Alveolar Gas Pressure Changes with Resistive Loads in Man

Abstract

Respiratory responses to a single breath during which a resistive load was applied were studied in 8 conscious subjects. There was an increase in inspiratory time (T₁), an increase in end-tidal Pco₂ (P_ETco₂) and a decrease in end-tidal Po₂ (PetO₂) on the resisted breath. 12 subjects were given a single inspiration of a mixture of air containing increased CO₂ and reduced O₂. This gas mixture induced changes in P_ETCO₂ and P_ETO₂ approximately double those seen with the resistive loads. There was no change in tidal volume (V_T), T₁ or expiratory time during the first breath. During the following breath there was a small increase in T₁ and V_T· The results indicate that although resistive loading may cause changes in PetCCCO₂ and P_ETO₂, these changes are unlikely to contribute to the respiratory responses during the first loaded breath.