[Show abstract][Hide abstract] ABSTRACT: Pulsed ultrasound was found to induce pulmonary capillary hemorrhage (PCH) in mice about 25 years ago but remains a poorly understood risk factor for pulmonary diagnostic ultrasound. In early research using laboratory fixed beam ultrasound, thresholds for PCH had frequency variation from 1-4MHz similar to the Mechanical Index. In recent research, thresholds for B mode diagnostic ultrasound from 1.5-12MHz had little dependence on frequency. To compare the diagnostic ultrasound method to laboratory pulsed exposure, thresholds for fixed beam ultrasound were determined using comparable methods at 1.5 and 7.5MHz. PCH thresholds were lower for simple fixed-beam pulse modes than for B mode and in approximate agreement with early research. However, for comparable timing parameters, PCH thresholds had little dependence on ultrasonic frequency. These findings suggest that the MI may not be directly useful as a dosimetric parameter for safety guidance in pulmonary ultrasound.
[Show abstract][Hide abstract] ABSTRACT: Background:
The Michigan Trauma Quality Improvement Program (MTQIP) is a collaborative quality initiative sponsored by Blue Cross Blue Shield of Michigan and Blue Care Network (BCBSM/BCN). The MTQIP benchmark reports identified our trauma center as a high outlier for venous thromboembolism (VTE) episodes. This study outlines the performance improvement (PI) process used to reduce the rate of VTE using MTQIP infrastructure.
Trauma patients admitted for > 24 hours, with an Injury Severity Score (ISS) ≥ 5, were included in this study. We performed a preliminary analysis examining prophylaxis drug type to VTE, adjusted by patient confounders and timing of first dose, using MTQIP data abstracted for our hospital. It showed that patients receiving enoxaparin had a VTE rate that was half that of those receiving unfractionated heparin (odds ratio 0.46, 95% CI 0.25 to 0.85). Guided by these results, we produced the following plan: consolidation to single VTE prophylaxis agent and dose, focused education of providers, initiation of VTE prophylaxis for all patients-with clear exception rules-and dose withholding minimization. Results were monitored using the MTQIP platform.
After implementation of our focused PI plan, the VTE rate decreased from 6.2% (n = 36/year) to 2.6% (n = 14/year). Our trauma center returned to average performance status within MTQIP.
Participation in MTQIP provided identification of trauma center outlier status for the outcome of VTE. Analysis of MTQIP data allowed creation of a local action plan. The MTQIP infrastructure supported execution and monitoring of the action plan consistent with loop-closure practices, as advocated by the American College of Surgeons Committee on Trauma, and a positive performance improvement result was achieved with VTE reduction.
Journal of the American College of Surgeons 08/2015; 221(3):661-8. DOI:10.1016/j.jamcollsurg.2015.05.006 · 5.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The usual duration of ECMO in patients with severe acute respiratory distress syndrome (ARDS) is 7-10 days. Prolonged duration ECMO (defined as > 14 days) is increasingly being documented with native lung recovery or as a bridge to lung transplantation. We report a case of prolonged duration ECMO (6,364 hours, 265 days) requiring no complete circuit exchange. As critical care improves, prolonged ECMO will continue to pose unique technological and ethical challenges that test our expectations of this treatment modality. There is a critical need for diagnostic modalities to provide objective assessment of native lung recovery in patients requiring prolonged duration ECMO.
ASAIO journal (American Society for Artificial Internal Organs: 1992) 11/2014; 61(2). DOI:10.1097/MAT.0000000000000181 · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
Lung contusion is a major risk factor for the development of acute respiratory distress syndrome. Hypoxia-inducible factor-1α is the primary transcription factor that is responsible for regulating the cellular response to changes in oxygen tension. We set to determine if hypoxia-inducible factor-1α plays a role in the pathogenesis of acute inflammatory response and injury in lung contusion.
