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CVS * > S1 Haemodynamics > Flashcards

S1 Haemodynamics Flashcards

1
Q

What is serum?

A

Plasma without clotting factors

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2
Q

Is plasma viscosity or blood viscosity more common?

A

Plasma viscosity

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3
Q

What protein is present in plasma that is used as a clinical marker for inflammation?

A

CRP (c-reactive protein)

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4
Q

What is the movement of blood called?

A

Haemodynamics

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5
Q

What is laminar flow?

A

Smooth flow, maintains energy, silent, typical

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6
Q

What is turbulent flow?

A

Disorganised, noisy, energy is lost

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7
Q

Where is the lowest resistance in the blood vessel?

A

In the centre on the of the vessel

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8
Q

What is the critical Reynolds number?

A

The point when flow and perfusion pressure become mismatched

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9
Q

When does turbulent flow happen?

A

When pressure increase is beyond which the flow can match linearly

E.g. in stenosis in arteries (narrowing of arteries) flow is altered due to the artery being narrower

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10
Q

What units are flow and pressure measured in?

A

Flow - volume transferred per unit time (L/min)

Pressure - force per unit area (mmHg)

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11
Q

What equations related to haemodynamics do you need to know?

A
  • pulse pressure (PP) = systolic blood pressure (SBP) - diastolic blood pressure (DBP)
  • mean arterial pressure (MAP) = DBP + ((SBP - DBP)/3) = DBP + 1/3PP
  • cardiac output (CO) = heart rate (HR) x stroke volume (SV)
  • MAP = CO x total peripheral resistance (TPR)
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12
Q

What is conductance in haemodynamics?

A

Measure of the ease of flow

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13
Q

What is resistance in haemodynamics?

A

Measure of the difficulty of flow

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14
Q

What has to happen to change blood supply to an organ?

A
  • resistance - biggest contributor to change in flow

* change in pressure

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15
Q

What happens to the pressure difference if resistance is increased and flow is maintained?

A

Pressure difference increases

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16
Q

How is flow related to resistance, inversely or directly?

A

Inversely

E.g. if resistance increases, flow decreases

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17
Q

What are primary factors in effecting resistance of flow?

A
  • diameter - most important
  • length of vessel
  • viscosity
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18
Q

Are flow and radius inversely or directly related?

A

Directly (proportional)

E.g. radius decreases, flow decreases

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19
Q

A small change in radius has a… (linked to effect on flow)

A

…large impact on the flow and/or resistance

20
Q

Which vessels play the biggest part in peripheral resistance?

A

Arterioles (and small arteries)

21
Q

Is resistance higher or lower in the pulmonary circulation compared to the systematic system? How can you tell this based off the heart?

A

Lower in pulmonary circulation due to shorter and wider vessels.

There is more cardiac muscle on the left side of the heart (provides blood to systematic system) than on the right side (provides blood to pulmonary circulation)

22
Q

What is velocity, V (in haemodynamics)?

A

The distance fluid (blood) moves in a given time (cm/s)

23
Q

In which blood vessels is velocity slower? Why?

A

In capillaries (compared to the aorta and large arteries) due to a larger cross-sectional area

24
Q

Why is a lower velocity useful in capillaries?

A

Useful for effective diffusion

25
Q

Is velocity higher in capillaries or veins?

A

Higher in veins

26
Q

Is velocity higher in arteries, capillaries or veins?

A

Arteries, due to a higher pressure in arteries compared to veins and capillaries

27
Q

What is cardiac output?

A

The total flow

28
Q

What is the pressure difference?

A

The mean aortic pressure minus central venous pressure

29
Q

What is mean arterial pressure determined by?

A

Cardiac output and total peripheral resistance

30
Q

What two things govern pulse pressure?

A

Volume of blood ejected and the compliance of the arterial system

E.g. increase stroke volume during exercise with relative compliance of vessels causing an increase in pulse pressure

31
Q

What can reduce the compliance of arteries?

A

Atherosclerosis - plaque build up inside arteries

32
Q

What is a pulse?

A

A shock wave that arrives slightly before the blood itself

33
Q

What is a strong pulse described as?

A

A bounding pulse

34
Q

What is the pulse pressure?

A

The difference between diastolic and systolic pressures

35
Q

How is blood pressure measured, directly to indirectly?

A

Indirectly

36
Q

What is normal, healthy pulse pressure?

A

40mmHg

37
Q

What can increase pulse pressure?

A
  • heart block - bradycardia
  • vasodilation ( peripheral resistance decreased)
  • exercise
38
Q

What is thrill and bruit?

A

in turbulent flow

Thrill - blood flow can be felt

Bruit - blood flow cam be heard

39
Q

What is auscultation?

A

Listening to sounds from the heart, lungs, other organs with a stethoscope

E.g. can be used in measuring blood pressure

40
Q

What are korotkoff sounds?

A

Sounds and changes in sounds (laminar to turbulent flow) heard when estimating blood pressure

41
Q

Describe using auscultation to measure blood pressure.

A
  1. Put on blood pressure (sphygmomanometer) cuff above elbow
  2. Find pulse of brachial artery with stethoscope
  3. Inflate cuff until flow is no longer heard
  4. Deflate to wait to hear when sounds come back
  5. Inflate again above initial inflation an deflate slowly, recording the blood pressure in mmHg when changes in sounds are heard - 1st change is systolic pressure 2nd is diastolic pressure
  6. Repeat after a few minutes to ensure accurate estimation
42
Q

Why does the cuff cause turbulent flow?

A

Cuff is reducing the artery diameter - increasing resistance

43
Q

What is important when estimating blood pressure by auscultation?

A
  • the cuff size
  • positioning of the cuff
  • measure in both arms
  • ensure patient is sat comfortably with legs uncrossed and feet flat on ground
  • ensure patient’s arm is supported and at heart level
  • repeat
  • take blood pressure at resting heart rate
44
Q

Is pressure higher above or below the heart level?

A

Below the level of the heart due to gravity maintaining a pressure gradient

45
Q

What is postural hypotension?

A

Dizziness upon standing

CVS * (17 decks)

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