Wheezing in children

Dr Divya Nair

Department of Pediatrics,

Mahavir Hospital & Research Centre,

Hyderabad.

Introduction Wheeze is a continuous & musical sound that

originates from oscillations in narrowed

airways

Mostly heard in expiration due to critical

airway obstruction

Sign of lower (intra-thoracic) airway

obstruction

If there is widespread narrowing of airways

leading to various levels of obstruction to

airflow (eg. asthma), polyphonic wheeze is

heard i.e. sounds of various pitches

Monophonic wheeze (single pitch) is produced

in larger airways during expiration eg. distal

tracheomalacia, bronchomalacia

Infants & children are prone to wheeze due to different set of lung mechanics ( as compared to older children & adults)

Obstruction to airflow airway caliber

compliance of lung

1) Resistance = 1/ ( radius of tube)4

In children < 5 years, small caliber peripheral

airways can contribute upto 50% of airway

resistance

Marginal additional narrowing can cause further

flow limitation & subsequent wheeze

2) Compliant chest walls, especially in newborns,

leads to intra-thoracic airway collapse due to

inward pressure produced in expiration

3) Differences in tracheal cartilage composition &

airway muscle tone causes further increase in

airway compliance

All these mechanisms combine to make the

Infant more susceptible to airway collapse

Increased resistance

Subsequent wheeze

Many of these are outgrown in the 1st year

of life itself

4) Immunologic & molecular influences:

Infants have increased levels of lymphocytes &

neutrophils in BAL fluid

Variety of inflammatory mediators have been

implicated eg. Histamine, leukotrienes,

interleukins, etc

Fetal & early post-natal “programming” affects the

structure & function of fetal lung by factors

including fetal nutrition, fetal & neonatal exposure

to maternal smoking

DD’s of wheezing: 1) INFECTION:

Viral : RSV (Bronchiolitis)

Human metapneumovirus

Influenza, Parainfluenza

Adenovirus

Rhinovirus

Others: TB

Chlamydia trachomatis

Histoplasmosis

2) ASTHMA:

i) Transient wheezer - risk factor is primarily

diminished lung size

ii) Persistent wheezers – initial risk factors being

passive smoke exposure, maternal asthma

history, persistent rhinitis, eczema <1yr age,

increased IgE in 1st yr of life

At an increased risk of developing clinical

asthma

iii) Late onset wheezer

3) Anatomic abnormalities:

a) Central airway abnormalities:

- Malacia of larynx, trachea, bronchi

- Tracheoesophageal fistula ( H type)

- Laryngeal cleft (leading to aspiration)

b) Extrinsic airway anomalies (leading to com-

pression):

- Vascular ring/ sling

- Mediastinal LN’pathy (infection/ tumor)

- Esophageal foreign body

c) Intrinsic airway anomalies:

- Airway hemangioma

- Cystic adenomatoid malformation

- Bronchial/ lung cyst

- Congenital lobar emphysema

- Aberrant tracheal bronchus

- Sequestration

- CHD with L R shunt ( pulmonary edema)

- Foreign body

4) Immunodeficiency states:

- IgA deficiency

- B cell defiency

- AIDS

- Bronchiectasis

5) Mucociliary clearance disorders:

- Cystic fibrosis

- Primary ciliary dyskinesias

- Bronchiectasis

6) Bronchopulmonary Dysplasia

7) Aspiration Syndromes

- GERD

- Pharyngeal/ swallow dysfunction

8) Interstitial lung disease

9) Heart Failure

10) Anaphylaxis

11) Inhalation Injury – Burns

12) WALRTI, Wheeze a/w URTI

13) Drugs: Ibuprofen, Aspirin, Rifampicin, Erythromycin

Etiology: I) ACUTE BRONCHIOLITIS:

- It is acute inflammation of the airways

- predominantly a viral disease

- cause: RSV ( > 50%) , parainfluenza,

adenovirus, mycoplasma, human metapneumovirus

- more common in males, not breast fed, live in

crowded conditions

- older family members are source of infection

- LRTI manifestations are minimal in older patients in

whom bronchial edema is better tolerated

- RSV infection leads to a complex immune response

i) Eosinophils degranulate release Eosinophilic

Cationic Protein cytotoxic to airway epithelium

ii) IgE antibody release may be related to wheezing

iii) Other mediators: Chemokines (IL-8, Macrophage

Inflammatory Protein); Leukotrienes , IF gamma

- Characterized by bronchiolar obstruction with

edema, mucus & cellular debris

- Resistance in small airway is increased more in exhalation than

inspiration respiratory obstruction early air trapping &

overinflation complete obstruction atelectasis

- Hypoxemia occurs early in the course due to

VQ mismatch

- Hypercapnia develops due to severe

obstructive disease and respiratory fatigue

II) ALLERGY & ASTHMA:

