Download Approach to wheezing in infants and children Author: Khoulood

Approach to wheezing in infants and children
Author:
Khoulood Fakhoury, MD
Section Editor:
Gregory Redding, MD
Deputy Editor:
Elizabeth TePas, MD, MS
Contributor Disclosures
All topics are updated as new evidence becomes available and our peer review process is
complete.
Literature review current through: Nov 2016. | This topic last updated: Aug 31, 2016.
INTRODUCTION — Wheezing is a common presenting symptom of respiratory disease in
infants and children. A nationwide survey performed in the United States between 1988 and
1994 showed that the prevalence for wheezing amongst two to three year olds was 26 percent
and amongst 9 to 11 year olds was 13 percent [1]. One in three children experience at least one
acute wheezing illness before the age of three years [2,3]. Wheezing may be either a benign,
self-limited process or the presenting symptom of a significant respiratory disease [4]. The role
of the treating clinician is to try to reach the most likely diagnosis as quickly and efficiently as
possible so that therapy, if necessary, can be instituted and the parental concerns can be
addressed.
The most likely diagnosis in children with recurrent wheezing is asthma, regardless of the age of
onset, evidence of atopic disease, precipitating causes, or frequency of wheezing [5]. However,
other diseases can present with wheezing in infancy and childhood, and patients with asthma
may not wheeze. The differential diagnosis of wheezing includes a variety of congenital and
acquired conditions (table 1).
Clinical history and physical examination often allow accurate diagnosis. However, radiographic
examination, pulmonary function testing, bronchoscopy, sweat chloride concentration, and
selective laboratory studies are helpful tools in establishing the underlying etiology of wheezing
when used appropriately [5,6]. The initial evaluation of a wheezing child is directed toward the
exclusion of alternative diagnoses, followed by a therapeutic trial of bronchodilators if asthma is
suspected.
A diagnostic approach to wheezing in childhood is presented in this topic review. An overview of
recurrent wheezing phenotypes, a review of the causes of nonasthmatic wheezing in children,
and the diagnosis and management of asthma are presented separately. Virus-induced
wheezing and the emergent evaluation of children with acute respiratory distress are also
discussed separately. (See "Wheezing phenotypes and prediction of asthma in young
children" and "Wheezing illnesses other than asthma in children" and "Asthma in children
younger than 12 years: Initial evaluation and diagnosis" and "Asthma in children younger than
12 years: Treatment of persistent asthma with controller medications" and "Virus-induced
wheezing and asthma: An overview" and "Treatment of recurrent virus-induced wheezing in
young children" and "Emergency evaluation and immediate management of acute respiratory
distress in children".)
DEFINITION AND PHYSIOLOGY OF WHEEZING — A wheeze is a continuous musical sound
heard during chest auscultation that lasts longer than 250 msec [7]. It is produced by the
oscillation of opposing walls of an airway narrowed almost to the point of closure [8]. It can be
high pitched or low pitched, consist of single or multiple notes, and occur during inspiration or
expiration. Wheezes can originate from airways of any size throughout the proximal conducting
airways. Wheezing requires sufficient airflow to generate airway oscillation and produce sound
in addition to narrowing or compression of the airway. Thus, the absence of wheezing in a
patient who presents with acute asthma may be an ominous finding, suggesting impending
respiratory failure.
Wheezing caused by a large or central airway obstruction has a constant acoustical character
throughout the lung but varies in loudness depending upon the distance from the site of
obstruction. It is referred to as monophonic (or homophonous) wheezing. In contrast, the degree
of narrowing varies from place to place within the lung in the setting of small airway obstruction.
As a result, the sounds generated also vary in quality and acoustical character and are
described as polyphonic (or heterophonous) wheezes [9].
Some experts distinguish between wheezes and rhonchi based upon the dominant frequency,
or pitch, of the sound. Wheezes have a dominant frequency greater than 400 Hz, whereas
rhonchi are of lower frequency [10,11]. However, the clinical significance of this distinction, if
any, is not well defined [10].
Stridor refers to a monophonic sound that is loudest over the anterior neck. Stridor can be heard
during inspiration, expiration, or throughout the respiratory cycle, depending on the location and
severity of obstruction. In general, inspiratory stridor is prominent in the setting of extrathoracic
obstruction, whereas expiratory stridor suggests intrathoracic obstruction. (See "Assessment of
stridor in children".)
