Flow and Volume of BloodDept. of Biomedical Engineering

2003200449YOUNHO HONG

Contents Cardiac Output - Fick

- Indicator Dilution - Thermo Dilution

Electromagnetic flow meter Ultrasound flow meter - Transit time

- Continuous Doppla - Pulsed Doppla - Thermal Convection

Plethysmography

Indicator Dilution and Fick Method

FiCi

FoCo

dt

dm

F : flow C : concentrationThe unit of blood flow : l/min or ml/s

(infusion rate)

Mass Balance Equation

FCdt

dmFC oi

The quantity of in and out is the same,and there is no leakage.

io CCdtdm

F

# Indicator Dilution

# Fickdt

dm: O2 consumption, L/min ( measured by spirometer)

Ci = Cv : concentration in vein

Co = Ca : concentration in artery

io CCdtdm

F

Indicator Dilution ( Dye dilution Method)

Use Cardio green or Indocyannine green for a dye.

t

c(t)

bolusinjection

indicator dilution curve

TExtrapolation

recirculation

FtCdt

dvtC

dt

dmdvtCdmtC

dv

dm )()( ,)( ),(

mdttCFdm

dtFtCdmTT

00)(

)(

T

dttC

mF

0)(

Thermo-dilution

t

c(t)

bolusinjection

T

Use cold saline(4˚C)

]/[)(

3

0

1sm

dttTc

QF t

bbb

K][J/kg blood, ofheat specific

][kg/m density, blood

[J] injectate, ofcontent heat 3

b

b

iiii

c

cTVQ

Ultra Sound

t

skinultra-sound generator

Primary echo is bigger than secondary echo.

Transit time flowmeter

θD

μc

velocity of RBC, WBC and platelit

velocity of ultra sound (1) down-stream

cosc

Dtd

(2) up-stream

cosc

Dtu

2222

cos2

cos

cos2

coscos

c

D

c

D

c

D

c

Dttt du

)cos( 222 c

Doppler flowmeter(1) Continuous Doppler flowmeter

(cf) Radar system

objectfo, c

f+fd, c usmc /103 8 c

u

f

f

o

d

(2) Pulsed Doppler flowmeter

u1

u1u2

u2u3

t

Tfd1fd1

fd2fd2

fd3

x

f

Thermal convection flowmeter

F

T2

Thermister

(1) Bios current => Thermister heating(2) T2 Thermister is cooled by thermal convection.

Invasive, probe positioning is difficult.The stronger F gets, The sharper the temperature of T2

is decreased.

(cf.) respiratory monitoring by thermister

Temp. of inspiration is 25˚C.Temp. of expiration is 36.5˚C.

Plethysmography

iVcuffleg toes

open arteryclose vein

)( flowfdt

dv

Z(V)

tcuff cuff off

slope= flow(in artery)

slope= flow(in vein)

normal

VenousThrombosis

Respiratory System

# Architecture

Tracher

Bronchas

…

Alveoli

uT

uA

AT

AA

AATT AuAuQ air flow

velocity

cross-sectional area

[l/min or ml/s]

The total of volume flow is not changed.

TA

TTA uA

Auu velocity of the air

at alveoli is almost zero.

# Physiological functions- O2 transport into blood stream- CO2 removal from blood stream- Homeostasis of PH, PO2, PCO2

# Respiration

- Ventilatory mechanics => RC equivalent circuit model- Gas transport => Mass balance equation (Diffusion process)

Pressure measurement(1) Differential pressure transducer

diaphragm

P1 P2

diaphragm

strain gage

(2) Balloon Sensor

gas

hole

ballonP pressure

sensorair

pump

MPP Pi

metal switch

Vi

control

pressure (Pi)

+5V0V : switch on => P>Pi5V : switch off => P<Pi

Flow measurement(1) Rotating vane(2) Ultrasound flowmeter(3) Thermal convection(4) Pneumotachometer

# Pneumotachometer

Q(flow)

P1 P2

mouth

mesh screen

QRPP 21

measurement resistance

)(21 nCalibratioR

PPQ

Volume measurement(1) Water spirometer

mouth

CO2

absorber

water

air

pen

single turn potentimeter

TLC

Rv

FRV

vital capacity

TV

IC

ERC

Vc

(2) Dry spirometermouth

inspirationgas

expiratorygas (empty)

valvepistol

change the position of the pistol during breathing.

FRC measurnment

(1) He Dilution technique - Patient at FRC - Prepare a spirometer of volume Vsp and imitial He Concentration of FIHe

- Patient breaths Fb the spirometer - Find He concentration of expiratory gas FIHe

spF

FI

IspIsp

VF

FFFRC

FFRCVFV

He

HeHe

HeHe

)(

FRC measurnment

(1) N2 washout technique - Patient at FRC - Prepare a spirometer with O2, Vsp - Patient breaths to the spirometer - Measure N2 concentration in the expiratory gas

2)(8.0

NFsp FVFRCFRC

Gas concentration measurement

(1) Mass spectroscophy(2) Gas chromatography(3) Infrared spectroscophy(4) Ramen spectroscophy(5) Emission spectroscophy(6) Paramagnetic O2 analyzer

Gas transport measurement(1) Gas distribution test => single breath N2 washout - RC => TLC O2 inspiration - pause (hold breath) - Expiration and measure FN2

(2) Diffusion test => CO diffusion capacity - Inspire CO, He in the air to TLC from RC - Hold breath for 10sec - Expire to measure FFCO and FFHE

]ln[)47(

60

He

He

CO

CO

I

F

F

I

B

ACO F

F

F

F

Pt

UD

Thank You.