Hyperoxic-Induced Hypercapnia in Stable Chronic Obstructive Pulmonary Disease1–3

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Abstract
We investigated the mechanism of hyperoxic-induced hypercapnia in 17 stable patients with moderate to severe chronic obstructive pulmonary disease (mean FEV1 = 0.95 L and FVC = 2.43 L). Ventilatory and mouth occlusion pressure (P0.1) responses to hypercapnia and hypoxia were measured with standard rebreathing techniques. In a randomized, single-blind fashion, we studied the effect of 15 min of hyperoxia or air on transcutaneous carbon dioxide (PtcCO2), CO2 production , total minute ventilation , and calculated dead space to tidal volume ratio (Vd/Vt). With O2, the PtcCO2 (p < 0.01) and Vd/Vt (p < 0.02) increased. The change in PtcCO2 with O2 was not significantly related to the indices of respiratory drive, nor to the baseline PtcCO2 or SaO2, but was related to the FEV1 (p < 0.05). The O2 caused a slight decrease in mean and mean , but the effects in individual patients were variable. Both substantial increases or decreases in occurred, but these were accompanied by changes in in the same direction. The e...