Tissue Oximeter with Selectable Measurement Depth Using Spatially Resolved Near-Infrared Spectroscopy

Tissue oxygenation sensing at a few millimeters deep is useful for surgical and postoperative management. However, the measurement sensitivity at each depth and the proper sensor combination have not been clarified. Here, the measurement characteristics of oximetry by spatially resolved near-infrared spectroscopy were analyzed using Monte Carlo simulation and phantom experiment. From summing the sensitivities of each depth, it was quantitatively found that the measurement sensitivity curve had a peak, and the measurement depth can be adjusted by combining the two distances between the light source and the detector. Furthermore, the gastric tissue was 10–20% smaller in terms of measurement depth than the skin-subcutaneous tissue. A miniaturized oximeter was prototyped so that it could be used in combination with an endoscope or laparoscope. The optical probes consisted of light emitting diodes with wavelengths of 770 nm and 830 nm and photodetectors located 3 to 30 mm from the light source. Phantom experiments using the probes demonstrated the tendency of theoretical analysis. These results suggest the possibility of measuring tissue oxygen saturation with a selectable measurement depth. This selectable method will be useful for obtaining oxygenation information at a depth of 2–5 mm, which is difficult to measure using only laparoscopic surface imaging.

An Investigation of the Mechanisms Involved in Plate Load Testing in Rock

Accurate determination of rock mass deformation modulus is very important in rock engineering projects. The plate loading test (PLT) is a method that is generally used in dam construction projects to determine rock mass modulus. Numerical simulation was used to investigate the mechanisms involved in this test. The first objective of the paper was to employ 3D modeling in the interpretation of plate load tests conducted at the Bazoft dam site in Iran. Additionally, a parametric study of the effects of key parameters such as displacement measuring depth and loading plate diameter on the test results was another objective of the study. The moduli values determined numerically were compared against actual filed testing data determined from in-situ test data conducted at the Bazoft dam site, and the values determined from the ISRM suggested formula. The analysis showed that the optimum measurement depth for rock mass modulus calculation is approximately equal to the loading plate diameter and the data determined from measurement depths beyond one plate diameter can be unrealistic. Moreover, the plate diameter can have a significant effect on test results. As the measurement depth increases, the determined modulus values increase at a much more rapid pace when employing smaller size loading plates.

Abstract 255: A Novel and Accurate Method for Assessing Recoil During CPR Training

Introduction: In addition to accurate measurement depth and rate of each compression, accurate measurement of full recoil, after each compression, is mandatory for the CPR training. Permitting complete chest recoil during the decompression phase of CPR is essential for refilling the lungs and for adequate myocardial perfusion. Complete chest recoil is important but not evaluated during CPR training. Currently, the recoil is measured based on the residual force when the rescuer releases the hands. Recent clinical research shows the recoil measurements need to consider the release time, release velocity and release height. Hypothesis: With a commercially available smartphone providing real-time feedback (placed on an armband of the subjects), trainees will improve recoil performance using proper release velocity, release time and release height. Methods: Using a previously validated smartphone application utilizing the smartphone’s accelerometer, gyroscope and magnetometer, we measured these 3 variables. Total of ten sessions was recorded. Each individual CPR session was recorded in the application (acceleration streams, detected pumps with annotations, and the generated feedback). Audio and visual feedback was provided about the measured depth, rate, and recoil quality. Each session has 30 CPR pumps. The scripted patterns consisted of alternating (recoil on and off) window lengths of either 5 or 10 pumps, and the patterns varied between sessions. Recoil was considered to be good if releases velocity is >= 400mm/sec and release time is <=120ms and release height is >= 2 inches. Results: Using the output of a bayesNet classifier on the manually-annotated dataset, 84% true positives (success) was achieved for all the three metrics. Conclusions: With guided feedback recoil efficiency improved.

