Definition
Microcirculation is the system of very small caliber vessels (arterioles, capillaries, venules) responsible for substance exchange between blood and interstitial tissue. Distinction between macrocirculation (arteries, major veins) vs microcirculation (vessels <0.3 mm diameter). Microcirculation is the actual site of exchange: oxygen and nutrients IN; carbon dioxide and metabolic waste OUT. Skin is the 'visible window' of microcirculation: capillaries 5-10 micrometers diameter = red blood cells 7-8 micrometers, meaning red blood cells circulate in single file (capillary shunting). Tissue perfusion = microvascular density x microvascular blood flow. Dysfunctional microcirculation (reduced density, loss of vascular reactivity) = tissue hypoxia, waste accumulation, inflammation, altered aesthetic appearance (dull complexion, loss of firmness).
Capillary Anatomy
Capillaries are the smallest blood vessels and the sites of exchange:
Capillary structure
diameter 5-10 micrometers (red blood cells 7-8 micrometers), length 0.5-1mm. Wall = a single endothelial layer (flat cells). No smooth muscle. Very permeable wall. Density: 300-500 capillaries per mm² of skin.
Capillary types by permeability
Type 1 (continuous, skin, muscle): tight endothelial junctions, low molecular permeability. Type 2 (fenestrated, kidney, pancreas): small pores allowing passage of larger molecules. Type 3 (discontinuous, liver, spleen): very permeable. Skin = continuous type 1.
Exchange zones
arterial capillary segment (~1/3 proximal): filtration dominant (hydrostatic pressure > oncotic pressure). Venous capillary segment (~2/3 distal): reabsorption dominant (oncotic pressure > hydrostatic pressure). Equilibrium determined by Starling equation.
Associated cells
pericytes (minor smooth muscle cells) surround capillaries, enabling contraction. Endothelial cells: produce NO (vasodilator), endothelin (vasoconstrictor), play immune role. Basement membrane: filter, structural support.
Role of Microcirculation in Tissue Nutrition
Microcirculation is the essential bridge for nutrient delivery and waste elimination:
Oxygen delivery
Hemoglobin loads oxygen in lungs -> circulation -> capillaries deliver O2 to tissue. O2 extraction: approximately 25% O2 extracted by capillaries at rest, up to 75% with exercise. Deoxygenated Hb (blue-purple) returns to heart. Tissue hypoxia = metabolic distress (low ATP), accumulation of acid metabolites, inflammation.
Nutrient delivery
glucose enters capillaries -> fibroblasts synthesize collagen; amino acids -> protein biosynthesis; minerals -> enzymatic cofactors. Reduced capillary flow = cellular undernutrition = slowed metabolism, low collagen synthesis, accelerated apoptosis.
CO2 elimination
end product of anaerobic glycolysis (lactate, H+, CO2), diffuses into capillary -> circulation -> lungs excrete. Capillary stagnation = CO2 accumulation, local acidosis, inflammation.
Metabolic waste drainage
urea, ammonia, bilirubin, other metabolism end-products drained by venous capillaries to liver/kidney for detoxification. Drainage dysfunction = toxic accumulation.
Temperature regulation
dermis is richly vascularized = heat dissipation. Cutaneous capillary vasodilation increases heat loss; vasoconstriction reduces it. Thermoregulation dysfunction possible if microcirculation is abnormal.
Microcirculation Assessment Methods
Several techniques assess microcirculatory function:
Transcutaneous Doppler
high-frequency ultrasound evaluates arteriolar/capillary blood flow. Measures flow velocity, detects occlusions. Non-invasive, radiation-free. Easily accessible.
Capillaroscopy (videomicroscopy)
specialized microscope (x200-x600 magnification) visualizes live capillaries. Observes morphology (caliber, tortuosity), capillary density, flow stasis. Gold standard for microcirculation assessment. Used in research and some clinics.
Thermal imaging (thermography)
infrared camera measures skin temperature as a perfusion indicator. Poorly perfused areas are cooler. Uniform temperature indicates good microcirculation. Accessible technology but limited (environmental influence).
