asthma diagnosis

ProfessorProfessor

Abdur-Rab Khan Abdur-Rab Khan MRCP- FRCP MRCP- FRCP (UK)(UK)

Ayub Medical College AbbottabadAyub Medical College Abbottabad

Diagnosis of AsthmaDiagnosis of Asthma

HistoryHistory

Peak Expiratory Flow Rate Peak Expiratory Flow Rate (PEFR)(PEFR)

Measures how fast a person can exhale air

Requires a peak expiratory flow monitor

OmronMini-Wright AM2 Plus

PEFR VariabilityPEFR Variability

Asthma Diagnostic Clues:

• PEF Variability > 20%(basis: home monitoring 2-4x/day for 1-2 weeks)

• Improvement in baseline PEF by 20% after a 2-week therapeutic trial

PEFmax - PEFmin

PEFave

(pm, post-bd) (am, pre-bd)% Variability = X 100

0

50

100

150

200

250

300

350

1 2 3 4 5 6 7Days

PE

FR

(L

/min

)

pm PEFR

am PEFR

SpirometrySpirometry Recommended for the initial assessment of all

asthma suspects!

> 15% increase in FEV1.0

after ß-2 inhalation

Hallmark of Asthma: Reversibility!

Spirometry

Types of Flow Volume Curves

Normal Obstructive

Lit

ers

per

se

co

nd

Concavity

Asthma

Concavitypre-

bronchodilator

Improvedpost-bronchodilator

Good Measurements Good Measurements are Essential!are Essential!

Acceptable Loop

Unacceptable Loop

Is it Asthma?

Determine that the patient is experiencing episodic symptoms of airflow obstruction

Demonstrate that the obstruction is at least partially reversible

Exclude alternate diagnoses

Asthma wheezing

Lung Disease Overlap

Chronic Bronchitis

cough+sputum

Emphysema breathlessness

Airway Remodeling in Asthma

Denudation of the airway epithelium

Collagen deposition beneath the basement membrane

Edema

Mast cell activation

Inflammatory cell infiltration

COPD

Classifying Severity: BASED ON SYMPTOMS & LUNG FUNCTION

DaytimeSymptoms

Exacerbations Nightattacks

11

22

33

44

IntermittentIntermittent• <1x a week • Brief

MildMildpersistentpersistent

• >1x a week but < 1x/day

• May affect activity & sleep

ModerateModeratepersistentpersistent

• Daily • May affect activity & sleep

SevereSeverepersistentpersistent

• < 2x a month

• > 2x a month

• > once a week

• Frequent• Daily • Frequent• Limits

physical activity

FEV1 or PEF

• > 80% predicted• Variability < 20%

• > 80% predicted• Variability 20-30%

• > 60-80% predicted

• Variability > 30%

• < 60% predicted• Variability > 30%

THANK YOU THANK YOU