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Compression
Compression
17
Medical
Professional
03/12/2008

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Cards

Term
In Laplace's law how does radius of the limb affect pressure?
Definition

The greater the radius, the lower the pressure

In other words the bigger the circumference of the limb the lower the pressure 

Term
Describe a simple method of determining the stiffness of a material (Partsch)
Definition
By measuring the difference from the supine to standing position
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? 

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.
Term

Name the 3 types compression materials defined by elasticity and stretch characteristics

Give examples of each 

Definition

Elastic, long stretch--compression stockings

 

Inelastic, short stretch---multiple bandages consisting of elastic materials become inelastic 

 

Nonstretch--Unna boot Circaid

Term
What is the advantage of short stretch inelastic materials?
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 

Term
In the supine position, what external pressure is sufficient to reduce venous diameter?
Definition
10-15 mmHg
Term
Firm compression when applied bilaterally can increase preload of the heart to what degree?
Definition
Increase by 5%
Term
What is the mechanism that external compression reduces venous reflux?
Definition
Intermittant occlusion of the incompetent vein not by improving valve function
Term

What pressure is needed to occlude leg veins?

Supine? Standing? 

Definition

20mmHg supine

50-70mmHg standing 

Term
Name 4 contraindications to compression stockings
Definition

ABI < 0.5

Phlegmesia cerulea dolens

Uncontrolled congestive heart failure

Untreated septic phlebitis 

Term
Name three indications for compression shown to have a clear benefit by evidence based studies
Definition
  • Active venous ulceration
  • Prevention of post-thrombotic syndrome after DVT
  • Prevention of thromboembolic events after surgery when combined with anticoagulation prophylaxis
Term
By what degree does the use of compression stockings reduce the incidence of postthrombotic syndrome in proximal DVT?
Definition
50%
Term

What are the supine venous pressures at the following locations?

 

Small venules

 

Peripheral veins

 

Vena cava 

Definition

Venules 10-15mmHg

 

Peripheral veins 4-8 mmHg

 

 Vena cava 0-2mmHg 

Term
What is the standing pressure in veins?
Definition
60-90 mmHg
Term

Do elastic stockings increase or decrease tissue pressure?

 

What is the effect of compression on arterial flow? 

Definition

Increase!

 

Increases arterial flow with intermittant compression 

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 

 

 

Definition

Mean healing 93%

 

Recurrence with compression 16%

Without 100% 

Term
What is the disadvantage of short stretch compression?
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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