What are pulmonary function tests (PFTs), spirometry, and peak expiratory flow (PEF) measurements?

Pulmonary function tests (PFTs)—as the name implies—
are tests designed to measure and assess lung function.
PFTs were originally research tools, available
only in specialized academic hospital centers. They
are now widely available and are frequently performed
because of their usefulness in the diagnosis and treatment
of asthma. Keep in mind as you read this answer that the
lung function abnormalities seen in active asthma on PFT
testing are, by definition, reversible.

The term PFTs is used to collectively describe several
different specific tests of lung function. Spirometry is the
single most useful of the PFTs when it comes to asthma
diagnosis and treatment. Spirometry, in turn, includes
two important subtests. The first is called the peak expiratory
flow, abbreviated PEF. The second is the FEV1,
the forced expiratory volume in 1 second. Measurements
of PEF and FEV1 are thus parts, or subtests, of the
spirometry portion of the PFTs. The availability of inexpensive,
highly portable, and easy-to-use peak-flow monitors
makes it possible for every person with asthma
(even children) to measure his or her peak flow at home
on a daily basis in order to monitor asthma activity.
FEV1 measurements, on the other hand, require the use
of a spirometer, which is more costly, requires special
maintenance, and is not presently advised for home use.
Self-monitoring of PEF allows a person with asthma
insight into his or her condition and permits an assessment
of asthma control. Both PEF and FEV1 play a
pivotal role in the National Asthma Education and
Prevention Program’s (NAEPP’s) asthma diagnosis,
classification, and treatment guidelines.
To perform spirometry and PEF, the patient is first
asked to take a deep breath of room air. Then, that
biggest single breath is forcefully and rapidly exhaled
into a mouthpiece connected to the spirometer or peak
flow meter. The maneuver is repeated several times during
testing to ensure accurate and reproducible values.
The spirometer measures the exhaled lung volume, as
well as the flow of air through the mouthpiece for the
time that exhalation takes place.

The spirometry measurements
are recorded by the spirometer and are printed
out and graphed for review and future reference.
Each individual patient measurement is compared to
a predicted value. The predicted values for pulmonary
function tests are based on three variables: age, height,
and gender.Predicted values are different for a 21-year-old,
6-foot-tall man than for a 5-foot-tall, 64-year-old
woman. It follows that the PEF value (and the FEV1) that
would be considered within normal limits for a short,
older female with asthma would be abnormally low if
obtained by a tall, adolescent male with asthma, even
though they both had asthma.
Because asthma is characterized as a disease of lung emptying,
exhalation time is abnormally prolonged in symptomatic
asthma. Anyone with active asthma who attempts
to blow out all the candles on a birthday cake with one
single mighty blow of air knows about impaired lung emptying
firsthand! Depending on the degree of asthma and
other factors, such as how much airway narrowing, or
bronchospasm, is present, full exhalation during spirometry
might last as long as 14 seconds rather than the normal
5 to 6 seconds.The FEV1 and PEF values reflect the
efficiency and status of lung emptying, and thus provide
information about how a person with asthma’s lung
function is affected by his or her condition.
The FEV1 measures the amount (volume) of air that is
exhaled in the first second of forceful exhalation during
spirometry as you breathe out as hard and as fast as you
can after you have taken in a deep breath.When asthma
is poorly controlled, it takes longer than predicted for
the lungs to fully empty. Since the total exhalation time
is prolonged in symptomatic or inadequately controlled
asthma, it follows that the amount (volume) of air exhaled
during the first second of that exhalation is lower than
predicted. The FEV1 decreases in symptomatic or poorly
controlled asthma. With treatment, the lungs empty
more efficiently, and the FEV1 value returns to a normal
range. When asthma is suspected, spirometry is performed
before and after inhalation of a short-acting
bronchodilator medication to look for the normalization
of the FEV1—a phenomenon called reversibility. The
most up-to-date guidelines from the third EPR (Expert
Panel Report) of the National Heart, Lung, and Blood
Institute define a 12% or greater increase in a person’s
baseline FEV1 on spirometry after use of a bronchodilator
as a significant response.
When active or exacerbated asthma prolongs exhalation,
flow of air through narrowed air passages becomes
reduced. Spirometry in active asthma also reveals reduced
flow rates. The peak flow is the single greatest value of
flow measurement that occurs as the lungs start to empty.
Peak flows reflect the flow of air through the larger, so called
conducting airways in asthma. Peak flow generally
tracks asthma activity. Monitoring peak flow at home
allows for comparison of a person’s predicted PEF, with
his or her actual personal best measurements obtained
when the asthma is well controlled.
Home-based PEF monitoring can then help
identify even a mild exacerbation and guide medication
adjustment up or down, depending on how the PEF
value fluctuates from the personal best. Self-administered
PEF measurements over time are a component of asthma
action plans .

