Lung function experiments

In this final part of this simulation, we will compare pulmonary ventilation rate, tidal volume and breathing frequency at rest, during exercise, and during a period of maximum voluntary ventilation.

Maximum Voluntary Ventilation (MVV), also referred to as maximum breathing capacity or maximum minute ventilation, provides a measure of the maximum ability of the airways and thoracic muscles to move air in to and out of the lungs. MVV depends on body size, the forces generated by the respiratory muscles (both inspiratory and expiratory), the mechanical properties of the thoracic wall (rib cage and diaphragm) and upon airway resistance. Psychological factors are also involved (e.g., motivation).

In healthy young males, the mean MVV is about 140 l/min (range 100-180 l/min). For females, the mean is about 100 l/min (range 70-120 l/min). During rest and exercise, ventilation is driven by the rate of oxygen consumption and carbon dioxide production, whereas during the MVV procedure ventilation is driven by non-respiratory factors, i.e. higher brain centres.

In this section the subject was breathing as fast and as vigorously as possible for 15 to 20 seconds during which time respiratory data were recorded. Use the following trace to calculate the subjects’ tidal volume, the breathing frequency and the ventilation.

The trace below for exercise was taken just after the subject completed vigorous exercise. Use the trace to calculate the subjects’ tidal volume, the breathing frequency and the ventilation.