ASTHMA MANAGEMENT AND PREVENTION IN CHILDREN

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ASTHMA MANAGEMENT AND PREVENTIONIN CHILDREN

• Thanaphirat Mamaethong

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• Asthma is one of the most common chronic diseases
• The prevalence is increasing, especially among
  children
• The prevalence of asthma symptoms in children
  varies from 0 to 30 percent
• The highest prevalence occurring in Australia,
  New Zealand and England

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DEFINITION OF ASTHMA

• Asthma is a chronic inflammatory disorder of the
  airways in which many cells and cellular elements
  play a role.
• The chronic inflammation causes an associated
  increase in airway hyperresponsiveness
• Recurrent episodes of wheezing, breathlessness,
  chest tightness, and coughing, particularly at
  night or in the early morning.

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• These episodes are usually associated with
  widespread but variable airflow obstruction that
  is often reversible either spontaneously or with
  treatment.

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NATURAL HISTORY OF ASTHMA

• Asthma in children and adults is frequently found
  in association with atopy
• The production of abnormal amounts of IgE
  directed to epitopes expressed on common
  environmental allergens
• For most patients with asthma, the disease begins
  prior to 6 years of age.

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Infancy

• Asthma may develop during the first few months of
  life, but it is often difficult to diagnosis
• The condition most commonly associated with
  wheezing is thought to be respiratory viral
  infection.
• Those children who continue to wheeze in later
  childhood apparently have asthma related to
  atopy.
• Indicating the possible deleterious effect of
  asthma on the development of the lung

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Childhood

• The predominant feature associated with asthma in
  children is allergy.
• It has often been suggested that childhood asthma
  will disappear when the patient reaches
  adulthood.
• disappears in 30 to 50 percent of children
  (especially males) at puberty, but often
  reappears in adult life.

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• The prognosis of asthma appears to be worse when
  the child has eczema or a family history of
  eczema
• 5 to 10 percent of children with asthma that is
  considered to be trivial have severe asthma in
  later life.

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Pathophysiology
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• result in airway inflammation, which limits
  airflow from bronchospasm, mucosal edema, and
  mucus plugs.
• Although many of the mediators responsible
  cytokines,chemokines, and growth factors
• These factors are produced by mast cells,
  lymphocytes, eosinophils, basophils, epithelial
  cells, dendritic cells, and smooth muscle cells.

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• Airway inflammation in asthma may represent a
  loss of normal balance between two "opposing"
  populations of Th lymphocytes.
• Two types of Th lymphocytes have been
  characterized
• Th1 cells produce IL-2 and IFN-a, which are
  critical in cellular defense mechanisms in
  response to infection.
• Th2, in contrast, generates a family of cytokines
  (IL-4, -5, -6, -9, and -13) that can mediate
  allergic inflammation.

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Airway pathology

• There is evidence of both acute and chronic
  inflammation that is irregularly distributed
  throughout the airways, including the smallest
  airways (less than 2 mm in diameter), and the
  parenchyma.

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• Trophic changes
• hypertrophy and hyperplasia of airway smooth
  muscle
• increase in goblet cell number
• enlargement of submucous glands
• remodeling of the airway connective tissue

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RELATIONSHIP OF AIRWAY PATHOLOGY TO DISORDERED
LUNG FUNCTION

• Airway Hyperresponsiveness
• Airflow Limitation
• Acute bronchoconstriction.
• Swelling of the airway wall.
• Chronic mucus plug formation.
• Airway wall remodeling.

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• Chronic inflammation of the airways is associated
  with increased BHR, which leads to bronchospasm
  and typical symptoms.
• In some patients with chronic asthma, airflow
  limitation may be only partially reversible
  because of airway remodeling that occurs

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Mechanism

• Airway obstruction causes increased resistance to
  airflow and decreased expiratory flow rates.
• Decreased ability to expel air and may result in
  hyperinflation.
• The resulting overdistention helps maintain
  airway patency, thereby improving expiratory
  flow however, it also alters pulmonary mechanics
  and increases the work of breathing

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• In the early stages, when V/Q mismatch results in
  hypoxia, hypercarbia is prevented by the ready
  diffusion of CO2 across alveolar capillary
  membranes.
• Hyperventilation triggered by the hypoxic drive
  also causes a decrease in PaCO2.
• An increase in alveolar ventilation in the early
  stages of an acute exacerbation prevents
  hypercarbia.

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• With worsening obstruction and increasing V/Q
  mismatch, CO2 retention occurs. In the early
  stages, respiratory alkalosis results from
  hyperventilation.
• Later, the increased work of breathing, increased
  oxygen consumption, and increased cardiac output
  result in metabolic acidosis.
• Respiratory failure leads to respiratory acidosis.

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RISK FACTORS

• Host factors
• Genetic predisposition
• Atopy
• Airway hyperresponsiveness
• Gender
• Race

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• Environmental factors
• allergens and occupational sensitizers
• viral and bacterial infections
• diet
• tobacco smoke
• socioeconomic status
• family size

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• Exposure to allergens and respiratory (viral)
  infections are the main factors responsible for
  causing exacerbations of asthma and/or the
  persistence of symptoms

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DIAGNOSINGASTHMA
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CLINICAL DIAGNOSIS

• Symptoms episodic breathlessness, wheezing,and
  chest tightness.
• Seasonal variability of symptoms
• Positive family history of asthma and atopic
  disease

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Physical Examination

• May be normal
• The most usual abnormal physical finding is
  wheezing on auscultation
• However, some people with asthma mayhave normal
  auscultation but significant airflow limitation
  when measured objectively

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• Dyspnea, airflow limitation (wheeze), and
  hyperinflation are more likely to be present if
  patients are examined during symptomatic periods.
  
• Physical signs reflecting severity cyanosis,
  drowsiness, difficulty speaking, tachycardia,
  hyperinflated chest, use of accessory muscles,
  and intercostal recession.

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• There are two general patterns of wheezing in
  infancy
• Infants who have recurrent episodes of wheeze
  associated with acute viral respiratory
  infections, come from nonatopic families,no atopy
  themselves. These infants usually outgrow their
  symptoms in the preschool years and have no
  evidence of subsequent asthma.
• Other infants with asthma have an atopic
  background often associated with eczema. Symptoms
  in these children often persist through childhood
  and into adult life. In these children
  characteristics of airway inflammation can be
  found even in infancy.

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• In young children with frequent wheezing, a
  parental history of asthma along with the
  presence of other atopic manifestations in the
  child are significantly associated with the
  presence of asthma at age 6.
• Although in these young children there is the
  possibility of over treatment, the episodes of
  wheezing may be shortened and reduced in
  intensity by the effective use of
  anti-inflammatory medications and bronchodilators
  rather than antibiotics.

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• Asthma can often be diagnosed on the basis of
  symptoms.
• However, measurements of lung function, and
  particularly the reversibility of lung function
  abnormalities, greatly enhance diagnostic
  confidence in children 5 years and older.

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Measurements of Lung Function

• Forced expiratory volume in 1 second (FEV1)
• Forced vital capacity (FVC)
• Peak expiratory flow (PEF)

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FEV1/FVC ratios

• FEV1/FVC ratios of lt 80 percent, are suggestive
  of airflow limitation
• Where at least a 12 percent improvement in FEV1
  either spontaneously, after inhalation of a
  bronchodilator, or in response to a trial of
  glucocorticosteroid therapy favors a diagnosis of
  asthma

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Peak expiratory flow

• An important aid in the diagnosis and subsequent
  treatment of asthma is the PEF meter
• At least a 15 percent improvement after
  inhalation of a bronchodilator or in response to
  a trial of glucocorticosteroid therapy favors a
  diagnosis of asthma

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• A diurnal variation in PEF of more than 20
  percent is considered to be diagnostic of asthma

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Methods

• Diurnal PEF variability is as the amplitude (the
  difference between the prebronchodilator morning
  value and the postbronchodilator value from the
  evening before), expressed as a percentage of the
  mean daily PEF value.
• The minimum morning prebronchodilator PEF over 1
  week, expressed as a percent of the recent best
  (MinMax).
• This latter method has been suggested to be the
  best PEF index of airway lability

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• For patients with symptoms consistent with
  asthma, but normal lung function
• Measurements of airway responsiveness to
  methacholine, histamine, or exercise challenge
  may help establish a diagnosis of asthma
• These measurements are sensitive for a diagnosis
  of asthma, but have low specificity

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Bronchial provocation tests
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Exercise challenge
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Other diagnostic considerations in children
include the following

• The presence of recurrent nocturnal cough in an
  otherwise healthy child should raise asthma as a
  probable diagnosis.
• A trial of asthma medication is probably the most
  confident way to make a diagnosis of asthma in
  children.
• The use of diary cards to record symptoms and PEF
  (in children over 5 years of age) readings are
  important tools in childhood asthma management.

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• Some children with asthma present symptom with
  exercise. If there is doubt in the diagnosis, a
  6-minute running protocol followed by measurement
  of PEF showing a 15 percent drop or symptoms
  following exercise can help establish a diagnosis
  of asthma.
• Allergy skin tests, can help in the
  identification of risk factors
• Asthma should be considered if the child's colds
  repeatedly "go to the chest" or take more than 10
  days to clear up, or if the child improves when
  asthma medication is given.

