Term
| In Laplace's law how does radius of the limb affect pressure? |
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Definition
The greater the radius, the lower the pressure In other words the bigger the circumference of the limb the lower the pressure |
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Term
| Describe a simple method of determining the stiffness of a material (Partsch) |
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Definition
| By measuring the difference from the supine to standing position |
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Term
During walking are higher pressures obtained with elastic or inelastic material? When lying down which material shows a greater reduction in pressure? Why is this clinically relevant? |
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Definition
| Higher pressure peaks are obtained with inelastic than elastic material when walking. However, when lying down elastic bandages show only a mild reduction of pressure. The greater pressure loss of inelastic material is why these are better tolerated at night. |
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Term
Name the 3 types compression materials defined by elasticity and stretch characteristics Give examples of each |
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Definition
Elastic, long stretch--compression stockings Inelastic, short stretch---multiple bandages consisting of elastic materials become inelastic Nonstretch--Unna boot Circaid
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Term
| What is the advantage of short stretch inelastic materials? |
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Definition
They show a hih working pressure with high peaks during walking that are able to occlude veins intermittantly reducing(not elevating) ambulatory venous hypertension They also have a considerable drop in pressure when the patients lies down |
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Term
| In the supine position, what external pressure is sufficient to reduce venous diameter? |
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Definition
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Term
| Firm compression when applied bilaterally can increase preload of the heart to what degree? |
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Definition
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Term
| What is the mechanism that external compression reduces venous reflux? |
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Definition
| Intermittant occlusion of the incompetent vein not by improving valve function |
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Term
What pressure is needed to occlude leg veins? Supine? Standing? |
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Definition
20mmHg supine 50-70mmHg standing |
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Term
| Name 4 contraindications to compression stockings |
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Definition
ABI < 0.5 Phlegmesia cerulea dolens Uncontrolled congestive heart failure Untreated septic phlebitis |
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Term
| Name three indications for compression shown to have a clear benefit by evidence based studies |
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Definition
- Active venous ulceration
- Prevention of post-thrombotic syndrome after DVT
- Prevention of thromboembolic events after surgery when combined with anticoagulation prophylaxis
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Term
| By what degree does the use of compression stockings reduce the incidence of postthrombotic syndrome in proximal DVT? |
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Definition
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Term
What are the supine venous pressures at the following locations? Small venules Peripheral veins Vena cava |
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Definition
Venules 10-15mmHg Peripheral veins 4-8 mmHg Vena cava 0-2mmHg |
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Term
| What is the standing pressure in veins? |
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Definition
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Term
Do elastic stockings increase or decrease tissue pressure? What is the effect of compression on arterial flow? |
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Definition
Increase! Increases arterial flow with intermittant compression |
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Term
What is the mean incidence of healing an acute venous ulcer with compression after 5 months (Mayberry et al) What is the recurrence in those patients adherent to compression? Not adherent |
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Definition
Mean healing 93% Recurrence with compression 16% Without 100% |
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Term
| What is the disadvantage of short stretch compression? |
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Definition
Needs to be reapplied when pressure drops Up to 40% decrease in pressure within 2 hours due to rapid reduction in limb volume |
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