The Place of Forced Expiratory Volume in Relation to Other Lung Function Tests

¹ Pulmonary function departments of Baggot Street Hospital, Dublin, Ireland
² London Hospital, Whitechapel, London England

The purpose of this study was to relate the forced expiratory volume (FEV₁) to other lung function tests and to assess the factor of "reversibility." Six hundred thirty-five patients with "chronic nonspecific lung disease" were divided into those who showed an increase in the FEV₁ after a bronchodilator aerosol (469) and those who showed no response (166). There was a linear relationship between the FEV₁, and the steady-state diffusing capacity (gas transfer) which was most obvious in the non-responsive group and did not apply to the single breath technique of measuring gas transfer. There was a tendency for the Pv_CO2 to rise with a falling FEV₁ and, again, this was most marked in the non-responsive group, the Pv_CO2 rising sharply for a FEV₁, below one liter. The findings suggest, especially when the FEV₁ does not increase with the inhalation of a bronchodilator, that information about the steady-state Dco measurement may be deducted and an irreversible FEV₁ below one liter usually indicates pulmonary insufficiency.