Vasc- hemodynamics Flashcards

1
Q

when distended the cross-sectional area of the vein is how much larger than the corresponding artery?

A

3-4 times that of a corresponding artery

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2
Q

veins contain what fraction of the blood in the body?

A

2/3rds

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3
Q

role of calf muscle pump?

A
  • aids in the return of blood from the legs against the force of gravity
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4
Q

what do the muscles act as?

A

a power source

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5
Q

contraction of the calf muscles can generate hoe much pressure?

A

> 200 mmHg

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6
Q

increased hematocrit increases?

A

viscosity

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7
Q

the venous system is what type of pressure system?

A

low pressure system

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8
Q

The venous pressure of the lower limbs is comprised of what 3 main components?

A
  1. hydrostatic (gravitational) pressure
  2. residual pressure
  3. muscular and respiratory pressure
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9
Q

what is hydrostatic pressure?

A
  • due to the height of the venous blood column
  • applies to a patient in a standing position
  • flow from the furthest points (feet) must return to the right atrium
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10
Q

in the lower limbs- the main resistance to flow is due to?

A
  • microcirculation
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11
Q

define residual pressure

A

At the venous end of the capillaries, the venous pressure supplied by the arterial pressure is called residual pressure

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12
Q

purpose of augmentation***?

A

Venous flow can be augmented to observe a large bolus of blood flowing through a vein in an unobstructed vessel

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13
Q

veins are compressible due to?

A
  • a thinner muscular wall

- can rule out clot this way

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14
Q

what affects venous flow? **** (6)

A
  1. Respiratory variations
  2. Cardiac function
  3. Calf muscle pump
  4. Competent venous valves
  5. Venous pressure
  6. Exercise
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15
Q

hereditary risk factors of DVT? *****

A

blood disorders:

Antithrombin deficiencies
Elevated clotting factors
Plasminogen deficiency
Prothrombotic disease

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16
Q

acquired risk factors of DVT?

A
Age,obesity
Advanced malignancy
Recent surgery
Trauma
Immobolization
Pregnancy
O.C. use
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17
Q

what 3 things are included in virchow’s triad?

A
  1. Endothelial damage
  2. Venous stasis (suggests slow blood flow) ex. Long car ride, immobile
  3. Hypercoagulable state
18
Q

S/S of DVT **?

A
  1. Lower extremity swelling
  2. Pain
  3. Positive Homan’s sign-pain on forced dorsiflexion of the foot
19
Q

What is D-dimer test?

A
  • blood test

- measures fibrin degradation products that accumulate in the blood when thrombus forms

20
Q

DVT is unlikely if D-dimer is?

A

negative

21
Q

what can cause a false positive d-dimer? (4)

A
  • not helpful in patients over 80
  • hospitalized
  • pregnant
  • cancer
22
Q

what is acute thrombus look like?

A
  • Faintly echogenic, almost invisible
  • Detected by limited compression and faint visible edge of clot
  • Attached to the vein wall over short-area
  • May have a long snakelike clot swaying back and forth in the lumen
  • These poorly attached clots are a risk for emboli
23
Q

characterization of chronic thrombus?

A
  • complete dissolution of slow over time may occur
  • may become more solid
  • firmer and more echogenic
  • becomes better attached
  • less threat of embolization
  • large collaterals will develop
24
Q

5 complications of DVT?

A
  1. PE
  2. incompetent valves
  3. recurrent DVT
  4. varicose veins
  5. chronic venous insufficiency
25
Q

PE symptoms?

A
  • difficulty breathing
  • chest pain on inspiration
  • palpitations
26
Q

PE clinically?

A
  • low blood oxygen saturation and cyanosis

- rapid breathing and heart rate

27
Q

PE- severe cases?

A
  • collapse
  • abnormally low blood pressure
  • sudden death
28
Q

diagnosis of PE?

A
  • D-dimer
  • CT pulmonary angiography
  • pulse oximetry
29
Q

treatment of PE?

A
  • antigoagulent: heparin and warfarin
30
Q

PE- surgical intervention?

A
  • pulmonary thrombectomy
31
Q

what is often the first test performed when PE is suspected?

A

blood oxygen level

32
Q

The simplest way to measure blood oxygen levels is with a?

A

pulse oximeter

33
Q

what is a pulse oximeter?

A

It is a noninvasive way to monitor the percentage of hemoglobin that is saturated with oxygen

34
Q

what is concidered an abnormal saturation level?

A
  • <95%
35
Q

Post-thrombotic syndrome (PTS)- Vein walls and valves are permanently damaged in what % of cases?

A

60%

36
Q

Chronic venous obstruction & reflux manifests as (3)?

A
  1. chronic leg swelling
  2. ankle pigmentation
  3. ultimately ulcers form
37
Q

Primary varicose veins?

A
  • abnormally dilated and tortuous superficial veins in the absence of deep venous disease
  • History of DVT is rare
  • Result of valvular incompetence at SFJ
38
Q

secondary varicose veins?

A

associated with obstruction (DVT) or incompetence of the deep venous system valves

39
Q

what % of DVT’s occur in upper extremity?

A

10%

40
Q

what is the most common cause of DVT in upper extremity?

A

Placement of a VAD

41
Q

Most common site for central venous access device insertion

A

subclavian veins and IJV