venous hemodynamics kaye's class

  1. Structural Characteristics of veins
    • -Thin walled
    • -Collapsible
    • -3 layers- intima, media, adventitia – thinner media than arteries
    • -Venules smallest
    • -Valves are an extension of the intimal layer
    • -Bicuspid for unidirectional flow
  2. Perforators
    carry blood from the superficial system to the deep system
  3. Posterior Arch Vein
    has 3 ankle perforators and plays a major role in the development of venous stasis ulcers
  4. Venous Sinuses
    Intracranial and Lower extremity
  5. venous sinuses: intracranial
    spaces between the duramater and periosteum that drain the blood into the IJV- internal jugular vein
  6. venous sinuses: Lower extremity
    dilated channels in soleal and gastrocnemius muscles à drain into the PTV-posterior tibial veins and peroneals veins… major part of the calf pump muscle
  7. Peroneal veins
    empty the lateral leg
  8. PTVs posterior tibial veins
    empties posterior leg
  9. ATVs anterior tibials veins
    empties anterior leg
  10. popliteal vein
    formed from the anterior tibial veins and the tibeoperoneal trunk
  11. femoral vein
    popliteal vein becomes the femoral vein when it passes through the adductor hiatus
  12. CFV common femoral vein
    formed from the joining of the SFV-superficial femoral vein and the PFV- profundal femoris vein
  13. EIV- external iliac vein
    becomes EIV external iliac after passing the inguinal ligament
  14. CIV- common iliac vein
    formed from the joining of the external iliac and the internal iliac vein
  15. inferior vena cava
    formed by the joining of both common iliac veins and at the level of L4-L5 empties into the right atrium
  16. SSV- small saphenous vein or LSV lesser saphenous vein
    ascends the back of the calf
  17. GSV- great saphenous vein
    longest vein in the body originates on the dorsum of the foot and travels medially to the saphenofemoral junction at the level of the common femoral vein
  18. Radial veins
    empties the lateral hand and forearm
  19. Ulnar veins
    empties the medial forearm
  20. Brachial veins
    formed from the confluence of the radial and ulnar veins
  21. Axillary vein
    formed from the confluence of the brachial and basilic vein
  22. Subclavian vein
    formed from the confluence of the axillary vein and cephalic vein
  23. Innominate vein
    formed from the confluence of the subclavian and Internal jugular (brachiocephalic veins)
  24. SVC-superior vena cava
    formed by the confluence of the right and left innominate veins and dumps into the right atrium
  25. Basilica vein
    empties the medial aspect of the arm
  26. Cephalic vein
    empties the lateral aspect of the arm
  27. Venous Valve  Anatomy
    • -Critical role in maintaining proper direction of venous flow
    • -Bicuspid
    • -The number of valves varies according to genetics.
    • -Pressure changes control opening & closing of valves.
    • -Specialized valves, called an Ostial valves
  28. Veins without valves
    • Soleal sinuses
    • EIV external iliac vein (25% have valves)
    • CIV common iliac vein
    • IIV internal iliac vein
    • Innominate veins
    • SVC - superior vena cava
    • IVC (*can occur)
  29. Veins with Valves
    • -GSV great saphenous 12 (most below the knee)
    • -SSV superficial saphenous vein 6-12
    • -Perforators - each contains a valve
    • -PTV -ATV-Pero 7-12
    • -Pop and Fem 1-3 each
    • -CFV  1
    • Jugular 1

    *Variable # in upper veins
  30. Two kinds of pressure exerted on the venous walls
    • Intraluminal pressure
    •           and 
    • Interstitial pressure
  31. The difference between intraluminal and interstitial pressures is called the
    transmural pressure
  32. transmural pressure relates to
    to the volume of the blood that is within the vein at any given time, and as such, the cross-sectional shape of the vein will give you clues as to how much relative pressure there is.
