PT  - JOURNAL ARTICLE
AU  - BM Grandordy
AU  - J Paiva de Carvalho
AU  - J Regnard
AU  - D Florentin
AU  - D de Lauture
AU  - J Marsac
AU  - A Lockhart
TI  - The effect of intravenous phenylephrine on airway calibre in asthma
AID  - 10.1183/09031936.95.08040624
DP  - 1995 Apr 01
TA  - European Respiratory Journal
PG  - 624--631
VI  - 8
IP  - 4
4099  - http://erj.ersjournals.com/content/8/4/624.short
4100  - http://erj.ersjournals.com/content/8/4/624.full
SO  - Eur Respir J1995 Apr 01; 8
AB  - Tracheobronchial vasoconstriction and subsequent reduction of airway wall thickness due to the alpha 1-agonist methoxamine, might be responsible for prevention of exercise-induced asthma, and reduction of bronchial hyperresponsiveness to methacholine increase in exercise performance in patients with impaired left ventricular function. Since bronchial wall oedema plays an important role in asthma, we have now investigated the bronchial response to the intravenously administered alpha 1-agonist, phenylephrine, in asthma of various severity. Increasing noncumulative intravenous phenylephrine doses (100 to 600 micrograms) were injected in 18 asthmatic subjects (three groups: mild asthma, mild asthma with recent acute attack, severe obstructive asthma) and in 11 control subjects. Changes in specific airways resistance (sRaw) on phenylephrine were linearly related to the dose administered in 16 out of 18 asthmatic subjects, and in only 3 out of 11 control subjects. In the asthmatic subjects, sRaw increased in 10 patients whose asthma was mild, or bronchial obstruction mild to moderate, and decreased in the remaining 8 asthmatic subjects with more severe disease or with a higher degree of bronchial obstruction. Changes in forced expiratory volume in one second (FEV1) were consistent with those of sRaw. In the five asthmatic subjects who underwent the protocol twice, results were reproducible. There was no difference in the responses of heart rate between the three groups of asthmatic subjects. It is likely that phenylephrine acts both via airway smooth muscle contraction, an effect which might predominate in mild asthma, and via mucosal vasoconstriction, which might overcome the effect on smooth muscle in more severe asthma with bronchial wall oedema.(ABSTRACT TRUNCATED AT 250 WORDS)