Nonlethal closed-chest unilateral lung contusion was induced in a hypoxia reporter mouse model and type 2 cell-specific hypoxia-inducible factor-1α conditional knockout mice. The mice were killed at 5-, 24-, 48-, and 72-hour time points, and the extent of systemic and tissue hypoxia was assessed. In addition, injury and inflammation were assessed by measuring bronchoalveolar lavage cells (flow cytometry and cytospin), albumin (permeability injury), and cytokines (inflammation). Isolated type 2 cells from the hypoxia-inducible factor-1α conditional knockout mice were isolated and evaluated for proinflammatory cytokines following lung contusion. Finally, the role of nuclear factor-κB and interleukin-1β as intermediates in this interaction was studied.
Lung contusion induced profound global hypoxia rapidly. Increased expression of hypoxia-inducible factor-1α from lung samples was observed as early as 60 minutes, following the insult. The extent of lung injury following lung contusion was significantly reduced in conditional knockout mice at all the time points, when compared with the wild-type littermate mice. Release of proinflammatory cytokines, such as interleukin-1β, interleukin-6, macrophage inflammatory protein-2, and keratinocyte chemoattractant, was significantly lower in conditional knockout mice. These actions are in part mediated through nuclear factor-κB. Hypoxia-inducible factor-1α in lung epithelial cells was shown to regulate interleukin-1β promoter activity.
Activation of hypoxia-inducible factor-1α in type 2 cell is a major driver of acute inflammation following lung contusion.
Critical Care Medicine 07/2014; DOI:10.1097/CCM.0000000000000488 · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pulmonary aspiration is an important recognized cause of acute respiratory distress syndrome (ARDS). Better characterization of patients who aspirate may allow identification of potential risks for aspiration that could be used in future studies to mitigate the occurrence of aspiration and its devastating complications.
We conducted a secondary analysis of the Lung Injury Prediction Score (LIPS) cohort to better characterize patients with aspiration, including their potential risk factors and related outcomes.
Of the 5584 subjects at risk for ARDS and required hospitalization, 212 (3.8%) presented with aspiration. Subjects who aspirated were likely to be male (66% vs. 56%, p<0.007), slightly older (59 vs. 57years), Caucasian (73% vs. 61%, p=0.0004), admitted from a nursing-home (15% vs. 5.9%, p<0.0001), have a history of alcohol abuse (21% vs. 8%, p<0.0001) and have lower Glasgow Coma Scale (median 13 vs. 15, p<0.0001). Aspiration subjects were sicker (higher APACHE2), required more mechanical ventilation (54% vs. 32%, p<0.0001), developed more moderate-to-severe ARDS (12% vs. 3.8%, p<0.0001), and were two-fold more likely to die in-hospital, even after adjustment for severity of illness (OR=2.1; 95%CI: 1.2-3.6). Neither obesity nor gastroesophageal-reflux was associated with aspiration.
Aspiration was more common in men, with alcohol abuse history, a lower GCS, and when admitted from a nursing home. It is independently associated with a significant increase in the risk for ARDS as well as morbidity and mortality. Findings from this study may facilitate the design of future clinical studies of aspiration-induced lung injury.
[Show abstract][Hide abstract] ABSTRACT: Routine pulmonary ultrasound for diagnosis of disease or injury relies on interpretation of image features, such as comet-tail artifacts, which can also be indicative of the poorly understood phenomenon of ultrasound-induced pulmonary capillary hemorrhage (PCH). Evans blue extraction and bronchoalveolar lavage (BAL) were evaluated for assessment of PCH induced by ultrasound scanning. Rats anesthetized with ketamine with or without xylazine received sham or scanning for 5 min with a 7.6 MHz linear array. Evans blue extraction and BAL albumin measurements failed to demonstrate significant increases for scanning, even though the induction of comet-tail artifacts was significant. BAL cell counts had an insignificant increase relative to shams at a near-threshold Mechanical Index (MI) of 0.52 (P = 0.07), but a highly significant increase at MI = 0.9 (P = 0.001). The possibility of xylazine-induced elevated albumin was tested, but no significant decrease was found for sham or scanned rats with ketamine-only anesthesia. Interestingly, without xylazine, the widths of comet-tail artifacts in the ultrasound images were significantly smaller (P = 0.001) and cell counts in BAL fluid also were reduced (P = 0.014). The BAL cell-count method provides a valuable additional means of PCH quantification.
Microvascular Research 05/2014; 93. DOI:10.1016/j.mvr.2014.02.006 · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lung contusion (LC) is a common injury resulting from blunt thoracic trauma. LC is an important risk factor for the development acute lung injury, adult respiratory distress syndrome, and ventilator-associated pneumonia, all of which increase mortality from trauma. LC produces a nonspecific immune cellular response. Neutrophil recruitment is known to increase the severity of inflammation during LC. However, the exact role of macrophages in modulating the response to LC has not been well described.
We used a cortical contusion impactor to induce unilateral LC in mice. Thoracic micro computed tomographic scans of these animals were obtained to document radiologic changes over time following LC. To understand the role of macrophages during LC, liposomal clodronate was used to deplete macrophage levels before traumatic insult. Acute inflammatory attributes after LC were assessed, by measuring pressure-volume mechanics; quantifying bronchial alveolar lavage levels of leukocytes, albumin, and cytokines; and finally examining lung specimen histopathology at 5, 24, 48, and 72 hours after injury.
After LC, alveolar macrophage numbers were significantly reduced and exhibited slowed recovery. Simultaneously, there was a significant increase in bronchial alveolar lavage neutrophil counts. The loss of macrophages could be attributed to both cellular apoptosis and necrosis. Pretreatment with clodronate increased the severity of lung inflammation as measured by worsened pulmonary compliance, increased lung permeability, amplification of neutrophil recruitment, and increases in early proinflammatory cytokine levels.
The presence of regulatory alveolar macrophages plays an important role in the pathogenesis of acute inflammation following LC.
[Show abstract][Hide abstract] ABSTRACT: Several of the biological processes involved in the pathogenesis of acute lung injury and acute respiratory distress syndrome after lung contusion are regulated at a genetic and epigenetic level. Thus, strategies to manipulate gene expression in this context are highly desirable not only to elucidate the mechanisms involved but also to look for potential therapies. In the present chapter, we describe mouse and rat models of inducing blunt thoracic injury followed by electroporation-mediated gene delivery to the lung. Electroporation is a highly efficient and easily reproducible technique that allows circumvention of several of lung gene delivery challenges and safety issues present with other forms of lung gene therapy.
[Show abstract][Hide abstract] ABSTRACT: Lung contusion injury produces a vulnerable window within the inflammatory defenses of the lung that predisposes the patient to pneumonia. IL-10 is a known anti-inflammatory mediator produced by macrophages and capable of down-regulating acute lung inflammation. We investigated the impact of increased levels of IL-10 within the lung on survival and the host response to trauma in the setting of lung contusion and Gram-negative pneumonia.
A bi-transgenic, tetracycline inducible, lung specific human IL-10 overexpression (IL-10 OE) mouse model and single transgenic (TG-) control mice were used. Mice underwent lung contusion injury (LC) or sham injury (Sham) at time -6 hrs. At time 0 animals were inoculated intratracheally with 500 CFU of Klebsiella pneumoniae (Pneu). Bronchoalveolar lavage fluid (BAL), lung tissue specimens, or purified macrophages were collected. Lung tissue and blood bacteria levels were quantified. Cytokine levels were assayed by ELISA and gene expression levels were evaluated by real time PCR. Cell type identification and quantification was done using real time PCR and flow cytometry.
