Effect of Fluid Bolus Administration on Cardiovascular Collapse Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial.

Importance: Hypotension is common during tracheal intubation of critically ill adults and increases the risk of cardiac arrest and death. Whether administering an intravenous fluid bolus to critically ill adults undergoing tracheal intubation prevents severe hypotension, cardiac arrest, or death remains uncertain. Objective: To determine the effect of fluid bolus administration on the incidence of severe hypotension, cardiac arrest, and death. Design, Setting, and Participants: This randomized clinical trial enrolled 1067 critically ill adults undergoing tracheal intubation with sedation and positive pressure ventilation at 11 intensive care units in the US between February 1, 2019, and May 24, 2021. The date of final follow-up was June 21, 2021. Interventions: Patients were randomly assigned to receive either a 500-mL intravenous fluid bolus (n = 538) or no fluid bolus (n = 527). Main Outcomes and Measures: The primary outcome was cardiovascular collapse (defined as new or increased receipt of vasopressors or a systolic blood pressure <65 mm Hg between induction of anesthesia and 2 minutes after tracheal intubation, or cardiac arrest or death between induction of anesthesia and 1 hour after tracheal intubation). The secondary outcome was the incidence of death prior to day 28, which was censored at hospital discharge. Results: Among 1067 patients randomized, 1065 (99.8%) completed the trial and were included in the primary analysis (median age, 62 years [IQR, 51-70 years]; 42.1% were women). Cardiovascular collapse occurred in 113 patients (21.0%) in the fluid bolus group and in 96 patients (18.2%) in the no fluid bolus group (absolute difference, 2.8% [95% CI, -2.2% to 7.7%]; P = .25). New or increased receipt of vasopressors occurred in 20.6% of patients in the fluid bolus group compared with 17.6% of patients in the no fluid bolus group, a systolic blood pressure of less than 65 mm Hg occurred in 3.9% vs 4.2%, respectively, cardiac arrest occurred in 1.7% vs 1.5%, and death occurred in 0.7% vs 0.6%. Death prior to day 28 (censored at hospital discharge) occurred in 218 patients (40.5%) in the fluid bolus group compared with 223 patients (42.3%) in the no fluid bolus group (absolute difference, -1.8% [95% CI, -7.9% to 4.3%]; P = .55). Conclusions and Relevance: Among critically ill adults undergoing tracheal intubation, administration of an intravenous fluid bolus compared with no fluid bolus did not significantly decrease the incidence of cardiovascular collapse. Trial Registration: ClinicalTrials.gov Identifier: NCT03787732.

Evaluation and Management of Intermediate and High-Risk Pulmonary Embolism.

OBJECTIVE. The evidence regarding pulmonary embolism treatment has greatly advanced over the past 10 years, particularly in patients with right ventricular dysfunction or hemodynamic instability. Treatment options include systemic anticoagulation, systemic thrombolysis, catheter-assisted thrombus removal (mechanical with or without catheter-directed thrombolysis), and surgical embolectomy. CONCLUSION. This article will review the data available for treatment options and summarize the evidence-based guidelines on treatment of intermediate- or high-risk pulmonary embolism.

The role of cyclooxygenase-2 in mechanical ventilation-induced lung injury.

