Relationship between response to inhaled salbutamol and methacholine bronchial provocation in children with suspected asthma.
Fifty children (27 females, 23 males) ages 6-15 years who were referred for evaluation of suspected asthma had baseline FEV1 and FEF25-75 of greater than or equal to 80% and FEF50 greater than or equal to 70% of predicted values. All had these tests repeated on the same day, after inhaling salbutamol. On a subsequent day PC-20 (methacholine) was determined as an index of bronchial hyperreactivity (BH). Fourteen age-matched healthy children (6 females, 8 males) were studied in a similar manner. There was no significant relationship between the PC20 and the change in FEF25-75 or FEF50 following salbutamol. There was a negative correlation between the initial FEV1 (% predicted) and the percent change in FEV1 following salbutamol (P less than 0.01). An increase in FEV1 of greater than 6% occurred in 7/12 (58.3%) patients with PC20 less than or equal to 0.25 mg/mL (Group I); in 7/24 (29.2%) patients with PC20 = 0.26-2.0 mg/mL (Group II); in only 1/14 (7.1%) patients with PC20 greater than 2.1 mg/mL (Group III) and in none of those asymptomatic (control) children with PC20 greater than 8.0 mg/mL (Group IV). All subjects who had a change in FEV1 greater than 6% after salbutamol had a PC20 less than 8 mg/mL and this test detected the majority of patients with severe BH. However, although the sensitivity of the test was 100%, the predictive value was only 36%. We conclude that in the presence of a normal baseline FEV1 a change of greater than 6% following salbutamol inhalation is indicative of bronchial hyperreactivity.
Bibi
H
H
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
Montgomery
M
M
Pasterkamp
H
H
Chernick
V
V
D000280:Administration, Inhalation; D000293:Adolescent; D000420:Albuterol / Q000008:administration & dosage / Q000494:pharmacology*; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D001980:Bronchi / Q000187:drug effects* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects* / Q000502:physiology
D016210:Methacholine Chloride; D000420:Albuterol