Hospitalist Perceptions of Barriers to Lung Ultrasound Adoption in Diverse Hospital Environments.

Despite the many advantages of lung ultrasound (LUS) in the diagnosis and management of patients with dyspnea, its adoption among hospitalists has been slow. We performed semi-structured interviews of hospitals from four diverse health systems in the United States to understand determinants of adoption within a range of clinical settings. We used the diffusion of innovation theory to guide a framework analysis of the data. Of the 27 hospitalists invited, we performed 22 interviews from four hospitals of diverse types. Median years post-residency of interviewees was 10.5 [IQR:5-15]. Four main themes emerged: (1) There are important clinical advantages to LUS despite operator dependence, (2) LUS enhances patient and clinician experience, (3) Investment of clinician time to learn and perform LUS is a barrier to adoption but yields improved efficiency for the health system and (4) Mandated training and use may be necessary to achieve broad adoption as monetary incentives are less effective. Despite the perceived benefits of LUS for patients, clinicians and health systems, a significant barrier to broad LUS adoption is the experience of time scarcity by hospitalists. Future implementation strategies should focus on changes to the clinical environment that address clinician barriers to learning and adoption of new skills.

The potential to improve cell infiltration in composite fiber-aligned electrospun scaffolds by the selective removal of sacrificial fibers.

Aligned electrospun scaffolds are promising tools for engineering fibrous musculoskeletal tissues, as they reproduce the mechanical anisotropy of these tissues and can direct ordered neo-tissue formation. However, these scaffolds suffer from a slow cellular infiltration rate, likely due in part to their dense fiber packing. We hypothesized that cell ingress could be expedited in scaffolds by increasing porosity, while at the same time preserving overall scaffold anisotropy. To test this hypothesis, poly(epsilon-caprolactone) (a slow-degrading polyester) and poly(ethylene oxide) (a water-soluble polymer) were co-electrospun from two separate spinnerets to form dual-polymer composite fiber-aligned scaffolds. Adjusting fabrication parameters produced aligned scaffolds with a full range of sacrificial (PEO) fiber contents. Tensile properties of scaffolds were functions of the ratio of PCL to PEO in the composite scaffolds, and were altered in a predictable fashion with removal of the PEO component. When seeded with mesenchymal stem cells (MSCs), increases in the starting sacrificial fraction (and porosity) improved cell infiltration and distribution after three weeks in culture. In pure PCL scaffolds, cells lined the scaffold periphery, while scaffolds containing >50% sacrificial PEO content had cells present throughout the scaffold. These findings indicate that cell infiltration can be expedited in dense fibrous assemblies with the removal of sacrificial fibers. This strategy may enhance in vitro and in vivo formation and maturation of functional constructs for fibrous tissue engineering.

Association between a quantitative CT scan measure of brain edema and outcome after cardiac arrest.

BACKGROUND: Cerebral edema is one physical change associated with brain injury and decreased survival after cardiac arrest. Edema appears on computed tomography (CT) scan of the brain as decreased X-ray attenuation by gray matter. This study tested whether the gray matter attenuation to white matter attenuation ratio (GWR) was associated with survival and functional recovery. METHODS: Subjects were patients hospitalized after cardiac arrest at a single institution between 1/1/2005 and 7/30/2010. Subjects were included if they had non-traumatic cardiac arrest and a non-contrast CT scan within 24h after cardiac arrest. Attenuation (Hounsfield Units) was measured in gray matter (caudate nucleus, putamen, thalamus, and cortex) and in white matter (internal capsule, corpus callosum and centrum semiovale). The GWR was calculated for basal ganglia and cerebrum. Outcomes included survival and functional status at hospital discharge. RESULTS: For 680 patients, 258 CT scans were available, but 18 were excluded because of hemorrhage (10), intravenous contrast (3) or technical artifact (5), leaving 240 CT scans for analysis. Lower GWR values were associated with lower initial Glasgow Coma Scale motor score. Overall survival was 36%, but decreased with decreasing GWR. The average of basal ganglia and cerebrum GWR provided the best discrimination. Only 2/58 subjects with average GWR<1.20 survived and both were treated with hypothermia. The association of GWR with functional outcome was completely explained by mortality when GWR<1.20. CONCLUSIONS: Subjects with severe cerebral edema, defined by GWR<1.20, have very low survival with conventional care, including hypothermia. GWR estimates pre-treatment likelihood of survival after cardiac arrest.

Electrospun fibrous scaffolds with multiscale and photopatterned porosity.

The structural and mechanical properties of tissue engineered environments are crucial for successful cellular growth and tissue repair. Electrospinning is gaining wide attention for the fabrication of tissue engineered scaffolds, but the small pore sizes of these scaffolds limit cell infiltration and construct vascularization. To address this problem, we have combined electrospinning with photopatterning to create multiscale porous scaffolds. This process retains the fibrous nature of the scaffolds and permits enhanced cellular infiltration and vascularization when compared to unpatterned scaffolds. This is the first time that photopatterning has been utilized with electrospun scaffolds and is only now possible with the electrospinning of reactive macromers.

Biodegradable fibrous scaffolds with diverse properties by electrospinning candidates from a combinatorial macromer library.

The properties of electrospun fibrous scaffolds, including degradation, mechanics and cellular interactions, are important for their use in tissue engineering applications. Although some diversity has been obtained previously in fibrous scaffolds, optimization of scaffold properties relies on iterative techniques in both polymer synthesis and processing. Here, we electrospun candidates from a combinatorial library of biodegradable and photopolymerizable poly(beta-amino ester)s (PBAEs) to show that the diversity in properties found in this library is retained when processed into fibrous scaffolds. Specifically, three PBAE macromers were electrospun into scaffolds and possessed similar initial mechanical properties, but exhibited mass loss ranging from rapid (complete degradation within approximately 2 weeks) to moderate (complete degradation within approximately 3 months) to slow (only partial degradation after 3 months). These trends in mechanics and degradation mimicked what was previously observed in the bulk polymers. Although cellular adhesion was dependent on the polymer composition in films, adhesion to scaffolds that were electrospun with gelatin was similar on all formulations and controls. To further illustrate the diverse properties that are attainable in these systems, the fastest and slowest degrading polymers were electrospun together into one scaffold, but as distinct fiber populations. This dual-polymer scaffold exhibited behavior in mass loss and mechanics with time that fell between the single-polymer scaffolds. In general, this work indicates that combinatorial libraries may be an important source of information and specific polymer compositions for the fabrication of electrospun fibrous scaffolds with tunable properties.

Novel nano-composite biomaterials that respond to light.

Composites of nanoparticles and polymers are finding wide applications to alter material properties, conductivity, and utility. Here, we show that nano-composites can be designed to heat in the presence of near infrared light. This process is useful in transitioning materials through a transition temperature for a range of applications. For example, shape-memory materials (including polymers, metals, and ceramics) are those that are processed into a temporary shape and respond to some external stimuli (e.g., temperature) to undergo a transition back to a permanent shape and may be useful in a range of applications from aerospace to fabrics, to biomedical devices and microsystem components. In this work, we formulated composites of gold nanorods (<1% by volume) and biodegradable networks, where exposure to infrared light induced heating and consequently, shape transitions. The heating is repeatable and tunable based on nanorod concentration and light intensity.