Mechanical ventilation is necessary for patients with acute respiratory failure, but can cause or propagate lung injury. We previously identified cyclooxygenase-2 as a candidate gene in mechanical ventilation-induced lung injury. Our objective was to determine the role of cyclooxygenase-2 in mechanical ventilation-induced lung injury and the effects of cyclooxygenase-2 inhibition on lung inflammation and barrier disruption. Mice were mechanically ventilated at low and high tidal volumes, in the presence or absence of pharmacologic cyclooxygenase-2-specific inhibition with 3-(4-methylsulphonylphenyl)-4-phenyl-5-trifluoromethylisoxazole (CAY10404). Lung injury was assessed using markers of alveolar-capillary leakage and lung inflammation. Cyclooxygenase-2 expression and activity were measured by Western blotting, real-time PCR, and lung/plasma prostanoid analysis, and tissue sections were analyzed for cyclooxygenase-2 staining by immunohistochemistry. High tidal volume ventilation induced lung injury, significantly increasing both lung leakage and lung inflammation relative to control and low tidal volume ventilation. High tidal volume mechanical ventilation significantly induced cyclooxygenase-2 expression and activity, both in the lungs and systemically, compared with control mice and low tidal volume mice. The immunohistochemical analysis of lung sections localized cyclooxygenase-2 expression to monocytes and macrophages in the alveoli. The pharmacologic inhibition of cyclooxygenase-2 with CAY10404 significantly decreased cyclooxygenase activity and attenuated lung injury in mice ventilated at high tidal volume, attenuating barrier disruption, tissue inflammation, and inflammatory cell signaling. This study demonstrates the induction of cyclooxygenase-2 by mechanical ventilation, and suggests that the therapeutic inhibition of cyclooxygenase-2 may attenuate ventilator-induced acute lung injury.

CRISIS ventilator: A 3D printed option for ventilator surge in mass respiratory pandemics.

BACKGROUND: The COVID-19 pandemic revealed flaws in the stockpiling and distribution of ventilators. In this study, we assessed the durability, sterilizability, and performance of a 3D-printed ventilator. METHODS: SLS-printed devices were dropped from 1.83 m and autoclaved before evaluation on a COVID-19 simulated patient. The respiratory performance of an extrusion-printed device was studied using a variable compliance model. Ranges of sustainable respiratory rates were evaluated as a function of tidal volume. RESULTS: Autoclaving and dropping the device did not negatively impact minute ventilation or PIP for sustained ventilation. Equivalence was significant across all measures except for comparing the autoclaved and dropped with p = 0.06. Extrusion produced ventilators achieved minute ventilation ranging from 4.1 to 12.2 L/min for all simulated compliances; there was an inverse correlation between tidal volume and respiratory rate. CONCLUSION: The CRISIS ventilator is a durable, sterilizable, and reusable 3D-printed ventilator using off-the-shelf materials which could be employed variety of adult lung diseases. Further in-vivo testing is needed.

Simulating for Quality: A Centralized Quality Improvement and Patient Safety Simulation Curriculum for Residents and Fellows.

PROBLEM: Requirements for experiential education in quality improvement and patient safety (QI/PS) in graduate medical education (GME) have recently expanded. Major challenges to meeting these requirements include a lack of faculty with the needed expertise, paucity of standardized curricular models allowing for skill demonstration, and inconsistent access to data for iterative improvement. APPROACH: In October 2017, the authors began development of a centralized QI/PS flipped-classroom simulation-based medical education (SBME) curriculum for GME trainees across multiple disciplines at Oregon Health & Science University (OHSU). The curriculum development team included OHSU and Veterans Affairs faculty with experience in QI/PS and SBME, as well as house officers. The curriculum consisted of a preassessment and prework readings and videos (sent 3 weeks before the simulation day) and an 8-hour simulation day, with introductory activities, 4 linked simulation sessions, and concluding activities. The 4 linked sessions followed the same medication error from disclosure and reporting to root cause analysis, iterative implementation of an action plan, and consolidation of lessons learned into routine operations with Lean huddles. OUTCOMES: In academic year 2018-2019, 71 residents and fellows of various postgraduate years from 23 training programs enrolled in 2 pilot sessions. Learners reacted favorably to the simulation curriculum. Learner attitudes, confidence, knowledge, and skills significantly increased across all QI/PS domains studied. NEXT STEPS: This approach focuses a small cadre of educators toward the creation of a centralized resource that, owing to its experiential SBME foundation, can accommodate many learners with data-driven practice-based learning and improvement cycles in a shorter time frame than traditional QI initiatives. Next steps include the addition of a control group, assessment of the sustainability of learner outcomes, translation of learning to behavior change and improvements in patient and health system outcomes, and adapting the materials to include learners from different professions and levels.

