Ventilation Rate and End –- Tidal Steady State Pulmonary Diffusing Capacity (DLCO_ss2) at Rest

Abstract

End-tidal steady state diffusing capacity (DLCO_ss2) was measured with different ventilation rates at rest in healthy subjects and patients with pulmonary diseases. The results in the patients were compared with the Filley method (DLCO_ss1) during exercise. The DLCO_ss2 values in the patients at rest during normoventilation correlated better to exercise DLCO_ss1 than the DLCO_ss2 values obtained during hyperventilation. The reproducibility of DLCO_ss2 at rest with ‘standardized’ ventilation was comparable to that reported for exercise DLCO_ss1. The healthy subjects had low DLCO_ss2 values at rest when breathing quietly, but if correction for ventilation was made, they could be separated from those with pulmonary diseases.

Key Words:

• Diffusing capacity
• end-tidal gas
• hyperpnea
• transfer factor