Hemodynamics Flashcards
Venous, respiration, low rate, lower pressure are all indicative of what type of flow?
Phasic flow
Arterial, cardiac contraction, high rate, higher pressure are all indicative of what type of flow?
Pulsatile flow
Describes flow or velocity? Volume, how much?, Volume/time, liters/min
Flow
A unitless number indicating whether flow is laminar or turbulent.
Reynold’s number
Laminar or turbulent? Reynolds number less than 1500
Laminar
A Reynold’s number between 1500 and 2000 indicates laminar or turbulent flow?
If it is between 1500 and 2000, it is unknown.
A Reynold’s number greater than 2000 is turbulent or laminar?
Turbulent
A form of potential or stored energy that has the ability to perform work
Pressure energy
Energy associated with a moving object
Kinetic energy
Three forms of energy loss
Frictional loss, the viscous loss, inertial loss
Energy loss when the velocity of the fluid changes, such as occurs at a stenosis.
Inertial loss
At the most narrowed location: velocity is highest, kinetic energy is highest, pressure energy is lowest, law of conservation of energy
Bernoulli’s principal
Equals the weight of blood pressing on the vessel from heart level to the point of measurement.
Hydrostatic pressure
Pressure measured is greater than circulatory pressure because hydrostatic pressure is positive.
Below the heart
Pressure measured is less than circulatory pressure because hydrostatic pressure is negative.
Above the heart
What position is a patient in if hydrostatic pressure is zero at all locations?
Supine patient
What is the hydrostatic pressure at the fingertips with the hand elevated above the head?
-50 mmHg
What is the hydrostatic pressure at the head?
-30 mmHg
What is the hydrostatic pressure at a level even with the heart?
0 mmHg at the heart level
What is the hydrostatic pressure at the knee level?
75 mmHg of hydrostatic pressure at the knee
What is the hydrostatic pressure at the ankle level?
100 mmHg of hydrostatic pressure at the ankle level
What would the patient’s blood-pressure be at the ear level if their true circulatory pressure was 120 mmHg?
Since hydrostatic pressure is -30 mmHg at the ear level, the measurement would be 90 mmHg.
What would the patient’s blood-pressure be at the ankle level if their true circulatory pressure was 120 mmHg?
Since the hydrostatic pressure at the level of the ankle is 100 mmHg, then the measurement of blood pressure at the ankle would be 220 mmHg.
Vessel collapse, when opposing vessel walls touch each other.
Coaptation
Diaphragm moves down,
venous flow from legs decreases, venous return to heart increases
Inhalation – breathe in
Diaphragm moves up,
venous flow from legs increases, venous return to heart decreases
Exhalation – Breathe out
