Does wheezing mean that I have asthma?

No, not necessarily. The to-and-fro movement of air
through the lungs and tracheobronchial tree should
always be silent. A wheeze is an abnormal sound produced
by turbulent flow of air through the lungs. There
are many different causes of wheezing The occurrence of
a wheeze by itself without any other symptoms is unusual.
It is therefore important to note if the wheezing is recurrent
or if it is associated with other lung symptoms such
as breathlessness, cough, or mucus production.

Medical students learn that not all that wheezes is
asthma. Although most people with asthma will at some
point experience wheezing, not everyone who wheezes
has a diagnosis of asthma (Table 9). Some people who
wheeze will turn out to have a lung condition other than
asthma, while others will wheeze even though there is
no identifiable lung condition and the lungs appear
completely normal. The first category includes persons
with a cigarette-related lung disease such as COPD, for
example. Other lung diseases, such as bronchiectasis or
bronchiolitis, can also lead to wheezing. Certain lung
infections can cause wheezing in completely normal
lungs. Some people without any lung disease but who
have congestive heart failure can wheeze if they take in
too much fluid. Still others might wheeze after a severe
allergic reaction, such as to a bee sting, for example.
Gastric reflux, called GERD (gastroesophageal reflux
disease), is a disease of the digestive system and is an
example of a non-pulmonary condition that can mimic
asthma. Similarly, vocal cord dysfunction (VCD) syndrome
affects the voice box (larynx) and is often confused
with asthma. Finally, and especially in children, a
wheeze can be caused by a foreign body trapped in the
bronchial tree. Young children, in particular, explore the
world by putting objects in their mouths. From there,
it’s a short trip into the breathing passages. A foreign
body should be retrieved from the lung passages, usually
via bronchoscopy. Medical journals and textbooks have
described the successful retrieval of many disparate
items, including fish and chicken bones, coins, toy fragments,
and even a coffee stirrer.
If you have experienced wheezing, especially on more
than one occasion and perhaps associated with other
symptoms, consultation with your physician is the
appropriate next course of action. Your doctor will
be able to ascertain if the wheeze is due to asthma or
not and can advise you on what treatments would be
indicated for you.

What is a wheeze?

A wheeze is the sound generated when air travels
though a breathing passage (airway) that has become
narrowed. The narrowing can be due to mucus secretions
trapped within the airway or to the airway muscles’
constriction or tightening around the airway. The
airway narrowing due to asthma is reversible. Medications
prescribed for asthma help the narrowed airway
return to its normal state. A wheeze is best described
as a high-pitched whistling sound.Wheezing can occur
while breathing in (inspiratory wheezing, during the
inspiratory phase of the breath), while breathing out
(expiratory wheezing, during the expiratory phase of
the breath), or during the entire breath. Asthma is one
of several conditions that can cause wheezing, as
detailed further in the following question. If wheezing
is severe, it can be heard without a stethoscope.
Wheezing in asthma reflects ongoing lung inflammation
and airway narrowing, or bronchoconstriction. The sound
is generated by turbulent flow through constricted airways.
The presence of wheezing in asthma indicates that
the asthma is active, and that more intensive and efficacious
treatment is warranted.Wheezing is never normal
and should never be ignored. If airway narrowing and
inflammation are left untreated, there is a real risk of the
disease worsening, which can become potentially life
threatening.

What are the symptoms of asthma?

Medical textbooks correctly inform us that “classic”
symptoms of asthma are three in number: wheezing,
cough, and abnormal sensations of breathing, or dyspnea.
If you are studying for a knowledge test, mark
those three symptoms on your answer sheet. You will
get full credit for the right answers and will surely score
an A for your asthma knowledge! Typical asthma symptoms
that we see in the office or clinic, on the other
hand, represent variations of the big three: an unusual
awareness of breathing, uncomfortable breathing, chest
pressure or a feeling of chest discomfort, wheezing or
noisy breathing, labored breathing, coughing, mucus
production, and breathlessness with exertion or effort.
Nocturnal symptoms, such as waking from sleep with
uncomfortable breathing or wheezing, are indications
of less than optimal asthma control and are signs of an
asthma exacerbation. Asthma can manifest itself in various
modes, from mild to severe. A person with a
milder form typically experiences different symptoms
at different levels of frequency and intensity than a person
with a more severe form of asthma. Children may have
a persistent cough (often misdiagnosed as recurrent
bronchitis) as their only asthma symptom. Cough is, in
fact, the single most common asthma symptom in children.
Symptoms of asthma may thus differ from person
to person and may vary in an individual over time. Asthma
symptoms are usually episodic; symptoms may come
and go, and are not necessarily continuously present.

How do human lungs work?

The lungs are the major component of the respiratory
system . A good way to understand
the workings of the lungs is to consider their structure,
or anatomy . The human respiratory system
begins at the nose and includes the nasal passages, which
direct air to the back of the throat and into the windpipe,
or trachea. The trachea sits below the voice box
(larynx), and can be felt in the front of your neck as it
descends behind the breastbone (sternum) into the upper
chest. The trachea ends and divides into two branches:
the right mainstem bronchus and the left mainstem
bronchus. The right mainstem bronchus leads air to
and from the right lung, and the left mainstem bronchus
leads air to and from the left lung.

