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Asthma
Introduction
Asthma is a disease that affects the
breathing passages of the lungs. Over 17 million people in the United
States have asthma. A third of these are children.
- Asthma is caused by chronic inflammation of the bronchioles—the
breathing passages that bring air to the lungs. When these breathing
passages become inflamed, they swell and fill with mucus. In addition,
muscles within the breathing passages contract, causing even further
narrowing of the airway. It then becomes difficult for inhaled air to be
exhaled from the lungs. The narrowing of the breathing passages, which
increases the resistance to expired air flow, leads to the typical
symptoms of an acute asthma attack.
- When someone suffers an asthma attack, the inflammation and
bronchospasm make it difficult for the person to breathe. This is due
to an increase in the resistance to exhaled air brought about by
narrowing of the air passages.
- This higher resistance to exhaled air results in recurring
episodes of wheezing, breathlessness, chest tightness, and coughing,
which are the main symptoms of asthma.
- Asthma is a disease that cannot be cured, only controlled. It is
considered a chronic lung disease. Because the disease causes
resistance, or obstruction, to exhaled air, it is called an obstructive
lung disease. The medical term for such lung conditions is chronic
obstructive pulmonary disease, or COPD, which includes not only asthma,
but also chronic bronchitis and emphysema.
- Unlike other chronic obstructive lung diseases, asthma is
reversible. Between episodes of acute attacks, the person with asthma
usually has no signs or symptoms of the disease.
CAUSES
The major factor responsible for the
development of asthma is inflammation of the breathing passages.
- Common causes of inflammation include these:
- Respiratory irritants such as smoking, air pollution, respiratory
infections
- Exposure to allergy-causing substances such as molds and animal
dander
- Exposure to cold, dry weather
- Menstruation (In some women, there is a strong association between
the time of the menstrual cycle and their asthma symptoms.)
- Heredity (It is not known why some people develop asthma while
others do not, but there is a tendency for asthma to run in
families.)
SIGNS AND SYMPTOMSSIGNS AND SYMPTOMS
Regardless of the underlying
cause of asthma, when the breathing passages become irritated or infected,
inflammation occurs.
The combination of bronchospasm, tissue swelling, and mucus production
results in the signs and symptoms of an acute asthma attack.
- Here is the scenario of an asthma attack:
- The inflamed breathing passages begin to swell, which reduces the
amount of space available for air to pass through.
- In addition to swelling, the inflamed tissues produce a thick
mucus in an attempt to protect themselves from the source or
irritation.
- The breathing passages contain small muscles that contract when
they are stimulated. Inflammation can cause these muscles to contract,
which narrows the breathing passages even further. When this happens,
it is called bronchospasm.
- The most common sign of an acute asthma attack is wheezing. Wheezing
is a musical, whistling, or hissing sound heard when a person with
asthma breathes. Wheezes can occur during inhalation (breathing in) or
exhalation (breathing out), but are most often heard during exhalation.
Although wheezing is the most commonly described finding during an acute
asthma attack, not all asthmatics wheeze, and not all people who wheeze
are asthmatics.
- Other signs may be seen during an acute asthma attack:
- Coughing
- Difficulty breathing
- Difficulty speaking
- Feeling of chest
tightness
HOME CARE
The goal of asthma care at home involves using
medications to maintain normal or near-normal lung function. When a
person with asthma is able to control asthma attacks, the number of
hospital Emergency Department visits may be reduced or eliminated.
Asthma medications are divided into the categories of controller
medications and rescue medications.
- Controller medicines minimize the inflammation that causes an
acute asthma attack.
- Inhaled corticosteroids are the main class of medications in this
group. The inhaled steroids commonly in use act locally by
concentrating their effects directly within the breathing passages,
with very few side effects outside of the lungs. Beclomethasone
(Vancenase, Beclovent) and triamcinolone (Nasacort, Atolone) are
examples of inhaled corticosteroids.
- Leukotriene inhibitors are another group of controller
medications. Leukotrienes are powerful chemical substances that
promote the inflammatory response seen during an acute asthma attack.
By keeping these chemicals from producing swelling, leukotriene
inhibitors reduce inflammation. The leukotriene inhibitors are
considered a second line of defense against asthma and usually are
used along with corticosteroids. Zileuton (Zyflo), zafirlukast
(Accolate), and montelukast (Singulair) are examples of 3 leukotriene
inhibitors.
- Methylxanthines are another group of controller medications useful
in the treatment of asthma. This group of medications is chemically
related to caffeine. Methylxanthines do not reduce inflammation.
Instead, they dilate (open) the breathing passages. At one time,
methylxanthines were commonly used to treat asthma. Today, because of
significant caffeinelike side effects, they are being used less
frequently in the routine management of asthma. Theophylline and
aminophylline are examples of methylxanthine medications.
- Cromolyn sodium is another medication that can prevent the release
of chemicals that cause asthma-related inflammation. This drug is
especially useful for people who develop asthma attacks in response to
certain types of allergic exposures. When taken prior to an exposure,
cromolyn sodium can prevent the development of an asthma attack.
However, this medicine is of no use once an asthma attack has
begun.
- Rescue medications are used to treat asthma once an acute
attack has already begun.
- Beta-agonists are the most commonly used rescue medications. This
class of drugs is chemically related to adrenaline, a hormone produced
by the adrenal glands. Inhaled beta-agonists work rapidly within
minutes to open the breathing passages. By dilating the breathing
passages, the resistance to exhaled airflow is reduced, making it
easier to breathe.
- Beta-agonists do not reduce inflammation, so the underlying
mechanism causing the asthma attack is not being treated by
beta-agonists.
