Bronchial Asthma: Investigation

1. BRONCHIAL ASTHMA InvestigationS Muhammad Redzwan 081303583

2. FEV1 Forced Expiratory Value in 1 second. Using spirometry Volume of air that can forcibly be blown out in one second, after full inspiration. Average values for FEV1 in healthy people depend mainly on sex and age. Asthma: FEV1 ≥ 15% increase following administration of bronchodilator/trial of CS OR FEV1 ≥ 15% decrease after 6 minutes of exercise

3. PEFR Peak Expiratory Flow Rate. Measured with a small hand held device call Peak Flow Meter. PEF is a person's maximum speed of expiration. Patients need to record PEF after rising in the morning and before retiring in the evening . Asthma: >20% diurnal variation on ≥ 3 days in a week for 2 weeks

4. Challenge Test Sometimes patients with symptoms are suggestive of asthma have a normal lung function. Challenge test is done to these type of patient Administration of sequentially increasing of concentration of either histamine, mannitol or methacholine . Adenosine challenge test is more specific Expressed as dose of either substance needed to produce 20% decrease in the FEV1 Exercise challenge also can be done

5. Measurement of Allergic Status Skin prick tests can demonstrate atopy Measurement of total and allergen-specific IgE Full blood picture may show peripheral blood eosinophilia

6. Other Ix CXR is usually normal . May shows hyperinflation of lungs fields Lobar collapse if mucus occludes large bronchus Flitting infiltrates if allergic bronchopulmonary aspergillosis Assessment of eosinophilic airway inflammation . Sputum differential eusinophil count greater than 2% OR exhaled breath Nitric Oxide concentration Not specific

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8. Arterial Blood Gas (ABG) Important to assess severity of asthma attack Life-threatening Features PEF < 33% predicted (< 100 L/min) SpO2 < 92% or PaO2 < 8 kPa Normal or raised PaCO2 (Normal: 6 kPa ) Near fatal Asthma Raised PaCO2 and/or requiring mechanical ventilation

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