PPT 5 Fluids Flashcards

1
Q

What defines a fluid?

A

material that has the ability to flow

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2
Q

what states of matter are considered fluids?

A

liquids and gases

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3
Q

hydrostatics

A

is the study of fluids that are not moving.

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4
Q

hydrodynamics

A

is the study of fluids in motion

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5
Q

Venturi effect and/or bernoulli principle

A

When fluid flow through a constricted region of a tube, the velocity of fluid increases and lateral pressure decreases. (lateral pressure exerted by the fluid on the walls of the tube)

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6
Q

applications (examples) of the bernoulli principle and/or Venturi effect.

A

The Venturi oxygen mask, nebulizer, jet ventilator and injectors.

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7
Q

Laminar flow

A

streamlined, in a straight line.

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8
Q

What law describes laminar flow.

A

Poiseuille’s law

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9
Q

What is flow directly proportional to?

A

fourth power of radius (r)

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10
Q

is flow through large bore needles faster or slower than flow through small bore needles?

A

Flow through large bore needle is faster than small bore needle

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11
Q

Flow is directly proportional to?

A

gradient change in pressure.

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12
Q

Flow is inversely proportional to? (choose two)

A

fluid viscosity and

length of the tube

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13
Q

viscosity and flow in polycythemia?

A

increased viscosity, therefore decreased flow.

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14
Q

viscosity and flow in anemia?

A

decreased viscosity, therefore increased flow.

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15
Q

vessel diameter is also called?

A

radius

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16
Q

The relation between vessel diameter ( or radius) and resistance is?

A

Inverse, if one goes up the other will go down.

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17
Q

The greater the radius then the smaller or larger the resistance?

A

smaller

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18
Q

to what power of the radius is resistance inversely proportional?

A

radius (r) to the fourth power.

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19
Q

If a vessel has twice the length of another vessel but the same radius then?

A

The twice as long vessel will have twice the resistance to flow.

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20
Q

If the viscosity of the blood increases by 2 fold then the resistance to flow will increase by how much?

A

2- fold

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21
Q

Will an increase in radius reduce or increase resistance?

A

it will reduce resistance with an increase in radius.

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22
Q

change in radius alters resistance to the ? power of the change in radius.

A

fourth

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23
Q

a 2-fold increase in radius decreases resistance by how much?

A

16-fold

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24
Q

vessel resistance is very sensitive to change in what?

A

radius

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25
Q

formula for resistance to flow (laminar flow) (there are technically two formulas)

A
R= change P/F
R= 8nl/pie r^4
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26
Q

increasing radius of a needle or catheter on an IV can ? flow.

A

increase flow

27
Q

Smaller gauge numbers on an IV indicate?

A

larger diameters

28
Q

Selecting a needle with a shorter length can increase or decrease flow through an IV line?

A

increase

29
Q

If you increase the height of the IV bag then it ?

A

increases the hydrostatic pressure in the IV bag.

30
Q

How do you apply poiseuille’s law while transfusing packed RBCs?

A

Large diameter IV catheter, pressure bag and dilution by adding normal saline.

31
Q

what happens to your blood flow in polycythemia?

A

sluggish flow due to increase viscosity of blood.

32
Q

what happens to your blood flow in anemia?

A

increased blood flow due to decreased viscosity of blood.

33
Q

larger the endotracheal tube, what happens to the flow of gas?

A

the flow is better (more radius)

34
Q

anything that increases diameter of the airway is going to help with better flow, what is a medication that increases diameter of the airway?

A

Beta 2 agonist increase diameter of the airway.

35
Q

increasing peak inspiratory pressure leads to?

A

increased gradient which leads to increase delivery of tidal volume.

36
Q

Flow becomes turbulent if?

A
  1. Velocity of flow is high
  2. Tube wall is rough
  3. Kinks, bends, narrowing or branches in the tube.
  4. Fluid flow through orifice.
37
Q

Laminar flow does not become turbulent when fluid is flowing through an angled tube if the angle is less than?

A

25 degrees

38
Q

Does resistance to flow increase or decrease when flow becomes turbulent?

A

resistance to flow increases when flow becomes turbulent which leads to difficult ventilation.

39
Q

What formula predicts whether flow will be laminar or turbulent.

A

Reynolds number (Re)

40
Q

Reynolds number is directly proportional to?

A

fluid velocity, tube diameter (d), and fluid density (p)

41
Q

Reynolds number is inversely proportional to?

A

fluid viscosity (n)

42
Q

flow will become turbulent if ?

A

velocity gets high enough (narrowing of a vessel)

43
Q

When reynolds number is greater than ???, flow will change from laminar to turbulent?

A

greater than 1500-3000 flow will change

44
Q

When flow is turbulent what factor determines flow?

A

density (p) NOT viscosity.

45
Q

What affect do low density gases have on breathing (needed when someone is having an asthma attack)

A

they make breathing easier

46
Q

Name a low density gas we use in the OR?

A

Helium (He)

47
Q

helium/oxygen gas mixture is known as?

A

Heliox

48
Q

Whats special about Heliox when used during a severe asthmatic attack when the obstruction is causing flow to be turbulent?

A

heliox decreases work of breathing and restores laminar flow (because it is a low density gas)

49
Q

Flow is inversely proportional to? (when talking about turbulent flow)

A

density

50
Q

What are bruits?

A

Turbulent flow causes audible vibration called bruits

51
Q

Causes of turbulent blood flow? (4 examples)

A

High velocities

Sharp turns in the circulation

Rough surfaces in the circulation

Rapid narrowing of blood vessels

52
Q

Turbulence is increased by?

A

decreased Blood viscosity (e.g. decreased crit, anemia)

increased Blood velocity (e.g. narrowing of vessel)

53
Q

Who has the lower density helium or nitrogen?

A

Helium

54
Q

What is the Coanda Effect?

A

Tendency of fluid flow to follow a curved surface upon emerging from a constriction

This may cause preferential flow in one tube at a bifurcation

55
Q

If a constriction occurs at a bifurcation what will then occur? eventually leading to maldistribution.

A

Constriction occurs at bifurcation
then increase velocity and decrease pressure
thus fluid will stick to the side of branch leading to maldistribution

56
Q

What can a mucus plug cause if it occurs at the branching of the respiratory tree?

A

maldistribution of respiratory gases.

57
Q

What can cause unequal blood flow in the arteries?

A

Atherosclerotic plaque

58
Q

Formula for pressure in a fluid?

A

P=pgh

Pressure = density x acceleration due to gravity x height

59
Q

nonstandard but fairly common “pressure” units in terms of mass per area?

A

g/cm^2

N/m^2 is the standard metric unit of pressure.

60
Q

The pressure at any depth of a fluid can be calculated if? (if you know 2 other things)

A

you know the pressure at some other depth and the density of the fluid.

61
Q

at a given depth in a fluid that fluid exerts what kind of pressure in all directions?

A

the same pressure in all directions

62
Q

Does the container a liquid is in have any effect on the pressure?

A

pressure is independent of container shape.

63
Q

True or false Pressure applied to a confined fluid will increase pressure throughout the fluid by the same amount?

A

TRUE, if you increased pressure on top of a confined fluid by x amount then x amount pressure everywhere in the fluid goes up.