Browsing by Subject "Oxygenation"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Characterization of the peripheral artery disease symptom experience(2013-08) Schorr, Erica NicoleBackground: 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.Item Tissue-engineered islet graft design and assessment(2012-10) Suszynski, Thomas MarkDiabetes mellitus is a metabolic disease characterized by an inability to maintain normoglycemia and is usually associated with an insufficient beta-cell mass. Islet transplantation (IT, a beta-cell replacement therapy) has exhibited promise in reversing the diabetic state, yet it remains an experimental therapy only among a small subset of patients and widespread availability remains elusive. A main reason for its limited use is the large islet dose required to produce insulin independence, often requiring tissue from multiple donor pancreata. Abundant evidence exists suggesting that acute and chronic islet loss and dysfunction occur in the post-IT period. The minimum islet dose could be reduced if the quality (potency, viability) of the islet product is improved. Since islets do not possess the cellular machinery to produce energy effectively in the absence of oxygen, strategies that improve oxygenation during the ischemic period (donor cardiac death to complete revascularization) are important to develop. Due to the many steps involved in the process (pancreas preservation, and islet isolation, purification, culture, assessment, transplant and engraftment), the quality of an islet preparation can change. Thus, it is critical to develop improved islet quality assessment tools that enable accurate and quantitative characterization of islet viability and potency, which can be performed prospectively, and which do not require much tissue for assessment or which rely on non-invasive methods. Furthermore, intrahepatic IT may not be the optimal approach, and tissue-engineered strategies for extrahepatic IT may be better. The work presented herein focuses on improving islet quality assessment, examining the oxygenation status of the intraportally transplanted islet, and developing a tissue-engineered strategy for the design and non-invasive assessment of islet graft viability - all with the hope that someday IT could be used to successfully treat many more diabetics.