 

 The area where the trachea divides into the right and

left mainstem bronchi is called the carina. After the
split, the right and left mainstem bronchi leading to each
lung subdivide further into smaller and smaller tubelike
passages, via the branching tracheobronchial tree. As
the bronchi continue to subdivide into successively narrower
and narrower bronchi, they ultimately end in the
tiniest subdivision, the bronchiole. Each bronchiole
leads to the lung air sacs, the alveoli.

 The alveoli are highly specialized lung structures. They

are the gas-exchanging lung units. They ensure that
fresh, oxygen-rich (O2) inhaled air enters the body at the
same time that oxygen-poor, carbon dioxide-rich (CO2)
air exits (Figure 1B). Oxygen (O2) is required for life;
oxygen deprivation is rapidly fatal. As inhaled oxygen is
provided to the body’s organs via the lungs, “used” air—
composed mostly of carbon dioxide (CO2)—is excreted
by exhalation. Carbon dioxide is produced by the body’s
metabolism and is considered a “waste product.” Abnormal
accumulation of carbon dioxide in the body and the
bloodstream is detrimental to health and is responsible
for certain forms of respiratory failure.
The process that is responsible for the body’s oxygen
uptake and its carbon dioxide removal (or excretion) is
called respiration. Respiration is the primary, crucial
function of the lungs and of the respiratory system.
Physicians occasionally refer to respiration as “gas
exchange.” The exchanged gases are oxygen (O2) and
carbon dioxide (CO2). Exchange means that CO2 gas
is given up by the body and replaced by a fresh supply
of O2. The exchange takes place in the deepest lung, at
the level of the alveoli. Oxygen and carbon dioxide
exchange takes place along a specialized zone where each
air sac (alveolus) is in intimate contact with fine, minute
blood vessels called capillaries. The capillary bed completely
encircles the alveoli along the alveolar–capillary
membrane. Because of the structure of the alveolar–
capillary membrane, the inhaled oxygen (O2) easily
passes from the alveolus into the capillary blood that
then sends it to our organs. Similarly, the body’s CO2 is
carried through the bloodstream into the blood supply
of the alveolar–capillary membrane where it is given
up to the alveolus, and from there, exhaled by our
lungs with each breath. A normal resting adult breathes

 approximately 12–18 times a minute, children about 20

times a minute, and babies and infants even more frequently.
That number, the number of breaths a person
breathes in 1 minute, is termed the respiratory rate. We
should be unaware of our breathing in health, as respiration
should be automatic, effortless, and of course, painless.
Increases in the respiratory rate, sometimes perceived
as a kind of breathless sensation, can represent a normal
process as during exercise or sports and allows for increased
oxygen delivery to the body. A respiratory rate increase
can also indicate the onset of a medical concern; it may
in particular be a sign of increasing asthma symptomatology.
That is why measurement of respiratory rate,
along with pulse (or heart rate), blood pressure, and
temperature measurements are collectively referred to as
vital signs in medical terminology!

Is asthma preventable?

The development of asthma
is thought to arise from complex and poorly understood
interactions involving a person’s inborn genetic
characteristics and elements of the environment in which
he or she lives, from birth onward. Each of us is endowed
with a specific set of genes, inherited from our parents,
and there is obviously nothing we can do to alter our
genetic makeup.We might thus logically turn our focus
to what constitutes the elements of the environment in
which we live to see if any preventive measures could
prove helpful. An emerging body of scientific evidence
suggests that infection with certain common strains of
respiratory viruses early in life may predispose a child to
develop asthma. Although interesting and a guide for
additional research into such viruses and their relationship
to asthma, the observation does not carry practical
“real life” implications. How, indeed, to avoid a common
respiratory virus? There is no feasible way for any of us
to avoid catching one!

Over what other parts of our environments might we
have more “control”? We can, of course, modify specific
exposures in our indoor environments and in particular,
in our homes. In 2000, the Institute of Medicine published
a report called Clearing the Air: Asthma and
Indoor Air. It reviewed the available scientific evidence
about indoor air exposures and asthma. One aspect of
the report looked at those exposures that might represent
risk factors for the development of asthma. It concluded
that there is sufficient scientific evidence to
support a causal relationship between the development
of asthma and exposures to house dust mites as well as
a strong association between exposure to secondhand
smoke (called ETS for environmental tobacco smoke)
and asthma in younger children. The ETS exposure
included prenatal exposure. Exposure to cockroaches
and to the respiratory syncytial virus (RSV) were less
clear-cut risks for asthma, but both appeared to
increase the risk. Not everyone at an increased risk for
asthma will inevitably go on to develop the condition,
but it is both prudent and reasonable to decrease or
eliminate exposures to known risk factors as much as is
possible.

