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DMST 265 Vascular Sonography 1 > Module 2 Venous hemodynamics > Flashcards

Module 2 Venous hemodynamics Flashcards

1
Q

What is the primary function of the veins?

A

Return nutrient deficient blood back to heart

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2
Q

Veins act a reservior to do what?

A

Maintain homeostasis with 65% blood volume moving through veins at one time

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3
Q

Vein walls can expand and contract depending on what? 3

A
  1. Pressures
  2. Volumes
  3. Flow
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4
Q

The different pressures that effect the vein shape are what? 2

A
  1. Intramural (internal)
  2. Interstitial (external)
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5
Q

What does the veins permit in terms of blood pressure and volume?

A

Increase of blood volume without a significant increase in venous pressure

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6
Q

Veins are less elastic than arteries but more what?

A

Compliant

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7
Q

Veins adapt to changes in blood volume as a result of what? 4

A
  1. Limb position
  2. Muscle pump activity
  3. Venous valve functions
  4. Blood volume
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8
Q

Surplus fluids can be stored or adjusted to what?

A

Blood loss

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9
Q

Veins act similarly to what?

A

Rubber bands and can be stretched and collapsed in a variety of sizes

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10
Q

Extreme fluid overload or severe blood loss will affect what?

A

Central venous pressure

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11
Q

Veins have little resistance to blood flow when in what position?

A

In a supine position

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12
Q

The pressure difference form post capillary vein and the heart is what?

A

Low

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13
Q

Venous flow is affected by what?

A

Posture changes

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14
Q

Venous return to the heart is assisted by what? 4

A
  1. Cardiac cycle
  2. Respiration
  3. Muscles
  4. Valves
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15
Q

Muscular contraction of the heart affects what?

A

Pressure and flow of venous blood

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16
Q

Cardiac activity is evident where? 2

A
  1. Large central veins
  2. Large head and neck veins
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17
Q

Two periods of heart cycle increase venous flow, what are they?

A
  1. Opening of tricuspid valve
  2. Ventricular systole
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18
Q

When the tricuspid valve opens there is more what?

A

Volume in the heart, dropping the pressure

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19
Q

When the right ventricle contracts, what does it do? ( TV, RA, volume)

A
  1. Pulls the tricuspid valve down
  2. Expanding the right atrium
  3. Increasing the volume
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20
Q

What is respirophasicity?

A

Venous flow affected by movement of diaphragm

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21
Q

What are the two phases of breathing?

A

Inspiration and expiration

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22
Q

Effects of breathing vary with what?

A

Position and area of the body

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23
Q

Valsalva maneuver does what?

A

Increases pressure above and below diaphragm

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24
Q

During inspiration what is the diaphragm motion like?

A

Moves inferior

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25
Q

During expiration what is the diaphragm motion?

A

Superior

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26
Q

What is the intra-abdominal pressures during inspiration?

A

Increase

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27
Q

What is the intra-abdominal pressures during expiration?

A

Decrease

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28
Q

What is the intra-thoracic pressure during inspiration?

A

Decrease

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29
Q

What is the intra-thoracic pressures during expiration?

A

Increase

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30
Q

During inspiration what happens to the IVC?

A

Collapses

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31
Q

During expiration what happens to the IVC?

A

Dilates

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32
Q

During inspiration what happens to the lower extremity venous return?

A

Decrease

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33
Q

During expiration what happens to lower extremity venous return?

A

Increase

34
Q

During inspiration what happens to the upper extremity venous return?

A

Increase

35
Q

During Expiration what happens during upper extremity venous return?

A

Decrease

36
Q

Respiration effects can be diminished in what? 2

A
  1. Supine position
  2. Shallow breather
37
Q

Upper extremities can be more pulsatile because of what?

A

Close proximity to the heart

38
Q

Respiration has less of an effect on venous flow when in what position?

A

Venous flow when standing

39
Q

Contraction of voluntary muscles do what for veins?

A

Propels blood towards the heart

40
Q

In the presence of normal functional valves the blood will flow how?

A

In one direction

41
Q

Contraction results in decreased what?

A

Venous pressure by interrupting the hydrostatic column of blood

42
Q

At rest, with no muscle activity what does the veins do?

A

Act as reservoirs for blood collection

43
Q

Muscle contractions results in what in the veins? 3

A
  1. Decreased venous pooling
  2. Decreased capillary pressure
  3. Increased blood flow
44
Q

What does a muscle contraction do in terms of venous flow?

