Changes in distribution of lung perfusion and ventilation at rest and during maximal exercise.

A new method for evaluation of changes in the distribution of pulmonary perfusion and ventilation during exercise was applied to normal male volunteers. Ventilation and perfusion scans were done with the subjects seated on a bicycle ergometer. The resting studies utilized krypton 81 (81mKr) for ventilation and technetium 99m (99mTc) macroaggregate albumin intravenously for perfusion. Exercise studies were done when 80 percent of maximum predicted heart rate was maintained for five minutes and utilized 81mKr for ventilation and a tenfold dose of 99mTc for perfusion. Higher dose of 99mTc would minimize the effect of radioactivity left over from the resting study. This method allowed us to assess changes in ventilation and perfusion in normal subjects induced by exercise, but may also be applicable in a variety of cardiopulmonary conditions that affect pulmonary ventilation and perfusion or both.