asthma investigation

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Friday, May 20, 2011 INTEGRATED HEALTH SCIENCE 1


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CASE #1



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CONTENTS

INTRODUCTION.

LUNG FUNCTION TESTS.

EXERCISE TESTS.

HEAMTOLOGIC AND SPUTUM TESTS.

SKIN TESTS.

IMAGING.

AIRWAY RESPONSIVENESS. Exhaled Nitric Oxide.

DIFFERANTIAL DIAGNOSIS.



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INTRODUCTION Asthma diagnosis is usually apparent from

the symptoms ofvariable and intermittent

airways obstruction, but is usually confirmed

bymeasurements of lung functions.

Most of the tests are used formanagement

of the condition anddetection of the

complications. In Emergency situation treatment is done

without any investigations.



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LUNG FUNCTION TESTS Two devices are used:

Spirometry. Peak flow meter.

Used for measuring reducing (FEV1,FEV1/FVC, & PEF).

Measurement is done twice before and after treatment. Oximetry: to measure the amount of oxygen in your

bloodstream.

Measurement twice daily to monitor diurnal variation.

A 15% or greater improvement in FEV1 from the baseline15 min

after use of an inhaled short-acting 2-agonist e.g. salbutamol

is important for monitoring the effect of the drug as well as for the

diagnosis to be sure.



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Respiratory Function Tests

Tests of examining airways functions

Spirometry The peak flow meter

(PEF)Expensive Inexpensive

Impractical

for home use(Hospital, offices)

Practical

measure lung functionin any place

Accurate Rough (less accurate)


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Peak Flow MeterSpirometry


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ALL

CLEAR

CAUTION

MEDICAL

ALERT

This indicates good lung function

Follow the routine treatment for maintaining

asthma control

Patient may need more aggressive

medical management for asthma

50% - 80% of personal best

Patient needs immediate treatment with

an inhaled bronchodilator

Notify his physician or seek emergency care

50% or less of personal best

80% - 100% of personal best

Zone System of PEF Meter for

Evaluation of Breathing:


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EXERCISE TESTS

This test is useful in the diagnosis of EIA.

This test is usually done for children.

Exercise-induced asthma (EIA) is a condition ofrespiratory difficulty that is triggered by

aerobic exercise and lasts several minutes.

A treadmill or stationary bicycle



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HEAMATOLOGIC AND SPUTUM

TESTS Blood test are not highly significant.

Total serum IgE and that specific for allergen

RAST. Hyperesinophillia (>0.4 *10^9/L).

Crush man spirals as an epithelial remnant.



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SKIN AND ALLERGEN PROVACATION TESTS

The purpose of these tests are to identify

the allergen for prevention of anotherattack(Avoidance of the allergen).

Common allergens identified are:

Environmental like (dustmites, grasspollens).

Usually associated with other atopic

disorders like allergic rhinitis


Wheal and flare reaction


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IMAGING Imaging studys have not big role in diagnosing

asthma.

It shows hyperinflated lung as an obstructive

lung disease, Or pneumothorax.

Lung shadowing indicates pneumonia, or

bronchopulmonary asperillosis.

CT may shows areas of bronchiectasis or

bronchial wall theckening.

All these are not diagnostic to asthma.



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AIRWAY RESPONSIVENESS

This test indicates that the patient have airwayhyperresponsiveness.(Low concentration of

the agent initiate high response).

Rarely useful in clinical practice.

Done by using methacholine or histamine and

calculate the concentration that decrease

FEV1 by 20%. PC20 FEV1

Used for differential diagnosis ofchronic

cough with normal pulmonary function tests.



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Exhaled Nitric oxide

Exhaled nitric oxide (NO), a measure of airwayinflammation and an index of corticosteroid

response, is used in children as a test for the

efficacy of corticosteroids.



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DIFFERENTIAL DIAGNOSIS It is not difficult to differentiate asthma from other

conditions that cause wheezing and dyspnea like(tumor or bronchpulmonary dysplasia, laryngeal

edema).

Diagnosis of these cases is by flow volume loop

which shows a reduction in inspiratory as well as

expiratory flow while in asthma only expiratory.

Bronchoscopy demonstrate the site of narrowing.

Persistent wheezing in specific area of the chestindicate foreign body obstruction.

Eosinophilic pneumonias and systemic vasculitis may

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RESOURCESI. HARRISONS PRINCIPLES

OF INTERNAL MEDICINE17th ED.

II. HARRISONS MANUAL OF

INTERNAL MEDICINE 17th .

III. KUMAR & CLARK CLINICAL

MEDICINE 7th ED.

IV. Medscape , & e-medicine.

Friday, May 20, 2011 19INTEGRATED HEALTH SCIENCE


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Review Questions

What is the most significant and useful tests

for asthma management and monitoring?

Peak flow meter, and spirometry.


asthma investigation

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