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Hemodynamic and Doppler > Ch 18 Book > Flashcards

Ch 18 Book Flashcards

1
Q

Hemodynamic

A

study of blood moving through the circulatory system

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2
Q

Flow indicates

Units

A

volume of blood moving during a particular time

liters/min, L/min

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3
Q

Velocity indicates

Units

A

speed or swiftness of a fluid moving from one location to another

cm/s

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4
Q

Pulsatile Flow

A

occurs when blood moves with a variable velocity

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5
Q

Pulsatile Flow: Blood accelerates and decelerates b/c

A

cardiac contraction

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6
Q

Pulsatile Flow: Present in

A

arterial circulation

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7
Q

Phasic flow

A

occurs when blood moves with a variable velocity

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8
Q

Phasic flow: Blood accelerates and decelerates b/c

A

respiration

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9
Q

Phasic flow: Present in

A

venous circulation

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10
Q

Steady Flow

Ex:

A

occurs when a fluid moves at a constant speed or velocity

water flowing through a hose

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11
Q

Steady Flow: Present in

A

venous circulation when individual stop breathing for a brief moment

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12
Q

Laminar flow

A

when the flow streamlines are aligned and parallel

Characterized by layer of blood that travels at individual speeds

Commonly found in normal physiologic status

Silent flow

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13
Q

Laminar flow forms: Plug flow

A

occurs when all of the layers and blood cells travel at same velocity

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14
Q

Laminae flow forms: Parabolic flow

A

has a bullet-shaped profile.

Velocity is highest in the center

Gradually decreases to its minimum at the vessel wall

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15
Q

Turbulent flow

A

characterized as chaotic flow patterns in many different directions and at many speeds

Associated with cardiovascular pathology and elevated blood velocities

Found downstream from stenosis

Converts flow energy into other forms such as sound and vibration

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16
Q

Vortex

A

Small, hurricane like, swirling, rotational patterns appear

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17
Q

Murmur or Bruit

A

Sound associated with turbulence

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18
Q

Thrill

A

associated with turbulence

Described as a palpable murmur

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19
Q

Reynolds number

A

predicts whether flow is laminar or turbulent

2,000 = turbulent

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20
Q

Energy Gradient

A

Blood moves from regions of higher energy to lower energy

Energy is imparted to blood by the contraction of the heart during systole

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21
Q

Kinetic Energy

A

Associated with a moving object

Heavy moving objects have lots of kinetic energy as slow moving objects have little

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22
Q

Kinetic Energy:

Determined by two factors:

A

An object’s mass

The speed at which it moves

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23
Q

Pressure Energy

A

A form of stored or potential energy

Potential energy has the ability to perform work

major form of energy for circulating blood and creates flow by overcoming resistance

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24
Q

Gravitation Energy

Associated with

A

A form of stored or potential energy

elevated object

All elevated objects have stored energy (gravitation energy) that can perform work.

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25
Viscous Energy Loss
Describes the thickness of a fluid More energy is lost with movement of high viscosity Loss is associated with blood overcoming its internal stickiness and determined by the hematocrit
26
Viscous Energy Loss: Hematocrit
percentage of blood made up of red blood cells Normal value is 45% Anemia, hematocrit reduced and blood has a reduced viscosity Units: Poise
27
Frictional Energy Loss
Occur when flow energy is converted to heat as one object rubs against another Blood sliding across vessel walls creates heart
28
Inertial Energy Loss
“Objects at rest tend to stay at rest and objects in motion tend to stay in motion” – Sir Isaac Newton Energy is lost when the speed of a fluid changes, regardless of whether the fluid speeds up or slows down
29
Inertial Energy Loss: Inertia relates to
tendency of a fluid to resist changes in its velocity
30
Inertial energy loss occurs during three events
Pulsatile flow (arterial) Phasic Flow (venous) Velocity changes at a stenosis
31
Inertial Energy Loss: Velocity
Velocity increases as the vessel narrows Maximum velocity exists where the vessel is narrowest Velocity decreases as blood flows out of the stenosis into a vessel segment of normal diameter
32
Stenosis
Narrowing in the lumen of a vessel
33
Stenosis Effects
``` change in flow direction increased velocity as vessel narrows turbulence downstream from the stenosis pressure gradient across the stenosis loss of pulsatility ```
34
Stenosis Effects: increased velocity within the stenosis
highest where vessel is narrowest
35
Stenosis Effect: turbulence downstream from stenosis
post stenotic turbulence Lumen expands more dramatically than the streamlines of blood flow are able to fill it Streamlines are destroyed and turbulence appears Converted to sound (bruit) or vibrations (thrill) or both
36
Stenosis Effect: Pressure gradient across the stenosis
the pressure downstream from the stenosis is lower than the pressure upstream decreases the results from the loss of energy as blood moves through the stenosis
37
Bernoulli's Principle describes
relationship between velocity and pressure in a moving fluid
38
Bernoulli's Principle derived from
the principle of conservation of energy
39
Bernoulli's Principle states
with a steady flow, the sum of all forms of energy is same everywhere The sum of kinetic energy and pressure energy remains constant
40
Bernoulli's Principle: The Law of Conservation of Energy
states that energy is neither created nor destroyed, it is converted from one form to another
41
Arterioles
resistance vessels
42
Pressure gradient =
flow x resistance
43
Pressure gradient increase when either
Flow increases Resistance increases
44
Flow increases when either
Pressure gradient increases Resistance decreases
45
Fluids vs Electricity Fluids: Pressure Electricity: ______
Voltage
46
Fluids vs Electricity Fluids: Flow Electricity: ______
Current
47
Fluids vs Electricity Fluids: Resistance Electricity: ______
Resistance
48
Ohm's Law Units
Voltage = current x resistance Ohms
49
Veins
thin-walled collapsible low pressure: partially filled with blood, partially expanded low resistance vessels
50
Veins during exercise
increases changes from hourglass to oval than round allows veins to accommodate a large volume increases with a very small increase in pressure more round, resistance decreases, increasing outflow toward heart
51
Hydrostatic Pressure Unit
pressure related to the weight of blood pressing on a vessel measured at a height above or below heart level mmHg
52
Hydrostatic Pressure accuracy measured at
level of the heart too high, below the heart too low, above the heart
53
Hydrostatic Pressure- Supine
flat on your back All parts of the body are at the same level as the heart and the pressure is zero everywhere
54
Hydrostatic Pressure - Standing Upright at heart level
pressure 0 measured pressure accurately represents true circulatory pressure
55
Hydrostatic Pressure - Standing below heart level
positive | measured pressure will be higher than the true circulatory pressure
56
Hydrostatic Pressure - Standing above heart level
negative measured pressure will be lower than the true circulatory pressure
57
Respiration affects venous flow for two reasons
Venous system is low pressure Muscles responsible for respiration alter pressures in the thorax and the abdomen
58
Breathing affects two venous flows
Venous flow to legs Venous returns to heart, which comprises venous flow from the head, arms, and flow from the IVC to heart
59
Diaphragm
Responsible for breathing moves up and down, alternating the pressure in thorax and abdomen
60
Inspiration
Diaphragm moves downward towards the abdomen Thoracic pressure decreases Adnominal pressure increases Venous return to the hear increases Venous flow in legs decreases
61
Expiration
Diaphragm moves upward into thorax Thoracic pressure increases Abdominal pressure decreases Venous return to the heart decreases Venous flow in legs increases

Hemodynamic and Doppler (6 decks)

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