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What does the presence of a thrill indicate in a hemodialysis graft?
What does the presence of a thrill indicate in a hemodialysis graft?
What does loss of thrill in a dialysis graft typically suggest?
What does loss of thrill in a dialysis graft typically suggest?
What is the purpose of auscultation in assessing a hemodialysis graft?
What is the purpose of auscultation in assessing a hemodialysis graft?
What might the presence of a bruit in a hemodialysis graft suggest?
What might the presence of a bruit in a hemodialysis graft suggest?
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Which of the following factors typically contributes to creating pallor in a hemodialysis graft assessment?
Which of the following factors typically contributes to creating pallor in a hemodialysis graft assessment?
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What happens to the pressure in the deep venous system once it exceeds the pressure in the superficial system?
What happens to the pressure in the deep venous system once it exceeds the pressure in the superficial system?
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Which characteristic accurately describes the relationship between the pressures in the deep and superficial venous systems?
Which characteristic accurately describes the relationship between the pressures in the deep and superficial venous systems?
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In what manner does the deep venous system affect the superficial venous system under conditions of high pressure?
In what manner does the deep venous system affect the superficial venous system under conditions of high pressure?
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What physiological response occurs in perforators when deep venous pressure is significantly higher than superficial pressure?
What physiological response occurs in perforators when deep venous pressure is significantly higher than superficial pressure?
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Which statement is true regarding venous pressure dynamics?
Which statement is true regarding venous pressure dynamics?
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What could potentially occur if the deep venous system pressure does not exceed superficial system pressure?
What could potentially occur if the deep venous system pressure does not exceed superficial system pressure?
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What effect does consistently higher pressure in the deep venous system have on the superficial venous system?
What effect does consistently higher pressure in the deep venous system have on the superficial venous system?
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What is one possible outcome of perforators dilating?
What is one possible outcome of perforators dilating?
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What happens when perforators constrict?
What happens when perforators constrict?
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Which of the following is true regarding perforators in the vascular system?
Which of the following is true regarding perforators in the vascular system?
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How does dilation of perforators affect blood flow?
How does dilation of perforators affect blood flow?
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What is the significance of flow reversal in the context of perforators constricting?
What is the significance of flow reversal in the context of perforators constricting?
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Which statement is incorrect regarding the roles of perforators?
Which statement is incorrect regarding the roles of perforators?
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In which scenario would perforators likely constrict?
In which scenario would perforators likely constrict?
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Which of the following accurately describes the function of perforators?
Which of the following accurately describes the function of perforators?
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What happens when perforators dilate in relation to flow?
What happens when perforators dilate in relation to flow?
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What happens to antegrade diastolic flow when peripheral resistance decreases?
What happens to antegrade diastolic flow when peripheral resistance decreases?
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During calf muscle relaxation, blood primarily flows from which veins to which?
During calf muscle relaxation, blood primarily flows from which veins to which?
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Which condition is likely to enhance diastolic blood flow in the limbs?
Which condition is likely to enhance diastolic blood flow in the limbs?
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What role do perforators play in blood flow during calf muscle relaxation?
What role do perforators play in blood flow during calf muscle relaxation?
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Which of the following is an effect of decreased peripheral resistance?
Which of the following is an effect of decreased peripheral resistance?
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Which statement best describes the relationship between muscle relaxation and blood flow?
Which statement best describes the relationship between muscle relaxation and blood flow?
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How does increased antegrade diastolic flow affect overall circulation?
How does increased antegrade diastolic flow affect overall circulation?
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What primarily causes the change in blood flow direction during calf muscle relaxation?
What primarily causes the change in blood flow direction during calf muscle relaxation?
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Which physiological process is directly impacted by the relaxation of calf muscles?
Which physiological process is directly impacted by the relaxation of calf muscles?
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What effect does relaxation of calf muscles have on peripheral resistance?
What effect does relaxation of calf muscles have on peripheral resistance?
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How does the pressure within the abdominal cavity change during expiration?
How does the pressure within the abdominal cavity change during expiration?
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What happens to venous flow from the lower extremities during inspiration?
What happens to venous flow from the lower extremities during inspiration?
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What is an indication of normal capillary refill when testing capillary blush?
What is an indication of normal capillary refill when testing capillary blush?
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How does venous flow from the lower extremities respond during expiration?
How does venous flow from the lower extremities respond during expiration?
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Which action should be performed to effectively test the capillary blush response?
Which action should be performed to effectively test the capillary blush response?
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What occurs to pressure within the abdominal cavity during the act of inspiration?
What occurs to pressure within the abdominal cavity during the act of inspiration?
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What effect does the body's position have on venous flow from the lower extremities?
What effect does the body's position have on venous flow from the lower extremities?
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What is the primary factor affecting venous flow during abdominal pressure changes?
What is the primary factor affecting venous flow during abdominal pressure changes?
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Which of the following is NOT associated with capillary blush testing?
Which of the following is NOT associated with capillary blush testing?
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Which of the following correctly describes the venous flow response during abdominal cavity pressure changes?
Which of the following correctly describes the venous flow response during abdominal cavity pressure changes?
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Study Notes
Pressure and Blood Flow
- Hydrostatic pressure: The weight of a blood column within veins when standing is called hydrostatic pressure.
