Asthma

In Morning Report this week, we discussed the evaluation, diagnosis, and differential diagnosis of asthma, as well as the major considerations when asthma is “poorly controlled” in the ambulatory setting. To review some of the major points:

  1. Asthma diagnosis involves supportive clinical symptoms accompanied by characteristic abnormalities on spirometry.
    • FEV1<FVC below the Lower limit of normal (which is usually less than 0.75-.08)
      • note: this is DIFFERENT than COPD diagnosis which is <0.7 according to GOLD guidelines
    • Bronchodilator reversibility
      • as demonstrated by an improved in FEV1 of 200 cc AND by 12% (both are needed)
    • Methacholine challenge
      • Looking for the concentration of methacholine which lowers the FEV1 by 20%
      • <4 mg/cc is diagnostic
    • Excercise challenge
      • >10-15% decrease in FEV1 after excercise
  2. Asthma is not the only entity that causes wheezing, but is one of the more common causes.
    DDx Wheezzing
  3. “Poorly Controlled” asthma has it’s own differential diagnosis:
    • Indicators of asthma control are indicated in the table below:

      Asthma control.png

    • Possible contributors to poor control include:
      • Nonadherence or wrong puffer technique
      • Trigger exposure ongoing
        • Environmental allergens, secondhand smoke, viral illness, workplace chemicals, perfumes, air fresheners, excercise, cold, pre-menstrual
      • Comorbid influencers
        1. Upper airway disease-rhinitis/sinusitis
        2. GERD
        3. AERD (Aspirin exacerbated respiratory disease)
        4. Obesity
      • Wrong Diagnosis
        Other Causes of Poor asthma control.png

Suggested Reading: Canadian Thoracics Society Asthma Guidelines

 

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