A

Assists in venous flow in the deep and superficial veins is towards the heart

45
Q

What is muscle relaxation in relation to the venous system?

A

Small amount of flow occurs in the perforators, from the superficial to the deep veins

46
Q

What is the calf pump?

A

Contraction of the gastronemius and soleus muscles to most efficiently move blood.

47
Q

What is the calf capacitance high?

A

Generates pressures of about 200 mmHg per contraction

48
Q

What happens in a single contraction of a calf pump?

A

40-60% of the venous volume is ejected

49
Q

What does calf pump do? 2

A

Acts as a venous “heart” and
1. Squeeze the calf veins
2. Propels blood towards the heart.

50
Q

The efficiency of the calf pump is dependent on what? 3

A
  1. Ability of the calf muscles to contract
  2. Competency of the venous valves
  3. Patency of the outflow veins
51
Q

What does the venous valves do?

A

Direct blood flow to the heart and prevent retrograde flow (reflux)

52
Q

What kind of valves are available in venous valves?

A

Bicuspid and arise from the intimal layer

53
Q

Valves in perforation veins do what?

A

Direct flow from the superficial to deep veins

54
Q

At the valve site what happens to the vein?

A

Veins dilate slightly at the sinus and expands with increased pressure

55
Q

Where is a frequent site of thrombi formation due to stagnant flow?

A

Venous valves

56
Q

What impedes Venous return? 2

A
  1. Gravity
  2. Hydrostatic pressure
57
Q

For every 12 inches of vertical distance what happens?

A

22 mmHg of pressure is added

58
Q

What is hydrostatic pressure?

A

The weight of a column of blood at a given point

59
Q

Hydrostatic pressure is relative to what?

A

Right atrial pressure of zero

60
Q

What is hydrostatic pressure above the heart?

A

negative pressure

61
Q

When supine hydrostatic pressure is what?

A

Negligible (about 15 mmHg)

62
Q

When standing the ankle pressure rises to around what?

A

110 mmHg and the legs veins dilate to accept the blood pooling

63
Q

ASVD refers to what?

A

Blood volume

64
Q

When we walk what is the hydrostatic pressures?

A

25 mmHG

65
Q

What does transmural pressure determine?

A

The cross sectional shape of the vein

66
Q

What is transmural pressure?

A

The difference between intraluminal and interstitial pressure

67
Q

Intraluminal pressure is what?

A

The pressure within the vein walls

68
Q

Interstitial pressure is what?

A

The pressure exerted from outside the vein by surrounding tissue and fluid

69
Q

What is low transmural pressure?

A

The vein wall collapses and becomes elliptical in shape

70
Q

What is high transmural pressure?

A

The vein wall becomes circular and may even distend at higher venous pressures

71
Q

What makes intraluminal pressure?

A

Hydrostatic pressure

72
Q

Aside from the images of the vessels, we can identify normal and abnormal venous returns by evaluating what?

A

Doppler waveforms

73
Q

What is respirophasic?

A

When antegrade flow between the upper and lower extremity wave form is opposite due to changes in intrathoracic and intra-abdominal pressure.

The appearances between upper and lower extremities can be the same but the difference is with inspiration/ expiration.

74
Q

When a valsalva maneuver is performed what happens to intra-abdominal and intrathoracic pressure? What results from this?

A

Increased thoracic and abdominal pressure which in turn increases the pressure in both the upper and lower extremity veins

75
Q

During valsalva maneuver flow should do what?

A

It should stop or diminish in upper and lower extremities

76
Q

During valsalva maneuver release of breath will do what to flow?

A

Increase or augment flow

77
Q

Abnormal response is a reverse of flow during what?

A

Valsalva

78
Q

Some abnormal venous waveforms we will encounter are what? 3

A
  1. Continuously
  2. Pulsation
  3. Reflux
79
Q

What is the abnormal waveform of continuous?

A

A lack of respirophasicity usually the result of a more proximal obstruction from a clot or extrinsic mass

80
Q

What is the abnormal waveform of pulsatile?

A

When the heart beat is reflected into vessels further from the heart because of increased central venous pressure related to heart conditions

81
Q

What is the abnormal wave form of reflux?

A

Retrograde flow as a result of valve incompetence or Venus distension. A small amount is normal, but if prolonged represents venous insufficiency.

DMST 265 Vascular Sonography 1 (19 decks)

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