Obesity is a pandemic affecting more than 93 million adults in the U.S. Obese are defined as individuals with a Body Mass Index (BMI) of 30 or more. Several studies are demonstrating that this weight-to-height ratio does not fully characterize the patient’s pathophysiology. Monitoring muscle metabolism, the synthesis and breakdown of muscle protein, may be a more useful metric in the characterization of pathologies associated to weight gain. Long term imbalances of energy intake to energy expenditures lead to obesity. Total expenditure is the summation of energies related to the thermic effect of food, activity, and resting expenditure. While at rest, muscle metabolism is the primary component of resting energy expenditure.Daily energy release in muscle mass could significantly lead a net-loss of fat in the long-run, and thus potentially contribute to the prevention of obesity. Near Infrared Spectroscopy (NIRS) measurement of muscle oxygenation can be used to study muscle metabolism. NIRS has the advantage of being a non-invasive, reproducible, and inexpensive methodology. Unfortunately, commercial NIRS system fail to produce accurate results in the obese population due to excess adipose thicknesses (AT) that alter the optical signal. We have used Monte Carlo models of light transfer to probe the optimal source-detector separation necessary to use NIRS in the obese. We have also developed a low-cost wearable muscle oximeter targeted to individuals with high BMI. We will demonstrate our system validation in optical phantoms and volunteers.
Patients with spinal cord injuries (SCI) are often subject to continues stationary pressure on prominent bony areas which, over and extended period of time, become high risk regions for pressure ulcers. Pressure ulcers are as prevalent as 30% in those with SCI and are one of the leading causes of re-hospitalization. In order to develop a better understanding of the methods of treating and preventing these pressure ulcers, we have developed a voxilization based model of the ischial tuberosity based on a Monte Carlo framework. The 3D model of the underside of the pelvis, the ischial tuberosity, allows for variation of the layers of the skin, fat, and muscle created in Solidworks. From the 3D model, the simulation was done with Monte Carlo eXtreme, a GPU-based Monte Carlo model. Tissue layer changes due to movement of the muscle and compression when sitting which results in a significant reduction of the muscle thickness have been accounted for in our model. Skin and muscle profusion of SCI patients is not well known and limited experimental work has been conducted in this environment. This model can aid in the study of methods of improving and maintaining skin health and help with rehabilitation and prevention of pressure ulcers.