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| Pneumonia |
Reviewed by Anthony
W Chow, MD, FRCPC, FACP
Best Health Guide. April 2000.
Last modified November 1, 2001 |
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Pneumonia is a short-term inflammation of the lung
that is caused by an infection. |
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There are two types of pneumonia: community-acquired
and hospital-acquired (also called nosocomial). The first form is
transmitted between people in a community, while hospital-acquired
pneumonia is spread between patients in the hospital. As many infectious
organisms tend to thrive in either, but not both of these environments,
your doctor will try to figure out where you were infected in order
to determine which organism is likely to be responsible for your pneumonia. |
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Pneumonia often follows an infection of the upper
respiratory tract (the nasal passages, for example) when the body's
normal defenses are weakened. [FIGURE
1] |
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Under normal circumstances, large bacterial particles
are filtered out in the nasal passages. If smaller particles are inhaled,
the body triggers a cough or sneezing reflex to force them back out.
Tiny particles that bypass these sensors are then trapped in a blanket
of mucus, and are moved out of the lungs by the beating movements
of tiny, hairlike cells called cilia. Bacteria and other organisms
that manage to avoid this defense system are attacked by white blood
cells launched by the immune system. However, respiratory infections
such as influenza or a cold can alter the mucus blanket and create
an environment that favors the growth of bacteria. Other times, diseases
such as HIV or cancer weaken the immune system, preventing the body
from effectively fighting the bacterial and viral particles that bypass
the respiratory defenses. |
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Organisms can reach the airways in a number of ways,
including being inhaled or moving from other areas of the body. |
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Sometimes the organisms that cause pneumonia are directly
inhaled from the environment. More commonly, however, they move into
the lungs from the areas around the mouth and in the throat, where
they normally thrive without causing any harm. Sometimes, infections
from other areas of the bodysuch as the heart or veinscan move into
the lungs and cause pneumonia. |
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Figure 1. Pneumonia infection and fluid
accumulation
A weakened immune system will allow for
bacteria and other organisms that enter the airways of the lungs
to cause an infection. Fluid will then accumulate in the lungs,
leading to symptoms such as cough, shortness of breath, and
chest pain. [PLAY] |
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Pneumonia can produce a wide range of symptoms, including
a dry or productive (mucus-producing) cough, shortness of breath,
chills, and chest pain. [TABLE
1] |
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Specific symptoms are often associated with the particular
organism causing the infection. For example, the organism Streptococcus
pneumoniae, which is responsible for about two-thirds of all cases
of pneumonia, may cause an infection that comes on very abruptly,
and is accompanied by fever, chills, chest pain, and rusty or pink
mucus. On the other hand, a less typical pneumonia (caused by the
organism Mycoplasma pneumoniae) might come on slowly, with
headache, a general feeling of illness, a low-grade fever, and a dry
cough. |
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Symptoms in the elderly can be less specific, including
such things as rapid breathing and a low-grade fever. |
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Symptoms in the elderly may be difficult to recognize
since they differ significantly from the most typical pneumonia symptoms.
Rapid breathing (tachypnea) is probably the most important sign of
a respiratory tract infection in an elderly person. Pain in the upper
part of the abdomen is also common, as is mental confusion. |
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Your doctor will rule out other conditions, such as
bronchitis or heart problems, that produce similar symptoms. |
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Symptoms similar to those of pneumonia may be found
in bronchitis, substance abuse, drug reactions, blood clots in the
lungs (pulmonary emboli), heart failure, and certain forms of lung
cancer. Symptoms of these conditions, however, tend to be milder than
those associated with pneumonia. |
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Although pneumonia can affect all age groups, it tends
to be more severe among the elderly, the very young, and people with
certain coexisting illnesses. [TABLE
2] |
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Because a weakened immune system interferes with the
body's ability to protect itself against bacteria that enter the airways
of the lungs, people with immune diseases are at high risk for pneumonia.
