Overview
Inspection of the colour of the lower limbs in diabetics can suggest the presence of arterial insufficiency, venous insufficiency or infection.
Lower Limb Erythema
Look For
- Redness - unilateral, bilateral, localised or diffuse.
Causes of Lower Limb Erythema
- CellulitisTender, red, swollen, warm calf ± site of injury
- Skin conditionsMacules, papules, patches or plaques - localised / diffuse
- Lipodermatosclerosis (fibrosis of subcutaneous fat)Inverted bowling pin appearance with erythema / induration
- LymphoedemaNon-pitting oedema, usually bilateral
- Deep venous thrombosisRed, swollen, tender calf
- Superficial ThrombophlebitisTender area with erythema tracking along the course of a superficial vein
- Venous insufficiencyHyperpigmentation that may be associated with varicose veins or oedema.
- Dependent rubor(peripheral arterial disease)Dusky-red discolouration when the leg is elevated above the heart
Pallor of the Lower Limb
Look For
- Loss of colour in one or both lower limbs.
Causes of Pallor of the Lower Limb
- Anaemia
- Peripheral arterial disease
- Compartment syndrome
- Low cardiac output, due to cardiac disease
- Peripheral shutdown, due to increased sympathetic activity
Lower Limb Cyanosis
Look For
- Blue discolouration of the lower limb.
Significance
- Nail bed cyanosis is a type of peripheral cyanosis, or high levels of deoxygenated haemoglobin (hypoxaemia) in the peripheries. Always look for central cyanosis (under the tongue) when this is present.
Causes of Lower Limb Cyanosis
Central Cyanosis
- High altitude
- Obstructive lung disease, pulmonary oedema, pneumonia, pulmonary embolism
- Congenital heart disease
- Methaemoglobinaemia / sulfhaemoglobinaemia / carboxyhaemoglobinaemia
Peripheral Cyanosis
- As for central cyanosis
- Reduced cardiac output
- Vasoconstriction
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