This document summarizes various tests and measurements used to investigate asthma, including: - Spirometry tests such as FEV1 and PEFR to measure lung function and detect bronchodilation. - Challenge tests that expose patients to substances like histamine to provoke asthma symptoms if present. - Skin prick and blood tests to measure allergic status. - CXR and sputum tests to examine lung inflammation and rule out other conditions. - ABG tests to evaluate severity during asthma attacks by measuring oxygen and carbon dioxide levels.

1. 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

5. 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

7. Challenge Test
 Sometimes patients with symptoms are suggestive of
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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

10. 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

11. 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

12. and

13. 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

15.  Tadaaa.. Nothing here~ 