A peak-flow meter is an easy-to-use device designed to
help you assess the degree of your asthma control. Persons
who have moderate or severe persistent asthma,
persons with a history of severe exacerbations, and persons
who have difficulty perceiving when their asthma
worsens are most likely to benefit from self peak-flow
monitoring. Monitoring long-term, daily peak-flow
measurements detects early changes in asthma control
that require an adjustment in treatment and helps
gauge the responses to those treatment changes.
Asthma self-monitoring should be neither a bother
nor a nuisance. On the contrary, daily home peak-flow
monitoring has been shown to improve asthma control,
reduce exacerbations, and decrease absences from
school and work. Using a peak-flow monitor may also
increase your confidence as it helps you learn how to
optimize asthma control and achieve greater mastery
over your asthma. Most children can accurately measure
their peak flow under adult guidance starting at about
6 years of age. Peak-flow monitoring also allows for
objective decisions about modifying your asthma regimen
based on information contained in the written
asthma action plan your physician has provided.
If your physician gives you a prescription for home peakflow
monitoring, you will be asked to determine your
personal best value based on measurements obtained
when you feel well and are symptom-free. An asthma
action plan provides instructions on what asthma medication
to take as the peak-flow value falls into one of
three zones labeled green, yellow, or red. The green
zone includes peak-flow measurements in the range of
80–100% of your personal best. Yellow corresponds to
peak-flow measurements in the range of 60–80% of the
personal best value. The red zone includes all peak flow
values below 60% of your best. Peak-flow measurements
in the red zone indicate that your asthma is poorly controlled,
and that you will need to either contact your
physician, proceed to the emergency room, or both.

What diagnostic testing is used to diagnose asthma?

The most helpful diagnostic tests for suspected asthma
are pulmonary function tests, often referred to as PFTs
 and the single most important
PFT, both for asthma diagnosis and for follow-up, is
spirometry.Other useful medical tests include blood tests
and X-ray studies. Additional, more specialized studies
may be obtained depending on the clinical picture.

 An example of a specialized study is skin-prick testing for
suspected allergy. Blood tests are valuable in getting an
overall picture of a person’s health, as well as in excluding
other diagnoses. Assessment of immune function and
allergies, for example, can be performed in part via blood
testing. X-ray studies include conventional chest X-rays,
as well as three-dimensional chest CT (computerized
tomography) scans. Chest X-rays and CT scans provide
information about the anatomy or structure of the lungs
and larger breathing passages. In quiescent, controlled
asthma, the chest X-ray should be entirely normal. The
same is true of the chest CT scan. During an exacerbation,
however, the lungs’ appearance on an X-ray may
suggest what radiologists call hyperinflation, and the CT
might reveal air-trapping. Both findings reflect the uneven
lung filling and emptying when breathing occurs through
inflamed, constricted air tubes.
Magnetic resonance imaging, scanning, and positron
emission tomography scanning, while useful in other
types of lung diseases, are not required in diagnosing
asthma. The same is true of nuclear medicine scans,
such as ventilation-perfusion scans and gallium scans.

How is the diagnosis of asthma established?