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DIFFERENTIAL DIAGNOSIS

• An important step in ensuring diagnosis of asthma
  is the demonstration of reversible and variable
  airflow limitation, preferably by spirometry.
• Another diagnosis to consider in both children
  and adults is pseudoasthma, most often caused by
  vocal cord dysfunction

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• Very rare causes of recurrent wheezing,
  particularly in early infancy
• cystic fibrosis, recurrent milk aspiration,
  primary ciliary dyskinesia syndrome, primary
  immune deficiency, congenital heart disease,
  congenital malformations causing narrowing of
  intrathoracic airways and foreign body
  aspiration.
• Chest radiography is an important diagnostic test
  to exclude such alternative causes of wheezing.

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CLASSIFY ASTHMASEVERITY

• Intermittent, mild persistent, moderate
  persistent, or severe persistent
• Based on the combined assessments of symptoms and
  lung function in children over 5 years of age
• Severity of asthma will determine the type of
  treatment required

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• The presence of one of the features of severity
  is sufficient to place a child in that category.
• Children with intermittent asthma but severe
  exacerbations should be treated as having
  moderate persistent asthma.
• Children at any level of severityeven
  intermittent asthmacan have severe attacks.

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Exacerbations

• Episodic worsening is a major feature of asthma.
• There are multiple triggers for exacerbations,
  including stimuli that
• produce bronchoconstriction only (inciters)
  cold air, fog, or exercise
• promote airways inflammation (inducers)
  exposure to allergens, occupational sensitizers,
  ozone, or respiratory virus infection.

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A SIX-PART ASTHMAMANAGEMENTPROGRAM
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A six-part management program includes

• Part 1. Educate children/families to develop a
  partnership in asthma care.
• Part 2. Assess and monitor asthma severity.
• Part 3. Avoid exposure to risk factors.
• Part 4. Establish individual medication plans for
  long-term management in infants and preschool
  children, school children, and adolescents with
  asthma.
• Part 5. Establish individual plans to manage
  asthma attacks.
• Part 6. Provide regular follow up care.

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The goals for successful management of asthma are

• Minimal or no symptoms, including nighttime
  symptoms
• Minimal asthma episodes or attacks
• No emergency visits to physicians or hospitals
• Minimal need for reliever medications
• No limitations on physical activities and
  exercise
• Nearly normal lung function
• Minimal or no side effects from medication.

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Part 1 Educate Children/Families To Develop a
Partnership in Asthma Care.

• Children and their families can be actively
  involved in managing their asthma to prevent
  problems. They can learn to
• Avoid risk factors.
• Take medications correctly.
• Understand the difference between "controller"
  and "reliever medications.
• Monitor their status using symptoms and, if
  available, PEF in children over 5 years of age.
• Recognize signs that asthma is worsening and take
  action.
• Seek medical help as appropriate.

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Part 2 Assess and Monitor Asthma Severity.

• Monitoring includes review of symptoms and,
  measurement of lung function in children over 5
  years of age.
• PEF monitoring at every physician visit helps in
  evaluating the child's response to therapy and
  adjusting treatment accordingly.
• PEF greater than 80 percent of the child's
  personal best suggests good control.

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• Long-term PEF monitoring at home can help
  children and their families recognize early signs
  of worsening asthma before symptoms occur.
• Regular visits (at 1 to 6 month intervals as
  appropriate) are essential, even after control of
  asthma is established.
• At each visit review the questions

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Part 3 Avoid Exposure to Risk Factors.

• To improve the control of asthma and reduce
  medication needs, children should avoid exposure
  to risk factors

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Part 4 Establish Individual Medication Plans for
Long-Term Management in Infants and Preschool
Children, School Children, and Adolescents With
Asthma.

• Childhood and adult asthma share the same
  underlying pathophysiological mechanisms.
• However, because of the processes of physical and
  cognitive growth and development, the effects,
  and adverse effects, of asthma and asthma
  treatments in children differ from those in
  adults.
• Many asthma medications are metabolized faster in
  children than in adults, and young children tend
  to metabolize drugs faster than older children.

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Select Medications

• Two types of medication help control asthma
• Controller medications that keep symptoms and
  attacks from starting
• Reliever medications that work quickly to treat
  attacks or relieve symptoms.

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• Inhaled medications are preferred
• Because of their high therapeutic ratio high
  concentrations of low doses of drug are delivered
  directly to the airways with potent therapeutic
  effects and few systemic side effects.

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• Devices available to deliver inhaled medication
  include
• Pressurized metered-dose inhalers (pMDIs),
  breath-actuated metered dose inhalers, dry powder
  inhalers (DPIs), and nebulizers.
• Spacer devices make inhalers easier to use.
• Spacers also reduce systemic absorption and side
  effects of inhaled glucocorticosteroids.

