Assessment of Lower Limb Microcirculation: Exploring the Reproducibility and Clinical Application of Laser Doppler Techniques

Klonizakis, Markos; Manning, Gillian; Donnelly, Richard

doi:10.1159/000322853

Cited by 28 publications

(19 citation statements)

References 51 publications

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“…In brief, the protocol incorporated the following incremental charge-stimuli: 25 A applied for 10 s (i.e.250 Cb), 50 A for 10 s (500 Cb), 100 A for 10 s (1000 Cb) and 100 A for 20 s (2000 Cb), with a 4-min recording period between each dose. The protocol choice was made so that: a) effective ACh and SNP delivery was provided and b) the non-specific vasodilation observed with higher electrical charges is largely avoided, while at the same time, satisfactory reproducibility is achieved [36,37].…”

Section: Assessment Of Cutaneous Microvascular Functionmentioning

confidence: 99%

Effects of exercise training and Mediterranean diet on vascular risk reduction in post-menopausal women

Alkhatib

Klonizakis

2014

Clinical Hemorheology and Microcirculation

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This study tested the potential risk-reduction benefits of Mediterranean Diet (MD) and regular exercise training on microvascular activity and cardiorespiratory capacity in postmenopausal women. Fifteen sedentary postmenopausal participants (age = 54.6 ± 3.6) were randomised into either exercise training or exercise combined with following MD for eight-weeks, and were assessed for their cardiorespiratory capacity, and upper-and lower-limb endothelial cutaneous vascular conductance (CVC) test using Laser Doppler Fluximetry (LDF), coupled with measuring endothelium-dependent Acetylcholine Chloride (Ach) and -dependent Sodium Nitropurruside (SNP) vasodilators. Exercise training improved cardiorespiratory capacity as indicated by ventilatory threshold (11.5 ± 2.1 vs. 14.0 ± 3.0 ml·kg −1 ·min −1 , p < 0.05) and improved the microcirculatory perfusion results of CVC for both vasodilators Ach (p < 0.001, d = 0.65) and SNP (p = 0.003, d = 0.53) in the lower-limb and ACh (p = 0.01, d = 0.41) and SNP (p = 0.03, d = 0.48) in the upper-limb, all (p < 0.05). However, combining exercise with MD showed a stronger improvement in Ach (p = 0.02, d = 0.36) of the lower limb, than in exercise alone group. The results suggest that regular moderate exercise improves microcirculatory vascular function and increases exercise tolerance, both are responsible for reducing cardiovascular risk in postmenopausal women. However, combining MD with exercise suggests additional microvascular vasodialiatory improvement, suggesting an effective strategy for further cardiovascular risk-reduction in this high-risk group.

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Section: Assessment Of Cutaneous Microvascular Functionmentioning

confidence: 99%

Effects of exercise training and Mediterranean diet on vascular risk reduction in post-menopausal women

Alkhatib

Klonizakis

2014

Clinical Hemorheology and Microcirculation

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“…After achieving a stable recording of baseline flux, LDF responses to ACh and SNP were measured using an incrementaldose iontophoresis protocol, as described previously [2]. In brief, dose-response curves for ACh-and SNP-induced vasodilation were characterized using the following procedure to apply incremental charge-stimuli: 25 μA applied for 10 s (i.e.…”

Section: Assessment Of Cutaneous Microvascular Functionmentioning

confidence: 99%

“…It has been well-documented that the structural and functional integrity of the microcirculation to maintain blood flow, tissue oxygenation and nutrient delivery are among the factors that affect tissue viability and susceptibility in a range of diseases and conditions [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Mediterranean diet- and exercise-induced improvement in age-dependent vascular activity

et al. 2013

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The aging effect on microvascular integrity, marked by endothelial dysfunction and reduction in exercise tolerance, is a major cause of CVD (cardiovascular disease). Improved dietary habits, known to reduce morbidity and mortality, are also known to attenuate those aging effects. The present study investigated the effects of combined MD (Mediterranean diet) and exercise intervention on lower- and upper-limb cutaneous microvascular functions in an older healthy population. A total of 22 sedentary healthy participants (age, 55±4 years) underwent cardiopulmonary exercise tolerance test, and were assessed for their upper- and lower-limb vascular endothelial CVC (cutaneous vascular conductance) using LDF (laser Doppler fluximetry) with endothelium-dependent [ACh (acetylcholine chloride)] and -independent [SNP (sodium nitroprusside)] vasodilation. Participants were then randomized into two groups: MD and non-MD, and followed an 8-week intervention programme, which included discontinuous treadmill running based on each individual's exertion, twice per week. Exercise training improved CVC in both groups (e.g. 0.42±0.19 compared with 1.50±1.05 and 0.47±0.26 compared with 1.15±0.59 at 1000 μCb for MD and non-MD respectively; P<0.001). This was also combined by improvement in the exercise tolerance indicated by increased VT (ventilatory threshold) in both groups [12.2±2.8 compared with 14.8±2.8 ml·(kg of body weight)(-1)·min(-1) and 11.7±2.7 compared with 14.6±3.2 ml·(kg of body weight)(-1)·min(-1) for MD and non-MD groups respectively; P<0.05]. However, the MD group showed greater improvement in endothelium-dependent vasodilation than non-MD [ANCOVA (analyses of co-variance), P=0.02]. The results of the present study suggest that compliance with MD, combined with regular moderate exercise, improves age-provoked microcirculatory endothelial dysfunction and increases exercise tolerance, both responsible for reducing cardiovascular risk in this age group.