CLINICAL HISTORY — When a patient presents with a history of wheezing, it is crucial to ask
the patient or the parents to describe what they actually are experiencing or hearing. On many
occasions, the word "wheezing" is used as a general term to describe noisy breathing, including
snoring, congestion, rattling, gurgling noises, or stridor [12,13]. It is essential to try to validate
the symptom of wheezing if parental report is the only source of information and no wheezing is
heard on examination of the child. (See "Asthma in children younger than 12 years: Initial
evaluation and diagnosis".)
There are few studies that compare parent-reported respiratory illness in infants with clinical
diagnosis. In another study, parental report of wheezing in 139 infants and children was
compared with clinical findings of wheezing and diagnosis of asthma [14]. There was a less than
50 percent agreement between a clinician's finding of wheeze and asthma and parents' report of
wheeze. Fourteen percent of parents use the term "wheeze" to describe other noises, mainly
upper airway noises.
Two important aspects of the medical history include the patient's age at the onset of wheezing
and the course of onset (acute versus gradual) (table 1 and table 2). Acute onset of wheezing
raises the possibility of foreign body aspiration, particularly if there is a history of choking. In
addition, it is helpful to distinguish between intermittent and persistent wheezing. Persistent
wheezing presenting very early in life suggests a congenital or structural abnormality. In
contrast, paroxysmal or intermittent wheezing is a characteristic finding in patients with asthma.
Persistent wheezing with sudden onset is consistent with foreign body aspiration, whereas the
slowly progressive onset of wheezing may be a sign of extraluminal bronchial compression by a
growing mass or lymph node. Less frequently, patients with interstitial lung disease can present
with persistent wheezing. (See"Classification of diffuse lung disease (interstitial lung disease) in
infants and children" and "Approach to the infant and child with diffuse lung disease (interstitial
lung disease)".)
Cough is a symptom commonly associated with wheezing [15]. The nature of the associated
cough (wet versus dry) may be helpful in determining the underlying etiology. Wet cough
typically results from excessive mucus production, mostly due to infection or inflammation (eg,
bronchiectasis, cystic fibrosis, primary ciliary dyskinesia, asthma, and chronic aspiration). In
contrast, pure bronchoconstriction or structural causes for airway narrowing (eg, asthma, airway
malacia or compression, foreign body, vascular ring) are usually associated with a dry cough.
However, the underlying etiology of a dry cough can be complicated by a secondary process,
making this distinction difficult (eg, mechanical obstruction can lead to impaired mucus
clearance resulting in infection and a wet cough).
Among children younger than two years of age, the incidence of wheezing with respiratory
illnesses is approximately 30 percent and peaks between two and six months [16,17]. Typically,
these infants present with classic coryzal symptoms that progress to coughing, wheezing, and,
occasionally, respiratory distress over a period of three to five days; resolution is gradual over
approximately two weeks. These episodes are variably responsive to bronchodilators and
systemic glucocorticoids but not antibiotics, expectorants, or antihistamines. A symptom-free
period typically ensues, followed by recurrent wheezing with subsequent viral illnesses in as
many as 50 percent of babies.
Criteria for the diagnosis of asthma and initiation of treatment are discussed in detail separately
(table 3 andtable 4). Prompt institution of timely and appropriate pharmacotherapy, education,
and prevention strategies are appropriate in children who meet these criteria. (See 'Response to
treatment' below and "Asthma in children younger than 12 years: Treatment of persistent
asthma with controller medications", section on 'Our approach'.)
Features in the history that favor the diagnosis of asthma include:
●Intermittent episodes of wheezing that usually are the result of a common trigger (ie,
upper respiratory infections, weather changes, exercise, or allergens)
●Seasonal variation
●Family history of asthma and/or atopy
●Good response to asthma medications
●Positive asthma predictive index (see "Wheezing phenotypes and prediction of asthma in
young children", section on 'Asthma Predictive Index (API)')
Clinical features that suggest a diagnosis other than asthma include the following (table 2):
●Poor response to asthma medications, including inhaled bronchodilators, inhaled
glucocorticoids, or systemic glucocorticoids.
●A history of neonatal or perinatal respiratory problems and wheezing since birth suggests
a congenital abnormality. (See "Congenital anomalies of the intrathoracic airways and
tracheoesophageal fistula".)
●Wheezing associated with feeding or vomiting can result from gastroesophageal reflux
(GER) or impaired swallowing complicated by aspiration. (See "Clinical manifestations and
diagnosis of gastroesophageal reflux disease in children and adolescents" and "Sucking
and swallowing disorders in the newborn".)
