Inspiratory impedance during histamine-induced bronchoconstriction in patients with bronchial asthma.
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 less than 0.01 for both). After bronchoconstriction was reversed by administration of a beta 2-agonist bronchodilator (fenoterol), a significant decrease in P0.1/(VT/Ti) (p less than 0.001) and a significant increase in FEV1 (p less than 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 less than 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 less than 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.
Spinelli
A
A
Istituto di Clinica Medica III, Università degli Studi, Policlinico di Careggi, Firenze, Italy.
Lo Conte
C
C
Gorini
M
M
Duranti
R
R
Gigliotti
F
F
Scibilia
M R
MR
Scano
G
G
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy; D001985:Bronchial Provocation Tests / Q000379:methods*; D001986:Bronchial Spasm / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D005280:Fenoterol / Q000627:therapeutic use; D006632:Histamine / Q000031:analogs & derivatives*; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged
D005280:Fenoterol; D006632:Histamine; C027556:histamine phosphate