- Important cause of wheezing

- Characterized by:

airway inflammation,

bronchial hyper-reactivity,

reversibility of obstruction

- 3 identified patterns:

a) Transient early wheezer: 20% of population

Before the age of 3yrs had wheezing at least

once, with LRTI but never wheezed again

b) Persistent wheezer: 14% of population

Before 3yrs age had wheezing episodes

still wheezing at 6yrs age

c) Late onset wheezer: 15% of population

No wheezing by 3yrs but wheezing by

6yrs

- The remaining 50% of children had never

wheezed by 6yrs of age

III) CHRONIC INFECTIONS:

- Should be considered in infants who seem

to fall out of range of a normal clinical

course

- Cystic fibrosis is a common cause

- Persistent respiratory symptoms, digital

clubbing, malabsorption, FTT, electrolyte

abnormalities, resistance to bronchodilator

therapy

IV) CONGENITAL MALFORMATIONS:

- Causes wheezing in early infancy

- Findings can be diffuse or focal

- Can be from an ext compression/ intrinsic abn

- External vascular compression: vascular ring/

sling compressing trachea/ esophagus

- CVS causes: massive cardiomegaly, LA

enlargement, dilated pulmonary arteries

- Pulmonary edema d/t CHF lymphatic &

bronchial vessel engorgement obstruction &

edema of bronchioles Wheeze

V) FOREIGN BODY ASPIRATION:

- Can cause acute/ chronic wheezing

- Common between 2mths- 4 yrs of age

- Infants may present with atypical histories or

misleading radiological/ clinical findings

- D/d: asthma, other obstructive disorders

- Esophageal FB can transmit pressure to

membranous trachea compromises the

airway lumen

VI) GASTROESOPHAGEAL REFLUX:

- can cause direct aspiration into tracheo-

bronchial tree

- may trigger a vagal/ neural reflex

increased airway resistance

airway reactivity

VII) TRAUMA & TUMORS:

- rare causes of wheezing in children

- trauma of any type to TB tree (aspiration/ burns/ scalds)

inflammation of the airways subsequent wheeze

- SOL (lung/ extrinsic) compression

obstruction to airway

Clinical Manifestations HISTORY & PHYSICAL EXAMINATION

- ODP & associated factors of wheezing:

- Birth history: weeks of gestation, NICU admission,

h/o intubation/ O2 requirement, maternal

complications eg. Infn- HSV, HIV; prenatal smoke

exposure

- Past medical history: co-morbid conditions eg.

syndromes or association

- Social history:

Environmental history of smokers at home,

number of siblings, occupation of inhabitants at

home, pets, TB exposure

- Family history:

of CF, immuno-deficeincy, asthma in 1st degree

relatives OR

any other recurrent respiratory conditions should

be obtained

RISKS OF FAMILY HISTORY OF ATOPY

No family history : 16%

Single parent atopy : 22%Maternal Atopy : 32 %

Both parents atopic : 50%

(Aberdeen Study 1994)

Pertinent medical history in wheezing infant:

Did the onset of symptoms begin at birth or thereafter?

Is the infant a noisy breather & when is it most prominent?

Is there a history of cough apart from wheezing?

Was there an earlier LRTI?

Have there been any emergency department visits, hospitalizations, or ICU admission for RD?

Is there a history of eczema?

How is the infant growing & developing?

Is there associated failure to thrive?

Is there failure to thrive without feeding difficulties?

Are there s/o intestinal malabsorption including frequent , greasy, or oily stools?

Is there a maternal history of genital HSV infection?

What was the gestational age at delivery?

Was the patient intubated as neonate?

Does the infant bottle feed in the bed or crib, especially in propped position?

Are there any feeding difficulties including choking, gagging, arching, or vomiting with feeds?

Any new food exposure?

Is there a toddler in the home or lapse in supervision in which foreign body aspiration could have happened?

Change in caregivers or chance or non accidental trauma?

Physical examination:

- Vitals especially RR, SPO2

- Growth charts for s/o FTT

- Upper airway s/o atopy: boggy turbinates ,

posterior oropharynx cobblestoning

- Evaluate skin for eczema, hemangioma

- Midline lesions may be associated with

intrathoracic lesions

- Clubbing

- S/O RD- Tachypnea, nasal flaring, tracheal

tugging, SCR/ICR, excessive use of accessory

muscles

- Prolonged expiratory time, expiratory whistling

sounds

- Auscultation: aeration to be noted, expiratory

wheeze, lack of audible wheeze due to complete

airway obstruction

- Trial of bronchodilators to evaluate change of

wheezing

- Stridor +/-.

