생체계측 ii report #9 2005200427 송성진 medical instrumentation ii

생체계측 II Report #9

2005200427 송성진

Medical Instrumentation II

<Topics Covered in Chapter 8>

• Cardiac Output Fick Technique Method Indicator Dilution Thermodilution• Electromagnetic Flowmeter (Not good)• Ultrasound Flowmeters• Plethysmography


Chap 8. Part I. Flow and Volume of Blood

1. Indicator Dilution Method

• Fick Method• Indicator Dilution using

rapid injection• Thermodilution



iF oF FFF oi )(densityCi )(densityCo

dt

dm(Infusion rate) -> We Known

FCdt

dmFC oi (Mass balance

equation)

min/min// gllg

io CCdt

dmflowF )(Conclusio

n :

Fick Method


dt

dm

Substitution of Equation!

ao CC

vi CC

(O₂ density of Artery Blood)

(O₂ density of Vein Blood)

(O₂ Consumption, L/min)measure By Spirometer

Indicator Dilution using rapid injection


Dye Dilution MethodIndocyanine green (cardiogreen)

Extrapolation

Indictor dilution curve

)(tC

tBolus injection

Recirculation


Find Area!

)(tCdv

dm dvtCdm )(

FtCdt

dvtCdvtC

dt

d

dt

dm )()()(

TT

dttCFdmm00

)(

T

dttC

mF

0)(

Conclusion :


Weak Point : Once dye get an injection, it remains in our body.

The dye should be excreted in the urine. In order

to remeasure the blood flow, you should wait for a long time.

Thermodiltion (standard)


T

tBolus injection

Weak Point : We unknown temperature of Right artium.

Using 4 lumen catheter(Swan-Ganz catheter)


]/[)(

3

0

smdttTC

QF T

bbb

Conclusion :

][JCTVQ iiii (Heat content of injectate)

]/[ 3mkgb

]/[ KkgJCb

(Blood density)

(Specific heat of blood)


-> pressure element, approvaled by 1MHz frequency.Ex)

t

No reflection

Primary Echo

skin

2. Ultra Sound


2

f

v

MHzf

3

Near field

Far field

D

2.1sin

Transit Time Flowmeter


Du

Velocity of RBC, WRC, and plate.

c Velocity of ultrasound.


i ) Down stream ( = Blood flow direction)

ii ) Up stream ( = Blood flow reverse direction)

cosuc

DtD

coscos uc

D

uc

Dttt DU

cosuc

DtU

2222

cos2

cos

cos2

C

Du

uc

Du

Because… C >> ucosφ

Conclusion :

Continuous Doppler Flowmeter


u

c

u

f

f

o

d

cff d

cfo

Doppler frequency shift

Ex) aviation, ship, submarine…


Pulsed Doppler Flowmeter

D

1u2u

3u2u

1u

12321 uuuuu

Flow profile measuremen

t

Thermal Convection Flowmeter


Thermister

f

2T

1T

i ) Bias current -> Thermister heatingii ) T₂Thermister is cooled by thermal convection

Weak Point : Invasive and Probe position is difficult.


-> Volume, blood flow measurement

V

`i Howland Current

Source

Cuff

Artery openVein close

mmHg60

3. Plethysmography


t

Z)(v

Venous Thrombosis

NormalVolume

Cuff On Cuff Out

Slope = flow

Arterial

Patient monitoring (Respiration monitoring)

Part II. Pulmonary Function Test


1. ArchitectureTrachea

Bronchus

Alveoli

Area TT Au ,

AA Au ,

AATT AuAuQ

A

TTA A

Auu

TA uu Because… O₂ & CO₂ diffusion at alveoli


2. Physiological Functions

• O₂ transport into blood stream• CO₂ removal from blood

stream• Homeostasis of pH, Po₂, Pco₂


3. Respiration

• Ventilatory mechamis - RC equivalent circuit model

• Gas transport - Mass balance equation(Diffusion

process)


4. Pressure measurementDifferential pressure transducer

1P 2P

Diaphragm

i )

ii )1P 2P

Diaphragm

2C1C

1x 2x


iii )

Mesh screen

1P 2P

Differential pressure sensor

Q

Flow

Mouth

RQPP 21

R

PPQ 21 Conclusio

n :

Airpump


Ballon sensorHole Ballon

Gas

Pressure sensor

Pv5

MPiv

Control

Pressure

Metal switch

Switch On ->Switch Off ->

v0v5

iPP iPP


5. Flow measurement

• Rotating Vane• Ultrasound Flowmeter• Thermal Convection Flowmeter• Pneumotachometer (standard)


6. Volume measurement-> Plethysmography

t

TLC

FRC

RV

TV (Tidal Volume)

ERC

IC VC

Weak Point : It is Relative value, not absolute value.


Water Spirometer

Water

Air

Pen

Rotating Paper

Mouth

CO₂ absorber


Dry Spirometer

Air (gas)

Mouth

Inspiratory gas

Expiratory gas

Valve

Piston

Gas is Separated by two section


7. FRC measurementHe dilution technique - patient at FRC

- prepare a spirometer of volume VSP and

initial He, concentration of fIHE

- patient breaths tooth spirometer - find He concentration of expiration F

SPFHeFHeIHe VFFFFRC


N₂ washout technique - patient at FRC - prepare a spirometer of O₂, VSP

- patient breaths to the spirometer - Measure N₂ concentration in (FFN₂)

the expiratory.

2)(8.0 FNSP FVFRCFRC


8. Gas concentration measurement

• Mass spetroscophy• Gas chromatography• Infrared spectrography• Raman spectrography• Emission spectrography• Paremagnetic O₂ analyzer


9. Gas transport measurement

Gas distribution test(Single breath N₂ wachout) - RC -> TLC O₂ inspiration - Pause (hold breath) - Expiration and measure fN2


Diffusion test(CO diffusion capacity) - Inspire ω, He in air - fICO, fIHe

- Hold breath for 10sec - Expire to measure FFCO, FFHe

He

He

CO

CO

I

F

F

I

B

ACO f

F

F

f

Pt

vD ln

)47(

60

생체계측 ii report #9 2005200427 송성진 medical instrumentation ii

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