Week 9 - Lesson 1 (Part 4) Flashcards
What do perforators contain?
Valves that may become incompetent
What do perforators provide?
An anastomosis between deep and superficial systems
What do perforators drain?
Superficial blood into deep veins
Where are perforators more numerous?
In the lower leg
- has more valves
What do perforators maintain?
Correct direction of flow
What can larger perforators cause?
Varicosities
- eg) Hunter perforators
What are 5 characteristics of venous flow?
- Spontaneity
- Phasicity
- Augmentation
- Competence of valves
- Absence of pulsatility
What are used to evaluate DVT, SVT and incompetent valves? (3)
- Compression images
- Colour
- Duplex
What modality is the gold standard for imaging the veins?
US
What are 9 sonographic features of normal veins?
- Thin (invisible) wall
- Smooth wall
- Anechoic lumen
- Compressible
- Unidirectional flow toward the heart
- Flow augmentation with distal compression
- Spontaneous flow
- Phasic flow
- Flow ceases with valsalva maneuver
Where does spontaneous flow occur?
In veins closest to the heart
Where is spontaneous flow less frequently seen in?
The popliteal vein
Where is spontaneous flow not seen in?
Calf veins
Where is pressure in veins the lowest?
The furthest away from the heart
What has effects on the venous pressure? (4)
- Augmentation
- Valsalva maneuver
- Pumping the calf muscle
- Respiration
What kind of blood flow occurs in the lower extremities?
Phasic with respiration
What happens to blood flow during inspiration?
It ceases
What happens to blood flow during expiration?
Augments
- increases
What could pulsatility of flow be caused by? (2)
- Right sided heart failure
- The closeness of the veins to the heart
- eg) internal jugular vein flow
What happens to the diaphragm during inhalation?
It descends
What happens to the blood flow during inhalation for lower extremities?
Its impeded
- delayed
Why is the blood flow during inhalation for lower extremities impeded?
Due to the increase in intraabdominal pressure
What happens to the diaphragm during exhalation?
The diaphragm rises
Why does the diaphragm rise during exhalation?
Because intra-abdominal pressure decreases
What is the most important feature to rule out DVT?
Compressibility
- if a clot is in a vein it wont compress
What happens with augmentation?
Flow is dramatically increased
How does augmentation occur?
With manual compression of the calf muscle with your hand
What does augmentation confrim?
Patency of veins between the level where compression occurs and the level where where the probe is situated
Valsalva maneuver
When a patient bears down and an increase in abdominal pressure terminates extremity flow-closes the valves and demonstrates no flow reversal
- this demonstrates competent valves
What does venous valves regulate?
Venous pressure in the distal extremity
Where is a common location for cots to form?
Around veins
What is common after a DVT?
Broken/stuck valves
Rouleaux
Are stacks or aggregations of RBCs that form because of the unique discoid shape of the cells in vertebrates. The flat surface of the discoid RBCs gives them a large surface area to make contact with and stick to each other
- causes sluggish flow
What kinda of patients have rouleaux flow? (2)
- Pregnant
- Diabetics
- can be seen in normal patients also