FACTORS AFFECTING INTERPRETATION OF TISSUE DIELECTRIC CONSTANT (TDC) IN ASSESSING BREAST CANCER TREATMENT RELATED LYMPHEDEMA (BCRL)

Tissue dielectric constant (TDC) measurements are increasingly used as quantitative adjunctive tools to detect and assess lymphedema. Various factors affect measured TDC values that may impact clinical interpretations. Our goal was to investigate possible impacts of: 1) anterior vs. medial arm measures, 2) total body water (TBW%) and arm fat percentages (AF%), 3) measurement depth, and 4) skin firmness. In 40 healthy women (24.5±2.5 years), TDC was measured bilaterally on anterior forearm to 0.5, 1.5, 2.5, and 5.0 mm depths using a multiprobe device and on anterior and medial aspects using a compact device. TBW% and AF% were measured at 50KHz and skin firmness measured by skin indentation force (SIF). Results showed: 1) No statistically significant difference in TDC values between anterior and medial arm, 2) a moderate direct correlation between TDC and TBW% (r=0.512, p=0.001), 3) an inverse correlation between TDC and AF% (r= -0.494, p&lt;0.001) with correlations greatest at the deepest depth, and 4) a slight but statistically significant inverse correlation between TDC and SIF (r= -0.354, p=0.001). TDC values with compact vs. multiprobe were within 6% of each other with interarm (dominant/nondominant) ratios not significantly different. The findings provide a framework to help interpret TDC values among divergent conditions.

KARAKTERISTIK KEMIRINGAN LERENG, KEDALAMAN DAN KECERAHAN DALAM MENDUKUNG AKTIVITAS PERMANDIAN DI PANTAI MARUMASA KECAMATAN BONTOBAHASI KABUPATEN BULUKUMBA

This study aims to explain the characteristics of the slope, depth, and brightness, as supporting activities on the Marumasa beach, Bontobahari sub-district, Bulukumba district. This type of research is a survey research, with variable slope, depth and brightness of Marumasa coastal waters. Primary data in the form of direct measurement data in the field, and secondary data in the form of the Earth Map of Bulukumba Regency, Tanah Beru sheet, Sheet 2110-14 The results showed that Marumasa Beach has various slopes, the lowest slope with type I class or flat is between (0-2%) covering 1.17 hectares with a percentage of 45.88%, slope with type II class or sloping that is between (3 -8%) area of 0.73 hectares with a percentage of 28.63%, slope with type III class or sloping that is between (9-25%) area of 0.52 hectares with percentage of 20.39% and highest slope with type class IV or steep (26-40%) area of 0.13 hectares with a percentage of 5.10%. The results of the measurement of the depth value that has been corrected with the MSL value that is at the deepest A2 point, from the measurement results in the field has obtained the depth of the A2 point about 0.12 m and the lowest point is at point C1 with a measurement depth of 0.29 m with a correction value 0.10 m. The results of the measurement of the waters brightness at Marumasa Beach showed that the brightness value was 100% from all observation points. Marumasa beach characteristics are in the category S = very suitable (highly suitable) to be used as beach tourism (beach bathing).

Sensitivity of lightweight deflectometer deflections to layer stiffness via finite element analysis

A dynamic finite element (FE) model of lightweight deflectometer (LWD) loading on a two-layer soil system, validated with an analytical solution and experimental data, is presented. Peak dynamic FE vertical deflections can be substantially different (almost always smaller) than FE static deflections. The numerically simulated measurement depth of the LWD center sensor is found to be 2–2.5 times the plate diameter, deeper than other experimental studies. Using the FE model, we conduct a sensitivity analysis of peak vertical deflections to the top layer Young’s modulus and underlying Young’s modulus of two-layer systems. Peak deflections from the center sensor are found to be more sensitive to the top layer Young’s modulus while peak deflections at radial offsets are found to be more sensitive to the underlying layer Young’s modulus. Sensitivities of layer moduli to FE deflections offer guidance in selecting weighting factors for the inverse solver in an LWD back-calculation procedure.