  33. The greater the intraluminal pressure
    the greater the volume of flow, and therefore the larger and more circular the venous cross-sectional appearance will be.
  34. The lower the intraluminal pressure
    the lower the volume of flow will be, and the resulting appearance will become more elliptical or “dumbbell” shaped.
  35. The ability of the veins to accommodate relatively large changes in volume is termed
    compliance
  36. The high degree of compliance that veins exhibit (unlike arteries),
    has a strong influence on venous resistance.
  37. When the volume of flow is high, there is a corresponding high intraluminal pressure.
    When this occurs, the cross-sectional area of the vein will be fully distended (circular).
  38. When there is low intraluminal pressure and a correspondingly low volume of flow (which is the “natural state” of the vein
    because the veins are seldom completely full of blood); the shape of the vein is elliptical (or dumbbell).
  39. Hydrostatic pressure =
    weight of the column of blood extending from the heart to the level where the pressure is being measured.
  40. In an individual who is supine, the hydrostatic pressure is approximately equal to
    0 mmHg
  41. In a standing position, the hydrostatic pressure measured at the ankles is approximately
    100 mmHg
  42. If an extremity is raised above the level of the heart hydrostatic pressure
    decreases
  43. At rest the veins are reservoirs for blood. During physical activity
    the blood is propelled toward the heart.
  44. The calf muscle pump acts as the power source that overcomes the forces of gravity & propels the blood toward the heart
    As the calf muscle pumps & the venous blood is pushed forward, proximal valves are forced open & distal valves close.
  45. In normal venous systems, the contraction of the calf muscles force the blood toward the heart; and the relaxation of the calf muscles allows
    the blood to move from the superficial veins into the deep venous system
  46. Venous valves keep the blood from moving
    When valves are incompetent, flow will be both antegrade and retrograde.
  47. What happens during muscle RELAXATION
    When the calf or leg muscles relax, a potential “space” is created in the deep venous system. This physiologic process reduces pressure in the peripheral venous system, and permits the blood to flow from the superficial veins into the deep system by way of the perforators.
  48. Respiratory activity significantly
    affects venous flow in a recumbent or supine person
  49. Inspiration causes
    the diaphragm to descend or lower. Intrathoracic pressure will increase while intraabdominal pressure decreases; resulting in an increase of the inflow of blood from the arm and head veins, and cessation of the blood flow coming in the lower extremity veins
  50. Expiration causes the
    opposite to occur: Intrathoracic pressure will decrease, leading to an increase in venous flow from the lower extremities and a cessation of flow from the upper extremities.
  51. In the portal vein of an adult there is almost
    no variation of flow with respiration
  52. During the Valsalva maneuver
    As patient performs the Valsalva maneuver, all venous return stops. This causes a decrease in the volume of blood going back to the heart, which results in the loss of the spontaneous common for moral venous waveform
  53. CONTRAINDICATIONS TO PERFORMING THE VALSALVA MANEUVER
    • -Severe coronary artery disease
    • -Acute myocardial infarction
    • -Moderate to severe hypovolemia (decreased blood volume)
  54. Defining the Valsalva Maneuver
    • 1.Patient draws in a deep breath & holds it, & then bears down as if having a bowel movement.
    • 2.Causes a significant elevation of both the intrathoracic and intra-abdominal pressures; thus eliminating the pressure gradient between the thoracic cavity and the peripheral venous circulation. è No gradient = no flow.
    • 3.If all venous waveform signal is lost (i.e. venous flow is halted) & then the venous waveform signal is augmented/enhanced when the patient releases the deep breath…this is a normal response to the Valsalva maneuver & the valves are “competent”
  55. If, when the patient bears down, the venous waveform signal is augmented,
    this is an abnormal response to the Valsalva maneuver, and flow reversal from incompetent valves is indicated.
Author
139shay
ID
348576
Card Set
venous hemodynamics kaye's class
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venous hemodynamics kaye's class
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