Blood flow and oxygen level characterization of the forearm with changes in normal and shear loads.

Decubitus ulcers (Pressure ulcers) are localized areas of tissue-breakdown in the skin and the underlying tissues. The goal of our research was to study alteration of the oxygen levels and blood perfusion in the skin when normal and shear loads were applied on the forearm. Results of this study will provide information that can be related to decubitus ulcer development. In protocol 1, a total of 15 human subjects were tested in seven different conditions for changes in blood perfusion and transcutaneous oxygen during the application of normal and shear forces. In a second protocol, five subjects were tested for the effects of consistent levels of repeated normal and shear loads on the blood flow. A continuous measurement of blood perfusion and transcutaneous oxygen was performed on the forearm using a laser Doppler system, and the forces applied were measured using a multi-axis load cell. The force, blood flow and oxygen data were collected and statistical analyses were performed. From the analyses, it was found that the blood flow and transcutaneous oxygen decreased when shear was applied in addition to the normal force. The blood flow during the resting times increased gradually in protocol 1, where as in protocol 2, it decreased gradually.