The diagnosis of asthma is often straightforward, but
can also be time consuming and elusive. Asthma can
manifest differently in different individuals because of
its waxing and waning nature, as well as its variability.
A physician evaluating a patient with a typical, or textbook,
presentation will likely be able to diagnose asthma
correctly at the first visit. A patient with variant or
atypical symptoms may require repeat visits or specialized
diagnostic testing to confirm the suspected diagnosis
of asthma. More severe forms of asthma are usually
easier to pinpoint and diagnose accurately. Consider
some examples in each category. A previously healthy,
nonsmoking young adult who reports an episodic history
of intermittent wheezing, cough, chest discomfort,
and breathlessness with exposure to cold winter air is
describing a history typical of asthma. The college student
who sees the doctor because of a nagging cough and
who is concerned about chronic or recurrent bronchitis
and colds, might actually be asthmatic. Similarly, the
teenager who gets “really winded” playing racquetball,
and then gets used to coughing for a few hours after
each match, could certainly have asthma as well.

Asthma can be confidently diagnosed when specific
symptoms, physical examination findings, and specialized
lung test results are present. The first step in the evaluation
of suspected asthma is a complete detailed medical
history, during which the doctor and the patient meet face
to face for an in-depth conversation and exchange of
information. The patient will describe what symptoms he
or she is experiencing, and the physician will ask a series
of directed questions regarding lung health, followed by
more general health inquiries. In this fashion, the physician
will obtain information not only about the patient’s
specific pulmonary symptoms, but also about the presence
or absence of allergies, and other medical or surgical
conditions. Other important background information
derives from review of the patient’s medication history,
along with his or her travel, occupational, and social history.
Some questions may at first sound intrusive, but
should nonetheless be answered truthfully.When I ask a
patient if there is wall-to-wall carpeting in the bedroom,
or who does the vacuuming, for example, I am far from
interested in discussing domestic decorating or cleaning
arrangements. Rather, I am gathering facts to help me
decide whether an allergic response to the home environment
is a possibility. Similarly, when I ask, “Is anyone else
at home coughing, too?” or “Is anyone at home a smoker?”
I am searching for clues to help me hone in on the
correct diagnosis. All conversations between my patients
and me are entirely confidential; truthfulness between us
is an important part of the successful doctor–patient
relationship. Just as I would never think of telling a patient
an untruth, so, too, do I count on my patients to provide
me with an accurate description or history.
After history taking comes the physical exam. Most lung
specialists will perform a directed physical, with special
emphasis on the upper respiratory tract (nose, throat,
sinuses), lungs, and the skin. One can expect measurement
of vital signs, including blood pressure, respiratory
rate, pulse, and if necessary, temperature. Inspection, percussion,
and auscultation are techniques that examine the
lungs. Inspection refers to a visual look. The specialist will
check whether both lungs move in and out with each
breath, for example. Percussion involves gently tapping
on the chest, listening for clues as to whether or not the
lungs are full of air. If the lungs are full of air, the tapping
will sound resonant. If the lungs are not entirely filled
with air, then the tapping will give rise to a dull sound.
Auscultation requires a stethoscope.
The examiner will ask the patient to inhale
and exhale deeply and regularly during auscultation. The
presence or absence of wheezing is especially significant.
After the history and the physical exam are completed,
the doctor will begin to generate a list of diagnostic possibilities,
called the differential diagnosis.
The doctor’s clinical impression rates the
possible diagnoses in order of likelihood. It may sometimes
be obvious to the physician that asthma is present.
A pulmonary function test called spirometry (obtained
before and after inhalation of a bronchodilator medicine)
is indicated in order to confirm the suspected asthma
diagnosis. If spirometry is not confirmatory and if asthma
remains high on the list of possible explanations for
a patient’s symptoms, then additional diagnostic testing
is often obtained . The additional testing is helpful in excluding
alternative diagnoses and in determining
if asthma is the correct diagnosis in spite of the
spirometry results.

What are the similarities and differences between asthma and COPD?

