Cuff Deflation During HFOV

High frequency oscillatory ventilation takes advantage of unique principles of gas flow when respiratory frequencies exceed 3 Hz (180 breaths per minute). These gas flow principles enable the alveolar gas turnover at volumes below or equal to physiologic deadspace. One of these principles is call asymmetrical velocity profile. As Froese and Bryan described in their “State of the Art” article on high frequency ventilation: “Hazelton and Scherer have proposed that even in a straight tube, since the velocity profile in one direction is parabolic and flat in the reverse direction, there will be net convective transport of material. This mechanism may be particularly effective at bifurcations where the inspiratory velocity profile becomes skewed with the peak velocities near the inner wall, whereas the expiratory velocity profile is usually symmetric.”