Chapter 26 Assessment & Management of Patients w/ Vascular Disorders & Problems of Peripheral Circulation Flashcards
Where does the right side of the heart pump blood to?
This side of the heart pumps blood through the lungs into pulmonary circulation
Where does the left side of the heart pump blood to?
This side of the heart pumps blood to all other body tissues via systemic circulation
Function of the Vascular System
Supplies circulatory needs of tissues
Maintains blood flow & BP
Capillary filtration and reabsorption:
-Hemodynamic resistance
-Peripheral vascular regulating
mechanisms
What is the driving force that moves blood through the vascular system?
Ventricular contraction
Pathology of Peripheral Vascular Disorders
Pump failure = inadequate peripheral blood flow
* Heart Failure with reduced ejection fraction (HFrEF or systolic HF)
* Causes accumulation of blood in the lungs, reduced CO, and inadequate arterial blood flow to tissues
* Heart Failure with preserved ejection fraction (HFpEF or diastolic HF)
* Causes systemic venous congestion and reduced CO
Alterations in blood and lymphatic vessels (reducing flow)
* Arterial - damage or blockage to vessels by atherosclerotic plaque, thromboembolus, infection or inflammatory process, etc.
* Venous – thromboembolus obstructing vein, incompetent venous valves, or reduced effectiveness of surrounding muscles
* Lymphatic – tumor, damage from mechanical trauma, or inflammatory process
Circulatory insufficiency of the extremities
* Most disorders results in ischemia and produces symptoms of pain, skin changes, diminished pulses, and possible edema
Disorders & Diseases Seen in Peripheral Arterial Disease
Aneurysms
Aortic dissection
Embolism & Thrombosis
Raynaud’s phenomenon
Disorders & Diseases Seen in Peripheral Venous Disease
Venous Thromboembolism (VTE)
Venous Insufficiency or Postthrombotic Syndrome
Leg Ulcers
Varicose Veins
Physical Assessment of PAD
Areas to assess: Skin color, temperature, pulses
Expected Assessment Findings
-Cool & pale extremities
-Rubor
-Cyanosis
-Loss of hair, brittle nails, dry or scaling skin, atrophy & ulcerations
-Edema
-Gangrenous changes w/prolonged severe ischemia
Where do arteries distribute blood?
Distributes oxygenated blood from the LT side of the heart to the tissues
Arterioles
The smallest arteries that are generally embedded w/in the tissues
Function of Arterioles
Regulate volume & pressure in arterial system
Regulate blood flow to the capillaries
Arteries & Arterioles Wall Composition
3 layers: The intima, media, & adventitia
The Intima
Inner endothelial layer of arterial wall
Function of the Intima
Provides a smooth surface for contact w/moving blood
The Media
Middle layer made up of smooth muscle & elastic tissue
Function of the Media
Gives the vessel considerable strength
Allows to constrict & dilate to accommodate the blood ejected from the heart during each cardiac cycle (stroke volume)
Maintain an even steady blood flow
The Adventitia
Outer layer of connective tissue
Function of the Adventitia
Control diameter of the blood vessel via contracting & relaxing
How do arterioles offer resistance to blood flow?
Altering their diameter
Capillary Wall Composition
Lack smooth muscle & adventitia
Single layer of endothelial cells
What effect does the thin wall composition of capillaries have on circulation?
Permits rapid & efficient transport of nutrients to the cells & removal of metabolic wastes
What effect does a capillary wall’s diameter (5-10 mcm) have on red blood cell passage?
RBCs must alter their shape in order to pass through this blood vessel
As blood passes through tissue capillaries…
…O2 is removed & CO2 is added
What influences a capillary wall’s diameter?
Changes are passive
Influenced by contractile changes in the blood vessels that carry blood to and from the capillary
Precapillary Sphincter
A cuff of smooth muscle (located near arterioles end of capillary) that is responsible for controlling capillary blood flow (along w/arteriole)
What is the name of the larger blood vessel that capillaries join to form?
Venule
Where do veins distribute blood?
