Browsing by Subject "body composition"
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Item Body Composition Assessment and Protein Recommendations In Clinical Populations(2020-03) Price, KathleenMalnutrition, sarcopenia, cachexia, and frailty are terms that rely on muscle assessment, and they all have ongoing refinement in their definition and diagnostic criteria as well as significant clinical overlap. Uncertainties in how best to assess muscle objectively have led to subjectivity in their diagnoses, leading to confusion and misuse of these terms throughout the literature. Additionally, protein recommendations in the hospital which serve as the foundation for nutrition intervention to prevent or treat muscle loss are based on nitrogen balance studies that are non-specific and have known limitations. The clinical Registered Dietitian Nutritionist (RDN) is well-positioned to diagnose, track, and treat muscle wasting disorders in clinical populations, and improvement in both the assessment of muscle as well as protein recommendations to prevent or treat muscle loss will advance the clinical utility of RDN. A detailed look at the history of malnutrition in the medical literature indicates that body composition has long been known to be of critical importance to its diagnosis, and current efforts are underway to utilize body composition technologies to assess muscle in acute care settings. Computed tomography data can indicate best-treatment methods for individuals as well as those who would benefit from targeted nutrition intervention, and this dissertation discusses its utility for predicting outcomes in chronic pancreatitis patients undergoing a total pancreatectomy with islet autotransplantation and heart failure patients undergoing a heart transplant. Finally, this dissertation demonstrates that a multi-step feeding protocol of stable isotope amino acids is feasible to characterize whole body protein kinetics over a single study day to ultimately improve protein recommendations in patients with head and neck cancer. Ultimately, loss of muscle is known to worsen clinical outcomes and increase cost, and advancements in both muscle assessment using body composition technologies and protein recommendations using stable isotope amino acid tracers to prevent or treat muscle loss will improve the ability of the clinical RDN to positively impact patient prognosis.Item Body composition assessment of premature infants in the neonatal intensive care unit(2019-08) Nagel, EmilyPremature infants experience growth alterations that place them at risk for adverse metabolic and neurodevelopmental outcomes. Monitoring the quality of weight gain through body composition assessment in the neonatal intensive care unit (NICU) may help clinicians gauge the response to nutritional provision and guide future interventions that promote adequate growth and neurodevelopment while reducing the risk for obesity and metabolic disease. While length and weight are regularly tracked during an infant’s NICU stay, these measurements do not adequately represent total body adiposity shortly after birth. Thus, a method of body composition which is non-invasive, portable, and able to be frequently utilized in both critically ill and medically stable infants is desirable. Unfortunately, many current methods of body composition are invasive, expensive, involve ionizing radiation, or are unsuitable for repeated measurement in a medically fragile infant. Thus, this dissertation project explores methods to monitor body composition in premature infants in the NICU setting with a focus on ultrasound. The first study explored the ability of weight for length indices of the body to serve as proxies for adiposity in preterm infants. Indices examined include weight for length (W/L), body mass index (BMI), and ponderal index (PI). Each index was examined for its ability to predict fat mass (FM), fat-free mass (FFM), and percent body fat (%BF). None of the indices adequately reflected adiposity in preterm infants, indicating that assessing body composition in preterm infants requires more than weight and length measurements, and other methods of bedside assessment should be pursued. The second study examined the ability of ultrasound to assess body composition in premature infants in the NICU setting. Ultrasound images of the biceps, abdomen, and quadriceps were obtained for assessment of adipose and muscle thickness and were compared with body composition measurements (FFM, FM, %BF) taken using air displacement plethysmography (ADP). While ultrasound measurements of biceps and quadriceps muscle thickness correlated with total FFM, ultrasound measurements were not included in final models for predicting FFM. Biceps, abdomen, and quadriceps adipose thickness correlated with total FM and %BF, but only biceps adipose was selected in the final model predicting %BF. The sum of ultrasound adipose thickness measures was selected for the final model predicting %BF. However, all models had low predictive ability due to low proportion of variance explained (R2) and/or high prediction error (root mean square error, RMSE). While the study conducted here does not support the use of ultrasound measurements of adipose and muscle thickness of the biceps, abdomen, or quadriceps alone to predict body composition in preterm infants, exploration of additional sites or cross-sectional area may improve predictive ability. Additionally, ultrasound measurements may have some value as a prognostic tool for other clinical outcomes, such as neurodevelopment or readiness for NICU discharge. Regardless, this work highlights the need for clinical body composition methods appropriate for premature infants to help monitor for disease risk and assist in the refinement of current nutrition practices in the NICU.Item Dual X-Ray Absorptiometry May Not Be Sensitive Enough To Measure Changes In Regional Fat After Acute Exercise(2017-06) Brayton, SethABSTRACT Objective: We sought to determine if an acute bout of running accounts for measurable changes in total and regional body fat using Dual X-ray Absorptiometry (DXA). There is limited research about the change in body fat after an acute bout of physical activity. Knowing how body composition changes as a result of exercise is important for populations with symptoms of metabolic syndrome, such as overweight/obesity, increased waist circumference, high triglycerides, low levels of high density lipoprotein (HDL), increased total cholesterol, increased systolic and diastolic blood pressure, increased blood glucose and physical inactivity that can eventually lead to conditions like heart disease and diabetes (1). As the amount of visceral fat a subject has increases, so does their risk for metabolic syndrome. In addition, knowledge of body composition changes is useful in athletic populations for injury prevention and performance in athletes (2). Methods: Subjects that were between the age of 18 – 40, that reported a history of regular running exercise (approximately 45 minutes, 5 times a week), were otherwise healthy and could commit to running 90 minutes on a treadmill were recruited. All subjects completed a 90-minute run on a treadmill at 60% heart rate reserve (HRR). Body composition was measured before and immediately after the run to determine if DXA was sensitive enough to measure potential changes in body fat following acute exercise. For the present study, total and regional body fat was compared to show if particular regions had a greater change in fat during endurance exercise. The difference in pre-run to post run total and regional body fat was compared using paired t tests. Comparisons between normal weight, overweight/obese, and overall groups were made using nonpaired t tests. Statistical significance was accepted using P-value > 0.05 Changes to total and regional body fat were also compared to the least significant change (LSC) for DXA found in the literature for athletic populations. Results: A total of 16 lean (female = 7; male = 9; age = 28.1 ± 5.6 yrs; BMI = 22.0 ± 1.6 kg/m2) and 11 overweight or obese (female = 7; male = 4; age = 32.0 ± 5.2 yrs; BMI = 30.5 ± 4.8 kg/m2) were recruited and completed both study visits. Weight, VO2max, Body Mass Index (BMI), and baseline percent body fat were significantly different between the normal and overweight/obese groups. Height and age were not significantly different between the groups. No significant differences were found in the absolute change in normal and overweight/obese group. Absolute fat mass decreased slightly overall (-184.5 ± 443.6 g). There was no significant change in BF from arms or legs within the overall group. A significant loss of fat came from the trunk (-195.1 ± 488.3 g). Android/gynoid ratio change shows significant decrease (-0.02 ± 0.04), in the overall group. Although significant absolute fat loss from the trunk and the android/gynoid ratio, the difference in fat for the regions was not more than LSC using test-retest technique found in the literature. Conclusion: Significant differences in fat mass were observed from the trunk and the android/gynoid ratio regions after a 90-minute run at 60% HRR. However, when comparing these changes to the published research on least significant difference of DXA, the change in fat mass observed in this study is less than least significant difference of DXA. This means that the changes in fat measured by DXA in this study may not be accurate.