Effect of flow oscillations on the stationary concentration front in a hollow cast of the airways
Nitrogen was blown down a hollow cast of a pig lung at a steady flow of 6.7 ml/s and the concentration of oxygen and nitrogen were measured at various points through small holes in the cast, using a mass spectrometer. A stationary concentration front between nitrogen and oxygen was found within the cast. When an oscillation was imposed on the flow by a reciprocating pump the concentration front moved up the cast, and this movement was more marked at higher pump frequencies and stroke volumes. This suggests that series dead space should diminish with both increasing frequency and increasing stroke volume of the heart.
Key wordsAirway cast Diffusive mixing Dead space Stationary front Oscillatory flow
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