Doppler Principles Flashcards
A steady, continuous stream of something.
Flow
A vector quantity whose magnitude is a body’s speed and whose direction is the body’s direction of motion.
Velocity
A flow with periodic variations
Pulsatile Flow
A flow in which the velocity of the fluid at a particular fixed point does not change with time —called also stationary flow
Steady Flow
Uninterrupted flow in a fluid near a solid boundary in which the direction of flow at every point remains constant
Laminar Flow
The slipping along of a material through a conduit without plastic shear
Plug Flow
The slipping along of a material through a conduit without plastic shear
Plug Flow
Pertaining to flow conditions in blood vessels. Under THIS flow, blood cells in the middle of the vessels move the fastest, with a gradual decrease in flow velocity for points farther away from the center.
Parabolic Flow
A fluid flow in which the velocity at a given point varies erratically in magnitude and direction
Turbulent Flow
Any of several generally abnormal sounds heard on auscultation
Bruit
An abnormal slight tremor associated with a heart or vascular murmur, felt on palpation
Thrill
A number characteristic of the flow of a fluid in a pipe or past an obstruction
Reynold’s Number
Any change in energy over time or space.
Energy Gradient
Energy associated with motion
Kinetic Energy
The action of pressing or pushing against something
Pressure
It’s potential energy associated with the gravitational field.
Gravitational Energy
The resistance to flow offered by a fluid in motion
or The friction existing between contiguous layers of fluidTHIS in blood is 5 times that of water
Viscosity of Fluid
Water has a low viscosity compared to molasses
Pressure and Resistance Relationship
increase Pressure difference –> increases Flow
increase Resistance –> decreases Flow
increase Tube length –> increases Resistance
increase Radius –> decreases Resistance
increase Viscosity –> increases Resistance
Hemodynamics
Energy losses (conversions) in vessels result from flow acceleration (increased velocity), disturbed flow, and turbulence (entrances and exits of stenotic lesions)
As these occur, the resistance of the same vascular segment increases
Describes in the original equation that the radius of a stenosis has more effect than the length of a stenosis because the radius is raised to the 4th power
Poiseuille’s Law
Narrowing of a vessel lumen
Produces disturbed or turbulent flow
Body tries to keep volume flow rate constant - proximal to, in, and distal to a ……..
This is called the Continuity Rule
Stenosis
Explains that fluid moves against a pressure gradient from a point of low pressure to a point of high pressure
Total fluid energy remains the same
Pressure energy is converted to flow energy upon entrance to a stenosis
As flow energy increases, pressure energy decreases (velocity goes up; pressure goes down)
Bernoulli’s Principle
Therefore, if a stenosis has an area measurement that is ½ that of the proximal and distal vessel
The average flow speed within the stenosis is twice that of the proximal and distal ends
The Doppler shift is directly related to flow speed, not volume flow rate
Effects of Stenosis
The pressure that the fluid exerts on the walls of its container.
Hydrostatic Pressure
The act of breathing out
Expiration
The drawing in of breath; inhalation
Inspiration
