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78 Cards in this Set
- Front
- Back
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What is normal SBP/DBP?
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120/80
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How does bp change in Arteriosclerosis?
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Systolic BP increases mostly
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How does bp change in arteriosclerosis?
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Pulse pressure is decreased due to a very low systolic bp
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Why does Aortic stenosis cause a reduced pulse pressure?
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Because the valve is stiff and less blood is ejected
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What are 2 conditions where pulse pressure is increased due to both increased SBP and decreased DBP?
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-PDA
-Aortic regurgitation |
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How do you most accurately measure pulse pressure?
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By catheterization
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What is the "Windkessel effect"?
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The role of the elasticity of the aorta and large vessels to absorb the pulsatile volume and move bloodflow forward from the heart.
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What happens to pulse pressure as the pulse wave travels from large to smaller arteries?
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It gets dampened
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What are the 2 reasons for pulse damping?
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1. Vascular resistance
2. Vascular compliance |
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So what IS damping?
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The product of resistance and compliance
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What happens BP in most people as they age?
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It increases - particularly Systolic BP
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Is increasing BP with age normal?
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NO - it just shows that lots of old people have diseased vessels.
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How do you calculate MAP?
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2DBP + SBP
MAP = --------- 3 |
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Why are Veins extremely important? (2 reasons)
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1. They can constrict/enlarge, so can store & make blood available quickly
2. They return blood to the heart, which is necessary for CO |
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What is the balance that regulates RAP?
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1. RH's ability to pump out
2. Tendency for blood to flow INTO the right heart via veins |
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What is normal RAP?
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0 mm Hg
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What is RAP in a failing heart?
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20-30 mm Hg
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What is RAP when the heart is pumping vigorously but venous return is limited?
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-3 to -5 mm Hg
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Why is it important to realize that the veins are blood reservoirs?
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Because where the blood is determines what CO will be
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What happens to blood on a very hot day?
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It pulls in the venous plexus of the skin to help cool the body.
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What happens to CO as a result of veinous pooling in skin veins on a hot day?
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CO decreases a lot due to decrease veinous return
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Where are the veins most prone to collapse?
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In the thorax
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What is the avg pressure in the peripheral veins?
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ABout 4-6 mm Hg higher than in the Right atrium
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What happens to your blood as you stand in the same place for a long time?
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It pulls in your veins
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What is veinous pressure at
-The feet -Sagittal sinus |
Feet = 90 mm Hg
Sagittal Sinus = -10 mm Hg |
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What is arterial pressure at the feet?
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190 mm Hg
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Why is arterial pressure so high in the feet?
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Due to the weight of that column of blood under gravitational pressure, pressing down.
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Why doesn't blood normally pool in lower extremities and balloon out the veins?
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Because the veins act as a pump to return blood back to the heart!
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What happens to the pressure gradient in your vessels when you lie down?
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It goes away!
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Why do we say bp in the brain is NEGATIVE?
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Because the heart is the reference zero level
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What ALLOWS the veins to act as blood pumps to return it to the heart? (3 things)
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1. Valves
2. Leg muscles 3. Leg movement |
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What would happen if our leg veins did not have valves?
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The veins in our feet would have a pressure of 90 mm Hg
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What happens if there is no leg movement?
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The capillary pressure in legs elevates results in increased filtration of plasma fluid.
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How much of the blood volume can seep into the leg interstitium with only 15 minutes of standing still?
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10-20%!
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What is the most direct way to measure pressure in a vessel?
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Catheterize
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How do you measure pressure in the left heart?
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By introducing a catheter into the brachial/femoral artery and pass it retrograde into the ventricle.
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How do you know when you get to the left ventricle?
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Because of the pressure drop
-Aorta = 120/80 -LV = 120/5 |
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How do you measure pressure in the right heart?
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1. Introduce catheter into vein
2. Advance into the right atrium 3. Detect RAP of 0 |
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How do you measure pulmonary artery pressure?
