Session 1-Haemodynamics Flashcards
What is the fluid collected from unclotted blood called?
Plasma
What is the fluid collected from clotted blood called?
Serum
What is serum?
Plasma - clotting factors (in particular fibrinogen)
Which cells are in the buffy coat?
WBCs
Platelets
What is peripheral resistance?
Resistance of the arteries to blood flow ie. as arteries constrict, resistance increases and as they dilate, resistance decreases
What is the commonest cause of increase in plasma viscosity and therefore whole blood viscosity?
Multiple myeloma (cancer of plasma cells)
What is the name of the condition caused by an increase in RBCs?
Polycythaemia
What is the name of the condition caused by an increase in platelets?
Thrombocythaemia
What is the name of the condition caused by an increase in WBCs?
Leukaemia
Complete the sentence:
Marked increase in plasma viscosity can lead to _____________ whole blood viscosity and __________ of blood in peripheries.
Increased
Sludging
What can minor changes in plasma viscosity be a result of?
Raised levels of acute phase plasma proteins
Give examples of acute phase plasma proteins
Fibrinogen
Complement factors
C-reactive protein
What do acute phase proteins increase in response to?
Inflammation
True or false: minor changes in plasma viscosity can be used to ‘measure’ the inflammatory response
TRUE
What is the difference between flow and velocity of blood?
Flow is the volume of blood moving per unit time
Velocity is the distance blood travels per unit time
What are the two types of blood flow?
Laminar
Turbulent
What is laminar flow?
Blood usually flows in streamlines with each layer of blood remaining the same distance from the wall
When laminar flow occurs, velocity of blood in the centre of a vessel is greater than that toward the outer edge. What does this create?
Parabolic profile
What is turbulent flow?
Blood flowing in all directions in the vessel and continually mixing within the vessel
When does turbulent blood flow occur? (4)
1) when rate of blood flow is too great
2) when it passes by an obstruction in a vessel
3) when it makes a sharp turn
4) when it passes over a rough surface
What is the name given to the sound of turbulence in a peripheral artery?
Bruit
What is the name given to the feeling of turbulence?
Thrill
What is pulse pressure?
Peak systolic pressure - end diastolic pressure
How can mean arterial pressure be calculated from a descending aorta pressure tracing?
Area under the graph
How can the mean arterial pressure be estimated?
Diastolic pressure + 1/3 of pulse pressure
What does it mean if the mean arterial pressure falls below 70mmHg?
Organ perfusion is impaired
What is the pulse more accurately described as?
Shock wave that arrives slightly before the blood itself
What determines the strength or volume of the pulse? (2)
1) force with which left ventricle ejects blood into the arterial system
2) pulse pressure
What can reduced pulse volume result from? (3)
1) Left ventricular failure
2) Aortic valve stenosis
3) Hypovolaemia (severe dehydration, bleeding)
What is a pulse with reduced volume described as?
Thready
What is a strong pulse described as?
Bounding
True or false:
Tachycardia widens pulse pressure and leads to a bounding pulse
FALSE - bradycardia (such as heart block), not tachycardia
Complete the sentence:
_____ peripheral resistance lowers diastolic pressure and therefore ____________ pulse pressure
Low
Increases
What are some examples of low peripheral resistance?
Hot bath
Exercise
Pregnancy
What is the pulse obliteration pressure?
Systolic pressure (when pulse disappears)
What does a phase I sound indicate?
Systolic pressure
What does a phase V sound indicate?
Diastolic pressure