This includes people actively infected with the human immunodeficiency
virus (HIV), those with cancer and receiving chemotherapy, and organ
transplant patients. Other illnesses such as liver or kidney disease,
stroke, and heart disease also increase the risk for pneumonia. Additionally,
pneumonia can occur after a chest injury or surgery. Smoking and alcohol
or drug abuse also tend to increase a person's risk for pneumonia. |
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Visiting or living in certain locales can increase
your chances of getting pneumonia. [TABLE
2] |
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Studies show that people who reside in or have recently
traveled to the Southwest or the Ohio-Mississippi Valley are more
likely to encounter organisms that can cause rare forms of pneumonia,
as are people who have recently stayed in hotels. Exposure to birds
or farm animals can also increase a person's risk of acquiring pneumonia. |
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Your doctor will ask you about past illness and other
problems to determine what is causing your symptoms. |
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You should tell your doctor about any illnesses you
have, if you've recently been exposed to a person with HIV, or if
you've experienced any sort of lessened consciousness, impaired gag
reflex, or vomiting. Alcohol or intravenous drug abuse, smoking history,
a recent hospital or hotel stay, and exposure to birds and farm animals
can also provide important information about the potential source
of your infection. |
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You should also tell your doctor if you have had a
recent viral infection, flulike symptoms, or have recently traveled
to the Southwest or Ohio-Mississippi Valley. |
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A physical examination helps the doctor to diagnose
pneumonia. It can also help determine the severity of the disease. |
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Your doctor will listen to your heart, lungs, and
chest through a stethoscope for evidence that pneumonia is the likely
cause of your infection. For example, a crackling or bubbling sound
in the chest (rales) or rumblings in the chest that indicate fluid
build-up (rhonchi) are signs that would indicate pneumonia rather
than bronchitis (which is characterized by crackles and wheezing chest
sounds). Another sign of pneumonia is a dull thud as the result of
light tapping on the chest rather than the hollow drumlike sound that
normally occurs. |
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The doctor will record your vital signs, which include
temperature, pulse rate, blood pressure, and breathing speed. Up to
80% of people with pneumonia have abnormal vital signs. Additionally,
central nervous system signs such as mental confusion, in combination
with an extremely high or low fever, rapid heart rate, and labored
and heavy breathing, can indicate that pneumonia is severe enough
to constitute a medical emergency. |
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Chest x-rays are not always required to confirm a
diagnosis of pneumonia. |
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Most people with mild pneumonia can be effectively
treated without having a chest x-ray taken first. However, in people
with moderate to severe pneumonia, a chest x-ray is often taken to
determine the extent of disease and the need (if any) for additional
testing. X-rays are especially useful in people with weakened immune
systems since they can help assess whether or not pneumonia or some
other illness is responsible for symptoms. Chest x-rays can also be
used to show complications of disease, such as a build-up of pus in
the lungs (emypemas) or abscesses. |
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Laboratory tests are sometimes required to confirm
a diagnosis of pneumonia. |
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Laboratory testing is not usually necessary for people
with mild disease. Because treatment is started immediately, tests
will only be ordered if a medication does not help, or to help distinguish
between bacterial and viral pneumonia in severely ill patients. Lab
Tests are also useful for people whose pneumonia is caused by an organism
that is resistant to standard antibiotic treatment. |
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Relevant laboratory tests include such procedures
as a complete blood cell count (CBC), which measures the number and
type of white blood cells in the blood, a cold agglutinin test, which
indicates if certain antibodies are present as a result of infection,
a mucus (sputum) culture, and a Gram stain, which involves adding
a stain to culture to help identify possible causes of infection.
Patients with breathing difficulties may be given tests that are used
to assess the lungs' ability to move oxygen into the blood. These
include pulse oximetry and the arterial blood gas test. |
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Get a pneumococcal vaccination and an annual influenza
vaccination if you are at risk for pneumonia. |
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Influenza increases the risk of pneumonia because
it significantly weakens the natural defenses of the respiratory system
against invasion by bacteria and other organisms. That's why it's
important to have an annual influenza vaccination, especially if you
are age 65 or over, have a chronic illness, or have a weakened immune
system. Pneumococcal vaccinations have also proven effective in preventing
pneumonia, and vaccinations are recommended for people at high risk.
Unlike the influenza vaccine, which must be received annually, the
pneumococcal vaccine lasts for over six years. |
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Caregivers or family members of someone with pneumonia
should wash their hands frequently to prevent transmission. |
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Although there is no guarantee that a family member
or a caregiver won't catch pneumonia, the risk can be lowered with
frequent handwashing before eating, before touching the eyes or nose,
and after going outside. Eating foods that are rich in the antioxidant
vitamins C, E, and beta-carotene, such as dark cruciferous vegetables
(broccoli, carrots) and orange or yellow fruits and vegetables (oranges,
mangoes, apricots), may also help to boost the immune system. Additionally,
drinking lots of fluids to keep the mucus membranes hydrated can reduce
the risk of bacterial or viral transmission. |
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Submit your questions or comments on this topic.
We will consider them as we update our database. |
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