8 th 정진웅 MEDICAL INSTRUMENTATION

Chapter. 9 Respiratory System Measurement

From now on, we focus on two subject - PFT : pulmonary function test - Patient monitoring(Respiration monitoring)

Respiratory System Measurement ( Architecture ) trachea bronchia alveolar airflow velocity cross section area O 2 and CO 2 diffusion at alveolar

Respiratory System Measurement ◎ physiological function - O 2 transport into blood stream - CO 2 removed from blood stream - Homeostasis of ph, partial pressure of O 2, partial pressure of CO 2 Ventilatory mechanics Ventilatory mechanics ⇒ RC equivalent circuit model ⇒ RC equivalent circuit model Gas transport Gas transport ⇒ Mass balance equation ⇒ Mass balance equation (Diffusion process) (Diffusion process) ◎ Respiration

Respiratory System Measurement ◎ Pressure measurement ① Differential Pressure transducer Strain gage Diaphragm x1x1 x2x2 P1P1 P2P2 AB C1C1 C2C2 C

Respiratory System Measurement ② Balloon sensor pressure sensor hole (balloon) gas force pressure (P) air pump metal switch resistor 5V V1V1 0V : switch on P > P i or, 5V : switch off P < P i force pressure (P) control

Respiratory System Measurement ◎ Flow measurement ① Rotating vane ② Ultrasound flow-meter ③ Thermal convection flow-meter ④ Prieumotachometer

Respiratory System Measurement P1P1 P2P2 Q(flow) mouthmesh screen Diff pressure sensor measurement using with a injector resistance(fixed)

Respiratory System Measurement ◎ Volume measurement (plethysmography)

Respiratory System Measurement ① water spirometer mouth water air CO 2 absorber

Respiratory System Measurement ② dry spirometer Inspiratory gas expiratory gas mouth valve piston

Respiratory System Measurement ◎ FRC measurement ① Helium dilution technique - Patient at FRC - Patient at FRC - Prepare a spirometer of volume V SP and - Prepare a spirometer of volume V SP and initial He concentration of f IHE initial He concentration of f IHE - Patient brethes helium the spirometer - Patient brethes helium the spirometer - Find helium contradiction of expiration gas f FHE - Find helium contradiction of expiration gas f FHE

Respiratory System Measurement “ Equation of mass balance ”

Respiratory System Measurement ② N 2 washout technique - Patient at FRC - Patient at FRC - Prepare a spirometer with V SP, O 2 - Prepare a spirometer with V SP, O 2 - Patient brethes to the spirometer - Patient brethes to the spirometer - Measure N 2 concentration in the expiratory gas - Measure N 2 concentration in the expiratory gas

Respiratory System Measurement ◎ Gas concentration measurement ① Mass spectroswophy ② Gas chromatography ③ Infrared spectroswophy ④ Raman spectroswophy ⑤ Emission spectroswophy ⑥ Paramagnetic O 2 analyzer

Respiratory System Measurement ◎ Gas transport measurement ① Gas distribution test ⇒ single N 2 breathe washout ⇒ single N 2 breathe washout - RC → TLC O 2 inspiration - RC → TLC O 2 inspiration - Pause (Hold breath) - Pause (Hold breath) - Expiration and measure F N2 - Expiration and measure F N2

Respiratory System Measurement ② Diffusion ⇒ CO diffusion capacity ⇒ CO diffusion capacity - Inspire CO, He, in air to TLC ( F ICO, F IHe ) - Inspire CO, He, in air to TLC ( F ICO, F IHe ) - Hold breath for 10sec. - Hold breath for 10sec. - Expire to measure F FCO and F FHe - Expire to measure F FCO and F FHe CO diffusion capacity

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