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Optical Methods for Diabetic Foot Ulcer Screening
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Robert Bartlett, Gennadi Saiko, Alexandre Yu. Douplik
Laser Doppler imaging is a relatively mature diagnostic modality, which has been used in many clinical situations. Primarily, it is used to assess burn depth, but it is also applied in surgery, wound healing, and general vascular diagnostics. However, it has very limited applications in diabetic wound care.
Injuries Due to Burns and Cold
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
Partial-thickness burns do not involve the whole thickness of the skin, so some viable dermis remains. Included in this category are epidermal, superficial, mid-dermal and deep dermal burns. Epidermal burns, for example, sunburn, strictly are not true burns, but redness with some oedema. These burns are painful but will heal rapidly. Superficial dermal burns involve injury to the superficial layers of the dermis. Oedema separates the dead dermis from the underlying dermis, forming blisters but the intact dermis still has a good blood and nerve supply. These burns will blanche if touched and are very painful. Mid-dermal burns are difficult to assess clinically, even for experienced burn surgeons. The use of laser Doppler imaging can bring the accuracy of assessment up to 97%.13, 15 Deep dermal burns may mislead by their ‘pink’ appearance, caused by the coagulated haemoglobin retained in capillaries. The majority of the dermis is injured, but with accurate and careful debridement some residual underlying dermis can be retained.
Skin Structure and Function
Published in Golara Honari, Rosa M. Andersen, Howard Maibach, Sensitive Skin Syndrome, 2017
Skin microcirculation and perfusion can be affected by a number of exogenous and endogenous factors. Changes in cutaneous vascular perfusion may reflect a physiologic response such as thermoregulation or a pathologic response such as inflammation caused by exposure to chemical irritants and concomitant release of inflammatory mediators. Also, exposure to topical vasoactive drugs can affect skin circulation. Laser Doppler instruments measure the Doppler shift induced by the laser light that is being scattered by moving red blood cells. A signal is quantified based on the average red blood cell concentration and velocity. Since this measure is not an exact measure, it is referred to as flux, which has a linear relationship with the actual flow (35–37). Two distinct laser Doppler tools are used: the first is the laser Doppler flowmetry (LDF), which has a small probe touching the skin, measuring blood flow over a small volume (1 mm3 or smaller), and the second method is laser Doppler imaging (LDI), in which the laser beam is emitted at a certain distance above the skin surface and reflected by a computer-driven mirror to scan an area of the skin. LDI provides two-dimensional images mapping the perfusion but is a slow method. Quantifying fast changes in blood flow is easier with LDF compared to LDI (35).
Biologics and atherosclerotic cardiovascular risk in rheumatoid arthritis: a review of evidence and mechanistic insights
Published in Expert Review of Clinical Immunology, 2021
George A Karpouzas, Viet L Bui, Nicoletta Ronda, Ivana Hollan, Sarah R Ormseth
Both micro and macrovascular endothelial dysfunction have been reported in inflammatory arthritis and correlate with TNF and CRP [100]. Microvascular function can be evaluated noninvasively by measuring alterations in skin blood flow with laser Doppler imaging in response to delivery of vasoactive drug on a patch of skin on a patient’s forearm (laser Doppler iontophoresis). Macrovascular function is evaluated with brachial artery flow-mediated dilation (FMD). Low FMD correlates with coronary endothelial dysfunction on invasive assessments and predicts CVD risk in population-based studies [100]. A meta-analysis of 20 studies involving 852 RA patients and 836 controls indicated significantly lower FMD in RA [101]. More active inflammation is associated with more significant impairment in FMD.
Assessing structural and functional response of murine vasculature to acute β-adrenergic stimulation in vivo during hypothermic and hyperthermic conditions
Published in International Journal of Hyperthermia, 2019
Anna C. Crouch, Paige E. Castle, Lauryn N. FitzGerald, Ulrich M. Scheven, Joan M. Greve
Dobutamine administration during hypothermia resulted in smaller or no decreases in area for the carotid, suprarenal and infrarenal aorta compared to hyperthermic conditions. Crouch et al. [20] also demonstrated that the cross-sectional area of some core arteries decreases due to decreases in temperature, paralleling hypothermia-induced vasoconstriction known to occur in the skin/periphery. For example, while there was a 7% increase for the carotid artery at 35 °C compared to 37 °C, conversely, the areas of the infrarenal aorta and femoral artery decreased by 11% and 72%, respectively. Here, we show a 5% increase in area at the carotid, no change at the infrarenal aorta and a 13% increase in the femoral artery when dobutamine is applied at 35 °C. This suggests that reductions in area of the core arteries due to hypothermia are mitigated by the application of dobutamine. Similarly, Oung et al. [10] showed an increase in vasodilation from dobutamine during hypothermic conditions compared to normothermic conditions. Focusing on the femoral artery, the difference between a large reduction in area due to hypothermia, to minimize heat loss to the environment [15,17,19], and an enlargement when dobutamine [9] is applied during hypothermia would be hypothesized to cause further decreases in core temperature due to increased heat exchange with the environment. However, these structural changes are not necessarily indicative of blood flow changes. In addition to blood pressure measurements, laser Doppler imaging and phase contrast MRI could be used to determine whether changes in subcutaneous perfusion and blood flow velocity and volume, respectively, are accompanying geometric alterations.