●A history of choking, especially with associated coughing or shortness of breath, suggests
foreign body aspiration, even if it does not immediately precede onset of wheezing
symptoms. (See "Airway foreign bodies in children".)
●Wheezing with little cough suggests a purely mechanical cause of obstruction, such as
small airways, airway malacia, and vascular ring, since cough is a prominent component of
asthma in children [18].
●Symptoms that vary with changes in position may be caused by tracheomalacia,
bronchomalacia, or vascular rings. (See "Congenital anomalies of the intrathoracic airways
and tracheoesophageal fistula".)
●Poor weight gain and recurrent ear or sinus infections suggest cystic fibrosis,
immunodeficiency, or ciliary dysfunction. (See "Approach to the child with recurrent
infections" and "Cystic fibrosis: Clinical manifestations and diagnosis".)
●History of progressive dyspnea, tachypnea, exercise intolerance, and failure to thrive
suggest interstitial lung disease. (See "Classification of diffuse lung disease (interstitial lung
disease) in infants and children"and "Approach to the infant and child with diffuse lung
disease (interstitial lung disease)".)
PHYSICAL EXAMINATION — General examination of a wheezy child should include
measurement of weight and height, vital signs including oxygen saturation, and digital
inspection for the presence of cyanosis or clubbing. The latter findings suggest the presence of
a wheezing illness other than asthma (table 2).
Chest examination should focus on the following features:
●Inspection for the presence of respiratory distress, tachypnea, retractions, or structural
abnormalities. Pertinent findings include an increased anteroposterior (AP) diameter
associated with chronic hyperinflation, pectus excavatum caused by chronic airway
obstruction and exaggerated swings in intrathoracic pressure, or scoliosis complicated by
airway compression. (See "Pectus excavatum: Etiology and evaluation" and "Adolescent
idiopathic scoliosis: Clinical features, evaluation, and diagnosis", section on 'Clinical
presentation'.)
●Palpation to detect supratracheal lymphadenopathy or tracheal deviation.
●Percussion can define the position of the diaphragm and detect differences in resonance
among lung regions and is the most underperformed part of the examination.
●Auscultation allows identification of the characteristics and location of wheezing, as well
as variations in air entry among different lung regions. A prolonged expiratory phase
suggests airway narrowing. Wheezing caused by a large or central airway obstruction (eg,
vascular ring, subglottic stenosis, tracheomalacia) has a constant acoustic character
throughout the lung but varies in loudness depending upon the distance from the site of
obstruction. In contrast, the degree of narrowing varies from place to place within the lung
in the setting of small airway obstruction (eg, asthma, cystic fibrosis, primary ciliary
dyskinesia, aspiration). The presence of focal wheezing is usually indicative of a localized
and mostly structural airway abnormality, and, therefore, airway evaluation by imaging or
bronchoscopy is warranted.
●Crackles can be present in conjunction with wheezing in asthma and in a variety of other
conditions, such as those leading to bronchiectasis (eg, cystic fibrosis, primary ciliary
dyskinesia, immune deficiency). Early inspiratory crackles are often present in patients with
asthma due to air flowing through secretions or slightly closed airways during inspiration.
Late inspiratory crackles are usually associated with interstitial lung disease and early
congestive heart failure. Thus, the presence of crackles does not exclude the diagnosis of
asthma [19].
●Decreased wheezing after bronchodilator therapy is suggestive of asthma but does not
rule comorbid conditions if clinically suspected.
The remainder of the examination should focus on cardiac findings, including murmurs and
signs of heart failure. Examination of the skin for eczema (common in atopic patients) or other
cutaneous lesions may assist in diagnosis. Nasal examination may reveal signs of allergic
rhinitis, sinusitis, or nasal polyps. The presence of nasal polyps in children necessitates an
evaluation for cystic fibrosis. (See "Chronic rhinosinusitis: Clinical manifestations,
pathophysiology, and diagnosis" and "Cystic fibrosis: Clinical manifestations and
diagnosis" and"Acute bacterial rhinosinusitis in children: Clinical features and diagnosis",
section on 'Acute bacterial rhinosinusitis'.)
RADIOGRAPHY — A chest radiograph (anteroposterior [AP] and lateral films) needs to be
considered in children with new-onset wheezing of undetermined etiology or chronic persistent
wheezing not responding to therapies. It is not necessary to obtain a chest radiograph with
every exacerbation in children with asthma, unless there is a specific indication. (See "Acute
asthma exacerbations in children: Home/office management and severity assessment", section
on 'Chest radiograph'.)
