# Principles of Flow Measurement Franklin L. Scamman, MD Physics Series November 26, 2002.

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Principles of Flow Measurement Franklin L. Scamman, MD Physics Series November 26, 2002

Principles of Flow Q = Pressure/Resistance Laminar Turbulent

Vertical Flow Tube

How a Vertical Flow Tube Works

Tandem Flow Tubes

Rotameter

Positive Displacement- Narcomed

Rotameter- Ohmeda SE

Pneumotach

Flow Measurement Principle P1 P2 Counter pressure sensor flow in flow out Electronic flow measurement principle - laminar flow restrictions create a pressure difference P 1 - flow is calculated from P 1 l Used with Oxygen, Side gas, Bypass, and Agent flows Laminar flow restriction P 1 Ambient pressure P2 P1 = pressure difference P2 = correction (off-set) to ambient pressure

Clinical Spirometry Pitot tubes measure the pressure difference created by the gas flow Knowing the amount of pressure difference allows the gas module to calculate flow Flow is mathematically integrated over time to calculate volume

Pitot Tube Principles

Agent Adjustment Bypass flow measurement Agent flow measurement Aladin TM cassetteTemperature sensor Cassette ID Magnets Agent proportional. valve Inflow close valve Outflow close valve One way valve liquid flow prevention Restrictor

Agent Adjustment 1 2 3 3

Cardiac Thermodilution

Mathematics of Thermodilution Quantity = Volume X Concentration Volume = Flow X Time Quantity = Flow X Time X Concentration Flow = Quantity / (Time X Concentration)

Plot of Washout Curve

High and Low Cardiac Output

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