Comparison of capnovolumetry-derived dead space parameters with pulmonary function test in normal adults using histamine provocation

Abstract

Objectives: This study in healthy adults was conducted to explore the clinical application of capnovolumetric indices as compared to lung function parameters using histamine provocation. Methods: Forty healthy subjects received aerosol histamine or salbutamol in an automatic stimulation system with escalating doses of histamine. Dead space volumes of capnovolumetry and lung function parameters were examined with increased concentrations of histamine at a fixed time interval. The doses of histamine were selected from 0.0562mg-2.2mg and 0.1mg salbutamol was inhaled when a maximal dose of histamine was reached. Baseline values in each group were calculated prior to histamine inhalation. Results: Fowler dead space (VDF), Wolff dead space (VDW), threshold dead space (VDT), Bohr dead space (VDB), forced expiratory volume in 1s (FEV1) and peak expiratory flow (PEF) showed a dose-dependent reduction following histamine provocation, but there were no statistical differences in the measurements at baseline and post S6 provocation. The value of dC3/DV at the maximal dose was significantly increased over its baseline value (P<0.05). VDF, VDT and VDW were significantly increased after bronchodilator use (P<0.05 or <0.01). The changes in capnovolumetry did not correspond with the results of lung function test. Conclusions: The dC3/DV and airway dead spaces of capnovolumetry in healthy adults are significantly increased compared to lung function parameters before or after bronchodilator use, suggesting that capnovolumetry is feasible in diagnostic evaluation of airway reactivity, especially for persons who are unable to undertake lung function test.