COPD and asthma are lung ailments. Asthma and
COPD can both give rise to similar symptoms, and are
sometimes treated with the same medicines. Both conditions
can lead to variable breathlessness, wheezy breathing,
coughing, and mucus production. Some medicines
prescribed for the treatment of asthma, such as inhaled β2
agonists, corticosteroid inhalers, and theophylline, for
example, are also used in COPD treatment. Asthma and
the conditions caused by COPD may also demonstrate a
similar pattern of abnormality on the pulmonary function
test called spirometry. That similar pattern of abnormality
is called obstructive dysfunction.
To a pulmonologist involved in direct patient care,
COPD and asthma are completely different. The single
most common cause of COPD is cigarette smoking.
COPD is a disease of mid- to late-adulthood. It is the
fourth leading cause of death in the United States, and
it is a significant cause of lifestyle limitation reflecting
its chronic and progressive nature. COPD affects different
sites in the lung than does asthma, involving both
the lung tissue and the airways. COPD’s obstructive
dysfunction on spirometry is “fixed” or “irreversible”.
 Asthma has a genetic basis
and is often seen in persons who also carry a diagnosis of
allergy. It affects all ages and is frequently diagnosed
in children. The diagnosis of asthma is compatible with
a long and full life and the prognosis is excellent. Asthma
targets the lung airways. By definition, the obstructive
dysfunction demonstrated on pulmonary function tests
in asthma is reversible such that lung function has the
potential to fully normalize.

Is COPD related to asthma?

Asthma is a specific lung disease that is different from
emphysema and chronic obstructive bronchitis.COPD is
often used as a kind of shorthand to describe emphysema,
chronic obstructive bronchitis, or a combination of both.
 COPD always refers to diseases that are not asthma.
 The COPD group of lung diseases is not related to asthma,
although emphysema
and chronic obstructive bronchitis exhibit similarities to
asthma, reviewed in the next answer. Confusion seems to
arise under several circumstances. In the first case,
COPD can co-exist with asthma, typically in an older
adult with a history of cigarette smoking, and both conditions
are present together. Secondly, some medical
practitioners in a blatant misuse of language use the word
asthma to refer to the breathlessness characteristic of the
COPD group of lung diseases. They tell their patients
with pure emphysema or chronic obstructive bronchitis
that they have “a touch of asthma” rather than explaining
that the symptom of shortness of breath is a fundamental
manifestation of the COPD. Finally,COPD and asthma

What is COPD?

COPD is an acronym for the term chronic obstructive
pulmonary disease. Chronic obstructive pulmonary disease
is a descriptive term rather than a single disease,
although it usually is used to refer to emphysema or to
chronic obstructive bronchitis.

Technically, COPD refers in a general way to several
different lung conditions that demonstrate an abnormality
on spirometry, a type of pulmonary function test.
The abnormality that characterizes COPD is
called obstructive dysfunction. Several different lung
conditions typically exhibit the obstructive dysfunction
pattern of abnormality on pulmonary function testing.
They include emphysema, chronic obstructive bronchitis,
exacerbated asthma, and bronchiectasis. The two
first diseases, in particular, share several features. Both
emphysema and chronic obstructive bronchitis are
associated with cigarette smoking. Both exhibit obstructive
dysfunction on spirometry that does not completely
reverse with medication, and thus demonstrate a “fixed”
or “irreversible” type of obstructive dysfunction. Both
cause respiratory symptoms such as breathlessness or
cough. Interestingly, emphysema and chronic obstructive
bronchitis frequently co-exist, usually in a current or
former cigarette smoker.
Partly because emphysema and chronic obstructive
bronchitis appear at first glance to be so similar, physicians
have taken to using the term COPD to refer
specifically to either emphysema or chronic obstructive
bronchitis, or even to a combination of both. The use
of COPD as a kind of shorthand for the smoking associated
lung diseases, whether emphysema or chronic
obstructive bronchitis, has taken hold among medical
professionals as well as the general public, despite disapproval
from some linguistic purists.

Why do I usually cough after jogging or running or after participating in sports?