IL-10 OE mice demonstrated decreased 5 day survival compared to TG- mice following LC+Pneu (0 vs. 30%, p<0.0001). IL-10 OE mice had significantly higher lung bacteria counts (p=0.02) and levels of bacteremia (p=0.001) at 24 hrs. The IL-10 OE mice recruited more neutrophils into the alveoli as measured in BAL fluid compared to TG- mice. Alveolar macrophages from IL-10 OE mice displayed increased alternative activation (M2 macrophages, p=0.046) whereas macrophages from TG- mice exhibited classical activation (M1 macrophages) and much higher intracellular bacterial killing potential (p=0.03). IL-6, KC, and MIP-2 levels were significantly elevated in IL-10 OE LC+Pneu animals (p<0.05).
Lung specific IL-10 over expression induces alternative activation of alveolar macrophages. This shift in macrophage phenotype decreases intracellular bacterial killing, resulting in a more pronounced bacteremia and accelerated mortality in a model of lung contusion and pneumonia.
[Show abstract][Hide abstract] ABSTRACT: Cholesterol synthesis is a highly oxygen dependent process. Paradoxically, hypoxia is correlated with an increase in cellular and systemic cholesterol levels and risk of cardiovascular diseases. The mechanism for the increase in cholesterol during hypoxia is unclear. Hypoxia signaling is mediated through hypoxia-inducible factor (HIF)-1α and HIF-2α. The present study demonstrates that activation of HIF signaling in the liver increases hepatic and systemic cholesterol levels due to a decrease in the expression of cholesterol hydroxylases CYP7A1 and other enzymes involved in bile acid synthesis. Specifically, activation of hepatic HIF-2α (but not HIF-1α) led to hypercholesterolemia. HIF-2α repressed the circadian expression of Rev-erbα resulting in increased expression of E4BP4, a negative regulator of Cyp7a1. To understand if HIF-mediated decrease in bile acid synthesis is a physiological relevant pathway by which hypoxia maintains or increases systemic cholesterol levels, two hypoxic mouse models were assessed; an acute lung injury model and mice exposed to 10% O2 for three weeks. In both the models cholesterol levels increased with a concomitant decrease in expression of genes involved in bile acid synthesis. The present study demonstrates that hypoxic activation of hepatic HIF-2α leads to an adaptive increase in cholesterol levels through inhibition of bile acid synthesis.
[Show abstract][Hide abstract] ABSTRACT: Lung contusion (LC) is a unique direct and focal insult that is considered a major risk factor for the initiation of acute lung injury and acute respiratory distress syndrome. We have shown recently that consumption of nitric oxide (due to excess superoxide) resulting in peroxynitrite formation leads to decreased vascular reactivity after LC. In this study, we set out to determine whether the superoxide scavenger Mn (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) plays a protective role in alleviating acute inflammatory response and injury in LC.
Nonlethal, closed-chest, bilateral LC was induced in a rodent model. Administration of the superoxide dismutase mimetic MnTBAP concurrently in LC in rats was performed, and bronchoalveolar lavage (BAL) and lung samples were analyzed for degree of injury and inflammation at 5 and 24 h after the insult. The extent of injury was assessed by the measurement of cells and albumin with cytokine levels in the BAL and lungs. Lung samples were subjected to H&E and superoxide staining with dihydro-ethidium. Protein-bound dityrosine and nitrotyrosine levels were quantified in lung tissue by tandem mass spectrometry.
The degrees of lung injury after LC as determined by BAL albumin levels were significantly decreased in the MnTBAP-administered rats at all the time points when compared to the corresponding controls. The release of proinflammatory cytokines and BAL neutrophils was significantly less in the rats administered MnTBAP after LC. Administration of MnTBAP decreased tissue damage and decreased necrosis and neutrophil-rich exudate at the 24-h time point. Staining for superoxide anions showed significantly greater intensity in the lung samples from the LC group compared to the LC+ MnTBAP group. High-performance liquid chromatography/tandem mass spectrometry revealed that MnTBAP treatment significantly attenuated dityrosine and nitrotyrosine levels, consistent with decreased oxidant injury.
Superoxide dismutase mimetic-MnTBAP reduced permeability and oxidative injury in LC and may have a therapeutic role in diminishing inflammation in LC.
