Fixed, Dilated, and Cannulated - Medical Management of Elevated Intracranial Pressures due to a Large Intracranial Hemorrhage in a Patient on Veno-Venous Extracorporeal Membrane Oxygenation: Case Report

A 40-year-old woman presented with mediastinitis, necrotizing pancreatitis, and severe acute respiratory distress syndrome with refractory acidemia (pH 7.14) and hypercapnia (PaCO2 115 mmHg), requiring veno-venous extracorporeal membrane oxygenation (ECMO). Eight hours after cannulation, and rapid correction of PaCO2 to 44 mmHg, she was found to have bilaterally fixed and dilated pupils. Imaging showed a 60 mL left-sided temporoparietal intracranial hemorrhage with surrounding edema, 8 mm midline shift, intraventricular hemorrhage, and impending herniation. Decompressive hemicraniectomy was not offered due to concern for medical instability. After receiving a dose of mannitol, her pupillary and motor exam improved. An intracranial pressure (ICP) monitor was placed to guide hyperosmolar therapy administration, hemodynamic targets, and sweep gas titration. On hospital day (HD) 5, her ICP monitor was removed. Follow-up imaging revealed resolution of mass effect and no brainstem injury. She was subsequently extubated (HD 9) and discharged home (HD 40). One year after hospitalization, she is living at home with minimal residual deficits. This case highlights the utility of targeted, medical ICP management and importance of assessing response to conservative therapies when considering prognosis in patients on ECMO with severe acute brain injury.

Recent advances in nontuberculous mycobacterial lung infections

Nontuberculous mycobacteria (NTM) are members of the Mycobacterium genus other than Mycobacterium tuberculosis complex and Mycobacterium leprae. NTM are widely distributed in the environment and are increasingly recognized as causes of chronic lung disease that can be challenging to treat. In this brief review, we consider recent developments in the ecology, epidemiology, natural history, and treatment of NTM lung disease with a focus on Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex .

Syndecan-4 regulates early neutrophil migration and pulmonary inflammation in response to lipopolysaccharide

Proteoglycans (PGs) and their associated glycosaminoglycan side chains are effectors of inflammation, but little is known about changes to the composition of PGs in response to lung infection or injury. The goals of this study were to identify changes to heparan sulfate PGs in a mouse model of gram-negative pneumonia, to identify the Toll-like receptor adaptor molecules responsible for these changes, and to determine the role of the heparan sulfate PG in the innate immune response in the lungs. We treated mice with intratracheal LPS, a component of the cell wall of gram-negative bacteria, to model gram-negative pneumonia. Mice treated with intratracheal LPS had a rapid and selective increase in syndecan-4 mRNA that was regulated through MyD88-dependent mechanisms, whereas expression of several other PGs was not affected. To determine the role of syndecan-4 in the inflammatory response, we exposed mice deficient in syndecan-4 to LPS and found a significant increase in neutrophil numbers and amounts of CXC-chemokines and total protein in bronchoalveolar lavage fluid. In studies performed in vitro, macrophages and epithelial cells treated with LPS had increased expression of syndecan-4. Studies performed using BEAS-2B cells showed that pretreatment with heparin and syndecan-4 decreased the expression of CXCL8 mRNA in response to LPS and TNF-α. These findings indicate that the early inflammatory response to LPS involves marked up-regulation of syndecan-4, which functions to limit the extent of pulmonary inflammation and lung injury.

CD180 restricts replication of Legionella pneumophila in macropahges and is associated with susceptibility to Legionnaire’s Disease (110.25)

Legionella pneumophila (Lp) is a gram-negative bacterium that opportunistically infects the human alveoloar macrophage to cause a pneumonic illness known as Legionnaire’s Disease (LD). The role of CD180 (RP105), a non-signalling member of the TLR family that regulates TLR2 and TLR4 function, in Lp pathogenesis is unknown. We hypothesized that CD180 regulates susceptibility to Lp infection in mice and humans. We infected bone-marrow derived macrophages with Lp (Lp02 strain) and observed greater replication (~2-3-fold) in Cd180-/- mice compared to C57Bl/6 controls. This difference was present over a range of MOIs (0.1 to 2.0) at 24, 48, and 72 hours after infection. Enhanced replication of Lp in Cd180-/- macrophages was not associated with increased pyroptotic cell death, as assessed by IL-1β or LDH, or alterations in key innate immune cytokines or effectors, such as IL-6, TNF, or nitric oxide. We next examined whether CD180 polymorphisms were associated with LD with a study of 108 cases and 508 controls in the Netherlands. Four SNPs, rs574464, rs1428469, rs1697143, and rs1803440, were associated with protection from LD, with ODs ranging from 0.27-0.50 (p values: 0.005-0.045, analysis with dominant genetic model). The functional effects of these polymorphisms and the mechanism of CD180 regulation of Lp replication in macrophages are currently being examined. Together, these results suggest that CD180 critically mediates the immune response to Lp in mice and humans.

Differentiation of gram-negative bacterial aerosol exposure using detected markers in bronchial-alveolar lavage fluid

The identification of biosignatures of aerosol exposure to pathogens has the potential to provide useful diagnostic information. In particular, markers of exposure to different types of respiratory pathogens may yield diverse sets of markers that can be used to differentiate exposure. We examine a mouse model of aerosol exposure to known Gram negative bacterial pathogens, Francisella tularensis novicida and Pseudomonas aeruginosa. Mice were subjected to either a pathogen or control exposure and bronchial alveolar lavage fluid (BALF) was collected at four and twenty four hours post exposure. Small protein and peptide markers within the BALF were detected by matrix assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and analyzed using both exploratory and predictive data analysis methods; principle component analysis and degree of association. The markers detected were successfully used to accurately identify the four hour exposed samples from the control samples. This report demonstrates the potential for small protein and peptide marker profiles to identify aerosol exposure in a short post-exposure time frame.

Clinical features and analysis of risk factors for invasive candidal infection after marrow transplantation

Of 1506 marrow transplant patients from 1980 through 1986 reviewed for risk factors for invasive candidal infection defined by positive blood cultures, biopsy, or histologic evidence of tissue invasion, 171 (11.4%) had invasive infection, with a significantly higher incidence in the more recent years of review; 40% (69 patients) had evidence of tissue-invasive disease without fungemia. Of 102 patients with fungemia, 45% had candidemia alone with a mortality of 39%. Mortality in patients with tissue involvement was 90% with or without fungemia. Factors that increased infection were age, acute graft-versus-host disease, and donor mismatch. Factors that decreased infection included conditioning with 12 Gy of fractionated irradiation and cyclophosphamide, transplantation for aplastic anemia, and more rapid engraftment. Among fungemic patients, the number of days of fungemia was a risk factor for tissue invasion while more rapid engraftment was protective.