Air Trapping Correlates With Increased Frequency of Albuterol Use and Severity of Wheeze in Persistent Asthma.

BACKGROUND: Symptoms of asthma have been shown to correlate poorly with spirometric variables of obstruction. We hypothesized that lung volume measurements might correlate with symptoms and frequency of rescue inhaler use in asthma. METHODS: Patients with persistent asthma on treatment for ≥12 months were enrolled from university-based clinics. The association between lung volumes, spirometry, asthma symptoms, and rescue inhaler use were explored by using linear modeling. RESULTS: Among the 120 subjects, 76% were women. The mean age ± SD was 52 ± 15 y. With regard to ethnicity, 64% of the subjects were caucasian, 23% were Hispanic, and 13% were African-American. Twenty-one percent of the subjects reported chest pain. There was no significant correlation between asthma symptoms or rescue inhaler use to spirometry indices of obstruction. The residual volume percent of predicted showed a significant association with the wheeze score (r = 0.32, P = .001) and frequency of rescue inhaler use (r = 0.35, P ≤ .001). Linear contrast analysis showed that the mean wheeze score (P = .003) and frequency of rescue inhaler (P = .007) use increased linearly from the lowest to the highest quartiles of residual volume. Furthermore, multiple regression analysis showed an association only to the residual volume percent predicted value to the pressurized metered-dose inhaler score and the wheeze score. CONCLUSIONS: Frequent albuterol use and wheezing may be a sign of unrelieved air trapping. Chest pain is a unique symptom in persistent asthma, and the pathogenesis requires further studies. Lung volume measurement added to routine spirometry can help identify patients with asthma and with air trapping.