Surgery 11/2013; 154(5):980-90. DOI:10.1016/j.surg.2013.05.023 · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Despite the prevalence of blunt hepatic trauma in humans, there are few rodent models of blunt trauma that can be used to study the associated inflammatory responses. We present a mouse model of blunt hepatic trauma that was created by using a cortical contusion device. Male mice were anesthetized with ketamine-xylazine-buprenorphine and placed in left lateral recumbency. A position of 2 mm ventral to the posterior axillary line and 5 mm caudal to the costal margin on the right side was targeted for impact. An impact velocity of 6 m/s and a piston depth of 12 mm produced a consistent pattern of hepatic injury with low mortality. All mice that recovered from anesthesia survived without complication for the length of the study. Mice were euthanized at various time points (n = 5 per group) until 7 d after injury for gross examination and collection of blood and peritoneal lavage fluids. Some mice were reanesthetized for serial monitoring of hepatic lesions via MRI. At 2 h after trauma, mice consistently displayed laceration, hematoma, and discoloration of the right lateral and caudate liver lobes, with intraabdominal hemorrhage but no other gross injuries. Blood and peritoneal lavage fluid were collected from all mice for cytokine analysis. At 2 h after trauma, there were significant increases in plasma IL10 as well as peritoneal lavage fluid IL6 and CXCL1/KC; however, these levels decreased within 24 h. At 7 d after trauma, the mice had regained body weight, and the hepatic lesions, which initially had increased in size during the first 48 h, had returned to their original size. In summary, this technique produced a reliable, low mortality, murine model that recreates features of blunt abdominal liver injury in human subjects with similar acute inflammatory response.
Comparative medicine 10/2013; 63(5):398-408. · 0.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Acute lung injury (ALI) is associated with high mortality. Low tidal volume (Vt) ventilation has been shown to reduce mortality in ALI patients in the intensive care unit. Anesthesiologists do not routinely provide lung-protective ventilation strategies to patients with ALI in the operating room. The authors hypothesized that an alert, recommending lung-protective ventilation regarding patients with potential ALI, would result in lower Vt administration.
The authors conducted a randomized controlled trial on anesthesia providers caring for patients with potential ALI. Patients with an average or last collected ratio of partial pressure of arterial oxygen to inspired fraction of oxygen less than 300 were randomized to providers being sent an alert with a recommended Vt of 6 cc/kg predicted body weight or conventional care. Primary outcomes were Vt/kg predicted body weight administered to patients. Secondary outcomes included ventilator parameters, length of postoperative ventilation, and death.
The primary outcome was a clinically significant reduction in mean Vt from 508-458 cc (P = 0.033), with a reduction in Vt when measured in cc/kg predicted body weight from 8 to 7.2 cc/kg predicted body weight (P = 0.040). There were no statistically significant changes in other outcomes or adverse events associated with either arm.
Automated alerts generated for patients at risk of having ALI resulted in a statistically significant reduction in Vt administered when compared with a control group. Further research is required to determine whether a reduction in Vt results in decreased mortality and/or postoperative duration of mechanical ventilation.
[Show abstract][Hide abstract] ABSTRACT: Interstitial lung fibrosis can develop as a consequence of occupational or medical exposures, as a result of genetic defects, following trauma or acute lung injury leading to fibroproliferative acute respiratory distress syndrome (ARDS) or can develop in an idiopathic manner. The pathogenesis of each of these forms of lung fibrosis is poorly understood. They each result in progressive loss of lung function with increasing dyspnea and ultimately, most forms result in mortality. To better understand the pathogenesis of lung fibrotic disorders, multiple animal models have been developed. This review summarizes common and emerging models of lung fibrosis to highlight their usefulness for understanding cell-cell and soluble mediator interactions which drive fibrotic responses. Recent advances have allowed for development of models to study targeted injury of type II alveolar epithelial cells, fibroblast autonomous effects and targeted genetic defects. Repetitive dosing in some models has more closely mimicked the pathology of human fibrotic lung disease. We also have a much better understanding of the fact that the aged lung increases susceptibility to fibrosis. Each of these models reviewed in this report offer a powerful tool to study some aspect of fibrotic lung disease.