Carries deoxygenated blood from the tissues to the RT side of the heart
Venous System Equivalents of Arteriolar Vessels
Venules: Arterioles
Veins: Arteries
Vena cava: Aorta
Key Differences in Venous Wall Composition
Walls are thinner & less muscular
Layers are not as well-defined
How does the venous wall being thinner & less muscular affect blood flow?
Allows for the vessel to distend more than arteries
Greater distensibility & compliance allows for larger volumes of blood to remain in the veins under low pressure
SNS Stimulation Effect on Venous Blood Flow
Venoconstriction can reduce venous volume & increase volume of blood in the general circulation
Venoconstriction
Constriction of the veins
What happens when skeletal muscle contraction occurs in the extremities?
Creates the primary pumping action to facilitate venous blood flow back to the heart
Function of Lymphatic Vessels
Collects lymphatic fluid from tissues and organs & transports the fluid to the venous circulation
What are the two main structures of the lymphatic vessel system?
The thoracic duct & the right lymphatic duct
Where does the right lymphatic duct primarily convey lymph?
Conveys lymph primarily from the RT side of the head, neck, thorax, & upper arms
Where does the thoracic duct primarily convey lymph?
Conveys lymph from the remainder of the body
Factors that Affect Adequate Blood Flow
Efficiency of the heart to work as a pump, the patency & responsiveness of the blood vessels, & adequacy of circulating blood vol
Function of the Vascular System
Supplying the circulatory needs of tissue
Maintain blood flow & BP
Providing capillary filtration & reabsorption
Hemodynamic resistance
Factors that Affect The % of Blood Flow Received by Individual Organs
Rate of Tissue Metabolism
Availability of Oxygen
Function of the Tissue
When metabolic requirements increase…
…blood vessels dilate to increase the flow of O2 & nutrients to the tissues
When metabolic requirements decrease…
… vessels constrict & blood flow to the tissues decrease
Activities/Factors that Increase Metabolic Demand
Physical activity
Local heat application
Fever
Infection
Activities/Factors that Decrease Metabolic Demand
Rest/decreased activity
Local cold application
Cooling of the body
Ischemia
Lack of blood supply
What can cause ischemia to occur?
Ischemia can be caused if the blood vessels fail to dilate in response to accommodate for increased metabolic needs
Order of Blood Flow
LT side of the heart-> aorta-> arteries-> arterioles-> capillaries-> venues-> veins-> vena cava-> RT side of the heart
What is the cause of the unidirectional blood flow?
The differences in blood pressure between the arterial & venous system changes
Arterial vs Venous BP
Arterial BP: 100mmHg
Venous BP: 40 mmHg
(Fluid flows from an area of higher pressure->lower press)
When resistance increases…
…a greater press is req to maintain the same degree of flow
What happens if arterial pressure is chronically elevated?
Myocardium atrophies to compensate for the greater contractile force
Factors that Increase Blood Flow
Blood viscosity increases
Diameter of the vessels become greater than normal
Segments of the blood vessel are constricted
Bruit
Adventitious sound of blood flowing via narrowed portion of an artery
Hydrostatic Force
A driving pressure that is generated by the blood pressure
Osmotic Pressure
The pulling force created by plasma proteins
Which type of pressure is exerted at the arterial end of the capillary?
Hydrostatic pressure
Drives fluid out of the capillary-> tissue space
Which type of pressure is exerted at the venous end of the capillary?
Osmotic pressure
Osmotic pressure is greater than hydrostatic pressure->net reabsorption of fluid from the tissue space back into the capillary
Function of the Arterial End of the Capillary
Filtration
What happens to the excess filtrated fluid?
Enters lymphatic circulation
Edema
Accumulation of excess interstitial fluid
Possible Causes of Edema
Damage to capillary walls and subsequent increased permeability
Obstruction of lymphatic drainage
Elevation of venous pressure, or a decrease in plasma protein osmotic force
Function of the Venous End of the Capillary
Reabsorption
The Critical Factor that Determines Resistance in Vascular System
Vessel radius
Which system is responsible for regulating the peripheral vascular system?
SNS
Neurotransmitter responsible for SNS vasoconstriction
Norepinephrine
Increase in SNS activity causes vasodilation or vasoconstriction?
Vasoconstriction
Decrease in SNS activity causes vasodilation or vasoconstriction?
