Browsing by Subject "Near-infrared spectroscopy"

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    Characterization of the peripheral artery disease symptom experience
    (2013-08) Schorr, Erica Nicole
    Background: Claudication is the most commonly recognized symptom of PAD. It is classically described as an aching, cramping, painful, or tired feeling in the buttock or leg muscles. However, classic claudication is only reported in 7.5% to 33% of patients with PAD. Symptoms beyond classic claudication have been reported and suspected as being part of the symptom experience, but have not been validated as directly relating to changes in calf tissue oxygenation during exercise and subsequent recovery. Objective: The purpose of this study was to characterize the symptom experience of individuals diagnosed with PAD. Specific aims were to: (a) understand the symptom experience of individuals with PAD through in-depth qualitative interviews, and (b) simultaneously evaluate calf tissue oxygenation and self-reported symptoms experienced during treadmill exercise and throughout recovery. Method: Adults experiencing lower extremity symptoms during exercise due to underlying PAD were asked to participate. They were asked to: (a) complete a semi-structured interview to report their symptoms and describe their symptom experience in detail; (b) use a numeric rating scale (NRS) (0 to 5) to rate their symptoms during exercise and recovery; (c) provide descriptions of their symptom(s) during exercise and recovery; and (d) wear a near-infrared spectroscopy device to obtain information on tissue oxygenation during the exercise and recovery phases. Data were analyzed using content analysis, exploration of individual graphical trajectories, grouping trajectories, and multilevel modeling to examine the relationship between self-reported symptoms and calf tissue oxygenation. Results: A total of 40 participants were enrolled in this study. Participants were predominately Caucasian males. The average age of participants was 67.55 years (SD 9.18). Six themes emerged from 27 participant interviews: symptom descriptors, maintaining equilibrium, temporal fluctuations, the role of exercise, the perceived impact on QOL, and disease presence and treatment. During interviews, participants provided 24 symptom descriptors in 10 lower extremity locations. During treadmill exercise, participants provided 22 symptom descriptors in eight lower extremity locations. Under static and dynamic conditions, classic and `atypical' descriptors were used to describe discomfort in typical and `atypical' lower extremity locations. During three successive bouts of treadmill exercise, the largest drop in calf tissue oxygenation occurred between the start of exercise and the onset of symptom(s). During recovery, calf tissue re-saturation occurred steadily between maximum discomfort (i.e., a rating of 5 out of 5) and full symptom recovery. Individual changes in tissue oxygenation were related to total exercise time, baseline calf tissue oxygenation, exercise and recovery ratings, disease severity, and body-mass index. Conclusions: This study provides a preliminary understanding of the relationship between subjective symptom reporting and calf tissue oxygenation with a variety of PAD risk factors and individual characteristics. Continued research is necessary to validate `atypical' participant symptom reporting and broaden the currently accepted PAD symptom locations and descriptors. Despite the under-reporting of `atypical' symptoms compared to classic claudication, they do exist and they are no less important for the early detection, diagnosis, and treatment of PAD to minimize the impact of this painful, debilitating, and deadly disease.
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    Optimizing sample preparation and scanning methods for component analysis of raw milk by fourier transform near infrared spectroscopy
    (2013-04) Reuter, Anthony Joseph
    Raw milk is hard to analyze by NIR because of light scattering caused by large particles in the fat component; however, improvements to sample preparation and presentation could improve analysis. In this study, sample presentation and particle size reduction using homogenization was investigated for 160 diverse samples to predict component quantities in raw milk by FT-NIR. Excellent standard errors were obtained for all measured components following no-homogenization. Sonication and tube-dispersion methods were not different than no-homogenization, but were better compared to two-stage homogenization for moisture and casein due to whey protein denaturation during processing. High sample temperatures during analysis likely contributed to positive results for all component predictions compared to references. For sample presentation, static and dynamic flow-cell methods produced the best standard errors for components. Meanwhile, petri-dish presentation was accurate but may have been limited by the method design, which allowed for sample dehydration and loss of reflected light.