BOSTON — Wheeze, stridor and cough are among the most common sounds
made by children with respiratory conditions, but they are often misidentified,
especially in the emergency department, according to a presenter here at the
American Academy of Pediatrics 2011 National Conference and Exhibition.
Miles Weinberger, MD, professor of Pediatrics and director of the
Pediatric Allergy and Pulmonary Division at the University of Iowa
Children’s Hospital in Iowa City, Iowa, provided a breakdown of these
common sounds and their causes. He stressed the importance of listening and
observing the child carefully.
Weinberger said pediatricians should evaluate whether sounds are
inspiratory or expiratory, continuous or interrupted, or high-pitched or
low-pitched. They should also note the volume, location, duration and frequency
of the sound.
Wheeze
Wheezing is characterized by continuous musical sounds that are
typically expiratory. Wheezing can be caused by
bronchiolitis, asthma, cystic fibrosis, a foreign body
or bronchomalacia.
“Bronchiolitis is an important cause of wheezing among
infants,” Weinberger said. “The symptoms of asthma and bronchiolitis
are very similar but the difference is that asthma is recurrent and not just a
single episode as in bronchiolitis.”
There are different characteristics of wheezing, according to
Weinberger. Wheezing caused by a foreign body has a monophonic sound, in
contrast to the polyphonic sound of wheezing caused by asthma and
bronchiolitis.
“Especially with
asthma, it sounds like an orchestra tuning up, with
multiple sounds,” he said.
Parents will often tell the pediatrician that their child has been
wheezing. However, what parents call wheezing is not always true wheezing. In
fact, a study from 2000 reported that there is less than 50% agreement between
parents and clinicians on what is truly wheezing. “Wheeze” is the
most commonly used term for describing respiratory sounds.
Stridor
In contrast to the continuous steady sound of wheezing, stridor is a
musical sound with varying pitch. Stridor is common and appears in about 60% of
infants.
Common causes of stridor include croup, epiglottitis and laryngomalacia.
Chiari malformation, vocal cord paralysis and laryngeal foreign body are less
common causes. Vocal cord dysfunction syndrome can also cause stridor, but is
very rare.
“Laryngomalacia is certainly the most common cause of inspiratory
stridor,” Weinberger said, adding that it represents a delay in maturation
of supporting laryngeal structures.
The condition typically resolves by aged 2 years and is generally
benign. However, “rare cases can result in pulmonary hypertension,”
he said. “It is something to watch for in children with persistent
laryngomalacia because it does delay their growth and weight gain.”
Croup is the transient inflammation of the laryngeal area causing upper
airway obstruction characterized by inspiratory stridor that is generally
caused by a virus. Parainfluenza type 1 is the most common cause of croup,
followed by respiratory syncytial virus and Mycoplasma pneumoniae.
However, Weinberger stressed to the audience that a “croupy
cough” is not croup: “Croup involves the laryngeal area and is
stridor,” he said.
Epiglottitis, which is caused by a bacterial infection, is currently a
much less common cause of stridor because of widespread use of Haemophilus
influenzae type b vaccines, according to Weinberger. Streptococcus
pyogenes is also a common cause, and this infection can be
life-threatening.
Weinberger said that there has been some confusion in the past between
croup and epiglottitis. As a result, children were being sent for lateral neck
X-rays for croup.
“Epiglottitis looks and sounds nothing like croup. There is no
cough,” Weinberger said.
Vocal cord dysfunction syndrome (VCDS) is often misdiagnosed as asthma,
and may present in addition to asthma. This condition can be spontaneous or
exercise-induced.
Cough
Cough, defined as forceful exhalation after quickly raising
thoracoabdominal pressure, is caused by pertussis, protracted bacterial
bronchitis, acute viral bronchitis, asthma, M. or Chlamydia pneumoniae,
aspiration, cystic fibrosis, primary ciliary dyskinesia and possibly post-nasal
drip and gastroesophageal reflux disease.
Thanks to vaccines, classic pertussis, which was once known as the
“100-day cough,” is relatively uncommon.
“However, this disease is endemic in our population because
pertussis immunization has the lowest degree of complete effectiveness of all
the vaccines that children receive,” he said. “But we do see
pertussis, generally modified to an extent in immunized populations. It is
important to identify those with pertussis — not because we can cure them,
but because we can make them non-infectious [by treating with azithromycin] and
decrease the risk of the diseases being transmitted to infants who are at
substantial risk.”
Habit cough syndrome is characterized by a dry, barking cough that can
last for months and is sometimes misdiagnosed as asthma or tracheomalacia.
However, Weinberger said that this diagnosis can be made easily if the child
does not cough at night.
“If the child does not cough at night, there is no organic cause
for it and there is no reason to do other diagnostic tests,” he said.
Disclosure: Dr. Weinberger reports no relevant financial
disclosures.
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Caroline
Breese Hall
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This presentation describes well the differential of these common
respiratory signs among children. However, even for those with the ear of an
orchestra conductor, delineating these respiratory signs is often challenging,
especially among infants who have rapid respiratory rates, an average 50 to 40
per minute during the first 6 months of life, and who are often uncooperative.
During the coming winter months the number of infants with respiratory
infections being seen at emergency departments, clinics and private offices
will markedly increase, and wheezing will be the most frequent lower
respiratory tract sign. The great majority will have viral bronchiolitis, the
number one cause of hospitalization in the US among children in the first
year of life. Respiratory syncytial virus alone is estimated to cause each year
approximately 10 to 20 office visits to pediatric practices among every 100
children in the first year of life. Nevertheless, detection of this common
illness is often confounded by what is considered the hallmark of
bronchiolitis, the variability of the characteristic auscultatory findings.
Indeed, the wheezing and crackles may be intermittently absent. This emphasizes
the importance of repetitive examinations and a good history in detecting and
differentiating bronchiolitis from other less common causes of airway
obstruction.
Caroline Breese Hall, MD
Professor of
Pediatrics and Medicine
University of Rochester School of Medicine and
Dentistry
Disclosure: Dr. Hall reports no financial disclosures.
For more information:
- Weinberger
M. #F1123. Wheeze, stridor, cough and other respiratory noises.
Presented at: AAP 2011 National Conference and Exhibition. Oct 15-18, 2011.
Boston.