Flow and Volume of Blood Dept. of Biomedical Engineering YOUNHO 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 Fi Ci Fo Co F : flow C : concentration The unit of blood flow : l/min or ml/s (infusion rate) Mass Balance Equation The quantity of in and out is the same, and there is no leakage. # Indicator Dilution # Fick : O 2 consumption, L/min ( measured by spirometer) Ci = Cv : concentration in vein Co = Ca : concentration in artery

Indicator Dilution ( Dye dilution Method) Use Cardio green or Indocyannine green for a dye. t c(t) bolus injection indicator dilution curve T Extrapolation recirculation

Thermo-dilution t c(t) bolus injection T Use cold saline(4 ˚C)

Ultra Sound t skin ultra-sound generator Primary echo is bigger than secondary echo.

Transit time flowmeter θ D μ c velocity of RBC, WBC and platelit velocity of ultra sound (1) down-stream (2) up-stream

Doppler flowmeter (1) Continuous Doppler flowmeter (cf) Radar system object fo, c f+fd, c u (2) Pulsed Doppler flowmeter u1u1 u1u1 u2u2 u2u2 u3u3 t T fd 1 fd 2 fd 3 x f

Thermal convection flowmeter F T2T2 Thermister (1) Bios current => Thermister heating (2) T 2 Thermister is cooled by thermal convection. Invasive, probe positioning is difficult. The stronger F gets, The sharper the temperature of T 2 is decreased. (cf.) respiratory monitoring by thermister Temp. of inspiration is 25 ˚ C. Temp. of expiration is 36.5 ˚ C.

Plethysmography i V cuff leg toes open artery close vein Z(V) t cuff off slope = flow(in artery) slope = flow(in vein) normal Venous Thrombosis

Respiratory System # Architecture Tracher Bronchas … Alveoli uTuT uAuA ATATA air flow velocity cross-sectional area [l/min or ml/s] The total of volume flow is not changed. velocity of the air at alveoli is almost zero. # Physiological functions - O 2 transport into blood stream - CO 2 removal from blood stream - Homeostasis of PH, PO 2, PCO 2 # Respiration - Ventilatory mechanics => RC equivalent circuit model - Gas transport => Mass balance equation (Diffusion process)

Pressure measurement (1) Differential pressure transducer diaphragm P1P1 P2P2 strain gage (2) Balloon Sensor gas hole ballon P pressure sensor air pump MP P Pi metal switch Vi control pressure (Pi) +5V 0V : switch on => P>Pi 5V : switch off => P<Pi

Flow measurement (1) Rotating vane (2) Ultrasound flowmeter (3) Thermal convection (4) Pneumotachometer # Pneumotachometer Q (flow) P1P1 P2P2 mouth mesh screen measurementresistance

Volume measurement (1) Water spirometer mouth CO 2 absorber water air pen single turn potentimeter TLC Rv FRV vital capacity TV IC ERC Vc (2) Dry spirometer mouth inspiration gas expiratory gas (empty) valve pistol 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 F I He - Patient breaths F b the spirometer - Find He concentration of expiratory gas F I He

FRC measurnment (1) N 2 washout technique - Patient at FRC - Prepare a spirometer with O 2, Vsp - Patient breaths to the spirometer - Measure N 2 concentration in the expiratory gas

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

Gas transport measurement (1) Gas distribution test => single breath N 2 washout - RC => TLC O 2 inspiration - pause (hold breath) - Expiration and measure F N 2 (2) Diffusion test => CO diffusion capacity - Inspire CO, He in the air to TLC from RC - Hold breath for 10sec - Expire to measure F F CO and F F HE

Thank You.