Haemodynamics

Question 1

What is the difference between plasma and serum?

Answer 1

plasma is collected from unclotted whole blood. Serum is collected from clotted whole blood (serum= plasma-clotting factors such as fibrinogen)

Question 2

What does the buffy coat contain

Answer 2

WBC and platelets

Question 3

What determines the peripheral resistance of the CVS

Answer 3

vascular tone (how much vasoconstriction)

Question 4

what are causes of sludging of blood in peripheries

Answer 4

most common cause is multiple myeloma

polycythaemia (inc RBCC), thrombocythaemia (inc plat count), leukaemia (inc WBCC)

inc plasma viscosity

Question 5

What are used as a marker for inflammation

Answer 5

minor changes in plasma viscosity due to acute phase plasma proteins such as fibrinogen, complement factors and C-reactive protein.

Question 6

What are the two types of flow and what type does blood usually exhibit

Answer 6

laminar (blood usually is) and turbulent

Question 7

True or false, the velocity of blood in the centre of the vessel is lower than the outer edge in laminar flow

Answer 7

false, the velocity is greatest in the centre creating a parabolic profile

Question 8

what is turbulent flow and when does it occur

Answer 8

blood flowing multidirectional and continually mixing. Occurs when blood flow is too great, makes a sharp turn, passes over a rough surface or faces increased resistance

Question 9

what is it uncommon to find a pulse of the femoral artery in the elderly

Answer 9

calcification of the artery

Question 10

What is a post stenotic dilation

Answer 10

an area of dilation of a vessel following a narrowing (stenosis)

Question 11

What is the peak systolic and end diastolic pressures of the aorta and what does the difference give us.

Answer 11

120/80mmHg difference gives us the pulse pressure which is usually 40mmHg

Question 12

what does the dicrotic notch coincide with

Answer 12

the closure of the aortic valve and the S2 sound (end of systole)

Question 13

What can mean arterial pressure be estimated as

Answer 13

diastolic pressure plus a third of the pulse pressure giving a nominal value of 93mmHg

Question 14

At what mean arterial pressure does organ perfusion become impaired

Answer 14

70mmHg

Question 15

When can retrograde blood flow occur

Answer 15

when peripheral resistance is particularly high

Question 16

What is a pulse

Answer 16

the shockwave that arrives slightly before the blood in a vessel

Question 17

What is the strength or volume of a pulse determined by

Answer 17

the force with which the LV pumps blood. reduced force results in a weak “thready” pulse. increased force (bigger pulse pressure) results in a strong “bounding” pulse.

Question 18

What is a thready/weak pulse a sign of

Answer 18

hypovolaemia (dehydration or bleeding), aortic valve stenosis, LV failure

Question 19

Why does bradycardia lead to a bounding pulse

Answer 19

widens the pulse pressure by increasing diastolic runoff

Question 20

what does a low peripheral resistance do to diastolic pressure and pulse pressure

Answer 20

diastolic pressure would decrease as vasodilation increases. Pulse pressure would increase as end diastolic pressure has decreased

Question 21

Describe how a pulse is taken

Question 22

what does using too small of a BP cuff result in?

Answer 22

higher than normal BP reading, cuff should cover at least 80% of the arm.