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

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.

Below-knee amputee gait with dynamic elastic response prosthetic feet: a pilot study.

The purpose of this pilot study was to investigate some of the new dynamic elastic response (DER) prosthetic feet compared to the SACH foot and determine if any demonstrated trends of producing the most optimum gait. We investigated the gait of five below-knee amputees while wearing four different DER feet (Flex-Foot, Carbon Copy II, SEATTLE, STEN) and a standard SACH foot. Each subject used each foot for 1 month prior to in-depth gait analysis and energy expenditure testing at the Pathokinesiology Laboratory. Minimal differences in either free or fast walking were noted between the five feet. The Flex-Foot resulted in significantly different gait kinematics at the "ankle" compared to the other four feet, however, this foot did not produce an increased velocity nor an improved energy cost. The results of this pilot study indicated that during free or fast-paced walking on level ground there were no clinically significant advantages of any one of the feet tested. Based on this pilot data, recommendations are made for future studies including appropriate sample size.