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Restrictive impairment in patients with asthma
1Pulmonary Division, Department of Medicine, St Vincent Catholic Medical Centers-Queens Division, Mary Immaculate Hospital, Jamaica, NY 11432, USA. almiller@svcmcny.org
Respiratory Medicine
|June 27, 2006
Summary
True restrictive impairment, a lung function abnormality not caused by air trapping, affects at least 8% of asthma patients. This finding is often overlooked but does not exclude asthma diagnosis or treatment.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
Background:
- Asthma commonly presents with airflow obstruction, often indicated by reduced FEV(1) and FEV(1)/VC ratio.
- Some asthma patients exhibit reduced vital capacity (VC) due to air trapping (pseudorestriction).
- Previous research identified true restrictive impairment in asthma patients, distinct from air trapping.
Purpose of the Study:
- To confirm true restrictive impairment in asthma patients, excluding air trapping.
- To determine the prevalence of true restrictive impairment within an asthma population.
Main Methods:
- Retrospective review of pulmonary function tests and clinical records of asthma patients.
- Defined restriction as decreased TLC or VC with normal FRC and normal/high FEV(1)/FVC ratio.
- Excluded patients with findings suggestive of restriction like decreased DL or obesity.
Main Results:
- 24% of asthma patients (100/413) showed restriction; 8% (32/413) had true restrictive impairment after exclusions.
- In patients with increased BMI and normal DL, restrictive impairment resolved with bronchodilator therapy.
- Only 7 out of 81 patients with restriction showed increased FRC, indicating minimal air trapping.
Conclusions:
- True restrictive impairment is present in approximately 8% of asthma patients.
- This finding aligns with previous observations in asthma and reactive airways dysfunction syndrome.
- The presence of true restrictive impairment should not hinder asthma diagnosis or treatment.