In most cases, a plain chest radiograph provides a good image of the large airways, including
the tracheal air column and main stem bronchi. Plain films can also help differentiate between
diffuse and focal disease. The presence of generalized hyperinflation suggests diffuse air
trapping and airway disease, seen in asthma, cystic fibrosis, primary ciliary dyskinesia, and
aspiration. In contrast, localized findings suggest structural abnormalities or foreign body
aspiration. A chest radiograph can also detect parenchymal lung disease, atelectasis, and, in
some cases, areas of bronchiectasis.
In addition, chest radiographs may reveal cardiomegaly, enlarged pulmonary vessels,
pulmonary edema, or other signs of cardiac failure. Plain radiographs also are helpful in
detecting mediastinal masses or enlarged lymph nodes and may suggest the presence of
vascular rings (eg, right aortic arch). (See "Vascular rings and slings".)
Other radiologic studies may be helpful in selected cases (table 5). Chest computed
tomography (CT) can provide detailed anatomy of the mediastinum, large airways, and lung
parenchyma. Magnetic resonance imaging (MRI) with contrast (magnetic resonance
angiography [MRA]) or multidetector computed tomography (MDCT) [20] should be considered
when a vascular problem is suspected.
Barium swallow may help in identifying vascular rings, swallowing dysfunction, aspiration
syndromes including gastroesophageal reflux (GER), and some cases of tracheoesophageal
fistula. This study is indicated only when these conditions are suspected (table 5). A
videofluoroscopic swallowing study (also called a modified barium swallow) is suggested in
children <2 years of age without neurologic pathology who have recurrent wheezing that is
unresponsive to bronchodilators or inhaled or systemic glucocorticoids to identify possible
swallowing dysfunction [21]. (See "Aspiration due to swallowing dysfunction in infants and
children", section on 'Available diagnostic techniques' and "Gastroesophageal reflux in
infants" and "Clinical manifestations and diagnosis of gastroesophageal reflux disease in
children and adolescents" and 'Evaluation for gastroesophageal reflux' below.)
PULMONARY FUNCTION TESTS — Pulmonary function tests (PFTs) are an important
component of the diagnostic evaluation of a wheezy child. (See "Overview of pulmonary
function testing in children".)
Infant PFT, if available, is helpful in assessing airway obstruction. Moreover, this test can be
used to quantify the response to bronchodilators [5,22,23]. Airway resistance and functional
residual capacity also can be measured using gas dilution or body plethysmography and can
help quantify airway obstruction and the response to bronchodilators [5].
In older children who are cooperative, PFT with inspiratory and expiratory flow-volume loops is
helpful in determining the presence, degree, and location of airway obstruction, as well as the
response to bronchodilators (figure 1). Methacholine challenge testing and exercise testing can
confirm airway hyperreactivity in patients for whom the diagnosis of asthma still is in question.
(See "Overview of pulmonary function testing in children" and "Bronchoprovocation
testing" and "Flow-volume loops".)
RESPONSE TO TREATMENT — For patients with diffuse wheezing, a trial of inhaled
bronchodilators can be used to confirm the presence of reversible airway disease. However, a
partial or negative response may not rule out asthma. Inflammation and airway swelling may
contribute to wheezing, in addition to bronchoconstriction, especially in infants and young
children. Thus, if asthma is still suspected in a patient with chronic or persistent symptoms, the
combination of inhaled glucocorticoids and bronchodilators for at least two weeks (or five to
seven days of oral glucocorticoids if the patient has more severe symptoms) may result in
significant improvement in symptoms and help in making the diagnosis of asthma. Further workup is indicated if the response to this therapy is inadequate or if a comorbid condition is still
suspected in a patient who had a positive response to bronchodilator. (See "Asthma in children
younger than 12 years: Initial evaluation and diagnosis".)
LABORATORY STUDIES — There are few laboratory investigations that are useful in the initial
evaluation of the wheezy child. In most cases, the probable diagnosis is suspected on the basis
of the clinical history and physical examination. The role of laboratory tests, when indicated, is
either to confirm the diagnosis or to rule out other less likely diagnoses [6]. Complete blood
counts are important in patients with chronic or systemic symptoms and may reveal anemia,
leukocytosis, or leukopenia. Eosinophilia in this setting supports an underlying allergic process
or possible parasitic infection. Further studies should be obtained based upon the suspected
diagnosis (table 5).