Creation of an International Interprofessional Simulation-enhanced Mechanical Ventilation Course.

Background: Evidence shows poor adherence to strategies for reducing morbidity and mortality in intensive care unit (ICU) patients receiving mechanical ventilation globally. Best practice management relies on training all members of the interprofessional ICU team, each with complementary roles in patient management. Objectives: To develop and evaluate a novel two-phase, train-the-trainer, interprofessional and multicultural "Best Practice Management of the Ventilated ICU Patient" multimodality, simulation-enhanced curriculum for Thai education leaders in critical care. Methods: In phase 1 (Oregon Health and Science University cohort), two groups of nine ICU nurses and one critical care physician representing experts in critical care and education from a large hospital system in Thailand participated in a weeklong, immersive course consisting of didactic, simulation, and in situ immersive sessions focused on best practice management of mechanically ventilated ICU patients, as well as training in our educational techniques. Outcomes were assessed with pre- and postcourse knowledge assessments and overall course evaluation. In phase 2 (Thai cohort), participants from phase 1 returned to Thailand and implemented a lower fidelity curriculum in two hospitals, using the same pre- and posttest knowledge assessment in 41 participants, before the onset of the coronavirus disease (COVID-19) 6 pandemic. Results: In the Oregon Health and Science University cohort, the mean pretest knowledge score was 58.4 ± 13.2%, with a mean improvement to 82.5 ± 11.6% after completion of the course (P , 0.05). The greatest improvements were seen in respiratory physiology and advanced/disease-specific concepts, which demonstrated absolute improvements of 30.4% and 30.6%, respectively (P < 0.05). Participants had a high degree of satisfaction, with 90% rating the course as "excellent" and .90% reporting that the course "greatly improved" their understanding of best practices and comfort in managing mechanical ventilation. The Thai cohort had a mean baseline score of 45.4 ± 15.0% and a mean improvement to 70.3 ± 19.1% after training (P < 0.05). This cohort also saw the greatest improvement in respiratory physiology and advanced/disease-specific concepts, with 26.2% and 26.3% absolute improvements, respectively (P < 0.05). Conclusion: A novel, two-phase, interprofessional, multicultural, simulation-enhanced train-the-trainer curriculum was feasible and effective in improving education in best practice management of mechanically ventilated patients and may be a useful model for improving the care of ICU patients across the world.

Protective role of PI3-kinase/Akt/eNOS signaling in mechanical stress through inhibition of p38 mitogen-activated protein kinase in mouse lung.

AIM: To test the hypothesis that PI3K/Akt/eNOS signaling has a protective role in a murine model of ventilation associated lung injury (VALI) through down-regulation of p38 MAPK signaling. METHODS: Male C57BL/J6 (wild-type, WT) or eNOS knockout mice (eNOS(-/-)) were exposed to mechanical ventilation (MV) with low (LV(T), 7 mL/kg) and high tidal volume (HV(T), 20 mL/kg) for 0-4 h. A subset of WT mice was administered the specific inhibitors of PI3K (100 nmol/L Wortmannin [Wort], ip) or of p38 MAPK (SB203580, 2 mg/kg, ip) 1 h before MV. Cultured type II alveolar epithelial cells C10 were exposed to 18% cyclic stretch for 2 h with or without 20 nmol/L Wort pretreatment. At the end of the experiment, the capillary leakage in vivo was assessed by extravasation of Evans blue dye (EBD), wet/dry weight ratio and lung lavage protein concentration. The lung tissue and cell lysate were also collected for protein and histological review. RESULTS: MV decreased PI3K/Akt phosphorylation and eNOS expression but increased phospho-p38 MAPK expression along with a lung leakage of EBD. Inhibitions of phospho-Akt by Wort worsen the lung edema, whereas inhibition of p38 MAPK kinase restored activation of Akt together with alleviated capillary leakage. eNOS(-/-) mice showed an exacerbated lung edema and injury. The stretched C10 cells demonstrated that Wort diminished the activation of Akt, but potentiated phosphorylation of MAPK p38. CONCLUSION: Our results indicate that PI-3K/Akt/eNOS pathway has significant protective effects in VALI by preventing capillary leakage, and that there is a cross-talk between PI3K/Akt and p38 MAPK pathways in vascular barrier dysfunction resulting from VALI.

