What is involved in the assessment of reversibility of airway obstruction in spirometry for pulmonary function testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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When airway obstruction is identified on spirometry, assessing response to inhaled bronchodilators is useful. The ATS has recommended that the threshold for significant response be demonstration of an increase of at least 12% and 0.2 L in either FVC (provided the expiratory time for both sessions agree within 10%) or FEV1 on a spirogram performed 10-15 minutes after inhalation of a therapeutic dose of a bronchodilating agent. New standards recommend the use of four inhalations (100 mcg each, 400 mcg total dose) of albuterol administered through a valved spacer device. When concern about tremor or heart rate exists, lower doses may be used. Response to an anticholinergic drug may be assessed 30 minutes after four inhalations (40 mcg each, 160 mcg total dose) of ipratropium bromide. Failure to respond to bronchodilator challenge does not preclude clinical benefit from bronchodilators. A positive response to the bronchodilators may correlate with response to steroid therapy.

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