A modular device to measure the effects of plantar foot pressure on the microcirculation of the heel

Background: Past research has concentrated on foot function and plantar foot pressure, with many devices developed for this purpose. However, little is known of how cutaneous blood flow compensates for ambulatory repetitive circulatory insults and how ulceration occurs. Objectives: To develop a system to measure the effects of plantar foot pressure on cutaneous blood flow in the supine and semi-weight bearing positions. Method: A system was developed that integrated a laser Doppler fluxmeter with a pressure probe, allowing plantar foot pressure and skin blood flow to be recorded simultaneously. The system was tested using four volunteers (28 ± 8.6 years). Results: A significant difference existed between baseline laser Doppler flowmetry (LDF) in the supine and semi-weight bearing positions (P = 0.023). Differences between both positions also existed in the reduction in LDF levels following application of pressure (P = 0.015), the maximum hyperaemic response (P = 0.034) and time taken to reach maximum hyperaemic response (P = 0.019). Conclusion: The device has shown that with current technology it is now possible not only to investigate plantar foot pressure but also how it affects skin blood flow, which in some cases can lead to ulceration. The effect of plantar foot pressure on cutaneous blood flow differs depending on whether the subject is supine or semi-weight bearing. Thus, to understand the effects of plantar foot pressure on skin blood flow future researchers must ensure that subjects are in an upright position when recording.