Background: Asthmatic patients typically show obstructive patterns on spirometry with positive bronchodilator responses; however, other spirometric patterns were also reported.
Objective: to determine patterns of spirometry among asthmatic patients who attend the outpatient clinic with respiratory symptoms.
Materials and Methods: A cross-sectional study was conducted among 323 known asthmatic patients (59% females) who attended the outpatient clinic with respiratory complaints. A portable spirometer (All flow, Clement Clarke International, Harlow, UK) was used for lung function measurements. Measurements and reversibility tests were performed according to the American Thoracic Society (ATS) Guidelines for spirometry measurements.
Result: Normal spirometric pattern was found in only 21% of all participants, obstructive in 12%, mixed in 32%, and restrictive in 36%. The patterns had no relation with the gender or the body mass index of the participants. The majority had low FEF25 (88%), low FEF50 (83%), and low FEF25-75% (82%) indicating inflammation within the middle and small airways. Nearly half of those who showed positive FVC reversibility tests had a restrictive pattern on presentation (p < 0.001).
Conclusion: Our findings indicate poor lung function of asthmatic patients on presentation. The bronchodilator responses were positive in a considerable proportion of those who presented with non-obstructive patterns.
Key words: Asthma, Spirometry, Outpatient clinic
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