hemodynamics test and edelman chapter 18- test 1 Flashcards
hemo means
blood
dynamics means
power
hemodynamics means _________
“The study of blood circulation”
FLUID CHARACTERISTICS
Density definition
mass per unit volume (g/ml)
FLUID CHARACTERISTICS
mass definition
measure of an objects resistance to acceleration (inertia)
FLUID CHARACTERISTICS
viscosity definition
resistance to flow offered by a fluid in motion
(poise = 1 g/cm/s)
blood 50% higher than water
viscosity units
poise
1 poise = 1g/cm or .1kg/m
blood is a __________ fluid
Viscous
what does Viscous fluid mean
flows and conforms to the
shape of its container
blood consist of (breakdown of blood)
Consists of :
-Plasma (60%) - liquid component; water (90%) proteins, glucose, ions, hormones, & gases
-RBC - erythrocytes; contain hemoglobin for transporting oxygen
-WBC – leukocytes (five types); protect the body against disease
-Platelets - result from cell fragmentation within bone marrow; carry chemicals important to clotting
2 types of circulatory systems
Systemic - “peripheral circulation”
Pulmonary - “central circulation”
“peripheral circulation” aka
Systemic
characterized by high pressure and high resistance
“no room for all this blood!”
“peripheral circulation” aka systemic
“central circulation” aka
Pulmonary
characterized by low pressure and low Resistance
“I have room, feed me!”
“central circulation” aka pulmonary
___________ = Force exerted by the blood against the vessel wall
pressure
_____________= Opposition to flow (affected by the visocity of fluid, diameter and length of the vessel)
resistance
_______= the volume of blood passing through a vessel
flow
_________ Equation which says that flow in a long straight tube (vessel) is determined not only by the pressure difference, but also by any resistance to flow
Poiseuille’s
Used in understanding flow through long vessels as it moves away from the heart
volumetric flow rate
Q (volumetric flow rate = Δ Pressure/Resistance
Poiseuille’s Equation
if pressure difference increases then flow rate would ___________
increase
if diameter of vessel increases then flow rate would ________
increase
If length of vessel increases then flow rate would _________
decrease
if viscosity increases then flow rate would ____________
decrease
what rule
under conditions of constant flow, velocity must 🡩 to allow the same flow through a smaller space
Continuity Rule
Q= Cross-Sectional Area X Velocity
what does the Q stand for
Two types of NORMAL, laminar flow:
Plug flow
Parabolic flow aka laminar flow
when does plug flow happen and what is it
at the beginning of vessels. its when all the blood is moving at the same rate
what is parabolic/laminar flow?
when blood moves at different rate/velocity in a vessel. sides get slowed down while center is faster
3 patterns of flow
normal
disturbed
turbulent
disturbed flow is still considered a type of _________ flow
laminar
when can disturbed flow happen?
occurs during any change that keeps the blood moving forwards but the normal laminar flow lines are interrupted
Occurs at the:
Branching to smaller vessels
Curvature of a vessel
Obstruction in a vessel
Diverging cross-section
Localized slow rotation of concentric blood layers
Rotation creates regions of reversed flow
Occurs at bifurcations, widening vessels, and distal to an obstruction
EDDY FLOW
Area of stagnant flow divides the circular motion of eddy flow from the central region of high-velocity flow
Likelihood of turbulence is expressed by _________ number
Reynold’s
Reynolds number increases above __________ in a smooth vessel, TURBULENCE WILL OCCUR
2000
Typical volume of blood per minute is ___L/min, called cardiac output
5
Pressure progressively increases/decreases from arterial to venous circulation
decreases
No pulsatility expected in the ____ system
venous
relaxation of the heart is _________
diastole
BP=80 mm Hg
During ________ blood fills each of the atria and begins filling the ventricles.
diastole
________ is the contraction phase
Systole
(BP=90-120 mm Hg)
During ________ phase the right and left ventricle contract, pumping blood to the lungs and body, this occurs several tenths of a second after the right and left atria have contracted.
systole
The various arterial pressure fluctuations give rise to _______ flow in arteries
pulsatile
Pressure changes can result from the heart pump action or from ________ pressure changes in the vessel walls.
static
Arterial vessels are elastic – this allows luminal size to increase with additional pressure. This is called ___________
COMPLIANCE
Filling of the vessel causes additional force (pressure) applied to the blood within the vessel = _______________
STATIC PRESSURE
Areas of stagnation or diverging cross sections (bifurcations) are predisposed to __________________
plaque formation
Associated with degenerative changes in the arterial wall accompanied by lipid and calcium deposits
plaque obstruction
If obstruction is significant enough, volume flow rate will decrease
70 - 90% area = ______________
critical stenosis
Velocity
Dependent on:
-Tube diameter (🡩 velocity with 🡫 in diameter – continuity equation)
-Pressure gradient: In Doppler imaging, if the Pressure difference is INCREASED, flow INCREASES.
Venous return refers to the flow of blood from the periphery back to the ____________
The venous system does not use the heart as a pump but often uses muscle contraction as the driving force (pump)
right atrium.
2 types of viscosity
kinematic viscosity
dynamic viscosity
This type of viscosity is a measure of the resistive flow of a fluid UNDER THE INFLUENCE OF GRAVITY.
kinematic viscosity
Dynamic viscosity, absolute viscosity, or simple viscosity are terms used to distinguish the first quantity.
a type of viscosity
Absolute (dynamic) viscosity: Absolute measures of viscosity determine the force required to move a fluid. Absolute viscosity measurement assesses a fluid’s RESISTANCE TO FLOW under forced-flow conditions.
vs
Kinematic viscosity measures a fluids flowing characteristics resulting from the EFFECT OF GRAVITY on its mass. Measurement of kinematic viscosity addresses a fluids resistance to flow along WITH CONSIDERATION FOR GRAVITY.
