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DNURS 827 Advanced Physiology/Pathophysiology for Anesthesia I > Hemodynamics and Hemodynamic Measurements - Quiz 4 > Flashcards

Hemodynamics and Hemodynamic Measurements - Quiz 4 Flashcards

1
Q

How to measure Blood Flow

A

Velocity x Cross Sectional Area

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2
Q

In Ohm’s Law, what 2 factors determine blood flow through a vessel?

A

1) Difference in Pressure

2) Resistance

Flow (Q) = (PA - PV) / R

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3
Q

What is Blood Pressure

A

The force exerted by blood against the vessel wall

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4
Q

1 mmHg = ? cm-H2O

A

1 mmHg = 1.36 cm-H2O

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5
Q

What is Cerebral Perfusion Pressure

A

Cerebral Perfusion Pressure = MAP - CVP or ICP (whichever higher)

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6
Q

What has greatest impact on rate of bloow flow through a vessel wall regarding Poiseuille’s Law?

A

Diameter of Blood Vessel

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7
Q

What is Resistance

A

The impediment of blood flow in a vessel - cannot be directly measured

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8
Q

SVR Formula

A

SVR = [(MAP - CVP) / CO] X 80

Normal: 700-1600

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9
Q

PVR Formula

A

PVR = [(MPAP - PCWP) / CO] x 80

Normal: 100 - 300

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10
Q

Calculating resistance in blood vessels arranged in a series

A

Total Resistance = Sum of Resistance of Each Vessel

Rt = R1 + R2 + R3 + R4

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11
Q

Calculating blood vessel resistance in Parallel Arrangement?

A

1/Rt = 1/R1 + 1/R2 + 1/R3

Paralell Arrangement allows for Local Blood Flow Regulation

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12
Q

What happens to total resistance if you added another blood vessel in a parallel arrangement?

A

Total resistance would decreases - another channel for blood to flow through

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13
Q

What is Laminar Flow

A

Fluid particles following moving in smooth paths in layers in a parallel

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14
Q

What is Turbulent flow?

A

Turbulent flow occurs when it fluids make sharp turn or passes over rough surface, becoming disorderly.

Blood flows crosswise in vessel and form local eddies, increasing flow resistance due to friction.

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15
Q

Formula used to predict laminar vs turbulent flow

A

Reynold’s Number (NR)

NR = pDv / n

p = density
D = tube diameter
v = velocity
n = viscosity
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16
Q

Relationship of Hematocrit to Blood Viscosity?

A

Increasing Hematocrit increases Viscosity

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17
Q

Why does an increase in Blood Pressure cause a much greater increase in Blood Flow

A

As opposed to the arterial blood flow, an increase in venous blood pressure increases flow because the vessels become more rounded and lowers resistance –> increases venous return.

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18
Q

What is the mechanism that drives blood flow?

A

The difference in total energy between two points

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19
Q

What are the three primary factors that determine blood flow resistance in a single vessel?

A
  1. Vessel Diameter - most important
  2. Vessel Length
  3. Viscosity of Blood
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20
Q

Vessel resistance is ______ proportional to vessel length and blood viscosity

A

Directly Proportional

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21
Q

Vessel Resistance is _______ proportional to the radius to the fourth power

A

Inversely proportional

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22
Q

What is the basis of Bernoulli’s Principle?

A

Kinetic Energy and Pressure Energy can be interconverted so that total energy remains the same.

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23
Q

How does pulsatility effect flow resistance?

A

Increases flow resistance

24
Q

Cororany Perfusion Pressure =

A

Diastolic Pressure - LVEDP

25
Q

NR < 2000 = ?

NR: 2000-3000 = ?

NR > 3000 = ?

A

NR < 2000 = usually laminar

NR: 2000-3000 = variable

NR > 3000 = usually turbulent

26
Q

For non-Newtonian fluids, like blood, a decrease in flow _____ viscosity

A

Increases viscosity

27
Q

What is the most important monitor in the OR?

A

Eyes, Hands, and Ears of the Anesthetist

28
Q

Return-To-Flow Techniques for measuring BP

A

Palpation

Pulse Oximeter (Plethysmographic Waveform)

Arterial Catheter

29
Q

Insertion Sites for Art Lines

A

Radial

Brachial

Ulnar

Axillary

Femoral

Dorsalis Pedis

30
Q

What happens to pulse pressure in the leg relative to the proximal aorta?