American Journal of Respiratory Cell and Molecular Biology 03/2013; 49(2). DOI:10.1165/rcmb.2013-0094TR · 3.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: RATIONALE: The mechanisms contributing to hypoxia in lung contusion remain unclear and not temporally associated with the peak onset of acute inflammation. OBJECTIVE: We investigated the role of oxidative stress in alteration of pulmonary arterial (PA) reactivity following LC. Additionally, the role of antioxidants in reversing this process was examined. METHODS: PaO2 and PA reactivity were measured in rats subjected to bilateral LC. Rings were pretreated with a NO synthase (NOS) inhibitor, L-nitro arginine (LNA 10 M) or PEG-superoxide dismutase (SOD) and PEG-catalase (CAT) or both (LNA+SOD/CAT). Rings were constricted with norepinephrine (NE) and relaxed with an NOS agonist (A23187) or NO donor (SNAP). Immunochemical and mass spectrometric quantification for nitrotyrosine were performed. RESULTS: Rats were hypoxemic at 4h post-contusion compared to controls, but recovered by 24h (PaO2/FiO2 ratio: baseline- 443+28, 4h-288+46 and 24h-417+23). PA constriction to NOS inhibition and relaxation to A23187 were impaired 4h after LC. PA relaxation to SNAP was decreased at 4h and 24h after LC. These alterations in PA reactivity were reversed by SOD/CAT pretreatment. SOD1 and 2 mRNA was up-regulated and soluble guanylyl cyclase (sGC) mRNA was down-regulated 24h after LC. IHC and mass spectrometry revealed that levels of 3-nitrotyrosine were increased markedly at 4h following LC consistent with superoxide generation and formation of peroxynitrite. CONCLUSION: Collectively, this data suggests that consumption of NO due to excess superoxide resulting in peroxynitrite formation leads to diminished vascular reactivity following LC.
[Show abstract][Hide abstract] ABSTRACT: Recruitment of neutrophils and release of reactive oxygen species are considered to be major pathogenic components driving acute lung injury (ALI). However, NADPH oxidase, the major source of reactive oxygen species in activated phagocytes, can paradoxically limit inflammation and injury. We hypothesized that NADPH oxidase protects against ALI by limiting neutrophilic inflammation and activating Nrf2, a transcriptional factor that induces antioxidative and cytoprotective pathways. Our objective was to delineate the roles of NADPH oxidase and Nrf2 in modulating acute lung inflammation and injury in clinically relevant models of acute gastric aspiration injury, a major cause of ALI. Acid aspiration caused increased ALI (as assessed by bronchoalveolar lavage fluid albumin concentration) in both NADPH oxidase-deficient mice and Nrf2(-/-) mice compared with wild-type mice. NADPH oxidase reduced airway neutrophil accumulation, but Nrf2 decreased ALI without affecting neutrophil recovery. Acid injury resulted in a 120-fold increase in mitochondrial DNA, a proinflammatory and injurious product of cellular necrosis, in cell-free bronchoalveolar lavage fluid. Pharmacologic activation of Nrf2 by the triterpenoid 1-[2-cyano-3-,12-dioxooleana-1,9 (11)-dien-28-oyl]imidazole limited aspiration-induced ALI in wild-type mice and reduced endothelial cell injury caused by mitochondrial extract-primed human neutrophils, leading to the conclusion that NADPH oxidase and Nrf2 have coordinated, but distinct, functions in modulating inflammation and injury. These results also point to Nrf2 as a therapeutic target to limit ALI by attenuating neutrophil-induced cellular injury.
The Journal of Immunology 01/2013; 190(4). DOI:10.4049/jimmunol.1202410 · 4.92 Impact Factor