Accepted Manuscripts

Tabitha H.T. Teo, Ajay Ramani, Paul Munden, Sara Wilson, Sarah Kieweg and Dr. Ronald L. Dougherty
ASME J of Medical Diagnostics   doi: 10.1115/1.4040498
Treatment of vision-threating elevated intraocular pressure (IOP) for severe glaucoma may require glaucoma drainage device (GDD) implantation to shunt aqueous humor from the eye's anterior chamber and lower IOP to acceptable levels of 8-21 mm Hg. Non-valved GDDs (NVGDDs) cannot maintain IOP in that acceptable range during the early post-operative period; and require intra-operative modifications during the first 30 days after surgery. Other GDDs have valves to overcome this issue, but are less successful with maintaining long-term IOP. Our research goal is to improve NVGDD post-operative performance. Little rigorous research has been done to systematically analyze NVGDDs flow/pressure characteristics. We describe a system developed to assess the pressure drop for physiologic flow rates through NVGDD-like microtubes of various lengths/diameters. Experimental pressures for flow through hollow microtubes are near predictive theory's lower limit. A 50.4 micron inner diameter microtube yields a 35.1 mm Hg experimental pressure, while theory predicts 35.6-55.5 mm Hg. An annular example, 358.8 micron outside and 330.7 micron inside diameters, yields a 9.6 mm Hg experimental pressure, within theoretical predictions of 4.2-19.2 mm Hg. These results are repeatably consistent over 25 days, which fits the 20-35 day period needed for scar tissue formation to achieve long-term IOP control. Future efforts will use this validated experimental setup, corroborated by theory, to study the performance of various insert sizes, dissolving inserts, and drug eluding inserts.
TOPICS: Flow (Dynamics), Drainage, Pressure, Biological tissues, Surgery, Valves, Drugs, Pressure drop, Physiology
Houzhu Ding and Robert Chang
ASME J of Medical Diagnostics   doi: 10.1115/1.4040470
Skin thermal burn wounds are classified according to subjective assessments of wound depth that indicate divergent modes of medical intervention. However, clinically discriminating superficial partial from deep partial thickness burns remains a significant challenge, where only the latter requires excision and skin grafting. Motivated by the need for and ramifications of an objective burn wound assessment tool, this paper advances hyperspectral imaging (HSI) in a porcine skin burn model to quantitatively evaluate thermal burn injuries (superficial and deep partial thickness burns). Two-dimensional principal component analysis (2DPCA) for noise reduction is applied to images captured by HSI in the visible wavelength range. Herein, a multivariate regression analysis is used to calculate the total hemoglobin concentration (tHb) and the oxygen saturation (StO2) of the injured tissue. These perfusion profiles are spatially mapped to yield characteristic distributions corresponding to the burn wound degree validated histologically. The results demonstrate that StO2 and tHb diverge significantly for superficial partial and deep partial burns at 24 hr and 1 hr, respectively (p<0.05). A StO2 burn map at 1 hr post-burn yields a 2D burn contour that is registered with a burn color image. This early-stage burn-specific contour has implications to guide downstream burn excision and grafting.
TOPICS: Imaging, Skin, Wounds, Biomedicine, Noise control, Visible spectrum, Biological tissues, Oxygen, Principal component analysis, Regression analysis

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