Principles of Flow Measurement

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Principles of Flow Measurement

• Franklin L. Scamman, MD
• Physics Series
• November 26, 2002

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(No Transcript)
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Principles of Flow

• Q Pressure/Resistance
• Laminar
• Turbulent

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Vertical Flow Tube
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How a Vertical Flow Tube Works
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Tandem Flow Tubes
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Rotameter
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Positive Displacement- Narcomed
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Rotameter- Ohmeda SE
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Pneumotach
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Flow Measurement Principle
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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

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Pitot Tube Principles
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Agent Adjustment
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Agent Adjustment
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Cardiac Thermodilution
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Mathematics of Thermodilution

• Quantity Volume X Concentration
• Volume Flow X Time
• Quantity Flow X Time X Concentration
• Flow Quantity / (Time X Concentration)

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Plot of Washout Curve
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High and Low Cardiac Output