A

SBP rises and DBP falls, increasing pulse pressure

d/t

vessel branching and decreased arterial compliance

31
Q

What is damping in an arterial line tracing?

A

The transducer is exposed to a high signal from the pressure bag by flushing, causing transducer to vibrate.

Damping is the speed at which the vibration stops and returns to normal transduction.

32
Q

What is an overdamped art line?

A

Underestimation of SBP & overestimation of DBP (same MAP) due to frictional forces impeding wave form - wide, slurred wave

EX: Air bubbles, kink, stretchy tubing, low pressure bag, clots

33
Q

What is an underdamped art line

A

Overestimation of SBP and underestimation of DBP (same MAP) due to reverberation in the tubing - Peak, narrow waves

EX: Long stiff tube, increased vascular resistance

34
Q

3 Waves of CVP

A

A-Wave: Right Atrial Contraction (P-Wave on ECG)

C-Wave: Cusp of triscuspid valve - Right Ventricle Contraction (end of QRS)

V-Wave: Right Atrial Filling hitting triscuspid valve (After t-wave on ECG)

35
Q

What does a huge V-Wave on a CVP tracing suggest?

A

Triscuspid Regurgitation

36
Q

What are the waveforms seen when inserting a Swan-Ganz

A
  1. Right Ventricular Pressure
  2. Pulmonary Artery Pressure
  3. Wedge Pressure
37
Q

What info can be Directly gathered from a Swan?

A

CVP

Right Side Heart Pressures

Pulmonary Arterial Pressure

Pulmonary Capillary Occulsion Pressure/Wedge Pressure

Cardiac Output

Mix Venous Oxyhemoglobin Saturation (SvO2)

38
Q

What info can be Indirectly gathered by a Swan?

A

SVR
PVR
CI
SVI
Left Ventricular Stroke Work Index (LVSWI)
RVSWI
Oxygen Delivery (DO2)
Oxygen Uptake (VO2)

39
Q

Steps to inflating wedge?

A

???

Dont inflate wedge > 15 seonds

Dont Inflate with more than 1.5 mL of air

40
Q

Steps to Zeroing Tranducer

A
  1. Establish standard reference value, ambien atm. pressure = 0 mmHg
  2. Place transducer at verticle height relative to patient’s position
    • upper most blood level in measured chamber
    • 5 cm below left sternal border at 4 ICS
41
Q

Fick’s Principle

A

Cardiac Output =

O2 per minute absorbed by lungs (ml/min) / Arteriovenous O2 difference (mL/L blood)

42
Q

Thermodilution Method for measure Cardiac Output

A

Inject room temp solution, and measuring temperature over time.

43
Q

What is Pulsus Paradoxus?

A

A drop in BP > 10 mmHg on inspiration

The Reverse happens with Positive-Pressure Ventilation - treat with fluid

44
Q

What is the Natural Resonant Freqency in an art line?

A

How fast the system vibrates in response to a pressure signal

45
Q

What is the x-descent of the CVP tracing?

A

Downward movement of Right Ventricle as it contracts

(Happens before T-Wave)

46
Q

What is the y-descent on a CVP tracing?

A

Pulse pressure decrease due to opening of tricuspid valve

(Happens before P-wave)

47
Q

What does a loss of y-descent suggest?

A

Tamponade - restriction to RV filling

48
Q

Large area under thermodilution curve = ?

A

Low Cardiac Output

Vice Versa

49
Q

What is the most widely used method to determine Cardiac Output?

A

Thermodilution

50
Q

What is the most common problem obtaining accurate Cardiac Output measurement?

A

Improper Injectate Adminstration

51
Q

How to else to measure Cardiac Output other than Thermodilution?

A
  • Ultrasound methods - Esophageal Doppler
  • Bioimpedance
  • Partial CO2 Rebreathing Fick method
  • Lithium Dilution
  • Pulse Countour
52
Q

Poiseuille’s Equation

A

Flow inversely related : (radius4 x Change in Pressure) / (Viscosity x Length of Vessel)

53
Q

Flow is ______ proportional to the Pressure Gradient

A

Directly Proportional

54
Q

Flow is ________ proportional to Length of the Tube

A

Inversely Proportional

55
Q

Pulmonary Artery Catheter Waves

A

DNURS 827 Advanced Physiology/Pathophysiology for Anesthesia I (11 decks)

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