The presence of a persistent cough is always abnormal.
There are many reasons why cough may develop. Each
one of us has experienced a cough at some point in our
lives, when ill with a respiratory infection or a head
cold, for example. Most coughs due to the common cold
are short lived and tend to resolve within a month’s time.
When a cough lasts longer than 3–6 weeks or assumes
a particular repetitive pattern, take note. Lung specialists
define a chronic cough as a cough that has been
present for more than 8 weeks. The majority of individuals
with chronic cough who are not cigarette smokers
have one of three causes for their cough: asthma, stomach
reflux (GERD), or postnasal drip syndrome (recently
renamed UACS for upper airway cough syndrome).
Cough that regularly occurs with or following aerobic
exercise strongly suggests the presence of asthma unless
proven otherwise.
Exercise is considered a symptom trigger in all persons
with asthma. Exercise does not cause asthma but acts as
a stimulus to bronchoconstriction in asthma and leads
to increased airway inflammation. In young children in
particular, cough with exertion should never be
ignored; it may be the tip-off to the diagnosis of asthma
since cough is the most frequent symptom of asthma in
children.
Answering the question of why you might be coughing
after running or jogging would require an evaluation
that should begin with a medical history (including any
medication you are taking), discussion of cigarette smoking
if applicable, reviewing the chronology of the symptom,
and a physical examination with close attention to
the sinuses, throat, heart, and lungs. Additional testing
might include a chest X-ray (depending on your
individual medical history) and pulmonary function
testing.

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.

Asthma is a disease of children, isn’t it?

Asthma affects people of all ages and a diagnosis of asthma can be made in a child
as young as 2 years of age. Asthma is the most common
chronic disease of childhood. Asthma is not, however, a
disease limited to children. It is a myth that asthma is
only a disease of childhood, and that all children with
asthma will outgrow their asthma with time as they grow
into adulthood. Many people newly diagnosed with asthma are adults.
Although
some adults with asthma may have experienced asthma
as a child, others develop the condition the first time as
an adult. Asthma can thus develop at any age.

Why is asthma so common?

Asthma is very common, affecting approximately one of
every ten Americans at some point in their life, according
to 2001 data from the CDC’s National Health Interview
Survey. It is not clear why asthma has become such a
prevalent, chronic condition. One theory holds that physicians
have become more adept at diagnosing asthma
correctly so that the more precise identification and more
accurate counting of persons with asthma has led to a
perceived increase in diagnosed cases of asthma. Unfortunately,
the opposite is true—the diagnosis of asthma is
too often overlooked, particularly in older age groups and
in adolescents, especially in teenage girls. The fact is that
asthma has truly become more common. A more likely
theory implicates various environmental factors. Smoking,
for example, became socially acceptable for women
after World War II. Infants of mothers who smoke are at
risk for the development of wheezing and asthma in
childhood. Increasing air pollutants and small particles
found in urban or industrial areas may also play an important
role.  From the perspective
of an asthma specialist, the greater awareness of the
importance of air quality in general and the enactment of
laws banning smoking in all indoor public places, such as
in New York City, in particular are a crucial step toward
improving air quality for all.

Is it true that asthma is increasing?

Yes, asthma has increased steadily in the United States
through the 1980s and 1990s, as in other Westernized
countries. There are more persons diagnosed with asthma
now than ever before in the United States.The prevalence
of asthma—that is the total number of cases of
asthma in a population at any given point in time—
continues to increase worldwide . It may also
be true that allergic conditions are on the increase. The
reason why asthma is increasing in the United States
and in other industrialized nations is unclear. A farreaching
international effort to understand the scope of
increasing asthma (and allergy) in young people led in
1991 to the formation of the ambitious and ongoing
International Study of Asthma and Allergies in Childhood,
known as ISAAC, and accessible on the Internet
at http://isaac.auckland.ac.nz/. ISAAC describes itself
as “the largest worldwide collaborative research program
ever undertaken involving more than 100 countries
and 2 million children.” Findings that have emerged
from the ISAAC study include the observation that

English-speaking countries demonstrate the highest
prevalence rates for asthma and that Latin American
countries also have elevated asthma rates.
Of great concern to physicians are certain urban neighborhoods,
such as the South Bronx and East Harlem
in New York City, where rates of asthma hospitalization
and asthma deaths are among the highest in the nation,
and where nearly 20% of children have been diagnosed
with asthma.When looking at “the big picture” however,
U.S. data collected from 1980 to 1996 reveal, as mentioned
previously, an increase in asthma prevalence. Since
1995, there have also been increases in national rates
of office, clinic, and emergency room visits for asthma.
Those increases developed in parallel with a decrease in
the rates of hospitalization for asthma and of deaths
from asthma. Experts believe that the increase in the
number of outpatient visits is the result of better and more
effective asthma treatment in the setting of increasing
numbers of persons diagnosed with the disease. The
recorded drop in hospital admissions for asthma and
the reductions in the death rate are also consistent with
improved asthma care overall—an encouraging public
health statistic!