- Systemic blood pressure: Related to arterial pressures in the body.
- Pulmonary pressure: Related to pressure within the pulmonary arteries.
- Poiseuille's Law: Vessel radius is the most significant factor affecting blood flow in a vessel. A small change in radius significantly affects blood flow.
- Potential hemodynamic changes: Factors related to potential hemodynamic changes within a vessel include vessel length, vessel radius, and blood viscosity.
Cardiovascular Applications of Bernoulli's Principle
- Flow separation within the carotid bulb: Bernoulli's Principle explains turbulence and flow separation within the carotid bulb.
- Increased resistance to flow: Bernoulli's principle explains increased resistance to flow at areas with focal stenosis.
- Relationship between vessel radius and flow volume: Explained by Bernoulli's principle.
- Doppler signal aliasing: At high velocities, Bernoulli's principle is the reason for aliasing of the Doppler signal.
Deep Venous System Pressure and Perforators
- Bi-directional flow: Perforators dilate, which leads to bi-directional flow when deep venous system pressure consistently exceeds the superficial system pressure.
Exercise and Lower Extremity Blood Flow
- Vasodilation and Resistance: Exercise causes vasodilation, which concurrently decreases resistance in the lower extremities to meet oxygen demands of the muscles. More blood flow is encouraged distally in the extremities. An increase in diastolic flow is anticipated when peripheral resistance drops.
Calf Muscle Relaxation and Blood Flow
- Blood flow from superficial to deep veins: Calf muscle relaxation causes blood to flow through perforators from the superficial to deep veins, refilling the deep system of veins.
Blood Oxygen Content and Veins
- Pulmonary veins: Carry highly oxygenated blood in the body from the lungs to the left atrium (for systemic circulation).
Response to Valsalva Maneuver
- Femoral vein flow: Flow will stop at the beginning of the Valsalva maneuver; upon release, flow will be slightly augmented towards the heart and will normalize.
Capillary Blush Response
- Pallor and return of normal skin coloring: The capillary blush response is tested by compressing the radial and ulnar arteries to create pallor in the hand, then releasing, to time the return to normal coloring in the hand; longer times indicate arterial problems or obstructions.
- Elevation of the arm: Another method is raising the arm above the head for 60 seconds to produce pallor, then returning to a neutral position to assess time for the return to normal coloring, which assesses possible ischemic disease.
Hemodynamically Significant Stenosis
- Celiac axis diagnosis: Diagnosed with the PSV greater than 2.0 m/s.
- Ultrasound contrast agent and microbubbles: Microbubbles in ultrasound contrast agents increase reflectivity of flowing blood.
Doppler Evaluation for Erectile Dysfunction (ED)
- Cavernous arteries and dorsal veins: Doppler evaluation for ED assesses cavernous arteries and dorsal veins, using pre- and post-medication injections (such as papaverine)
Venous Perforators (Diameter)
- Diameter > 4 mm: Venous perforators with a diameter greater than 4 mm will typically demonstrate reflux.
Renal Artery Stenosis
- Hemodynamic significance: Renal artery stenosis is considered hemodynamically significant when the stenosis is greater than 60%.
Common Femoral Artery Velocity and Stenosis
- Velocity increase and stenosis levels: If the common femoral artery velocity increases from 0.8 m/s to 2.2 m/s, this indicates a 50% stenosis.
Abnormal Response to Papaverine Injection (Impotence Exam)
- PSV and EDV of arterial inflow: PSV and EDV will decrease/decline with papaverine injection.
Renal-Aortic Ratio (RAR)
- Abnormality criteria: RAR is indicated to be abnormal (greater than 3.5) for renal artery stenosis.
Peak Systolic Velocity (PSV)
- SMA stenosis: Hemodynamically significant stenosis of the SMA is diagnosed when the PSV is greater than 2.75 m/s.
Parenchymal Resistance Ratio (PRR)
- Calculation: PRR = EDV (End Diastolic Velocity)/PSV (Peak Systolic Velocity)
- Normal values: PRR should be typically > 0.2; Values < 0.2 suggest increased parenchymal resistance.
Vertebral Artery Stenosis (and Related Symptoms)
- Bilateral Visual Symptoms: Vertebrobasilar disease is commonly associated with bilateral visual symptoms.
Collagen Disorders and Arterial Dissection Risk
- Marfan syndrome and Ehler-Danlos syndrome: These collagen disorders increase the risk of arterial dissection.
Transcutaneous Oximetry
- Normal Value: 70-80 mmHg.
Venous Insufficiency and Pain
- Dependent position: Pain relief from lower extremity venous insufficiency occurs with the legs in a dependent position.
Pulse Volume Recording (PVR) and Revascularization
- Increased amplitude: Following successful revascularization, a prominent increase in amplitude (by >50%) in the PVR tracing is an expected finding.
Popliteal Artery
- Location and Branches: This artery is found in the popliteal fossa, branching into the anterior and tibioperoneal trunks.
- Scan Approach: Best for imaging is positioning the probe posteriorly to the popliteal fossa, where the artery is situated behind the vein.
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Description
Test your understanding of hemodialysis graft assessment with this quiz that covers key concepts such as thrills, bruits, and venous pressure dynamics. Evaluate your knowledge on auscultation techniques and the physiological responses involved in dialysis graft function.