Kinematic Viscosity equation
= Absolute Viscosity / Density.
what helps veins return blood back to heart
muscle movement
what is the doppler effect
A change in frequency that happens to ALL waves coming from a moving source.
A change in frequency or wavelength of a wave as a result of relative motion
2 components of sound
pitch
volume
what is pitch
perceived frequency (↑ frequency of a sound ↑ pitch)
what is volume
loudness/amplitude (displayed as brightness)
Blood flow converted into audible sound
Causes frequency “shifts” that are analyzed by the spectral analyzer
Accomplished through the DOPPLER EFFECT
doppler ultrasound
remember the train when it comes to sound
sound emitted by a source traveling TOWARD the observer has a higher frequency than the original transmitted frequency
This perceived frequency is lower when the source is moving AWAY from the observer
3 things you need to compute doppler effect
To computate you need
wave source
observer
reflector
The factor of two seen in any Doppler equation (for a moving reflector or scatterer) is the result of two Doppler shifts.
The first shift occurs when the sound wave strikes the cell—Impact.
The second shift is a result of the moving blood cell reflecting the sound wave back to the transducer—Return.
THINK TENNIS BALL HITTING CAR
Reflected Frequency – Operating Frequency = ???
(2 X Operating frequency (MHz) X reflector speed (m/s) X cos ) / Propagation speed (m/s) = ???
doppler shift
pertaining to doppler shift
if reflector speed increases than Doppler shift
increases
pertaining to doppler shift
if operating frequency increases than Doppler shift
increases
pertaining to doppler shift
if doppler angle increases than Doppler shift
decreases
If the incident frequency is 1 MHz, the propagation speed is 1200 m/s, the reflector speed is 12 m/s towards the source, and the Doppler angle is 5°, what is the Doppler shift?
2 X 1 MHz X 12 m/s X 1 24
_________________________ = _____
1200 m/s 1200
= .02
If the incident frequency is 5 MHz, the propagation speed is 1600 m/s, and the reflector speed is 8 m/s towards the source, the Doppler angle is 90° what is the Doppler shift?
2 X 5 MHz X 8 m/s X 0 = 0
1600 m/s 1600
= 0
The angle between the sound propagation and blood flow directions
doppler angle
Larger/smaller the angle, the smaller the Doppler shift will be for a given flow speed
larger
Optimum Doppler angle is _________
30 ° - 60°
At 90° (perpendicular) Doppler shift is 0 resulting in no spectral analysis or color fill
At 90 ° no information can be obtained because cosine of 90 = 0 and this ruins the Doppler formula
Combination of Doppler with gray-scale imaging is called _________ sonography
duplex
Spectral Doppler (pulsed and CW) measures __________ velocity while Color Flow measures ________ velocity
PEAK, MEAN
The packet size must _______ between accurate velocity measurements and temporal resolution
balance
Able to measure high velocities accurately because sound is on all the time and system is listening all the time.
WHICH TYPE OF ULTRASOUND
continuous wave (CW)
Use of CW means
no damping
Narrow BW
High Q factor
What does high blood pressure in babies mean
something wrong with renal arteries or kidneys
flow vs velocity
flow is how much (volume/time) and velocity how fast (distance/time)
3 basic forms of blood flow are
pulsatile
phasic
steady
pulsatile flow vs phasic flow vs steady flow
pulsatile(accelerated and decelerates) flow is in arteries due to cardiac contraction
phasic flow(accelerated and decelerates) is in veins due to respirations
steady flow is in vein during no respirations
what is laminar flow
lamina means layer
laminar flow is characterized by layers of blood that travel at individual speeds
3 forms of energy associated with blood
kinetic- determined by mass and speed
pressure
gravitational
as blood flows through the circulation energy is lost in 3 ways….
what are the 3 ways and how can they happen
viscous loss- thickness of fluid which is determined by hematocrit. normal is approximately 45%
frictional loss- blood sliding across vessel creates heat
inertial loss- relates to the tendency of a fluid to resist changes in its velocity
Why is the pressure downstream from a stenosis lower than the pressure upstream?
it is a result from the loss of energy as blood moves through the stenosis
bernoulli principle
describes the relationship between velocity and pressure in a moving fluid
hydrostatic pressure
pressure related to the weight of blood pressing on a vessel measured at a height above or below heart level
how do you make hydrostatic pressure zero to get accurate measurements
put a person supine
hydrostatic pressure at different locations
ankle
knee
waist
mid chest top of head
ankle 100mmHg
knee 75mmHg
waist 50mmHg
mid chest 0
top of head -30mmHg
equation for arterial pressure measured
measured pressure= circulatory pressure + hydrostatic pressure
what is the arterial pressure measure in the toe of the upright patient
240mmHg
140 + 100
what is the arterial pressure measured at the standing patients upper arm
140
140 + 0
what is the arterial pressure measured at patients knee
215
140 + 75
normally what happens to venous flow in the legs during inspiration?
A) increase
B) decrease
C) no change
B) decrease
all of the following occur during expiration except
A) venous return to the heart decreases
B) venous flow in the legs increases
C) abdominal pressure increases
D) the diaphragm rises into the thoracic cavity
C) abdominal pressure increases
Pressure produced by:
Contraction of the heart
Static filling pressure
Hydrostatic pressure
when to expect each of them
