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Understanding Ultrasound Physics/Edelman Ch 18
Understanding Ultrasound Physics
78
Medical
Professional
09/27/2010

Term
 Hemodynamics
Definition
 The study of blood moving through the circulatory system
Term
 Any volume divided by time(L/min, ml/s, etc)
Definition
 Flow is reported in what units?
Term
 FlowVolume Flow Rate
Definition
 This indicates the volume off blood moving during a particular time; it answers the question, "How much?"
Term
 Velocity
Definition
 This indicates the speed of a fluid moving from one location to another; it answers the question, "How fast?"
Term
 Any distance divided by time(cm/s, m/min, etc)
Definition
 Velocity is reported in what units?
Term
 Flow
Definition
 The following are forms of what?- pulsatile - phasic- steady
Term
 Pulsatile Flow
Definition
 This occurs when blood moves with variable velocity resulting from cardiac contraction (ex: arterial circulation)
Term
 Phasic Flow
Definition
 This occurs when blood moves with a variable velocity resulting from respiration (ex: venous circulation)
Term
Definition
 This occurs when blood moves at a constant velocity (ex: venous circulation when breathing stops for a moment)
Term
 Laminar Flow
Definition
 What kind of flow exists when flows are aligned and parallel
Term
 Laminar Flow
Definition
 The following are two forms of what?- Plug Flow- Parabolic Flow
Term
 Plug Flow
Definition
 This type of laminar flow occurs when all of the layers and blood cells travel at the same velocity
Term
 Parabolic Flow
Definition
 This type of laminar flow occurs when velocity is highest in the center of the lumen and weakest at the vessel wall
Term
 Is plug flow and parabolic flow a normal finding?
Definition
 Yes
Term
 Turbulent Flow
Definition
 What kind of flow exists when chaotic flow pattern - in many directions and many velocities - are present?
Term
 Turbulant Flow converts flow energy into other energy forms such as ___ and ___
Definition
 Sound & Vibration
Term
 Sound associated with turbulent flow is called a ___
Definition
 BruitMurmur
Term
 Vibrations associated with a turbulent flow is called a ___
Definition
 ThrillPalpable Murmur
Term
Definition
 Blood flows when the total fluid energy at one location differs from the total fluid energy at another location. What is this difference in energy called?
Term
 Which statement is more precise?blood flows due to a pressure gradient or blood flows due to an energy gradient
Definition
 Blood flows due to an energy gradient
Term
 The following are forms of what?- kinetic- pressure- gravitational
Definition
 Energy
Term
 Kinetic Energy
Definition
 This form of energy is associated with a moving object. It is determined by the object's mass and it's speed
Term
 Pressure Energy
Definition
 This form of energy is a form of stored or potential energy, which has the ability to perform work
Term
 Gravitational Energy
Definition
 This form of energy is a form of stored or potential energy that is associated with any elevated object.
Term
 How is energy imparted to blood?
Definition
 LV contraction during systole
Term
 As blood flows throughout the body, name three ways its energy is lost
Definition
 1. Viscous Loss2. Frictional Loss3. Inertial Loss
Term
 Viscosity
Definition
 This describes the thickness of a fluid
Term
 High Viscosity
Definition
 More energy is lost with the movement of (high or low?) viscosity fluids.
Term
 Hematocrit
Definition
 The percentage of red blood cells (and other cellular matter) in the blood is called what?
Term
 What is the normal hematocrit level?
Definition
 45%
Term
 What happens to blood viscosity if the hematocrit level drops (anemia)?
Definition
 With lower hematocrit levels, blood has reduced viscosity
Term
 Frictional Energy Loss
Definition
 This form of energy loss occurs when flow energy is converted to heat as one object rubs against another
Term
 Viscous Energy Loss
Definition
 This form of energy loss occurs when blood overcomes its own internal stickiness
Term
 Inertial Energy Loss
Definition
 This form of energy loss occurs when the speed of a fluid changes (regardless of whether it accelerates or decelerates)
Term
 Inertial Energy Loss
Definition
 What form of energy loss occurs at these three events:- pulsatile flow- phasic flow- stenosis
Term
 In a stenotic vessel, where does maximal velocity occur?
Definition
 At the vessel's narrowest point
Term
 In a stenotic vessel, where does reduced velocity occur?
Definition
 Beyond the vessel's narrowest point
Term
 A narrowing in the lumen of a blood vessel is called what?
Definition
 Stenosis
Term
 How does stenosis effect flow direction?
Definition
 Flow direction can change (turbulence) as blood flows through the narrowing
Term
 How does stenosis effect flow velocity?
Definition
 Velocity increases flowing into the narrowing and decreases past the narrowing
Term
 How does stenosis effect pressure?
Definition
 Increased pressure at the narrowing, decreased pressure past the narrowing (pressure gradient)
Term
 How does stenosis effect flow pattern (pulsatile, phasic, steady)?
Definition
 Pulsatile flow pattern converts to a steady flow pattern
Term
 With a flow OR resistence increase, what will happen to pressure gradient?
Definition
Term
 With a pressure gradient increase OR a resistance decrease, what will happen to flow?
Definition
 Flow Decrease
Term
 The ___ the pressure difference, the ___ the flow rate
Definition
 Greater
Term
 What is the formula for calculating pressure gradient?
Definition
 PG = Flow x Resistance
Term
 The pressure gradient formula is similar to what other formula?
Definition
 Ohm's Law (voltage = current x resistance)
Term
 Vein walls are (thick|thin) and (collapsible|noncollapsible)
Definition
 ThinCollapsible
Term
 During normal function, veins are (high|low) pressure and (fully|partially) filled
Definition
 LowPartially
Term
 The cross-sectional shape of a vein during normal function is ___
Definition
 Flattened & Hourglass Shaped
Term
 Are veins typically low or high resistance vessels?
Definition
 Low Resistance (like arteries)
Term
 How can veins handle a large volume increase without a similar increase in pressure?
Definition
 Cross-sectional shape can increase to oval and then circle
Term
 Normal veins increase flow to the heart with a (large|small) increase in pressure
Definition
 Small
Term
 The shape and volume of veins are determined by the pressure acting to expand them. What is this pressure called?
Definition
 Transmural Pressure
Term
 After what point do venous pressures attain their highest levels?
Definition
 After veins are stretched to their maximum dimension
Term
 Hydrostatic Pressure
Definition
 The weight of blood pressing on a vessel measured at a height above or below heart level
Term
 Hydrostatic pressure is reported in what units?
Definition
 mmHg
Term
 Blood pressure is accurately assessed when taken where?
Definition
 At the level of the heart
Term
 When blood pressure is taken above or below the level of the heart, ___ pressure introduces ___ into the measurement
Definition
 Hydrostatic PressureError
Term
 When blood pressure is taken above the level of the heart, the measurement is too (high|low) due to ___
Definition
 LowHydrostatic Pressure
Term
 When blood pressure is taken below the level of the heart, the measurement is too (high|low) due to ___
Definition
 HighHydrostatic Pressure
Term
 What is the hydrostatic pressure of a patient in the supine position?
Definition
 0 mmHg
Term
 Is a blood pressure measured anywhere on a supine patient accurate?
Definition
 Yes
Term
 A supine patient's arterial BP (measured at the arm) is 140 mmHg. What is the hydrostatic pressure at all locations within the arterial circulation?
Definition
 0 mmHg
Term
 140 mmHg
Definition
 A supine patient's arterial BP (measured at the arm) is 140 mmHg. What is the arterial pressure at their knee?
Term
 A supine patient's arterial BP (measured at the arm) is 140 mmHg. What is the arterial pressure in their carotid artery?
Definition
 140 mmHg
Term
 In a standing patient, where are negative hydrostatic pressures found? Positive hydrostatic pressures?
Definition
 - Above the level of the heart+ Below the level of the heart
Term
 Measured BP is a combination of what two other measurable pressures?
Definition
 Circulatory Pressure + Hydrostatic Pressure
Term
 Downward movement of the diaphragm occurs during what portion of the respiration process?
Definition
 Inspiration
Term
 Upward movement of the diaphragm occurs during what portion of the respiration process?
Definition
 Expiration
Term
 What occurs to thoracic blood pressure and blood flow during inspiration?
Definition
 1. Thoracic pressure decreases 2. Thoracic venous flow increases
Term
 What occurs to thoracic blood pressure and blood flow during expiration?
Definition
 1. Thoracic pressure increases2. Thoracic venous flow decreaese
Term
 What occurs to lower body blood pressure and blood flow during inspiration?
Definition
 1. Lower body pressure increases 2. Lower body venous flow decreases
Term
 What occurs to lower body blood pressure and blood flow during expiration?
Definition
 1. Lower body pressure decreases2. Lower body venous flow increases
Term
 What happens to venous flow in the legs during inspiration?
Definition
 Decreases
Term
 All of the following occur during expiration except:A. venous return to the heart decreasesB. venous flow in the legs increasesC. abdominal pressure increasesD. diaphragm rises into the thoracic cavity
Definition
 C. abdominal pressure increases
Term
 When venous flow in the leg decreases, venous return to the heart ___
Definition
 Increases
Term
 When venous flow in the leg increases, venous return to the heart ___
Definition
 Decreases
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