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HFOV Mechanisms of Gas Transport

HFOV Mechanisms of Gas Transport. HFOV Mechanisms of Gas Transport. Direct bulk flow Taylor dispersion Pendeluft Asymmetric velocity profiles Cardiogenic mixing Molecular diffusion. Krishnan CHEST 2000. Convection (Bulk Flow) Ventilation.

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HFOV Mechanisms of Gas Transport

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  1. HFOV Mechanisms of Gas Transport

  2. HFOV Mechanisms of Gas Transport • Direct bulk flow • Taylor dispersion • Pendeluft • Asymmetric velocity profiles • Cardiogenic mixing • Molecular diffusion Krishnan CHEST 2000

  3. Convection (Bulk Flow) Ventilation • Even with small tidal volumes, direct alveolar ventilation occurs to short path length units that branch off of the primary airways.

  4. Augmented (Taylor) dispersion • Complicated interplay between convective forces and molecular diffusion • Addition of convective flow to a diffusive process significantly increased dispersion of molecules

  5. Penduluft • At high frequencies, distribution becomes strongly influenced by time constant inequalities. Gas from fast units (short time constants) will empty into the slow (long time constants) units.

  6. Expiration Inspiration Net Effect Asymmetrical Velocity Profile

  7. Cardiogenic Mixing • The heart beat adds to the the peripheral gas mixing.

  8. Molecular Diffusion • Is felt to be one of the major mechanisms for gas exchange in the alveolar regions. • It is responsible for the gas exchange across the AC membrane and also contributes to the transport of O2 and CO2 in the gas phase near the membrane. • This may be due to the increased turbulence of molecules.

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