Testing for infection — Viral infection is an important cause of wheezing in children and is
mediated through numerous mechanisms. The interrelationship of viral infection, wheezing, and
the development of asthma in children is complex and changes according to the patient's age,
the presence of atopy, and environmental factors. (See "Virus-induced wheezing and asthma:
An overview".)
Viruses in the Paramyxoviridae family (eg, respiratory syncytial virus and parainfluenza virus)
and picornavirus family (eg, human rhinovirus) are important precipitants of wheezing in young
children. Metapneumovirus, another member of the Paramyxoviridae family, is a newly
recognized human pathogen that can result in upper and lower respiratory tract infection and
may present with wheezing [24,25]. Thus, viral studies can be helpful in confirming the etiology
of wheezing in young children presenting with symptoms suggestive of bronchiolitis. However,
they are not routinely recommended. (See "Human metapneumovirus infections" and "Virusinduced wheezing and asthma: An overview" and "Parainfluenza viruses in children", section on
'Diagnosis' and"Respiratory syncytial virus infection: Clinical features and diagnosis", section on
'Diagnosis'.)
Sputum stain and cultures may be useful in a setting suggestive of bacterial infections, including
atypical infections (eg, mycobacterial or fungal infections), that can result in wheezing.
Tuberculin skin testing and specific serologic assays can be helpful if these infections are
suspected. Serologic testing for Mycoplasmamay be considered if such an infection is
suspected since Mycoplasma is an increasingly recognized cause of wheezing and may
predispose children to the subsequent development of asthma [26,27]. (See "Mycoplasma
pneumoniae infection in children", section on 'Possible relation to asthma' and "Overview of
nontuberculous mycobacterial infections in HIV-negative patients" and "Clinical manifestations
and diagnosis of allergic bronchopulmonary aspergillosis" and "Tuberculosis disease in
children", section on 'Pulmonary tuberculosis'and "Community-acquired pneumonia in children:
Clinical features and diagnosis", section on 'Laboratory evaluation'.)
Sweat chloride test — The sweat chloride test allows clinicians to assess physiologic changes
associated with cystic fibrosis and is indicated in children with chronic lung problems, including
wheezing. It is expected that the majority of patients with cystic fibrosis will be diagnosed at birth
due to newborn screening for cystic fibrosis. However, false negatives can occur. Thus,
obtaining a sweat test is appropriate if clinical suspicion of the disease remains. (See "Cystic
fibrosis: Clinical manifestations and diagnosis".)
The presence of diarrhea, failure to thrive, and/or clubbing should raise the suspicion for cystic
fibrosis and warrants further evaluation. One should also have a low threshold to obtain this test
in a patient with persistent or recurrent pulmonary symptoms that are unresponsive to asthma
therapies, especially when wheezing is associated with a chronic productive cough, since
identifying a patient with cystic fibrosis has major implications for the patient, the family, and
future reproductive decisions [18]. The sweat chloride test should be undertaken at a facility with
substantial experience, and clinicians interpreting the results should be aware of other
conditions that result in elevated sweat chloride concentrations (table 6). (See "Cystic fibrosis:
Clinical manifestations and diagnosis".)
Other studies — Immunoglobulin levels can be used to screen for immunodeficiencies.
Elevated immunoglobulin E (IgE) can be indicative of an allergic process. If there is a high
suspicion of immunodeficiency, then a more detailed immunologic work-up is appropriate (table
5). (See "Approach to the child with recurrent infections" and "Laboratory evaluation of the
immune system" and "Overview of skin testing for allergic disease"and "Overview of in vitro
allergy tests".)
ENDOSCOPY — Endoscopy is a diagnostic tool used in patients with suspected foreign body
aspiration, persistent symptoms, or inadequate response to therapy. Rigid bronchoscopy is
used in patients with sudden onset of wheezing and suspected foreign body aspiration. Flexible
bronchoscopy can identify structural airway abnormality, including airway malacia (during
spontaneous breathing when performed under conscious sedation) [21]. Nasopharyngoscopy,
which allows visualization of the vocal cords and larynx without lower airway endoscopy, is a
less invasive alternative in infants and children with evidence of extrathoracic obstruction. This
approach provided a diagnosis in 75 of 82 cases (91 percent) in one series without evidence of
lower airway disease during a mean follow-up interval of six years [28]. Bronchoscopy with
bronchoalveolar lavage (BAL) is useful in cases where infection, aspiration, or interstitial lung
disease is suspected [21]. (See"Airway foreign bodies in children" and "Approach to the infant
and child with diffuse lung disease (interstitial lung disease)" and "Aspiration due to swallowing
dysfunction in infants and children", section on 'Available diagnostic techniques'.)