Oscillometry and plethysmography
measures local volume variations reflecting pulsatile blood flow. Calculated indices reflect vascular compliance, resistance.
Functional tests
vascular reactivity assessed via reactive hyperemia (temporary circulation occlusion -> release -> flow increases). Reaction amplitude indicates endothelial function. Dysfunction = reduced reactivity.
Blood biomarkers
vascular function molecules (NO, endothelin, growth factors) reflect endothelial health. Useful for deep pathology.
Clinically
skin color observation (pallor = hypoperfusion, redness = inflammation), blanching test (compress skin = white, release = color returns in 1-2 sec normal, >2 sec = possible stasis).
Effects of Aesthetic Treatments on Microcirculation
Technological treatments improve microcirculation through several mechanisms:
Pressotherapy
external compression -> reduced interstitial pressure ('unloading' capillaries) -> reopening compressed capillaries -> increased functional capillary density. Blood flow increases 2-4x during treatment. Pump mechanism: cyclic inflation-deflation simulates muscle contractions -> endothelial pump activation -> vasodilatory NO production (endothelium produces NO in response to mechanical shear stress). Result: lasting post-treatment vasodilation for 2-4h. Microcirculation improved. Clinically: rosy skin (post-treatment erythema), warmth sensation, better apparent perfusion.
Mechanical massage
tissue mobilization stimulates shear stress -> endothelial activation -> NO production -> vasodilation. Suction-aspiration creates local suction -> endothelial traction -> mechanical stimulation of flow-dependent dilation. Effect duration shorter than pressotherapy (1-2h) as less systematic.
Manual lymphatic drainage/aspiration
depression creates capillary stimulation -> endothelial traction -> NO induction. Interstitial fluid mobilization reduces pressure (loosens capillaries) -> improved flow. More subtle effect than pressotherapy.
Radiofrequency/laser
dermal collagen stimulation -> remodeling => reduced fibrosis -> improved vascular compliance -> better flow. More long-term effect (weeks-months) than immediate effect.
Optimal combination
pressotherapy (maximum acute microcirculation improvement) + mechanical massage (aesthetic remodeling) + radiofrequency (collagen remodeling) = maximum acute + chronic structural microcirculation improvement.
Scientific Sources
Data based on: Levy et al. (normal microcirculation), Collis et al. (mechanical massage improves circulation), Feldman et al. (pressotherapy flow), Schoop et al. (capillaroscopy assessment)
Frequently Asked Questions
Pressotherapy is the best; it improves capillary density + flow up to 4x.
Pressotherapy: 2-4 hours post-treatment; mechanical massage: 1-2 hours.
Capillaroscopy (direct visualization), transcutaneous Doppler, thermography, vascular reactivity test.
Yes: less dull complexion, better firmness, improved healing, reduced dark circles.
Yes, positively: collagen stimulation = remodeling = improved long-term vascular compliance.
1-2x per week pressotherapy; 2x/week mechanical massage for cumulative effect.
Sources scientifiques
- Non-Invasive Techniques for Skin Microcirculation. Non-invasive Techniques for Assessment of Skin Microcirculation. Frontiers in Medicine (2022) . PMID: 35174132
- The Cutaneous Microcirculation Research. The Cutaneous Microcirculation: Physiology and Assessment Methods. Journal of Dermatology (2000) . PMID: 11147672
- Collis N et al.. The effect of mechanical massage, manual massage and mobilisation on blood flow in the healthy and scarred skin. Plast Reconstr Surg (2007) ;119 (6) :1949-1955 . PMID: 17440374
- Feldman JL et al.. Pneumatic compression effectively reduces lower extremity lymphedema. Lymphat Res Biol (2012) ;10 (2) :80-86 . PMID: 22686164
- Levy BI. Microvascular heterogeneity in hypertension. J Hypertens (2003) ;21 (3) :487-493 . PMID: 12612549
- Mortimer PS, Rockson SG. New developments in clinical aspects of lymphatic disease. J Clin Invest (2014) ;124 (3) :915-921 . PMID: 24590289
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