Three-Dimensional Printed Ventilators: A Rapid Solution to Coronavirus Disease 2019-Induced Supply-Chain Shortages.

OBJECTIVE: To examine rapidly emerging ventilator technologies during coronavirus disease 2019 and highlight the role of CRISIS, a novel 3D printed solution. DATA SOURCES: Published articles, literature, and government guidelines that describe and review emergency use ventilator technologies. STUDY SELECTION: Literature was chosen from peer-reviewed journals and articles were limited to recent publications. DATA EXTRACTION: All information regarding ventilator technology was extracted from primary sources. DATA SYNTHESIS: Analysis of technology and relevance to coronavirus disease 2019 physiology was collectively synthesized by all authors. CONCLUSIONS: The coronavirus disease 2019 pandemic has placed massive stress on global supply chains for ventilators due to the critical damage the virus causes to lung function. There is an urgent need to increase supply, as hospitals become inundated with patients requiring intensive respiratory support. Coalitions across the United States have formed in order to create new devices that can be manufactured quickly, with minimal resources, and provide consistent and safe respiratory support. Due to threats to public health and the vulnerability of the U.S. population, the Food and Drug Administration released Emergency Use Authorizations for new or repurposed devices, shortening the approval timeline from years to weeks. The list of authorized devices varies widely in complexity, from automated bagging techniques to repurposed sleep apnea machines. Three-dimensional printed ventilators, such as "CRISIS," propose a potential solution to increase the available number of vents for the United States and abroad, one that is dynamic and able to absorb the massive influx of hospitalized patients for the foreseeable future.

Development and evaluation of a simulation-based transition to clerkship course.

BACKGROUND: Transition to clerkship courses bridge the curricular gap between preclinical and clinical medical education. However, despite the use of simulation-based teaching techniques in other aspects of medical training, these techniques have not been adequately described in transition courses. We describe the development, structure and evaluation of a simulation-based transition to clerkship course. APPROACH: Beginning in 2012, our institution embarked upon an extensive curricular transformation geared toward competency-based education. As part of this effort, a group of 12 educators designed, developed and implemented a simulation-based transition course. The course curriculum involved seven goals, centered around the 13 Association of American Medical Colleges Core Entrustable Professional Activities for entering residency. Instructional techniques included high-fidelity simulation, and small and large group didactics. Student competency was determined through a simulation-based inpatient-outpatient objective structured clinical examination, with real-time feedback and remediation. The effectiveness of the course was assessed through a mixed methods approach involving pre- and post-course surveys and a focus group. EVALUATION: Of 166 students, 152 (91.6%) completed both pre- and post-course surveys, and nine students participated in the focus group. Students reported significant improvements in 21 out of 22 course objectives. Qualitative analysis revealed three key themes: learning environment, faculty engagement and collegiality. The main challenge to executing the course was procuring adequate faculty, material and facility resources. REFLECTION: This simulation-based, resource-heavy transition course achieved its educational objectives and provided a safe, supportive learning environment for practicing and refining clinical skills.

Mechanical Ventilation Training During Graduate Medical Education: Perspectives and Review of the Literature.

