Reduced Arteriovenous Shunting Capacity After Local Heating and Redistribution of Baseline Skin Blood Flow in Type 2 Diabetes Assessed With Velocity-Resolved Quantitative Laser Doppler Flowmetry
- Ingemar Fredriksson1,
- Marcus Larsson1,
- Fredrik H. Nyström2,
- Toste Länne2,
- Carl J. Östgren3 and
- Tomas Strömberg1
- 1Division of Biomedical Instrumentation, Department of Biomedical Engineering, Linköping University, Linköping, Sweden;
- 2Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden;
- 3Division of Community Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
- Corresponding author: Ingemar Fredriksson, .
OBJECTIVE To compare the microcirculatory velocity distribution in type 2 diabetic patients and nondiabetic control subjects at baseline and after local heating.
RESEARCH DESIGN AND METHODS The skin blood flow response to local heating (44°C for 20 min) was assessed in 28 diabetic patients and 29 control subjects using a new velocity-resolved quantitative laser Doppler flowmetry technique (qLDF). The qLDF estimates erythrocyte (RBC) perfusion (velocity × concentration), in a physiologically relevant unit (grams RBC per 100 g tissue × millimeters per second) in a fixed output volume, separated into three velocity regions: v <1 mm/s, v 1–10 mm/s, and v >10 mm/s.
RESULTS The increased blood flow occurs in vessels with a velocity >1 mm/s. A significantly lower response in qLDF total perfusion was found in diabetic patients than in control subjects after heat provocation because of less high-velocity blood flow (v >10 mm/s). The RBC concentration in diabetic patients increased sevenfold for v between 1 and 10 mm/s, and 15-fold for v >10 mm/s, whereas no significant increase was found for v <1 mm/s. The mean velocity increased from 0.94 to 7.3 mm/s in diabetic patients and from 0.83 to 9.7 mm/s in control subjects.
CONCLUSIONS The perfusion increase occurs in larger shunting vessels and not as an increase in capillary flow. Baseline diabetic patient data indicated a redistribution of flow to higher velocity regions, associated with longer duration of diabetes. A lower perfusion was associated with a higher BMI and a lower toe-to-brachial systolic blood pressure ratio.
Clinical trial reg. no. NCT01049737, clinicaltrials.gov.
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- Received January 18, 2010.
- Accepted April 1, 2010.
- © 2010 by the American Diabetes Association.
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