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Controller Medications

• inhaled glucocorticosteroids
• systemic glucocorticosteroids
• leukotriene modifiers
• sodium cromoglycate (cromolyn sodium)
• Nedocromil sodium
• Methylxanthines
• long-acting inhaled ?2-agonists,
• long-acting oral ?2-agonists.

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Reliever Medications

• ?2-agonists.
• Anticholinergic agents.

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• A stepwise approach
• The number and frequency of medications increase
  (step up) as the need for asthma therapy
  increases,
• and decreases (step down)when asthma is under
  control.

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• Step up if control is not achieved and sustained.
  Generally,improvement should be achieved within 1
  month.
• Step down if control is sustained for at least 3
  months
• Review treatment every 3 to 6 months once asthma
  is under control.

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• Consult with an asthma specialist when other
  conditions complicate asthma, the child does not
  respond to therapy, or treatment at steps 3 or 4
  is required.

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Part 5 Establish Individual Plans to Manage
Asthma Attacks

• Do not underestimate the severity of an attack
  severe asthma attacks may be life threatening.

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• Children/adolescents at high risk for
  asthma-related death includethose with
• History of near-fatal asthma.
• Hospitalization or emergency visit for asthma
  within the past year, or prior intubation for
  asthma.
• Current use of, or recent withdrawal from, oral
  glucocorticosteroids.
• Over-dependence on rapid-acting inhaled
  ?2-agonists.
• History of psychosocial problems or denial of
  asthma or its severity.
• History of noncompliance with asthma medication
  plan.

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Patients should immediately seek medical care
if...

• The attack is severe
• The response to the initial bronchodilator
  treatment is not prompt and sustained for at
  least 3 hours.
• There is no improvement within 2 to 6 hours after
  oral glucocorticosteroid treatment is started.
• There is further deterioration.

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Asthma attacks require prompt treatment

• Inhaled rapid-acting ?2-agonists are essential.
  If inhaled medications are not available, oral
  bronchodilators may be considered.
• Oral glucocorticosteroids introduced early in the
  course of a moderate or severe attack help to
  reverse the inflammation and speed recovery.
• Oxygen is given at health centers or hospitals if
  the patient is hypoxemic.

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• Methylxanthines are not recommended if used in
  addition to high doses of inhaled ??2-agonist.
• However, theophylline can be used if inhaled
  ?2-agonists are not available. If the patient is
  already taking theophylline on a daily basis,
  serum concentration should be measured before
  adding short-acting theophylline.
• Epinephrine (adrenaline) may be indicated for
  acute treatment of anaphylaxis and angioedema.

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Therapies not recommended for treating attacks
include

• Sedatives (strictly avoid).
• Mucolytic drugs (may worsen cough).
• Chest physical therapy/physiotherapy (may
  increase patient discomfort).
• Hydration with large volumes of fluid for adults
  and older children (may be necessary for younger
  children and infants).
• Antibiotics (do not treat attacks but are
  indicated for patients who also have pneumonia or
  bacterial infection such as sinusitis).

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• Mild attacks can be treated at home if the
  child/family is prepared and there is a personal
  asthma management plan that includes action steps

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• Moderate attacks may require, and severe attacks
  usually require, care in a clinic or hospital

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Monitor Response to Treatment

• Evaluate symptoms and, as much as possible, peak
  flow.
• In hospital, also assess oxygen saturation
  consider arterial blood gas measurement in
  patients with suspected hypoventilation,
  exhaustion, severe distress, or peak flow 30-50
  percent predicted.

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Part 6 Provide Regular Followup Care

• Children with asthma and their families need
  regular supervision and support by a health care
  professional
• Once asthma control is established, regular
  followup visits, continue to be essential.
• During these visits, monitor and review treatment
  plans, medications, and level of asthma control.

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SPECIAL CONSIDERATIONS ARE REQUIRED IN MANAGING
ASTHMA IN RELATION TO

• Pregnancy
• Surgery
• Physical activity
• Rhinitis
• Sinusitis and nasal polyps
• Occupational asthma
• Respiratory infections
• Gastroesophageal reflux
• Aspirin-induced asthma.

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REFERENCES

• GLOBAL STRATEGY FOR ASTHMA MANAGEMENT AND
  PREVENTION, UPDATED 2005, the Global Initiative
  for Asthma (GINA) program
• POCKET GUIDE FOR ASTHMA MANAGEMENT AND PREVENTION
  IN CHILDREN, Updated 2005, the Global Initiative
  for Asthma (GINA) program
• Is asthma curable?, ???????? ????????????,
  ??????????????????????? 2, ???? 2540
• Asthma ,Girish Sharma, MD., www.eMedicine.com

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THANK YOU