How many Americans have Asthma?

Asthma is a very common lung disease. It has been
described in all ethnic groups and in all ages, from childhood
into the golden years. The U.S. Centers for Disease
Control and Prevention’s (CDC’s) National Center for
Health Statistics reports that asthma currently affects
more than 22.2 million Americans or 7.9% of the
population, including over 6.7 million children younger
than 18 years of age (Table 2). Another way of looking
at the information is that 7.3% of American adults currently
have asthma, as do 9.3% of all young persons aged
15 years or younger . Asthma is the most common
chronic disease of childhood. It is also the primary
cause of school absences due to a chronic condition.
Young people aged 5–17 years with asthma miss more
than 12.8 million school days annually in the United
States. Asthma is responsible for interference with adults’
daily activities as well, given that over 10 million work
days are lost annually to poorly controlled asthma.
The cost of asthma is significant both for individuals
and for our society as a whole. Experts refer to the burden
of asthma. The CDC estimates that in 2006, asthma accounted
 for 10.6 million visits to office-based
physicians, 1.3 million visits to hospital clinics, and
1.8 million visits to hospital emergency departments.
The rate of emergency department visits for asthma
was higher in children than in adults, and the highest
rate of asthma requiring emergency department care
was for children 4 years of age and younger. Hospitalizations
for asthma appear to be decreasing over
recent years, and presently approximate close to half a
million yearly, with higher rates of hospitalization among
children than among adults. The highest rate of hospitalization
for treatment of asthma, similar to the rate of
emergency room utilization is for children aged 4 and
younger.
Experts are interested in reducing the burden of asthma
illness and the rates of hospitalization in the United
States as in all other countries. The fact that the hospitalization
rates for asthma in the United States have
been decreasing may reflect the beneficial effects of
the introduction of newer asthma therapies, including
medications such as those referred to as “controller” or
“maintenance” medicines, reviewed later in the text. This
book will help you learn about asthma and good management
practices, and it will present strategies that may
assist you in better understanding your condition. Knowing
that asthma is so common serves as a reminder that
you are far from alone. Properly treated asthma allows
for a full and rewarding lifestyle, and that fact, along with
the fact that millions of American have been diagnosed
with asthma, explains why you will see persons with
asthma achieve just about everything, everywhere! I have
met athletes with asthma, teachers with asthma, actors
with asthma, and lawyers and doctors with asthma. As
one patient of mine confided with a grin, “Doc, if I can
brush and floss my teeth twice a day every day of my life,
what’s the big deal with taking a few more minutes to
inhale medicine that keeps me healthy?”

What is asthma?

Asthma is a very common, highly treatable lung condition.
Millions of individuals worldwide, children and
adults, carry a diagnosis of asthma. Asthma’s symptoms
relate to breathing and to the respiratory system. Symptoms
of asthma vary in frequency and in intensity and
may include cough, wheeze, increased mucus production,
uncomfortable breathing, and shortness of breath. Asthma
severity not only varies from person to person, but can

also fluctuate in a given person over time. A major goal of
asthma treatment is directed at symptom prevention as
well as at symptom control. Some people with mild
asthma experience infrequent symptoms. Others, whose
asthma is more persistent, at the other end of the asthma
severity spectrum, may require several daily lung medications
taken regularly to control their disease, normalize
their lung functioning, and attain a symptom-free state.
Physicians who specialize in asthma care firmly believe
that even the most severely affected asthma sufferers
can be treated successfully. Modern asthma management
and contemporary therapies allow persons diagnosed
with asthma to lead full, active lives. Successful
asthma treatment requires an understanding of the disease
in general as well as how it manifests itself in a particular
person, combined with attentive medical care and
the forging of a cooperative partnership between patient
and physician