The effect of voluntary hyperventilation on arterial blood gases and gas exchange in patients with chronic obstructive lung disease.

A 2 min test of voluntary hyperventilation (VHV) was performed on 19 patients with chronic obstructive lung disease (COLD) and on eight control subjects. The average decrease in PaCO2 in the patients in this test was 4.6 mmHg (11%) and the average increase in PaO2 was 12.3 mmHg (19.1%). The average decrease of PaCO2 in control subjects was 16.5 mmHg (48.6%) and the average increase in PaO2 was 38.0 mmHg (46.2%). In patients with COLD, PaCO2 changes during VHV correlated significantly with respiratory exchange ratio; the correlation with minute and alveolar ventilation and deltaVO2/deltaVE ratio during VHV was of borderline significance. PaCO2 changes during VHV did not correlate with FEV1 (percent of predicted) or FEV1/VC%. The possible mechanisms of changes in blood gas tensions during and after the end of VHV test are discussed. The VHV test seems to be useful in evaluation of patients with COLD.