The human body undergoes extreme loadings on a daily basis

Ulcers and Blood Flow

The human body undergoes extreme loadings on a daily basis - whether it is from running, jumping rope, or shoveling snow off the walk. The majority of the time, injury does not result from these activities. However, as a person becomes older, or if a person’s health is compromised through disease, the human body cannot respond as efficiently to these daily challenges. When discussing loads and injury, many do not think about injury to the skin and its underlying tissues.

Loading on the skin can be problematic, particularly for individuals who are seated for the majority of the day – such as the elderly or those with spinal cord injuries. For these individuals wounds can extend from the surface of the skin down to the muscle and sometimes the bone. These wounds are known as pressure ulcers, bed sores, or pressure sores. Over three million Americans have pressure ulcers, suggesting that current prevention practices are insufficient. Pressure ulcers severely compromise an individual’s health, are prone to infection, have lengthy and expensive recovery periods, have high reoccurrence rates, and in some cases can result in amputations.

Of particular interest to Tamara Reid Bush are the mechanics that occur at the interface with the skin. In the case of the ulcers on the bottom or back of the buttocks, the interface between the skin and chair is studied. Forces on the skin, both shear (parallel to the skin’s surface) and normal (perpendicular to the skin surface), play a strong role in the formation of these ulcers. As the loading on the skin is increased, reduced regional blood flow occurs, resulting in decreased oxygen and nutrition to the area, which then leads to tissue death and ulcer formation.

Dr. Bush is one of the first researchers to study the effects of combined normal and shear loading on the skin. She has studied how various loadings impact blood flow and perfusion to the skin level as well as deep vessel flow. Her work couples experimental aspects with imaging and modeling.

The goals of Dr. Bush’s research on ulcers are to 1) develop a tool that allow clinicians to identify events that occur prior to the onset of an ulcer, making the prevention techniques more robust and reducing the number of individuals affected; 2) to design a seat that will cycle loads from one body region to another so that sustained loading to one location does not occur; and 3) to reduce the shear loads occurring on the skin. Dr. Bush’s skin mechanics research extends to prosthetic users who are also prone to ulcers and to stasis ulcers (wounds on the lower limb).