DUSTIN R. HAFERBECKER
DEFINITION OF THE COMPLAINT
Noisy breathing in infants is a common presenting complaint. The first step toward formulating a differential diagnosis is to characterize the type of sound heard. Stertor, a low-pitched rattling inspiratory noise, is caused by obstruction of airway above the level of the larynx. It is frequently heard in infants with nasal congestion and is often of little consequence. Stridor, a harsh, high-pitched respiratory sound typically heard on inspiration, often indicates laryngeal obstruction. Wheezing, a musical sound heard on expiration, is caused by partial obstruction of the lower airway. In young children, sometimes expiratory noises cannot be easily distinguished from inspiratory ones, and at times both may be present. Among these causes of noisy breathing, wheezing is the most common of clinical significance.
COMPLAINT BY CAUSE AND FREQUENCY
The causes of wheezing in childhood vary by age (Table 1-1) and may also be grouped in categories based on the following criteria: (1) Anatomic (extrinsic or intrinsic to the airway), (2) Inflammatory/Infectious, (3) Genetic/Metabolic, or (4) Miscellaneous causes (Table 1-2).
TABLE 1-1. Causes of wheezing in childhood by age.
TABLE 1-2. Causes of wheezing in childhood by mechanism.
A thorough study of the child’s history is essential to arrive at an accurate diagnosis in a child who presents with wheezing. Consideration of age at onset, course and pattern of illness, and associated clinical features provides a useful framework for creating a differential diagnosis. The following questions may help provide clues to the diagnosis:
• What was the age at onset of wheezing?
—Onset at birth or during early infancy suggests congenital structural abnormalities. Congenital diaphragmatic hernias are usually detected on prenatal ultrasound. Vascular rings and aberrant vessels can cause wheezing or other respiratory symptoms early in life. Infants <2 years of age are more susceptible to lower respiratory infection, such as bronchiolitis, whereas adolescents are more likely to have asthma or infection caused by atypical bacteria, such as Mycoplasma pneumoniae.
• Is the wheezing a new onset or recurrent?
—The initial episode of wheezing in a previously healthy infant in conjunction with symptoms of upper respiratory tract infection usually indicates bronchiolitis. A sudden onset of wheezing is also characteristic of anaphylaxis; particularly in the presence of urticaria, stridor, or pertinent environmental exposures. Recurrent episodes of wheezing may suggest gastroesophageal reflux. However, if precipitated by upper respiratory infections, recurrent wheezing may suggest reactive airways disease. Recurrent wheezing or “difficult to control asthma” should lead to a consideration of cystic fibrosis, immotile cilia syndrome, recurrent aspiration, immune deficiency, or anatomic abnormalities.
• Is the wheezing episodic or persistent?
—Persistent wheezing suggests mechanical obstruction from a variety of causes, such as airway foreign body, congenital airway narrowing, or external compression by a mediastinal mass or vascular anomaly.
• Was the episode of wheezing preceded by choking or gagging?
—Aspiration of a foreign body is sometimes associated with the sudden onset of symptoms after gagging or choking. Foreign body aspiration is most common in children between the ages of 1 and 4 years. Symptoms depend on the size and location of the foreign body. The wheezing may be unilateral and secondary bacterial infection may occur.
• Was the wheezing preceded by upper respiratory tract infection?
—Antecedent upper respiratory tract infection is suggestive of an underlying inflammatory or infectious etiology.
• What is the child’s weight and height?
—Features suggestive of cystic fibrosis include failure to thrive, steatorrhea, or recurrent infections.
• Is there a history of recurrent bacterial infection?
—Children with cystic fibrosis often have recurrent respiratory tract infections. Ciliary dyskinesis is associated with frequent cough, sinusitis, and otitis media.
• Is there a history of preterm birth or did the child require mechanical ventilation or prolonged supplemental oxygen after birth?
—Bronchopulmonary dysplasia chronic lung disease of prematurity should be considered.
• Are there allergic shiners, Dennie lines, nasal crease, or atopic dermatitis?
—The presence of atopy increases the likelihood of asthma.
• Are symptoms exacerbated by feeding?
—Gastroesophageal reflux and tracheoesophageal fistula should be considered. H-type tracheoesophageal fistulas may not be accompanied by esophageal atresia.
• Was the mother tested for sexually transmitted diseases during pregnancy?
—Chlamydia trachomatis pneumonia may present during the second month of life with nonpurulent conjunctivitis, wheezing, and pneumonia without fever.
• Is there a family history of wheezing or asthma?
—A family history of asthma in either or both parents increases the risk of the patient having asthma to 2-3 times above the baseline prevalence.
1. Bjerg A, Hedman L, Perzanowski MS, et al. Family history of asthma and atopy: in-depth analyses of the impact on asthma and wheeze in 7- to 8-year-old children. Pediatrics 2007;120:741-748.
The following cases represent less common causes of wheezing in childhood.