BACKGROUND: Management of mechanical ventilation (MV) is an important and complex aspect of caring for critically ill patients. Management strategies and technical operation of the ventilator are key skills for physicians in training, as lack of expertise can lead to substantial patient harm. OBJECTIVE: We performed a narrative review of the literature describing MV education in graduate medical education (GME) and identified best practices for training and assessment methods. METHODS: We searched MEDLINE, PubMed, and Google Scholar for English-language, peer-reviewed articles describing MV education and assessment. We included articles from 2000 through July 2018 pertaining to MV education or training in GME. RESULTS: Fifteen articles met inclusion criteria. Studies related to MV training in anesthesiology, emergency medicine, general surgery, and internal medicine residency programs, as well as subspecialty training in critical care medicine, pediatric critical care medicine, and pulmonary and critical care medicine. Nearly half of trainees assessed were dissatisfied with their MV education. Six studies evaluated educational interventions, all employing simulation as an educational strategy, although there was considerable heterogeneity in content. Most outcomes were assessed with multiple-choice knowledge testing; only 2 studies evaluated the care of actual patients after an educational intervention. CONCLUSIONS: There is a paucity of information describing MV education in GME. The available literature demonstrates that trainees are generally dissatisfied with MV training. Best practices include establishing MV-specific learning objectives and incorporating simulation. Next research steps include developing competency standards and validity evidence for assessment tools that can be utilized across MV educational curricula.

Oxidized phospholipids reduce ventilator-induced vascular leak and inflammation in vivo.

BACKGROUND: Mechanical ventilation at high tidal volume (HTV) may cause pulmonary capillary leakage and acute lung inflammation resulting in ventilator-induced lung injury. Besides blunting the Toll-like receptor-4-induced inflammatory cascade and lung dysfunction in a model of lipopolysaccharide-induced lung injury, oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) exerts direct barrier-protective effects on pulmonary endothelial cells in vitro via activation of the small GTPases Rac and Cdc42. To test the hypothesis that OxPAPC may attenuate lung inflammation and barrier disruption caused by pathologic lung distension, we used a rodent model of ventilator-induced lung injury and an in vitro model of pulmonary endothelial cells exposed to pathologic mechanochemical stimulation. METHODS: Rats received a single intravenous injection of OxPAPC (1.5 mg/kg) followed by mechanical ventilation at low tidal volume (LTV) (7 mL/kg) or HTV (20 mL/kg). Bronchoalveolar lavage was performed and lung tissue was stained for histological analysis. In vitro, the effects of OxPAPC on endothelial barrier dysfunction and GTPase activation were assessed in cells exposed to thrombin and pathologic (18%) cyclic stretch. RESULTS: HTV induced profound increases in bronchoalveolar lavage and tissue neutrophils and in lavage protein. Intravenous OxPAPC markedly attenuated HTV-induced protein and inflammatory cell accumulation in bronchoalveolar lavage fluid and lung tissue. In vitro, high-magnitude stretch enhanced thrombin-induced endothelial paracellular gap formation associated with Rho activation. These effects were dramatically attenuated by OxPAPC and were associated with OxPAPC-induced activation of Rac. CONCLUSION: OxPAPC exhibits protective effects in these models of ventilator-induced lung injury.

Status Asthmaticus and Central Herniation: A Case for Multidisciplinary Critical Care.

A 24-year-old woman with history of asthma was intubated emergently for acute status asthmaticus triggered by acute respiratory syncytial virus infection and treated with permissive hypercapnia. Her ventilation was complicated by auto-positive end-expiratory pressure and elevated peak airway, plateau, and central venous pressures. On hospital day 2, she was noted to have anisocoria. Imaging showed diffuse cerebral edema with central herniation. Difficult ventilation and hypercapnia directly contributed to her severe cerebral edema. Comanagement between neurologic and medical/pulmonary intensivists enabled the management of the competing treatment requirements for status asthmaticus and cerebral edema. This case highlights the importance of balancing conflicting physiologic needs and collaboration between teams.

