Deep breaths, methacholine, and airway narrowing in healthy and mild asthmatic subjects.
Deep breaths taken before inhalation of methacholine attenuate the decrease in forced expiratory volume in 1 s and forced vital capacity in healthy but not in asthmatic subjects. We investigated whether this difference also exists by using measurements not preceded by full inflation, i.e., airway conductance, functional residual capacity, as well as flow and residual volume from partial forced expiration. We found that five deep breaths preceding a single dose of methacholine 1) transiently attenuated the decrements in forced expiratory volume in 1 s and forced vital capacity in healthy (n = 8) but not in mild asthmatic (n = 10) subjects and 2) increased the areas under the curve of changes in parameters not preceded by a full inflation over 40 min, during which further deep breaths were prohibited, without significant difference between healthy (n = 6) and mild asthmatic (n = 16) subjects. In conclusion, a series of deep breaths preceding methacholine inhalation significantly enhances bronchoconstrictor response similarly in mild asthmatic and healthy subjects but facilitates bronchodilatation on further full inflation in the latter.
Crimi
Emanuele
E
Dipartimento di Medicina Interna, Università di Genova, 16132 Genova, Italy.
Pellegrino
Riccardo
R
Milanese
Manlio
M
Brusasco
Vito
V
D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D016084:Bronchoconstriction / Q000187:drug effects*; D016085:Bronchoconstrictor Agents / Q000494:pharmacology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects*; D005652:Functional Residual Capacity; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology*; D012123:Pulmonary Ventilation; D012016:Reference Values; D012115:Residual Volume; D015656:Respiratory Mechanics; D012143:Respiratory Physiological Phenomena; D012720:Severity of Illness Index; D013997:Time Factors; D014797:Vital Capacity / Q000187:drug effects*
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride