The Application of Biomedical Engineering Techniques to the Diagnosis and Management of Tropical Diseases: A Review <s> Laser Doppler Velocimetry <s> Abstract Laser Doppler flowmetry (LDF) is a technique for continuous monitoring of microvascular perfusion. Commercially available flowmeters in general are equipped with probes constructed for performing measurements on superficial tissue surfaces, but small (∅ = 0.45 mm) metallic needle probes for in-tissue measurements are also available. In this study a flexible single-fiber LDF probe with a total diameter of 0.5 mm has been inserted into human tibial muscle and used for assessment of local muscle blood flow. Local muscle perfusion shows a considerable spatial variation. If the probe position is not changed between consecutive measurements, reproducible curve parameters are obtained. Vasomotion was not observed in any measurement. The hyperemic blood flow response was recorded after tourniquet deflation. Time to reach peak magnitude as well as duration of the hyperemic blood flow response was increased significantly ( P P P <s> BIB001 </s> The Application of Biomedical Engineering Techniques to the Diagnosis and Management of Tropical Diseases: A Review <s> Laser Doppler Velocimetry <s> Impedancegraphy and laser Doppler flowmetry were used to measure whether limb circulation changes following post-traumatic immobilization and edema. Intermittent pneumatic compression was used for edema treatment. Limb blood flow due to edema was unchanged compared to the contralateral healthy leg. Intermittent pneumatic compression reduced edema very significantly (p less than 0.001). Intermittent compression showed a slight but significant (p less than 0.01) improvement in impedancegraph blood flow after treatment. Laser Doppler skin blood flow decreased non-significantly following the compression treatment. <s> BIB002 </s> The Application of Biomedical Engineering Techniques to the Diagnosis and Management of Tropical Diseases: A Review <s> Laser Doppler Velocimetry <s> To compare skeletal muscle microvascular blood flow at rest and during reactive hyperemia in septic patients, a prospective, controlled trial was conducted on 16 patients with severe sepsis and a control group of 10 patients free of infection in the intensive care unit of a university hospital. Systemic hemodynamics, whole-body oxygen transport, and skeletal muscle microvascular blood flow at rest and during reactive hyperemia were measured. Reactive hyperemia was produced by arrest of leg blood flow with a pneumatic cuff; on completion of the 3 min ischemic phase the occluding cuff was rapidly deflated to 0. Hemodynamic and oxygen-derived variables were determined invasively. Skeletal muscle microvascular blood flow data were obtained using a laser Doppler flowmetry technique and values expressed in millivolts. Whole-body oxygen delivery in septic patients was increased compared with control subjects. Resting skeletal muscle blood flow was decreased in septic patients compared with control subjects (233 ... <s> BIB003
Laser Doppler velocimetry has been widely used for assessment of various physiological parameters, particularly involving blood perfusion and circulation BIB001 BIB002 BIB003  . The technique has also been recently applied to DHF patients to evaluate the microcirculation changes due to plasma leakage and increase of microvascular permeability  . The preliminary findings of this study indicated that there were significant differences between basal laser Doppler flux in normal healthy subjects and DHF patients. These results also implied that the technique has the potential as an indicator to microcirculatory changes in DHF patients. The study has not; however been able to conclusively differentiate the DHF severity stages using this technique.