Non invasive assessment of physiopathologic events during methacholine inhaled test in asthmatics

Respiratory and pulmonary vascular modifications induced by methacholine inhaled challenge in 20 asthmatic outpatients were studied non invasively by means of echo-Doppler. Eight healthy volunteers were studied as a control group. A significant reduction in oxemia (-22 mmHg) as a hyperreactive marker (PD15O2) was observed in asthmatics and it was strictly related to PD20FEV1(r = 0.82 and p < 0.005). Again in asthmatics we observed a significant increase in sPAP (from 27±2 to 39±9 mmHg) evaluated by means of echo-Doppler: This variation was time related to hypoxic phase. Hypoxemia lasted 9±5 minutes but neither this index nor the basal lung function or the methacholine challenge results were related to the echo-Doppler measurements which were useful for evaluating the pulmonary vascular response. Finally our study suggests that: a) a significant decrease in oxemia was strictly related to the bronchial response in asthmatics; b) a transient increase in sPAP was present and time related to hypoxia only asthmatics; C) the lack of relationship among vascular and bronchial response was probably due to different distribution of ventilatory and vascular reflexes in each subject.