Air Trapping Hyperinflated chest

Barrel shaped

Loss of cardiac dullness

Liver pushed down

Hoover sign

Normal diagphragm movement

Hyperinflation = diaphragm flattened

Diaphragm contraction = paradoxical inward

movement of lower interrcostal area during

inspiration

In Acute Bronchiolitis:

- h/o exposure to older contact with URTI

infant 1st develops mild URTI with sneezing &

rhinorrhea may be associated with

decreased appetite & fever gradually RD

ensues with paroxysmal wheezy cough,

dyspnea, irritability

- Apnea may be more prominent than

wheezing early in the course of disease esp

with very young infants ( < 2 mths ) or former

premature infants

- Degree of tachypnea doesn’t always correlate

with degree of hypoxemia/ hypercarbia

- Fine crackles/ overt wheezes present

- Hyperinflation of lungs palpation of liver &

spleen

Diagnostic evaluationInitial evaluation depends on likely etiology

1. Chest Xray: hyperinflation, SOL,

s/o chronic diseases like

bronchiectasis, focal infiltrates

2. Trial of bronchodilators-

diagnostic & therapeutic in

bronchiolitis & asthma, won’t effect fixed obstruction

May worsen wheezing in tracheal/ bronchomalacia

3. Baseline immunity in complicated cases

Exclude other conditions

4) Structural problems: bronchoscopy

5) URTD : Polysomnography

6) Esophageal disease: Barium swallow, pH probes, Upper GI scopy

7) Primary ciliary dyskinesia: nasal ciliary motility, Exhaled NO,

Electron Microscopy, saccharine test

8) TB: mantoux, induced sputum/ gastric lavage/ BAL = Culture,

microscopy & PCR

9) Bronchiectasis: HRCT scan, BAL

10) CF: sweat test, nasal potentials, genotypes

11) Systemic immune deficiency: Ig subtypes,

lymphocytes & neutrophil function, HIV

12) Cardiovascular disease: echo, angiography

13) Viral testing (PCR, viral culture) is helpful if diagnosis

is uncertain.

Treatment

1) Comfort the child –

Try to keep your baby calm. Having a cough and a

noisy wheeze frightens children and breathing is

more difficult when they are upset.

2) Offer frequent liquids –

Drinking less but more often may be easier

3) Bronchodilators:

- administer inhaled short acting beta-2 agonist

(eg salbutamol) & observe the response

- Children < 3 yrs: inhaled medications by MDI

with mask & spacer, if therapeutic benefit

demonstrated

- response is unpredictable

- Therapy to be continued in all asthma

patients with exacerbations with viral

illness

4) Ipratropium bromide:

- can be used as adjunct therapy

- also useful in patients with significant tracheal or

bronchomalacia

- Anticholinergic agent

5) Oral/ IV steroids:

- used for atopic wheezing infants thought to have

asthma i.e. refractory to other medications

6) Inhaled steroids:

- appropriate for maintenance therapy in known reactive

airways but not useful in acute illness

- to be used if significant h/o atopy ( food allergy, eczema)

present

- maintenance treatment with inhaled steroids is

recommended for multiple-trigger wheeze.

7) In acute bronchiolitis:

- hospitalze

- mainstay of treatment is supportive

- hypoxemic child: cool humidified oxygen

- avoid sedatives

- keep head & chest elevated at 30 degree angle

- NG tube feeds to avoid aspiration

- resp decompensation tracheal intubation

- Bronchodilators show modest short term

improvement in clinical features

- Nebulized epinephrine more effective

8) Montelukast is recommended for the treatment of

episodic (viral) wheeze,to be started when symptoms of a

viral cold develop

9) Ribavarine: antiviral administered by aerosol

- Used for children with CHD/ CLD

10) No role of antibiotics unless secondary bacterial

infection

Prevention 1) Reduction in severity & incidence of ac. bronchiolitis due to

RSV is possible through administration of pooled Hyperimmune

RSV Intravenous Immunoglobulin (RSV IVIg, Respigam) and

2) Palivizumab, a monoclonal antibody to the RSV F protein, before &

during RSV season

It is recommended for children < 2yrs age with chronic lung disease

(BPD) or prematurity

3) Inhaled corticosteroids and montelukast may be

considered in preschool child with recurrent wheeze.

4) Avoid smoking –

Smoking in the home or car increases the risk of respiratory

problems in children

5) Educating parents regarding causative factors and

treatment is useful.

6) Allergen avoidance may be considered when sensitisation

has been established

7) Meticulous handwashing is the best measure

to prevent nosocomial infection

Prognosis Approx 60% of infants who wheeze, will stop wheezing

Ac. Bronchiolitis: highest risk in 1st 2-3 days ; Case Fatality Rate < 1%

Death apnea, severe dehydration, uncompensated resp acidosis

Mean duration of symp - 12 days

High incidence of wheezing & asthma in children with h/o

bronchiolitis

CHD/ BPD/ Immuno-deficiency:

More severe disease, higher morbidity & mortality

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