Hemodynamics

Question 1

PV loops: what is V0

Answer 1

Intersection of ESPVR w/ x axis

Always >0 since small volume remains in LV w/o increasing pressure

Question 2

Define compliance based on PV loops

Answer 2

Compliance = 1/slope

Question 3

Schematize time variance elastance

Answer 3

ESPVR and EDPVR

Question 4

Time variance elastance curve; what does the slope means

Answer 4

Closely related to Tau

Question 5

Sensors of CV control systems

Answer 5

JGA - Na
High pressure baroR: carotid and Ao sinuses
Low pressure baroR - LA
LV mechanoR

Question 6

Normal CO

Answer 6

1000ml/kg/min
Large breed: 4-5L/min at rest

Question 7

Normal SV

Answer 7

1.5ml/kg
Large breed 60ml

Question 8

Normal Systemic BP

Answer 8

120/80mmHg

Question 9

Normal venous BP

Answer 9

5mmHg (mean)

Question 10

Blood volume

Answer 10

7% of BW

Question 11

Define frequency

Answer 11

of times wave cycle/sec

Question 12

Units of pressure

Answer 12

Dynes/cm2
mmHg

Question 13

Continuous flow in Ao during cardiac cycle

Answer 13

Ventricular systole => aorta distension
Ventricular diastole => aorta recoil

Question 14

Components of aortic pressure trace

Answer 14

Incident wave: antegrade propagation of flow when Lv ejects in Ao

Reflected waves: retrograde propagation from peripheral portions of Ao
Summates w/ incident wave
Reflected wave is sum of waves from distal sites

Recorded wave = incident + reflected waves

Question 15

Characteristic of recorded wave vs incident wave of AoP

Answer 15

Late systolic accentuation

Question 16

Natural frequency

Answer 16

Frequency at which the pressure
measurement system oscillates or responds when shock-excited.

Question 17

High frequency response range

Answer 17

ratio of output amplitude to input amplitude

highest possible natural frequency as well as optimal damping

Question 18

Factors influencing natural frequency

Answer 18

–directly proportional to the lumen size of the catheter.

–Inversely proportional to the length of the catheter and
associated tubing.

–Inversely proportional to the square root of the catheter and tubing compliance and the density of the fluid filling the system.

Question 19

Sources of errors and artifacts

Answer 19

Deterioration of frequency response
–Introduction of tubing that is long, narrow, or
compliant
–Air bubbles

Damping
Underdamping: KT whip artifacts
Overdamping: decr frequency response

Question 20

What should we look for to localize

Answer 20

DIASTOLIC PRESSURE

Question 21

Ohms law

Answer 21

V=IR
Voltage = driving pressure
Current = blood flow
Resisteance = afterload

Question 22

Poiseuille’s law

Answer 22

Q = (P2-P1)r4/nL

Flow equal pressure difference, radius
Incr PG
Incr radius
= incr flow

Inversely proportional to length and viscosity
Incr viscosity or longer tube = decr flow

Question 23

Echo measure of CO

Answer 23

SV = CSA x VTI
ml/cycle

Usually LVOT CSA
pir4

CO = SV x HR
ml/min

Question 24

Fick principle CO measurement

Answer 24

VO2/Ca-Cv

VO2 = O2 consumption in ml/min
Ca: O2 content from PV
Cv: O2 content from venous site

Question 25

O2 saturation

Answer 25

SaO2: % of heme binding sites saturation by O2

Question 26

PaO2 def

Answer 26

partial pressure of FREE O2 = not bound to Hb

Question 27

What variables needed to know CaO2 ie arterial O2 content

Answer 27

how much Hb + saturation

Question 28

CaO2 calculation

Answer 28

Hb (mg/dL) x 1.34 mlO2/mg Hb) + PaO2

Question 29

Principles of indicator dilution CO

Answer 29

1. Known amount of known subst 2. Uniform mixing 3. Concentration of subst downstream 4. Concentration change over time correlates to rate of BF

Question 30

Types of indicators

Answer 30

Indocyanine green, saline, cold/heat

Question 31

Characteristics of high output thermodilution curve

Answer 31

Small AUC

Question 32

Characteristics of low output thermodilution curve

Answer 32

High AUC due to delayed flow

Question 33

Thermodilution accuray

Answer 33

w/i 20% of gold standard (dye dilution/Fick) Less reliable if low CO (small temp change) = overestimate CO Severe TR less accurate PI can affect Underestimate CO in high output states

Question 34

SVR equation

Answer 34

MAP - CVP/CO

Question 35

CO equation

Answer 35

MAP-CVP/SVR

Question 36

Wood units

Answer 36

1mmHg/L/min

Question 37

Woods units conversion to dynes

Answer 37

x 80

Question 38

MAP equation

Answer 38

Syst + 2xdiast/3

Question 39

Normal arterial pressures: systemic and pulmonar

Answer 39

Arterial: 70-105mmHg Pulmonary: 9-18mmHg

Question 40

Cardiac index

Answer 40

CO/BSA

Question 41

Vascular resistance equations and normal

Answer 41

SVR: MAP -CVP/CI n= 1970-2390 dynes PVR: PAP - PAWP n = 255-285 dynes

Question 42

Effect of hydralazine on central AoP

Answer 42

Decrease syst diast and mean pressure Incr pulse pressure

Question 43

Dynamic vs fixed obstruction features

Answer 43

Fixed: slow rising upstroke and low pulse pressure Pulses tardus and parvus Dynamic: obstruction later in systole, sharp rise

Question 44

Premature beat and obstruction

Answer 44

Fixed: INCREASe pulse pressure Dynamic: smaller PP and INCREASED PG

Question 45

Constrictive vs restrictive on LVP and RVP

Answer 45

RESTRICTIVE: CONCORDANT changes w/ breathing CONSTRICTIVE: DISCORDANT changes RVP increases in inspiration = LVP decreases due to limited volume in heart and cannot expand w/ IVS pushing from R

Question 46

Hemodynamic changes w/ AI

Answer 46

Large pulse pressure