Flow to lung compartments with different time constants: effect of choice of model

The thesis that an accelerating flow generator provides more even ventilation than a constant flow generator originated from studies using mechanical lung models. We simulated such studies by use of mathematical models. We found that the conclusions of these previous studies were dependent on the particular characteristics of their mechanical models. Studies employing more commonly used models indicate that constant flow generators, in fact, tend to provide more uniform ventilation, especially with long inspiratory times.