- The most common side effects of beta-agonists include an
increase in heart rate and shakiness. Albuterol (Proventil,
Ventolin) is the most frequently used beta-agonist medication.
- Anticholinergics are another class of drugs useful as rescue
medications during an acute asthma attack. Inhaled anticholinergic
drugs open the breathing passages, similar to the action of the
beta-agonists. Inhaled anticholinergics take slightly longer to
achieve their effect, but they last longer than the beta-agonists.
Anticholinergic drugs are often used together with a beta-agonist drug
to produce a greater effect than either drug can achieve by itself.
Ipratropium bromide (Atrovent) is the inhaled anticholinergic drug
currently used as a rescue asthma medication.
If you have asthma, you
should have an action plan worked out in advance with your doctor. This
plan should include instructions on what to do when an acute asthma attack
occurs, when to call the doctor, and when to go to a hospital's Emergency
Department.
- As a general guideline, 2 puffs of an inhaled beta-agonist (a rescue
medication) can be taken, with 1 minute between each puff. If there is
no relief, an additional puff of inhaled beta-agonist can be taken every
5 minutes. If there is no response after 8 puffs, which is 40 minutes,
your doctor should be called.
- Your doctor should also be called if you develop an acute asthma
attack when you are already taking oral or inhaled steroids or if your
inhaler treatments are not lasting 4 hours.
Although asthma is a
reversible disease, and there are treatments available, people can die
from a severe asthma attack.
- During an acute asthma attack, if severe shortness of breath occurs,
or you are unable to reach your doctor in a short period of time, you
must go to the nearest hospital's Emergency Department.
- If you are alone, do not risk driving yourself to the hospital. Dial
911 immediately for an emergency medical transport.
PHYSICIAN DIAGNOSIS
In the Emergency Department, the
doctor will first assess the severity of the asthma attack. General
findings used to determine the severity of the attack include noting how
well you can speak and whether you are using neck or chest muscles in
order to breathe.
- If this is your first suspected asthma attack, the doctor will
search for other causes of wheezing and shortness of breath.
- Measurements of how well you are breathing will probably be taken.
This might include having you breathe into a spirometer,
a device that measures how forcefully you can breathe out. A painless
probe, called a pulse
oximeter, will be placed on your fingertip to measure the amount of
oxygen in your bloodstream.
- A blood test may be performed to determine if an infection might be
contributing to this attack. On occasion, it is necessary to sample
blood from an artery to determine exactly how much oxygen and carbon
dioxide are present in your body.
- A chest x-ray may also be taken.
PHYSICIAN TREATMENT
While the evaluation is going
on, treatment will be started.
- You may be placed on oxygen.
- You may be given an inhaler
treatment using an aerosolized beta-agonist, with or without an
anticholinergic agent.
- Another method of providing inhaled beta-agonists is by using a metered dose
inhaler or MDI. An MDI delivers a standard dose of medication per
inhalation. MDIs are often used along with a "spacer" or holding
chamber. A dose of 6-8 puffs is sprayed into the spacer, which is then
inhaled. The advantage of an MDI with a spacer is that it requires
little or no assistance from the respiratory therapist.
- If you are already on steroid medications, or have recently stopped
taking steroid medications, or if this appears to be a very severe
attack, you may be given a dose of IV steroids.
- If you are taking any methylxanthines, such as theophylline or
aminophylline, the blood level of these drugs will be checked, and you
may be given this medication through an IV.
- People who respond poorly to inhaled beta-agonists may be given an
injection or IV dose of an injectable beta-agonist such as terbutaline
or epinephrine.
PROGNOSIS
You will be observed for at least several
hours while your test results are obtained and evaluated. You will be
monitored for signs of improvement or worsening.
- If your breathing improves, and you are able to breathe forcefully
enough through the spirometer, most likely you will be sent home from
the Emergency Department.
- If you do not respond well enough to treatment, or if you cannot
breathe out forcefully enough through the spirometer, you will need
either additional Emergency Department treatment or admission to the
hospital.
- If you have a past history of being admitted to the hospital for
asthma attacks, if you have ever been placed on a ventilator for your
asthma, or if you have other serious diseases, there is a greater chance
that you will require hospital admission.
- The presence of other serious respiratory illnesses or injuries,
such as pneumonia or pneumothorax (a "collapsed" lung) would also
warrant admission to the hospital.
PREVENTION
You need to know how to prevent or
minimize future asthma attacks.
- If you develop asthma attacks as a result of an allergy, you will
need to avoid any known substances that could trigger an attack.
- You must continue to take your asthma medications when you are
discharged. Although the symptoms of an acute asthma attack go away
after appropriate treatment, asthma itself never goes away. It is a
chronic lung disease, and future attacks can occur. Your medications
will be reviewed and may be adjusted.
FOLLOW-UP
You will be instructed to contact your
doctor, or you will be referred to a doctor who can follow up with
long-term asthma treatment and prevention. You should arrange to be seen
within a few days after discharge from the Emergency Department.
- If your symptoms return, or if you begin to feel worse, you should
immediately return to the Emergency Department.
- Asthma is a long-term disease, but it can be managed. Your active
involvement in treating this disease is vitally important. By taking
your regularly prescribed medications as directed, following up in the
office periodically, and avoiding any known allergic substances, you can
help minimize the frequency and severity of your asthma
attacks.
Caption: Picture 1. A child with asthma using a metered dose inhaler.
Caption: Picture 2. An adult with asthma using a spirometer to measure how
forcefully she can exhale.
Caption: Picture 3. A pulse oximeter measures the amount of oxygen in your
bloodstream.
Caption: Picture 4. A person with asthma receives an inhalation treatment
using a hand-held nebulizer.
Caption: Picture 5. A child with asthma uses a metered dose inhaler with a
spacer.
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