Vasodilation
What is formed from the interaction of renin & angiotensinogen?
Angiotensin I
Which organ is renin synthesized by?
The kidneys
What is angiotensin-converting enzyme (ACE) responsible for?
Converting angiotensin I-> angiotensin II
Is angiotensin II a potent vasodilator or vasoconstrictor?
It is a potent vasoconstrictor (especially arterioles)
Proinflammatory Cytokines
Substances liberated from platelets that aggregate at the damaged vessel site, causing arteriolar vasoconstriction & continued platelet aggregation at injury site
When does inadequate peripheral blood flow occur?
This occurs when the heart’s pumping action becomes inefficient
What does heart failure (HF) w/ reduced LT ventricular ejection fraction cause?
Causes an accumulation of blood in the lungs & reduction of forward flow (CO) -> inadequate arterial blood flow to the tissues
Which type of heart failure is characterized by a REDUCED LT ventricular ejection fraction?
Systolic HF (HFrEF)
What does heart failure (HF) w/ PRESERVED LT ventricular ejection fraction cause?
Causes systemic venous congestion & reduced CO (forward flow)
What type of heart failure is characterized by a PRESERVED LT ventricular ejection fraction?
Diastolic HF (HFpEF)
Thromboembolus
A blood clot that may have been dislodged from the vessel where it originally formed
Effects of a Sudden Arterial Occlusion vs. a Gradual Arterial Occlusion
Sudden: Can cause profound and irreversible tissue ischemia & tissue death
Gradual: Less risk of sudden tissue death due to collateral circulation that may develop-> giving the tissue time to adapt to gradually decreasing blood flow
Factors that Reduce Venous Blood Flow
Thromboembolus obstructing a vein
Incompetent venous valves
Reduction in the effectiveness of surrounding muscle pumping action
Effects of Reduced Venous Blood Flow
Increased venous pressure
Subsequent increase in capillary hydrostatic pressure
Increase of net filtration of fluid out of the capillaries-> interstitial space
Increase in subsequent edema
Gerontological Considerations for Venous Blood Flow
Cellular proliferation & fibrosis-> intima thickens
Elastin fibers of media become calcified, thin, & fragmented
Overall changes cause vessels to stiffen-:
- Increased peripheral resistance
- Impaired blood flow
- Increased ventricular workload-> hypertrophy, ischemia, systolic HF
General Arterial Insufficiency Characteristics
Pain: Intermittent claudication to sharp, unrelenting, constant pain
Pulses: Diminished/absent
Skin:
-Color: Dependent rubor w/ elevation pallor of foot
-Texture: Shiny, dry skin w/ cool to cold temp
-Hair: Loss os har over toes & dorsum of foot
-Nails thickened & ridged
General Venous Insufficiency Characteristics
Pain: Aching, throbbing, cramping
Pulses: Present but may be diff to palpate due to edema
Skin:
-Color: Pigmentation in area of medial & lateral malleolus, may be red & blue (freq associated w/dermatitis)
-Texture: Skin thickened & tough
Arterial Insufficiency Ulcer Characteristics
Location: Tip of toes, web spaces, heel or other pressure points if pt is immobile
Pain: Very painful
Depth of ulcer: Deep, often involving joint space
Shape: Circular
Ulcer base: Pale to black & wet to dry gangrene
Leg edema: Minimal unless kept in dependent position constantly to relieve pain
Venous Insufficiency Ulcer Characteristics
Location: Medial malleolus, lateral malleolus, or anterior tibial area
Pain: Minimal to very painful
Depth: Superficial
Shape: Irregular border
Ulcer base: Granulation tissue
-Beefy red to yellow fibrinous in chronic long-term ulcer
Leg edema: Moderate to severe
Intermittent Claudication
Pain, discomfort, or fatigue is caused by the inability of the arterial system to provide adequate blood flow to the tissues in face of increased demands for nutrients & O2 during exercise
-Described as aching, cramping, or inducing fatigue or weakness that occurs w/some degree of activity
What position can help alleviate intermittent claudication pain?
Placing the extremity in a dependent position reduces the pain
-Some patients may sleep w/affected leg hanging over the side of the bed or sleep in a reclining chair