points), and age 18 to 65 years. Exclusion: patients in unstable or critical condition. Patients were graded as stable or borderline (increased risk of systemic complications).

OUTCOMES

: Incidence of acute lung injuries.

RESULTS

Ten European Centers, 165 patients, mean age 32.7 +/- 11.7 years. Group intramedullary nailing, n = 94; group external fixation, n = 71. Preoperatively, 121 patients were stable and 44 patients were in borderline condition. After adjusting for differences in initial injury severity between the 2 treatment groups, the odds of developing acute lung injury were 6.69 times greater in borderline patients who underwent intramedullary nailing in comparison with those who underwent external fixation, P < 0.05.

CONCLUSION

Intramedullary stabilization of the femur fracture can affect the outcome in patients with multiple injuries. In stable patients, primary femoral nailing is associated with shorter ventilation time. In borderline patients, it is associated with a higher incidence of lung dysfunctions when compared with those who underwent external fixation and later conversion to intermedullary nail. Therefore, the preoperative condition should be when deciding on the type of initial fixation to perform in patients with multiple blunt injuries.