Possible Environmental Factors in Asthma Development

The development of asthma reflects a particular genetic or innate predisposition
to the disease. In addition, environmental influences have been recognized as
significant in the emergence of clinical asthma. The precise interplay between
environmental and hereditary factors leading to asthma is still insufficiently
understood. It has long been noted that some environmental exposures
are associated with progression to asthma while other types of exposures might
possibly prevent or delay the development of asthma in susceptible persons. The
complex relationships are the subject of ongoing research, at the molecular level,
in laboratory animals, and in human populations.

Possible Environmental Factors in Asthma Development
Possible environmental
factors include:
Indoor environments Outdoor environments
Indoor allergens Outdoor allergens & pollens
Dust mites Air pollution
Pet dander Diesel emissions
Cockroach es Particulates
Mold Ozone, sulfur dioxide
Cigarette smoke
Products of combustion
Gas ranges/heaters (NO2)
Coal heaters
Attendance at daycare
Respiratory infections at an early age
“Tight” buildings, modern materials
&
Indoor environments play a greater role than outdoor ones in terms of asthma
development.
The 2000 report on: Clearing the Air: Asthma and Indoor Air Exposures from the
Institute of Medicine concludes that there is sufficient evidence to support a causal
relationship between asthma development and exposures to dust mites (increased
risk of asthma) and environmental tobacco (probably increased risk). Cockroaches,
cats, and dogs carry a “maybe” increased risk.

 Allergy involves our immune systems, which play an
important role in asthma as well. An allergy is a very
specialized immune response to a specific agent, called
an allergen. Examples of allergens include a variety of
agents, such as cat dander, cockroach, mold, peanut,
penicillin, and ragweed to mention just a few. Most people
can play with a cat or eat peanuts, take penicillin for
a strep throat infection, or inhale ragweed in late summer
in the Northeast and suffer no ill effects at all.
That is because they are not allergic to any of those
allergens. Exposure to an allergen is harmless to a person
who is not allergic to that particular allergen. The person
who is allergic to cats or to peanuts, on the other
hand, will, upon exposure to cats or peanuts, develop
one or more allergy symptoms. Allergy symptoms may
arise from different body organs, including the skin
(hives), membranes of the eye (conjunctivitis) and nose
(rhinitis), the intestines (cramping, nausea, vomiting,
diarrhea), as well as the lungs (wheeze).

What causes asthma?

Asthma is believed to result from a complex interplay
between a person’s genes and various environmental factors
at a specific time in his or her life. It can thus be
viewed as the result of interactions that occur between
internal (genetic) elements and external (environmental)
exposures.
 Environmental factors that have been studied
include viruses such as RSV (respiratory syncytial virus),
cockroaches, cigarette smoke, exhaust, farm animals, medications
(including acetaminophen), pesticides, pets, and
wood smoke. The data are intriguing and raise further
questions that continue to stimulate research both into
genetic and environmental features. Recent attention
has, for example, focused on factors that may affect the
unborn child’s immune system. Given the elevated rate
of childhood asthma and the observation that more than
half of children with asthma are diagnosed by the age of
3, researchers have also sought to examine the possible
influence of prenatal environments on the developing
fetus’s risk of developing asthma early in life. Some studies
in particular have suggested the possibility of (but not
proved) a link between lower-than-normal vitamin D
levels in mothers during pregnancy and the development
of asthma in their children. More research into why some
persons, but not others, go on to develop asthma in the
course of their lifetimes is desperately needed. In the case
of vitamin D’s importance, for example, a clinical trial
was scheduled to begin in late 2009 to investigate if adequate
maternal vitamin D supplementation in pregnancy
leads to a decrease in asthma during the child’s first
three years of life. The trial is titled, “Maternal Vitamin
D Supplementation to Prevent Childhood Asthma
(VDAART)”; details are available on the Web at
 http://www.clinicaltrials.gov/ct2/show/NCT00920621. Vitamin
D is also thought to perhaps play a role in asthma symptom
severity. John Brehm and colleagues published
“Serum Vitamin D Levels and Markers of Severity of
Childhood Asthma in Costa Rica” in the May 2009
American Journal of Respiratory and Critical Care Medicine
and provided evidence of an inverse relationship between
vitamin D levels and measures of allergy and asthma
severity in Costa Rican children with asthma. The
authors also point out that the “Results of some, but not
all, epidemiologic studies suggest that vitamin D deficiency
is associated with an increased incidence of asthma
symptoms . . . higher maternal intakes of vitamin D
during pregnancy are associated with decreased risks for
recurrent wheeze in young children suggesting that vitamin
D may play a role in the development of asthma.”
Clinicians have long noted that certain viral infections
seem to be related to the development of asthma in predisposed
individuals, both children and adults. Physicians
refer to particular “asthmagenic” viruses (such as RSV) that
cause typical respiratory infection and symptoms at first,
only to leave the patient with an asthma-like condition.
Not all infectious agents are viruses, however, and attention
has also been directed to other infectious organisms
and their possible role in asthma development.
Lung infection with a common bacterium (not a virus)
called Chlamydia pneumoniae (recently renamed Chlamydophila
pneumoniae) has in particular been suggested (but
not proven) as a possible cause of reversible asthma in
adults.