| Exacerbations
of COPD
Flare-ups are common and affect quality
of life BY Krishna B. Sharma, MD |
|
Chronic
obstructive pulmonary disease (COPD) is a lung disease affecting 4% of Canadians.
It destroys alveoli and their supporting structures, causing airways to collapse.
Inflammation and increased mucus production further impair the patient's ability
to empty air from the lungs. With spirometry testing, we measure partially reversible
airflow obstruction, since in COPD, improvement with bronchodilators isn't as
significant as in asthma. Along with respiratory symptoms such as shortness of
breath, cough, wheeze and sputum production, we're starting to recognize the systemic
effects of the disease, including skeletal muscle dysfunction, right heart failure
and depression. COPD is a major cause of death in Canada, now the fourth leading
cause in men, and fifth in women. The driving force behind the high morbidity
and mortality is exacerbations of the disease. What's
a COPD exacerbation?
Anthonisen's Winnipeg criteria state that
an acute exacerbation is defined by a sustained worsening of dyspnea, cough or
sputum production leading to an increased use of maintenance medications or the
addition of supplemental drugs, usually for at least 2 consecutive days. Although
x-ray and laboratory testing is helpful, this is a clinical diagnosis. The average
patient will have two to three flare-ups or acute exacerbations of COPD (AECOPD)
every year. Surveys suggest that patients only report about half of these episodes
to the family doctor. It's often difficult to pinpoint
exactly what causes the exacerbation in the first place. Over half of the triggers
are thought to stem from infection, especially viral upper respiratory tract infections.
Bacterial super-infection after a viral "cold" can also cause one. Non-infectious
triggers include exposure to cold air or allergens like pet dander. In addition,
irritants such as cigarette smoke and air pollution can set off an AECOPD. How
do flare-ups affect a patient's life?
If COPD patients are asked
about their disease, they generally feel that exacerbations contribute most to
the reduction in quality of life, due to the weeks of shortness of breath and
fatigue. Recurrent episodes also lead to higher death rates; a 2005 study showed
that only 40% of COPD patients with more than three flare-ups per year were alive
after 5 years. Every year after our late 20s, we lose
a few millilitres of our forced expiratory volume in one second (FEV1),
reflecting an age-related decline in lung function. We know that COPD patients
with only infrequent flare-ups have an accelerated deterioration in FEV1,
about 30 mL per year. A 2002 study confirmed that those who experience more frequent
exacerbations have an even worse rate of decline, up to 40 mL per year. Exacerbations
are the number one reason that COPD patients are seen in the family doctor's office,
emergency room (ER) and hospital ward. A 2000 survey shows that if hospitalization
is required, patients stay an average of 10 days, and 50% will be re-admitted
within 6 months. Even with mild-to-moderate disease, there's a 4% mortality rate
if the person has to stay in hospital. This rate rises to 24% if the individual
has acute respiratory failure and ends up in the intensive care unit. Which
patients are at high risk?
Those with particularly serious airflow
obstruction as measured by spirometry tend to have more frequent and severe flare-ups.
This is especially true if they continue to experience them despite high doses
of bronchodilators and supplemental oxygen at home. People with compliance issues,
such as those who continue to smoke or don't take their puffers on a regular basis,
will have more exacerbations. What
investigations are needed?
Take a thorough history, as not all
coughing and shortness of breath is due to AECOPD. Physical examination and a
chest x-ray are useful to exclude congestive heart failure, pneumothorax and pneumonia.
An echocardiogram and cardiac enzymes are usually ordered in the ER, as dyspnea
alone can be a symptom of cardiac ischemia. If a patient's oxygen saturation level
is low or the individual is known to have severe COPD, an arterial blood gas (ABG)
should be collected. COPD patients with poor lung function,
frequent flare-ups (more than three per year), and those who have taken antibiotics
in the past 3 months are at higher risk for atypical or resistant organisms as
a cause for their exacerbation. In these people, consider sending sputum samples
for gram stain, culture and sensitivity to help guide antibiotic selection. |
