Maximum Voluntary Ventilation Prediction from the Velocity-Volume Loop

¹ Pensacola, Florida

1. When an MVV V-V loop is superimposed on a maximum (forced vital capacity) V-V loop, it follows the maximum envelope during the major portion of a breath half cycle until it breaks away abruptly, transects the zero velocity abscissa, and joins the maximum envelope for the other breath half cycle.

2. Because of the relationship of the MVV V-V loop to the maximum V-V loop, it is possible to simulate the MVV V-V loop by erecting perpendiculars at either end of the tidal volume. If this is done for a variety of assumed tidal volumes, MVV V-V loops at a number of breathing frequencies are simulated.

3. By use of the equation Time-V²/Area, the calculated time for moving each assumed tidal volume in and out of the lungs is found. From the tidal volume and the time necessary for its movement, breathing frequency and MVV are calculated.

4. The "correct" (optimum) placement of the tidal volume on the vital capacity axis is found by use of a family of curves (breathing frequency-limit of inspiration) which are evolved from the maximum V-V loop.

5. The predicted MVV values over a wide range of breathing frequencies calculated from a single maximum V-V loop compare favorably with MVV values obtained with the usual 15-second MVV test.