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Push the catheter through the right ventricle into the pulmonary artery
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What do you measure when you push a catheter through the right ventricle and pulmonary artery until you can't push it anymore?
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Pulmonary wedge pressure
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What is the most common way to measure blood pressure?
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By the Auscultatory method
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What is the basis for the Auscultatory method?
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The fact that you can HEAR bloodflow
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What happens as you increase the cuff pressure?
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You're increasing transmural pressure until the artery collapses.
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What do you hear when the artery collapses?
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Nothing
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What happens as you deflate the cuff?
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You decrease transmural pressure until the point where the systolic pressure in the vessel is able to flow through the weakening constriction again.
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What is the difference in quality of the Systolic and diastolic pressure?
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Systolic = sharp/tapping
Diastolic = Muffled |
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What are the sounds generated by the auscultatory method called?
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Korotkoff sounds
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What is the reference point for circulatory pressure measurement? Why?
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The triscupid valve - because this level is relatively independent of body position - gravity has little effect on pressure here.
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What is another method for indirect BP measurement other than Auscultatory?
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Oscillometric
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What is the basis of Oscillometric measurement?
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Doppler - using an ultrasonic transducer to detect movement of the arterial wall
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Why is radio-opaque fluoroscopy used during catheterization for direct pressure measurements?
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To be able to see where the catheter is as you're inserting it.
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What should Right atrial pressure be?
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About 0 mm Hg
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What is the normal SBP/DBP in the right ventricle?
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20/0 mm Hg
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What is the normal pulmonary artery pressure?
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20/5 mm Hg
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What is the normal Pulmonary wedge pressure?
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5-10 mm Hg
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What is the normal Left Atrial pressure?
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5-10 mm Hg!
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What is the normal Left Ventricular Pressure?
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120/5
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What is the normal aortic pressure?
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120/80
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What is Pulmonary wedge pressure used to determine? Why?
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Left atrial pressure - because left heart catheterization is much riskier and this allows for accurate measurement.
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What is a common way to measure cardiac output?
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Thermodilution
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What is the basis of thermodilution?
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You inject a really cold substance and measure its flow past a temp sensor; the temp gradient is plotted; the area of deviation is proportional to Cardiac output.
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What is the drawback of the thermodilution method?
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It only measures cardiac output at that one moment in time; CO changes constantly so it's not necessarily really accurate.
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So the two dilution principle methods for measuring CO are:
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-Thermodilution
-Dye dilution |
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What is the more common and easier way to measure CO?
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Fick's principle
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What is the normal O2 content in the blood in the veins? Arteries?
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Veinous Content O2 = 160 ml/L
Arterial Content O2 = 200 ml/L |
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How much oxygen is normally taken up at the lungs?
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200 ml/min
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So how do you calculate CO using Fick's principle?
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Q160 + 200 = Q200
Q = 200/40 = 5L/min |
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What is Intra-aortic balloon pumping?
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A way to support circulation by putting a balloon into the aorta
-During systole deflate -During diastole inflate Decreases |
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How is Intra-aortic balloon pumping done? What is its result?
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-During systole deflate
-During diastole inflate -Just as systole starts, suck air into balloon, pulling blood into the left ventricle. |
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What is the major effect of Intra-aortic balloon pumping?
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Decreases afterload - makes it negative, and makes it easier for the heart to pump.
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What is Radionuclide imaging used to measure?
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Heart function
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What do you know if the heart doesn't take up radiolabeled isotope?
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It's ischemic
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What is a totally noninvasive way to measure cardiac function?
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Echocardiography
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What is the basis of echocardiography?
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Measurement of sound waves to generate functional and anatomical information.
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What is M-mode used for?
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Seeing in 2 dimensions
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What does M-mode allow you to see?
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If the valves are closing, etc... 2 dimensions.
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What can X-ray really show?
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Increased heart mass in cardiac failure
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Why does heart mass increase in cardiac failure?
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Because the body tries to increase stroke volume by increasing preload; but as the heart works harder, the muscle hypertrophies.
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