venous hemodynamics kaye's class

• -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

carry blood from the superficial system to the deep system

has 3 ankle perforators and plays a major role in the development of venous stasis ulcers

Intracranial and Lower extremity

spaces between the duramater and periosteum that drain the blood into the IJV- internal jugular vein

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

empty the lateral leg

empties posterior leg

empties anterior leg

formed from the anterior tibial veins and the tibeoperoneal trunk

popliteal vein becomes the femoral vein when it passes through the adductor hiatus

formed from the joining of the SFV-superficial femoral vein and the PFV- profundal femoris vein

becomes EIV external iliac after passing the inguinal ligament

formed from the joining of the external iliac and the internal iliac vein

formed by the joining of both common iliac veins and at the level of L4-L5 empties into the right atrium

ascends the back of the calf

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

empties the lateral hand and forearm

empties the medial forearm

formed from the confluence of the radial and ulnar veins

formed from the confluence of the brachial and basilic vein

formed from the confluence of the axillary vein and cephalic vein

formed from the confluence of the subclavian and Internal jugular (brachiocephalic veins)

formed by the confluence of the right and left innominate veins and dumps into the right atrium

empties the medial aspect of the arm

empties the lateral aspect of the arm

• -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

• 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)

• -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

• Intraluminal pressure
•           and 
• Interstitial pressure

transmural pressure

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.

the greater the volume of flow, and therefore the larger and more circular the venous cross-sectional appearance will be.

the lower the volume of flow will be, and the resulting appearance will become more elliptical or “dumbbell” shaped.

compliance

has a strong influence on venous resistance.

When this occurs, the cross-sectional area of the vein will be fully distended (circular).

because the veins are seldom completely full of blood); the shape of the vein is elliptical (or dumbbell).

weight of the column of blood extending from the heart to the level where the pressure is being measured.

0 mmHg

100 mmHg

decreases

the blood is propelled toward the heart.

As the calf muscle pumps & the venous blood is pushed forward, proximal valves are forced open & distal valves close.

the blood to move from the superficial veins into the deep venous system

When valves are incompetent, flow will be both antegrade and retrograde.

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.

affects venous flow in a recumbent or supine person

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

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.

no variation of flow with respiration

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

• -Severe coronary artery disease
• -Acute myocardial infarction
• -Moderate to severe hypovolemia (decreased blood volume)

• 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”

this is an abnormal response to the Valsalva maneuver, and flow reversal from incompetent valves is indicated.