EFFECT OF FOOT COMPRESSION ON THE VELOCITY AND THE VOLUME OF BLOOD FLOW IN THE DEEP VEINS
B. Andrews, K Sommerville, S Austin, N. Wilson and N. L. Browse |
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| The A-V Impulse System reduces the incidence of deep vein thrombosis by pneumatically compressing the venae comitantes of the lateral plantar artery, causing an increase in the velocity of blood in the proximal axial veins. Using a duplex scanner the effects of altering the pressure, pulse duration andfrequency of foot compression on the velocity and volume of blood flow in the superficial femoral and popliteal veins were quantified. In 20 legs, foot compression of 50, 125 and 200 mmHg significantly increased the maximum venous bloodflow by 9.0, 13.4 and 15.1 ml/s respectively (P < 0.001). | Conversely, reducing the frequency of compression from 6 to 3 cycles per min significantly increased the rise in peak flow from 10.1 to 14.8 ml/s (P < 0.001). Changing the duration of compression from 1 to 3 s had no significant effect on peak flow. Increased blood flow is best achieved with high-pressure low-frequency foot compression. Increasing the duration of compression beyond 1 s has no effect on augmentation of flow in the deep veins. |
| MEASUREMENT OF FEMORAL VEIN BLOOD FLOW DURING TOTAL HIP REPLACEMENT
DUPLEX ULTRASOUND IMAGING WITH AND WITHOUT THE USE OF A FOOT PUMP
UNIVERSITY OF BRISTOL AND THE AVON ORTHOPAEDIC CENTRE, BRISTOL, ENGLAND |
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| We examined ten femoral veins with duplex ultrasound during total hip replacement to demonstrate the operative manoeuvres which cause venous obstruction and to assess prophylactic measures which may overcome it.
Exposure of the acetabulum by distraction of the femur, with a hook was less likely to occlude flow than retraction with bone levers. |
Adequate exposure of the femoral shaft by adduction, flexion and either internal or external rotation caused cessation of flow in all cases. In four cases an A-V Impulse System foot pump was activated during periods of stasis. In each case it overcame the obstruction and produced peak velocities which were twice that of the resting state.
In five cases, towards the end of the procedure, debris was seen travelling proximally through the femoral vein. |
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