EVALUATION FOR GASTROESOPHAGEAL REFLUX — Gastroesophageal reflux (GER) is
common among children <2 years of age with recurrent wheezing. Thus, 24-hour esophageal
pH monitoring is suggested in infants and children with recurrent wheezing, particularly in
children <2 years of age with recurrent wheezing who are unresponsive to bronchodilators or
inhaled or systemic glucocorticoids, since GER symptoms may be subtle in this age group [21].
Evaluation for GER is also suggested for older children with poor response to asthma therapies,
especially if they have any suggestive symptoms. Presenting symptoms may include excessive
burping or emesis, coughing after meals, and nocturnal cough or wheeze and discomfort
indicated by crying and/or arching of the back. A positive response to empiric therapy (acid
suppression) may be used to support a presumed diagnosis of GER [6]. (See "Clinical
manifestations and diagnosis of gastroesophageal reflux disease in children and adolescents".)
Twenty-four-hour esophageal pH monitoring is preferred over an upper gastrointestinal series or
gastroesophageal scintigraphy for the diagnosis of GER. Multichannel intraluminal impedance
monitoring (MII) is a technique that permits measurement of all reflux episodes, including those
that are weakly acidic or alkaline. It is usually used in combination with pH monitoring. In a trial
comparing the two techniques, combined MII-pH monitoring detected reflux events that caused
symptoms twice as often as pH monitoring alone [29].
SUMMARY
●Wheezing is a common presenting symptom of respiratory disease in children. It may be
either a benign, self-limited process or the presenting symptom of a significant respiratory
disease. The most likely diagnosis in children with recurrent wheezing is asthma. However,
other diseases can present with wheezing in childhood, and patients with asthma may not
wheeze (table 1). (See 'Introduction' above.)
●A wheeze is a continuous musical sound heard during chest auscultation that lasts longer
than 250 msec. It is produced by the oscillation of opposing walls of an airway narrowed
almost to the point of closure. It can be high pitched or low pitched, consist of single or
multiple notes, occur during inspiration or expiration, and originate from airways of any
size. (See 'Definition and physiology of wheezing' above.)
●When a patient presents with a history of wheezing, it is crucial to ask the patient or the
parents to describe what they actually are experiencing or hearing. On many occasions,
the word "wheezing" is used as a general term to describe noisy breathing, including
snoring, congestion, gurgling noises, or stridor. Two important aspects of the medical
history include the patient's age at the onset of wheezing and the course of onset (acute
versus gradual). Certain clinical features favor the diagnosis of asthma or suggest another
diagnosis (table 2). (See 'Clinical history' above.)
●General examination of a wheezy child should include measurement of weight and height;
vital signs including oxygen saturation; digital inspection for the presence of cyanosis or
clubbing; a complete chest examination; and cardiac, skin, and nasal examinations.
(See 'Physical examination' above.)
●Anteroposterior (AP) and lateral chest radiographs are suggested in children with newonset wheezing of undetermined etiology or chronic persistent wheezing not responding to
therapies. Other radiologic studies may be helpful in selected cases (table 5).
(See 'Radiography' above.)
●Pulmonary function tests (PFTs) are an important component of the diagnostic evaluation
of a wheezy child. Infant PFT, if available, is helpful in assessing airway obstruction. In
older children who are cooperative, PFT with inspiratory and expiratory flow-volume loops
is helpful in determining the presence, degree, and location of airway obstruction, as well
as the response to bronchodilators (figure 1). (See'Pulmonary function tests' above.)
●For patients suspected of having asthma, a trial of inhaled bronchodilators with or without
glucocorticoids can be used to confirm the diagnosis prior to initiating a more extensive
work-up. Further work-up is indicated if the response to therapy is inadequate.
(See 'Response to treatment' above.)
●There are few laboratory investigations that are useful in the initial evaluation of the
wheezy child. Any studies obtained beyond chest radiographs and PFTs should be based
upon the suspected diagnosis (table 5). These studies include tests to examine for viral,
bacterial, or fungal infections; sweat chloride test to diagnose cystic fibrosis, evaluation for
immunodeficiency, or allergy; endoscopy to examine for foreign body aspiration,
tracheomalacia, or interstitial lung disease; and work-up for gastroesophageal reflux (GER)
if indicated. (See 'Laboratory studies' above and 'Endoscopy' above.)
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