Pulmonary Manifestations of Primary Immunodeficiency Disorders.

Pulmonary disease, ranging from infectious pneumonia, lung abscess, and empyema to structural lung diseases to malignancy, significantly increase morbidity and mortality in primary immune deficiency. Treatment with supplemental immunoglobulin (intravenous or subcutaneous) and antimicrobials is beneficial in reducing infections but are largely ineffective in preventing noninfectious complications, including interstitial lung disease, malignancy, and autoimmune disease. A low threshold for suspecting pulmonary complications is necessary for the early diagnosis of pulmonary involvement in primary immunodeficiency disorders, before irreversible damage is done, to improve patient outcomes.

Improved management of acute asthma among pregnant women presenting to the ED.

BACKGROUND: A multicenter study in the late 1990s demonstrated suboptimal emergency asthma care for pregnant women in US EDs. After a decade, follow-up data are lacking. We aimed to examine changes in emergency asthma care of pregnant women since the 1990s. METHODS: We combined data from four multicenter observational studies of ED patients with acute asthma performed in 1996 to 2001 (three studies) and 2011 to 2012 (one study). We restricted the data so that comparisons were based on the same 48 EDs in both time periods. We identified all pregnant patients aged 18 to 44 years with acute asthma. Primary outcomes were treatment with systemic corticosteroids in the ED and, among those sent home, at ED discharge. RESULTS: Of 4,895 ED patients with acute asthma, the analytic cohort comprised 125 pregnant women. Between the two time periods, there were no significant changes in patient demographics, chronic asthma severity, or initial peak expiratory flow. In contrast, ED systemic corticosteroid treatment increased significantly from 51% to 78% across the time periods (OR, 3.11; 95% CI, 1.27-7.60; P = .01); systemic corticosteroids at discharge increased from 42% to 63% (OR, 2.49; 95% CI, 0.97-6.37; P = .054). In the adjusted analyses, pregnant women in recent years were more likely to receive systemic corticosteroids, both in the ED (OR, 4.76; 95% CI, 1.63-13.9; P = .004) and at discharge (OR, 3.18; 95% CI, 1.05-9.61; P = .04). CONCLUSIONS: Between the two time periods, emergency asthma care in pregnant women significantly improved. However, with one in three pregnant women being discharged home without systemic corticosteroids, further improvement is warranted.

Children and Adults With Frequent Hospitalizations for Asthma Exacerbation, 2012-2013: A Multicenter Observational Study.

BACKGROUND: Earlier studies reported that many patients were frequently hospitalized for asthma exacerbation. However, there have been no recent multicenter studies to characterize this patient population with high morbidity and health care utilization. OBJECTIVE: To examine the proportion and characteristics of children and adults with frequent hospitalizations for asthma exacerbation. METHODS: A multicenter chart review study of patients aged 2 to 54 years who were hospitalized for asthma exacerbation at 1 of 25 hospitals across 18 US states during the period 2012 to 2013 was carried out. The primary outcome was frequency of hospitalizations for asthma exacerbation in the past year (including the index hospitalization). RESULTS: The cohort included 369 children (aged 2-17 years) and 555 adults (aged 18-54 years) hospitalized for asthma exacerbation. Over the 12-month period, 36% of the children and 42% of the adults had 2 or more (frequent) hospitalizations for asthma exacerbation. Among patients with frequent hospitalizations, guideline-recommended outpatient management was suboptimal. For example, among adults, 32% were not on inhaled corticosteroids at the time of index hospitalization and 75% had no evidence of a previous evaluation by an asthma specialist. At hospital discharge, among adults with frequent hospitalizations who had used no controller medications previously, 37% were not prescribed inhaled corticosteroids. Likewise, during a 3-month postdischarge period, 64% of the adults with frequent hospitalizations were not referred to an asthma specialist. Although the proportion of patients who did not receive these guideline-recommended outpatient care appeared higher in adults, these preventive measures were still underutilized in children; for example, 38% of the children with frequent hospitalizations were not referred to asthma specialist after the index hospitalization. CONCLUSIONS: This multicenter study of US patients hospitalized with asthma exacerbation demonstrated a disturbingly high proportion of patients with frequent hospitalizations and ongoing evidence of suboptimal longitudinal asthma care.

