An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot

This source preferred by Jon Cobb

Authors: Cobb, J.E.

http://eprints.bournemouth.ac.uk/312/

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot. Jonathan Edwin Cobb Plantar ulceration is a complication of the diabetic foot prevalent in adults with type 11 diabetes mellitus. Although neuropathy, microvascular disease and biornechanical factors are all implicated, the mechanism by which the tissue becomes pre-disposed to damage remains unclear. Recent theories suggest that the nutritional supply to the tissue is compromised, either by increased flow through the arteriovenous anastomoses ('capillary steal' theory) or through changes in the micro vascu I ature (haemodynamic hypothesis). Clinical data to support these ideas has been limited to assessment of the unclad foot under rest conditions. A limitation of previous studies has been the exclusion of static and dynamic tissue loading, despite extensive evidence that these biornechanical factors are essential in the development of plantar ulceration. The present study has overcome these problems by allowing assessment of plantar blood flow, in-shoe, during standing and walking. The system comprises a laser Doppler blood flux sensor operating at 780nm, load sensor, measurement shoe, instrumentation, and analysis software. In-vitro calibration was performed using standard techniques. An in-vivo study of a small group of diabetic subjects indicated differences in the blood flux response between diabetic neuropaths, diabetics with vascular complications and a control group. For example, following a loading period of 120s, relative increases in response from rest to peak were: Control (150% to 259%), Vascular (-70% to 242%), Neuropathic (109%-174%) and recovery times to 50% of the peak response were: Control (33s to 45s), Vascular (43s to >120s), Neuropathic (>120s). Dynamic re-perfusion rates (arbitrary units per millisecond) obtained for the swing phase of gait were: Control (6.1 a. u/ms to 7.9 a. u/ms), Vascular (4 a. u/ms to 6.2 a. u/ms), Neuropathic (2.3 a. u/ms to 4.5 a. u/ms).

This data was imported from PubMed:

Authors: Cobb, J. and Claremont, D.

http://eprints.bournemouth.ac.uk/312/

Pages: 417-425

Increased pressure due, to sensory neuropathy, is important in the development of plantar ulceration in type II diabetes. However, additional factors are thought to pre-dispose the skin tissue to ulceration. Autonomic neuropathy and microangiopathy are the basis for the capillary steal theory and the haemodynamic hypothesis, developed to explain the aetiology of this type of ulcer, in terms of microvascular complications. The aim of the present study was to develop a system to allow assessment of blood flow at prevalent sites of ulceration. Previous studies have been limited to assessment of the bare foot under rest conditions. The new system allows measurements to be made in-shoe, during static and dynamic loading. The system comprises a laser Doppler sensor, a load sensor, measurement shoe, instrumentation and analysis software. The measurement shoe was designed to minimise movement artefact and provide thermal insulation for the foot. A simple flow rig was used to characterise the sensor. The blood flux response was linear (<5% deviation from ideal) for particle concentrations up to 0.25% and for mean particle velocities up to 8mm s(-1). The worst case drift in the response over a six-month period was 3.7%. Device to device repeatability varied by 12.5% over five devices.

This data was imported from Scopus:

Authors: Cobb, J. and Claremont, D.

http://eprints.bournemouth.ac.uk/312/

Pages: 417-425

DOI: 10.1016/S1350-4533(01)00060-1

Increased pressure due, to sensory neuropathy, is important in the development of plantar ulceration in type II diabetes. However, additional factors are thought to pre-dispose the skin tissue to ulceration. Autonomic neuropathy and microangiopathy are the basis for the capillary steal theory and the haemodynamic hypothesis, developed to explain the aetiology of this type of ulcer, in terms of microvascular complications. The aim of the present study was to develop a system to allow assessment of blood flow at prevalent sites of ulceration. Previous studies have been limited to assessment of the bare foot under rest conditions. The new system allows measurements to be made in-shoe, during static and dynamic loading. The system comprises a laser Doppler sensor, a load sensor, measurement shoe, instrumentation and analysis software. The measurement shoe was designed to minimise movement artefact and provide thermal insulation for the foot. A simple flow rig was used to characterise the sensor. The blood flux response was linear ( < 5% deviation from ideal) for particle concentrations up to 0.25% and for mean particle velocities up to 8 mm s -1 . The worst case drift in the response over a six-month period was 3.7%. Device to device repeatability varied by 12.5% over five devices. © 2001 IPEM. Published by Elsevier Science Ltd. All rights reserved.

This data was imported from Web of Science (Lite):

Authors: Cobb, J. and Claremont, D.

http://eprints.bournemouth.ac.uk/312/

Pages: 417-425

DOI: 10.1016/S1350-4533(01)00060-1

This data was imported from Europe PubMed Central:

Authors: Cobb, J. and Claremont, D.

http://eprints.bournemouth.ac.uk/312/

Pages: 417-425

Increased pressure due, to sensory neuropathy, is important in the development of plantar ulceration in type II diabetes. However, additional factors are thought to pre-dispose the skin tissue to ulceration. Autonomic neuropathy and microangiopathy are the basis for the capillary steal theory and the haemodynamic hypothesis, developed to explain the aetiology of this type of ulcer, in terms of microvascular complications. The aim of the present study was to develop a system to allow assessment of blood flow at prevalent sites of ulceration. Previous studies have been limited to assessment of the bare foot under rest conditions. The new system allows measurements to be made in-shoe, during static and dynamic loading. The system comprises a laser Doppler sensor, a load sensor, measurement shoe, instrumentation and analysis software. The measurement shoe was designed to minimise movement artefact and provide thermal insulation for the foot. A simple flow rig was used to characterise the sensor. The blood flux response was linear (<5% deviation from ideal) for particle concentrations up to 0.25% and for mean particle velocities up to 8mm s(-1). The worst case drift in the response over a six-month period was 3.7%. Device to device repeatability varied by 12.5% over five devices.

The data on this page was last updated at 04:42 on September 22, 2017.