Clinical role of rapid-incremental tests in the evaluation of exercise-induced bronchoconstriction.
OBJECTIVE
To determine whether rapid-incremental work rate (IWR) testing would be as useful as standard high-intensity constant work rate (CWR) protocols in eliciting exercise-induced bronchoconstriction (EIB) in susceptible subjects.


METHODS
A cross-sectional study performed in a clinical laboratory of a tertiary, university-based center.


METHODS
Fifty-eight subjects (32 males, age range, 9 to 45 years) with suspected EIB were submitted to CWR testing (American Thoracic Society/European Respiratory Society guidelines) and IWR testing on different days; 21 subjects repeated both tests within 4 weeks. Spirometric measurements were obtained 5, 10, 15, and 20 min after exercise; a FEV1 decline > 10% defined EIB.


RESULTS
Twenty-seven subjects presented with EIB either after CWR or IWR testing; 21 subjects had EIB in response to both protocols (kappa = 0.78, excellent agreement; p < 0.001). Of the six subjects in whom discordant results were found, two had EIB only after IWR. Assuming CWR as the criterion test, IWR combined high positive and negative predictive values for EIB detection (91.3% and 88.6%, respectively). Tests reproducibility in eliciting EIB were similar (kappa = 0.80 and 0.72 for CWR and IWR, respectively; p < 0.001). Total and intense (minute ventilation > 40% of maximum voluntary ventilation) ventilatory stresses did not differ between EIB-positive and EIB-negative subjects, independent of the test format. There were no significant between-test differences on FEV(1) decline in EIB-positive subjects (25.7 +/- 10.8% vs 23.7 +/- 10.0%, respectively; p > 0.05). Therefore, no correlation was found between exercise ventilatory response and the magnitude of EIB after either test (p > 0.05).


CONCLUSIONS
Rapid-incremental protocols (8 to 12 min in duration) can be as useful as high-intensity CWR tests in diagnosing EIB in susceptible subjects. Postexercise spirometry should be performed after incremental cardiopulmonary exercise testing when EIB is clinically suspected.
De Fuccio
Marcelo B
MB
Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Diseases, Federal University of São Paulo, São Paulo, Brazil.
Nery
Luiz E
LE
Malaguti
Carla
C
Taguchi
Sabrina
S
Dal Corso
Simone
S
Neder
J Alberto
JA
D000293:Adolescent; D000328:Adult; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology*; D002648:Child; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000009:adverse effects*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption