Understanding and preventing lower respiratory tract infections
Lung infections are the most common problem associated with CF. Once again, the main cause is poor airway clearance created by thick, sticky mucous.
In normal lungs, the oxygen from the air is drawn through the nose and mouth, travels down the trachea (windpipe) into the right and left bronchus (large airway tubes) and bronchioles (small airway tubes) and then finally into millions of alveoli (air sacs). From the alveoli the oxygen is absorbed into the blood stream and is carried to all parts of the body.
To help the breathing process, the lungs have their own natural clearance methods. Your airways produce a thin coat of mucous that catches the dust and bacteria that you breathe in daily. This thin mucous is swept up towards the windpipe by tiny beating hairs called cilia, where it can be coughed up or swallowed.
In CF lungs, this mucous is thick and sticky, which makes it harder for the
cilia to do their job of sweeping mucous away from your lungs. Instead of being
cleared away, the thick mucous builds up in the airways, and plugs them up this
can cause air trapping, airway closure and infection.
You can't avoid all infections, but you can avoid some by being aware of
their causes, potential consequences and symptoms. Seeking early treatment at
the first sign of infection (like coughing more or feeling tired) may help
prevent and delay lung damage. In the long run, lung infections end up causing
irreversible damage to the lung tissue.
What are the causes of Lung Infection?
Bacteria, viruses and fungi are germs that cause infection, bacteria cause most of the lung infections in people with CF. The most common types of bacteria in adults with CF are Pseudomonas aeruginosa, Staphylococcus aureus and Haemophilus influenzae. Burkholderia cepacia and Stenotrophomonas maltophilia are less common bacteria that are known to cause infection in some people with CF. Viruses and fungi can also cause infections.
What are the types of Lung Infection?
There are two types of lung infection: chronic infection and acute exacerbation
(or a sharp worsening of symptoms). Chronic infection is an infection that is
present nearly all the time, with fairly mild symptoms. Exacerbations are
periods of noticeable increases in the signs and symptoms of the infection,
including a decline in lung function. A sharp or sudden worsening of symptoms is
in itself a symptom o fan acute exacerbation.
Cycle of Lung Infection in C F
Chronic lung infection Inflammation Cells die and release enzymes and DNA Increased mucous Mucous plugging and obstruction
What happens during an exacerbation?
Infection causes the airways to become swollen. When the airways become
swollen, the inside opening of the airway become smaller than usual. The mucous
becomes darker, thicker, and harder to expel. Your body will also produce more
mucous in response to the lung infection. This mucous may block your airways,
creating an ideal breeding ground for bacteria to grow - which in turn can lead
to more infection.
Repeated infections damage the airways permanently, making the mucous even
harder to remove. Also, when your airways are damaged and plugged with mucous,
oxygen has a much harder time reaching the air sacs in your lungs and less
oxygen enters the bloodstream.
How can I cut down on the frequency of acute exacerbations?
One of the best ways to fight acute exacerbations is to make it hard for infections to develop. Taking medications that are prescribed to reduce inflammation or thin your mucous secretions as well as taking antibiotics, either inhaled or oral, that your doctor prescribes may help reduce the frequency of exacerbations.
wash your hands often, especially after coughing or handling mucous.
avoid, within reason, other persons with colds and other bacterial or viral infections or respiratory illnesses
get a flu shot every year
keep your nebulizer, PEP device, and other equipment clean and dry.
don't share your equipment with others
avoid tobacco smoke and other irritants (air pollution, pollen, mold, barbecue smoke, burning leaves)
avoid touching your eyes, nose, and mouth (bacteria and viruses can be transferred from your hands and thus enter your body)
change the furnace filters in your home regularly; keep the air ducts clean
avoid outdoor activities if the air quality is poor
Symptoms of an Exacerbation
Symptom
Explanation
Increased frequency of coughs and/or nighttime coughs
a wet, loose cough indicates increased mucous production
a dry, hacking cough may mean that the airways are narrowed or irritated
Increased amount and thickness of mucous, change in color of the mucous, or any blood in the mucous
acute infection irritates the airways, creating more mucous.
the colour of the mucous may change when bacteria is growing in it
if an acute infection continues, the airways become more irritated and may begin bleeding (hemoptysis)
Increased fatigue (feeling tired all the time)
fatigue means that the body is using more energy to fight the infection
infections in CF don't always cause the sort of tiredness that you might have with the flu or other viral illnesses
Decreased appetite, weight loss
when the body is using calories to fight infection, fewer calories are available to maintain weight
when you are sick you may not feel like eating, but you need to increase your food intake to fight the infection
Increased shortness of breath (SOB)
if your lungs are already quite damaged, shortness of breath may be the first symptom of an infection that you notice
during an acute infection, your lungs may have a harder time providing the body with enough oxygen, your doctor may prescribe oxygen during this period
shortness of breath usually occurs when the infection is severe
Low-grade fever (37.3° to 37.7° Celsius)
your temperature may go up slightly at the beginning of an infection
What do I do if I notice any symptoms of an infection?
Contact your CF team. Even if you are unsure, or your symptoms are just starting, it's wise to contact your CF team for early treatment. Do your airway clearance treatments more often. Keep a thermometer at home so that you can check for a low-grade fever (37.3° to 37.7° Celsius).
You may be asked to come to clinic and have some tests done to monitor the status of your lungs. The tests could include a chest x-ray, lung function tests (PFT's) and a sputum test to check for bacteria. A chest x-ray can give a picture of the damage within the lungs and detect any number of things, for example: increased mucous in the lungs, pneumonia, areas of lung collapse or thickened scarred airways. PFT's measure how the lungs are working and can detect small changes in lung function. They can give a good idea of whether the larger or smaller airways are affected by mucous plugging, how much air trapping there is, and whether you have reactive airways. Checking what type of bacteria grows in your mucous helps to determine which antibiotics you should take.
How are exacerbations treated?
If the exacerbation is mild, your healthcare team will reassess and adjust your maintenance therapy. Treatment may
include: adding or changing antibiotics, starting aerosolized antibiotics (if
this is not already part of your daily treatment plan) increasing the frequency
of airway clearance treatments using bronchodilators (reliever medication that
relaxes the muscle that goes around the airways, opening them and making it
easier to breath) increasing caloric and fluid intake rest. Sometimes medication
is prescribed to help thin the mucous (thinner mucous can be easier to cough
up). Moderate or severe exacerbations usually require intravenous antibiotic therapy (at home or at the
hospital), frequent airway clearance treatments, as well as the other treatments
noted above - especially rest and good nutrition.
Remember — taking action at the first sign of an infection when your symptoms are still mild can help treat many
exacerbations, and prevent more severe ones from happening.
Resources and Educational Materials
David M. Orenstein. Cystic Fibrosis: A guide for Patients and Family. 2nd ed. Philadelphia: Lippincott- Raven: 1997.
Reference
This article was adapted from an article by Joan Zukosky, RN, BSN, Adult CF Nurse Coordinator, Barnes-Jewish Hospital, Washington University Medical School, St. Louis, Missouri (in Genentech's CF Toolbox)
