Faculty Bibliography

Background: Lower extremity compression ultrasound (US) for deep venous thrombosis (DVT) assessment by emergency physicians varies in technique and accuracy across published reports. This stems from differences in experience and training as well as paucity of data describing the minimal components needed to perform an accurate exam. Furthermore, no data exists describing emergency physician agreement during formal DVT ultrasound reviews. Emergency physician reviewer agreement is critical to developing a universal, standardized, and accurate approach to lower extremity compression US in the emergency department (ED). Study Objectives: This study evaluates agreement between expert sonographer reviewers in each component of the lower extremity compression US performed at our institution. We hypothesized emergency physician expert reviewers will strongly agree on all components of the review process. Methods: This is a prospective, observational study of ED patients at an urban, academic ED. Adult patients receiving an ED lower extremity compression ultrasound for DVT assessment prior to any other imaging study for DVT assessment were eligible. Enrollment was based on a convenience sample. Lower extremity compression US was performed by the treating physician per our departmental standard method: incremental compression and evaluation for complete coaptation of deep veins are performed from the common femoral vein and saphenous vein junction terminating ten centimeters distal over thigh, and again starting at the popliteal vein (PV) and terminating at the PV trifurcation. Data to calculate a Wells DVT score was also collected. ED lower extremity compression US studies were later evaluated by two of three expert ultrasound reviewers using a checklist of predetermined critical components (Table 1). These components were based on a literature review of exam elements thought to be valuable for DVT assessment and are included in our standard review process. Each category was judged as either present or !

We investigated the folding of rectangular stimuli-responsive hydrogel-based polymer bilayers with different aspect ratios and relative thicknesses placed on a substrate. It was found that long-side rolling dominates at high aspect ratios (ratio of length to width) when the width is comparable to the circumference of the formed tubes, which corresponds to a small actuation strain. Rolling from all sides occurs for higher actuation, namely when the width and length considerably exceed the deformed circumference. In the case of moderate actuation, when both the width and length are comparable to the deformed circumference, diagonal rolling is observed. Short-side rolling was observed very rarely and in combination with diagonal rolling. On the basis of experimental observations, finite-element modeling and energetic considerations, we argued that bilayers placed on a substrate start to roll from corners due to quicker diffusion of water. Rolling from the long-side starts later but dominates at high aspect ratios, in agreement with energetic considerations. We have shown experimentally and by modeling that the main reasons causing a variety of rolling scenarios are (i) non-homogenous swelling due to the presence of the substrate and (ii) adhesion of the polymer to the substrate.

We report an approach for the fabrication of fully biodegradable self-rolled tubes based on patterned polysuccinimide/polycaprolactone bilayers. These polymers are biocompatible, biodegradable, produced industrially, and are already approved for biomedical purposes. Both polycaprolactone and polysuccinimide are hydrophobic and intrinsically water-insoluble. Polysuccinimide, however, hydrolyzes in physiological buffer environment yielding water-swellable polyaspartic acid that causes the rolling of the polymer bilayer and formation of tubes. We demonstrate the possibility to encapsulate yeast cells using self-rolled tubes.