Blood flow analysis for prediction of pressure ulcer development using diffuse correlation spectroscopy

Abstract

Microcirculation is essential for supply of oxygen and nutrients to organ tissues as well as the removal of waste products of metabolism. Consequently, microcirculatory blood flow is of substantial interest to clinicians for assessing tissue health, particularly in regards to pressure injuries and suspected deep tissue injury. We used optical methods of noninvasive diffuse correlation spectroscopy (DCS) and diffuse near infrared spectroscopy (DNIRS) to predict the development of pressure injuries by measuring dermal and subcutaneous red cell motion. We recruited 14 rehabilitation patients with non blanchable redness in the sacrococcygeal area and 20 healthy volunteers from Magee Rehabilitation Hospital in Philadelphia, PA. Among the rehabilitation patients, 3 developed open pressure injuries (PO) within four weeks of enrolling while 11 patients did not (PNO). Our measurement protocol consisted of three stages in order to collect blood flow changes during baseline, applied body weight pressure, and released pressure stages. The characteristic time of DCS temporal correlation function scattered light intensity, $\tau_{\exp }$, characterized the tissue blood flow and were compared for both patient groups. Results from baseline measurements showed $\tau_{\exp }$ values approximately five times larger (p=0.0002) for POs compared with PNOs, suggesting POs have faster blood flow than PNOs in their respective areas of redness. Similar differences were obtain for two next monitoring stages. Preliminary results suggest the used method is able to accurately predict the progression of early stage pressure injuries in the sacrococcygeal area.