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“…3 LDI assesses a larger area of skin from a distance using a scanning motion that incorporates the entire lower limb and foot. 11 The wavelength of laser, speed of scanning, and distance between the scanner and the leg affect tissue penetrance and must be kept constant to allow meaningful comparison of serial measurements.…”

Section: Current Techniques Laser Dopplermentioning

confidence: 99%

Assessment of Tissue Perfusion in the Lower Limb

Bajwa

Wesolowski

Patel

et al. 2014

Circ: Cardiovascular Imaging

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Downloaded from Bajwa et al Assessment of Lower Limb Perfusion 837when compared with normal limbs and cannot quantify the severity of perfusion deficit. 12 More recent studies show that LDF is a good discriminator of skin flap perfusion and can predict the likelihood of healing after limb amputation.13 LDI is used in preclinical animal models of limb ischemia (eg, the murine hindlimb ischemia model) for high throughput testing of interventions, including angiogenic therapies. The technique allows longitudinal acquisition of data but is limited by motion artifact, ambient temperature variations, and perfusion measurements, which are weighted toward the larger vessels that are shallow and reside on the surface of the limb musculature. 14 Transcutaneous Oxygen PressureThe measurement of transcutaneous oxygen pressure (TcPo 2 ) is a noninvasive technique that allows longitudinal assessment of local oxygen diffusion from the capillary bed through the skin epidermis and provides an indication of the amount of oxygen delivered to the tissue. TcPo 2 measurements can reflect the severity of PAD, 15 assess ulcer healing potential, 16 and determine the optimal level for limb amputation. 17 A TcPo 2 <20 to 30 mm Hg is consistent with CLI, 2,15,18 and levels <40 mm Hg are associated with poor healing after amputation. 18 Inhalation of 100% oxygen would normally result in TcPo 2 >100 mm Hg, but in patients with CLI the TcPo 2 does not rise >30 mm Hg. 18 Oxygen therapy resulting in <10 mm Hg rise in limb TcPo 2 is associated with an >60% chance of an amputation at that level not healing. 18 A rise of >40 mm Hg in TcPo 2 after limb revascularization is considered significant and increases the chances of tissue healing. 15,18 TcPo 2 measurements vary in different tissues and under different physiological conditions. Barriers to diffusion, such as edema, increased oxygen consumption secondary to inflammation, and vasoconstriction, may lead to falsely low TcPo 2 readings falsely. Readings are also affected by temperature, with a 1°C reduction in the thermistor temperature resulting in a 2% to 3% lower TcPo 2 reading. 18 Indocyanine Green Fluorescence AngiographyThis technique has been used for many years to image retinal vessels, 19 and more recently in the assessment of microanastomoses in surgical flap reconstruction surgery, detection of arteriovenous malformations, and measurement of hepatic blood flow. 20 Indocyanine green is a fluorescent dye that is activated by near-infrared laser light at ≈780 nm. 21 This allows a penetrance of 3 mm from the surface of the skin to assess the subdermal microcirculation. 20,22 A semiquantitative measure of perfusion is obtained by measuring pixel fluorescence intensity in different areas of the image from the limb. Perfusion measured by indocyanine green fluorescence angiography correlates with LDI in the hindlimb ischemia model 23 and predicts the likelihood of amputation healing in man. 21 This technique can identify patients with peripheral arterial occlusions who have extensive collater...

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Assessment of Lower Limb Microcirculation: Exploring the Reproducibility and Clinical Application of Laser Doppler Techniques

Cited by 28 publications

References 51 publications

Effects of exercise training and Mediterranean diet on vascular risk reduction in post-menopausal women

Effects of exercise training and Mediterranean diet on vascular risk reduction in post-menopausal women

Mediterranean diet- and exercise-induced improvement in age-dependent vascular activity

Assessment of Tissue Perfusion in the Lower Limb

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