Histamine inhalation provocation tests were performed in 18 asymptomatic asthmatic patients with progressively increasing doses of a pressurized aerosol of histamine phosphate. Forced expiratory volume in 1 s (FEV1), total neuromuscular output, assessed by mouth occlusion pressure (P0.1), mean inspiratory flow (VT/Ti), and the P0.1/(VT/Ti) ratio, which represents an index of effective inspiratory impedance of the respiratory system, were measured. With histamine, compared to control, FEV1 decreased and P0.1/(VT/Ti) increased (p <0.01 for both). After bronchoconstriction was reversed by administration of a β2-agonist bronchodilator (fenoterol), a significant decrease in P0.1/(VT/Ti) (p <0.001) and a significant increase in FEV1 (p <0.01) were noted as compared to histamine. With histamine, change in P0.1/(VT/Ti) was found to be related to its pre-histamine value (p <0.01). Furthermore, with histamine and fenoterol, changes in P0.1/(VT/Ti) and concurrent changes in FEV1 were found to be significantly related (p <0.001). From these data we calculated that the P0.1/(VT/Ti) ratio provides a useful tool in the clinical assessment of histamine-induced bronchospasm.
|Number of pages||7|
|Publication status||Published - 1987|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine