title: Changes in residual volume during induced bronchoconstriction in healthy and asthmatic subjects.
abstract: The increase of residual volume (RV) was investigated during acute bronchoconstriction induced in healthy subjects by methacholine (MCh) (Group 1, n = 13) and in asthmatics by MCh (Group 2, n = 21), or housemite dust (Group 3, n = 11) during early and late airway responses (EAR and LAR), or a series of deep breaths (Group 4, n = 7). In all subjects the difference between residual volume after partial (RVp) and maximal maneuver (RV), expressed as a percentage of control FVC, increased during bronchoconstriction and was correlated with the percent increase of maximal to partial flow ratio at 50% of control FVC (M/P50) (r = 0.854, p < 0.0001). At comparable reduction of partial expiratory flow at 50% of control FVC (VP50), the decreases of FEV1 and FVC were less in healthy than asthmatic subjects, whereas the change of FEV1/FVC was similar in all groups, reflecting similar change in slope of flow-volume curves. The increase of RVp was similar in all groups (range: 15 to 19%), but the increase of RV was 6 +/- 1% (SEM) in healthy subjects and significantly greater (range: 11.1 to 13.3%) in all groups of asthmatics (p < 0.02, analysis of variance [ANOVA]). The effect of deep inhalation (DI) on the airway caliber as assessed by the increase of M/P50 was higher in normal subjects than in all groups of asthmatics (p < 0.0001). A negative correlation was found between the increases of RV and M/P50 in all groups (r = -0.358, p < 0.01), suggesting that healthy subjects had a limited increase of RV because of a marked bronchodilator effect of DI.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Servizio di Fisiopatologia Respiratoria, Ospedale A, Carle, Cuneo, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Pellegrino
authors.forename: B
authors.initials: B
authors.lastname: Violante
authors.forename: R
authors.initials: R
authors.lastname: Selleri
authors.forename: V
authors.initials: V
authors.lastname: Brusasco
mesh_terms: D000328:Adult; D000485:Allergens; D000818:Animals; D039741:Antigens, Dermatophagoides; D001249:Asthma / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005540:Forced Expiratory Flow Rates; D005541:Forced Expiratory Volume; D006023:Glycoproteins; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D012115:Residual Volume / Q000502:physiology*; D014797:Vital Capacity
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D006023:Glycoproteins; D016210:Methacholine Chloride