[Respiratory control in diffuse interstitial lung disease]

Whether the change of lung volume affect ventilatory responsiveness to chemical stimuli has not been studied in patients with interstitial lung disease (ILD). We measured the responses of minute ventilation (VE), tidal volume (VT), and occlusion pressure (P0.1) to hypercapnia (HCVR) and hypoxia (HVR) in these patients. Breathing efficiency (delta VE/delta P0.1) and effective compliance (delta VT/delta P0.1) were also measured under the same stimuli. 1) HCVR and HVR were measured in one female patient with hypersensitivity pneumonitis. VE responses during low VC phase (VC; 71% of predicted value) were similar to that during increased VC phase (VC; normal level) in both HCVR and HVR. However, VT responses of low VC phase were lower than those of increased phase, and P0.1 responses of low VC phase were higher than those of increased VC phase. Both breathing efficiency and effective compliance of low VC phase were lower than those of increased VC phase. 2) Thirty one patients with ILD were divided into two groups: low VC group; VC < 80% of predicted value, and normal VC group; VC > 80% of predicted value. HCVR and HVR were compared between two groups. Mean values of VE response to hypercapnia and hypoxia in low VC group were lower than those of in normal group, although they were not significantly different. VT response to hypercapnia and hypoxia were significantly lower of low VC group than those of normal VC group. Mean values of P0.1 responses to hypercapnia and hypoxia of low VC group were higher than those of normal VC group, although they were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)