Potential application of photoplethysmography technique in evaluating microcirculatory status of STAMP patients:...

Diabetes mellitus and peripheral vascular disease often lead to infections that result in lower extremity amputations. Transcutaneous oxygen pressure (TcPO2) has been shown by many investigators to be a highly reliable means of assessing cutaneous blood supply and, thus, predicting healing potential. However, TcPO2 measurements are time-consuming and subject to technical difficulties. For this reason, a potential application of photoplethysmography (PPG) as a method for assessing the level of cutaneous circulation was investigated by comparing PPG peak-to-peak voltages with corresponding TcPO2 measurements. The comparisons were made at 37 locations in 20 patients with an age range of from 20 to 81 years (mean = 64.4 years). Although the two methods are intrinsically different and measure two different physiological parameters, the peak-to-peak voltages from PPG were compared with TcPO2 measurements since TcPO2 was reported to be the best single adjunct in determining healing potential after amputation. Linear regression analysis correlating output peak-to-peak voltages from PPG with TcPO2 yielded a correlation coefficient of 0.60. The anatomic locations did not affect the PPG or the TcPO2 measurement. The results of this study encourage further investigation of this technique and instrumentation as a method of assessing the level of cutaneous circulation and ultimately aid in determination of optimal amputation levels.