Consists of subpapillary and deep dermal venous plexuses in the skin; superficial veins and deep veins
The superficial veins in the lower limb are the long saphenous and short saphenous vein (from "safin" - hidden)
The deep veins are the CFV, SFV, popliteal vein, anterior and posterior tibial veins and peroneal veins
The branches of the LSV at the SFJ are the: epigastric vein, circumflex vein, femoral vein
Intersaphenous communications occur at the (1) LSV (2) Giacomini vein (3) calf plexus (4) SSV (5) direct communicating veins
Venous return
90% of venous blood returns to the heart via deep veins, 10% by superficial veins
Predominanty from the calf muscle pump
Some contribution from diaphragmatic inspiration
An internal venous valve acts as a mechanism to prevent backflow of blood; backpressure from a column of blood allows the valves to close within the vein
During muscle relaxation, negative pressure "sucks" blood from the superficial system to the deep system
Abnormalities of the venous return are caused by one or a combination of four factors
Failure of the calf muscle pump
Venous obstruction (DVT)
Immobilisation
Economy class syndrome
Post surgery
Abdominal
Obesity
Childbirth
Medications
OCP
Oestrogens
Others
Polycythaemia
Hypercoagulability
DIC
Dysfibrinogenia
Tumours
Valvular incompetence with venous reflux
Obesity with compression of the common femoral vein
The end result is that all tributaries will eventually become enlarged
Venous Assessment
Clinical examination: tourniquet test
Doppler flow examination
Photoplethysmography (PPG)
Duplex scanning
Venography (especially for patients ho have had previous surgery or complex DVT)
Physiological venous parameters
Venous pressure
Catheter - transducer - processor - display
Increased flow results in lower pressure
Veins should fill only from arterial circulation, usually ~25 seconds