Mechanisms, detection, and potential management of microcirculatory disturbances in sepsis.

Despite improvements in resuscitation and treatment of sepsis, the morbidity and mortality remain unacceptably high. Microvascular dysfunction has been shown to play a significant role in the pathogenesis of sepsis and is a potential new target in the management of sepsis. Clinical studies, aided by new techniques that allow for real-time assessment of the microcirculation, have shown that disturbances in microcirculatory flow are common in sepsis and correlate with worse outcomes. Bedside measurement of microcirculatory perfusion has become simpler and more accessible, and may provide key insights into prognosis in sepsis and guide future therapeutics, much like mean arterial pressure (MAP), lactate, and mixed central oxygen saturation (SvO(2)) do now. The authors review here the role of microcirculatory dysfunction in sepsis and its potential role as a therapeutic target in sepsis.

Use of consomic rats for genomic insights into ventilator-associated lung injury.

Increasing evidence supports the contribution of genetic influences on susceptibility/severity in acute lung injury (ALI), a devastating syndrome requiring mechanical ventilation with subsequent risk for ventilator-associated lung injury (VALI). To identify VALI candidate genes, we determined that Brown Norway (BN) and Dahl salt-sensitive (SS) rat strains were differentially sensitive to VALI (tidal volume of 20 ml/kg, 85 breaths/min, 2 h) defined by bronchoalveolar lavage (BAL) protein and leukocytes. We next exploited differential sensitivities and phenotyped both the VALI-sensitive BN and the VALI-resistant SS rat strains by expression profiling coupled to a bioinformatic-intense candidate gene approach (Significance Analysis of Microarrays, i.e., SAM). We identified 106 differentially expressed VALI genes representing gene ontologies such as "transcription" and "chemotaxis/cell motility." We mapped the chromosomal location of the differentially expressed probe sets and selected consomic SS rats with single BN introgressions of chromosomes 2, 13, and 16 (based on the highest density of probe sets) while also choosing chromosome 20 (low probe sets density). VALI exposure of consomic rats with introgressions of BN chromosomes 13 and 16 resulted in significant increases in both BAL cells and protein (compared to parental SS strain), whereas introgression of BN chromosome 2 displayed a large increase only in BAL protein. Introgression of BN chromosome 20 had a minimal effect. These results suggest that genes residing on BN chromosomes 2, 13, and 16 confer increased sensitivity to high tidal volume ventilation. We speculate that the consomic-microarray-SAM approach is a time- and resource-efficient tool for the genetic dissection of complex diseases including VALI.

Oxidized phospholipids reduce vascular leak and inflammation in rat model of acute lung injury.

RATIONALE: Acute inflammation and vascular leak are cardinal features of acute lung injury and the acute respiratory distress syndrome. Nonspecific tissue inflammation and injury in response to infectious and noninfectious insults lead to oxidative stress and the generation of lipid oxidation products, which may inhibit the acute inflammatory response to bacterial components. OBJECTIVE: To test the hypothesis that oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC) may attenuate the acute lung inflammatory response to lipopolysaccharide (LPS) and enhance lung vascular barrier recovery, we used in vivo and in vitro models of LPS-induced lung injury. METHODS: Rats received intratracheal aerosolized LPS (5 mg/kg) or sterile water with concurrent intravenous injection of OxPAPC (0.5-6.0 mg/kg) or saline alone. Nonoxidized PAPC was used as a control. At 18 h, bronchoalveolar lavage was performed and the lungs were removed for histologic analysis. Measurements of endothelial transmonolayer electrical resistance and immunofluorescent analysis of monolayer integrity were used in an in vitro model of LPS-induced lung vascular barrier dysfunction. MEASUREMENTS AND MAIN RESULTS: In vivo, aerosolized intratracheal LPS induced lung injury with profound increases in bronchoalveolar lavage neutrophils, protein content, and the inflammatory cytokines interleukin 6 and interleukin 1beta, as well as tissue neutrophils. OxPAPC, but not nonoxidized PAPC, markedly attenuated the LPS-induced tissue inflammation, barrier disruption, and cytokine production over a range of doses. In vitro, oxidized phospholipids attenuated LPS-induced endothelial barrier disruption and reversed LPS-induced cytoskeletal remodeling and disruption of monolayer integrity. CONCLUSIONS: These studies demonstrate in vivo and in vitro protective effects of oxidized phospholipids on LPS-induced lung dysfunction.

