Haemodynamics 3

Question 1

What is serum?

Answer 1

Plasma without the clotting factors

Question 2

Clinical use of CRP (c-reactive protein)

Answer 2

Used as a marker for inflammation

Question 3

Serum vs plasma?

Answer 3

Fluid from unclothed blood is plasma and fluid collected from clotted blood is serum

Question 4

What are haemodynamics?

Answer 4

The factors that govern movement of blood from one are of CVS to another

Question 5

What is blood?

Answer 5

Mixture of cells and plasma

Question 6

What ways can blood flow?

Answer 6

Laminar flow and turbulent flow.

Laminar flow is silent, smooth and typical of most vessels. The fluid on the inside moves faster as it has no friction with the endothelium. Maintains energy

Turbulent flow is disorganised and noisey. Energy is lost. Pressure increases beyond a level that flow can match it linearly

Question 7

What is flow?

Answer 7

Volume transferred per unit time (L/min)

Question 8

What is pressure?

Answer 8

Force per unit area measured in mmHg millimetres of mercury

Question 9

How do you change flow?

Answer 9

Either change resistance or pressure gradient

Question 10

What is resistance?

Answer 10

Pressure difference over flow. If flow is maintained under increased resistance then pressure difference must increase

Question 11

What vessels are primarily responsible for total peripheral resistance?:

Answer 11

Arterioles

Question 12

What is velocity?

Answer 12

Distance blood travels in a given time (cm/s)

Question 13

What feature of capillaries makes them good for diffusion other than that they are once cell thick?

Answer 13

They have a vast cross sectional area much greater than the aorta or arteries. This results in reduced velocity and more time for diffusion

Question 14

What is pulse pressure?

Answer 14

Systolic blood pressure minus diastolic blood pressure

Question 15

What is mean arterial pressure?

Answer 15

Average arterial pressure for one cardiac cycle

Diastolic pressure plus one third of pulse pressure

Time weighted calculation

Cardiac output X total peripheral resistance

Question 16

Under what mean arterial pressure value does organ perfusion become impaired?

Answer 16

Below 70mmHg

Question 17

What can increase or decrease pulse pressure?

Answer 17

Exercise or atherosclerosis etc

Question 18

What do you feel when taking a pulse?

Answer 18

The hock wave that arrives just before the blood itself

Question 19

How to lower a strong pulse?

Answer 19

Decrease peripheral resistance- vasodilation

Reduce stroke volume

Slow down the heart

Question 20

How do you change resistance to flow?

Answer 20

Major thing is to change blood vessel diameter

Change length of vessel

Viscosity of blood

Question 21

What is the difference between parallel and series resistance?

Answer 21

Series involves adding the resistance of the vessels while parallel involves adding the conductance of each vessel which is 1/resistance

Question 22

Why does MAP stay relatively constant during exercise?

Answer 22

Peripheral resistance is decreased

Question 23

What is the principle behind blood pressure measurement?

Answer 23

Able to hear turbulence

Question 24

What is the name of the sounds created by blood flow?

Answer 24

Korotkoff sounds

Question 25

How do you take blood pressure manually?

Answer 25

Put cuff just over brachial artery

Increase pressure until flow is occluded

Then slowly release pressure until first korotkoff sound is heard- this is systolic blood pressure .

Continue to release pressure until no ore sound is heard- this is diastolic blood pressure

Question 26

Pointers for taking manual blood pressure?

Answer 26

Ensure cuff is correct size

Measure in both arms. Ensure patient sat comfortable with both feet flat on ground.

Have arm supported and at level of heart. If it is below then the pressure will be higher and if above pressure will be lower.

Repeat several times and mean taken of two closest values.

If patient is lying down its okay as reassure will be the same across the body