The effects and the mechanism of single and long-term administration of
theophylline on ventilatory regulation were investigated in patients with
chronic obstructive pulmonary disease (
COPD). The ventilatory and mouth occlusion pressure (P0.1) responses during CO2 rebreathing were measured before and 4 hours after oral, single administration of
theophylline in 15 patients with
pulmonary emphysema, 15 patients with
asthma and 10 healthy subjects. Ventilatory response to CO2 (VE/PCO2) was increased in patients with
asthma and P0.1 response to CO2 (P0.1/PaCO2) was increased in patients with
pulmonary emphysema after single
theophylline administration. In patients with
pulmonary emphysema, the increase in P0.1 was more marked than that in maximum inspiratory pressure static (MIPS). The effect of long-term administration of
theophylline was studied in 8 patients with
COPD and 8 patients with restrictive
lung disease. In patients with
COPD, P0.1/PaCO2 was significantly increased and the increase was maintained until three months later. These findings suggest that
theophylline is effective in improving ventilatory and occlusion pressure responses to CO2 in patients with
asthma probably by its bronchodilating effect, and in patients with
pulmonary emphysema by its direct effect on the ventilatory control system.