Functional genomic insights into acute lung injury: role of ventilators and mechanical stress.

Acute lung injury (ALI) is a complex and devastating illness, often occurring in the setting of sepsis and trauma. Despite recent advances in the understanding and treatment of ALI, pathogenic mechanisms and genetic modifiers in ALI remain incompletely understood. Furthermore, there has been increasing interest in the identification of genetic variations that contribute to ALI susceptibility and severity in order to gain unique insights into ALI pathogenesis and to design novel treatment strategies. However, the sporadic nature of ALI and the lack of family-based cohort studies preclude conventional genomic approaches such as linkage mapping (or "positional cloning"). We have used a "candidate gene approach" with extensive gene expression profiling studies in animal (rat, murine, canine) and human models of ALI to identify potential ALI candidate genes associated with sepsis and ventilator-associated lung injury. These studies, when combined with innovative in silico bioinformatics approaches, revealed both novel (pre--B-cell colony enhancing factor, myosin light chain kinase) and previously identified (interleukin 6, macrophage migration inhibitory factor) gene candidates. Subsequent single nucleotide polymorphism discovery and genotyping studies revealed polymorphisms that demonstrate an influence on ALI susceptibility in patients. These studies indicate that the candidate gene approach is a robust strategy to provide novel insights into the genetic basis of ALI, and the identification of potentially novel therapeutic targets.

Bioinformatic identification of novel early stress response genes in rodent models of lung injury.

Acute lung injury is a complex illness with a high mortality rate (>30%) and often requires the use of mechanical ventilatory support for respiratory failure. Mechanical ventilation can lead to clinical deterioration due to augmented lung injury in certain patients, suggesting the potential existence of genetic susceptibility to mechanical stretch (6, 48), the nature of which remains unclear. To identify genes affected by ventilator-induced lung injury (VILI), we utilized a bioinformatic-intense candidate gene approach and examined gene expression profiles from rodent VILI models (mouse and rat) using the oligonucleotide microarray platform. To increase statistical power of gene expression analysis, 2,769 mouse/rat orthologous genes identified on RG_U34A and MG_U74Av2 arrays were simultaneously analyzed by significance analysis of microarrays (SAM). This combined ortholog/SAM approach identified 41 up- and 7 downregulated VILI-related candidate genes, results validated by comparable expression levels obtained by either real-time or relative RT-PCR for 15 randomly selected genes. K-mean clustering of 48 VILI-related genes clustered several well-known VILI-associated genes (IL-6, plasminogen activator inhibitor type 1, CCL-2, cyclooxygenase-2) with a number of stress-related genes (Myc, Cyr61, Socs3). The only unannotated member of this cluster (n = 14) was RIKEN_1300002F13 EST, an ortholog of the stress-related Gene33/Mig-6 gene. The further evaluation of this candidate strongly suggested its involvement in development of VILI. We speculate that the ortholog-SAM approach is a useful, time- and resource-efficient tool for identification of candidate genes in a variety of complex disease models such as VILI.