What is the role of forced expiratory volume (FEV1) testing in the evaluation of status asthmaticus?

Updated: Jun 17, 2020
  • Author: Constantine K Saadeh, MD; Chief Editor: John J Oppenheimer, MD  more...
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A drop in the FEV1 to less than 25% of the predicted value indicates a severe airway obstruction. A patient with an FEV1 of greater than 60% of the predicted value may be treated in an outpatient setting, depending on the clinical situation. Some with associated fixed obstruction may have abnormal spirometry at baseline. Also, in very obese patients, FEV1 may be diminished. Thus, evaluation of the FEV1/FVC is quite helpful. However, if the patient's FEV1 or PEF rate drops to less than 50% of predicted, admission to the hospital is recommended.

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