CO2換気応答に及ぼす気道攣縮寛解の影響

The Effect of bronchodilator on ventilatory response during CO2 rebreathing in patients with asthma

　換気における呼吸調節系は（1）刺激受容部sensor，（2）制御部controller，（3）作動部effectorより構成されている^1）。

　このような呼吸調節系のうち，血腋ガスレベルを調節する化学調節系は，ガス交換—血液ガス系restoring sys—temと，血液ガス—換気系driving systemよりなり，閉鎖回路を形成している。

　To clarify the machanism of the ventilatory regula-tion on airway obstruction, the effect of bronchodilator on ventilatory response in patient with asthma (n=16) was studied by comparing with that of the healthy subjects (n=5).

　CO₂ rebreathing method (Read, Whitelaw et al) was employed to measure ventilatory and occlusion pressure response before and after the administration of aminophylline (AM).

　The minute ventilation (V_E) and mouth occlusion pressure (P_0･1) at rest were increased with administering AM in both groups.

　In the healthy group, the ventilatory response to CO₂ (V_E/PA_CO2) increased slightly, and occlusion pressure response to CO₂ (P_0･1/PA_CO2) increased considerably with administering AM.

　On the other hand, in the asthmatic group increase of V_E/PACO₂ (from 2.00±1.51 to 2.47±2.47l/min/ mmHg) was more than that of P_0.1/PACO₂ (from 0.45± 0.21 to 0.53±0.29cmH₂O) after administering AM.

　These results suggested that AM, because of its bronchodilating effect and direct stimulation to the central respiratory center and respiratory muscles activity, is effective in enhancing ventilatory response to CO2 by widening narrowed airway.