Bronchitis (acute)

Author : Dr Ralph Gonzales Professor of Medicine University of California San Francisco

2008-07-16

What is Bronchitis?

Source : CDC

• Bronchitis refers to inflammation of the airways of the lung, which is usually manifested by cough.

• When illness lasts < 3-6 weeks, it is referred to as “acute bronchitis”

• “Chronic bronchitis” refers to patients with underlying lung disease who have cough and phlegm production regularly for > 6 months (a topic for a separate knol).

The term “bronchitis” refers to inflammation of the bronchus or bronchiolar portions of the lung. It can result from a wide variety of causes that include infections, environmental exposures, and allergic reactions, and is especially troublesome for individuals who have chronic lung disease. The main feature of bronchitis is cough. Individuals with chronic lung disease who have a daily cough with phlegm production are often diagnosed with “chronic bronchitis.” In this Knol, we will deal primarily with bronchitis in adults who do not have chronic bronchitis, also referred to as “acute” bronchitis.

Acute bronchitis is most commonly caused by a viral respiratory infection in patients who have no underlying lung disease. The National Health Interview Survey reports that 1 in 20 adults experience 1 or more episodes of acute bronchitis each year, and the vast majority of these individuals will seek medical attention.

Technically, the term “acute bronchitis” applies to individuals who have been coughing for less than 3-6 weeks and in whom pneumonia or any other obvious cause has been excluded. For patients who cough for longer than 6 weeks, and who have persistent or chronic cough, additional tests and/or treatments should be pursued to identify some other cause of the cough—such as postnasal drip, asthma, or gastroesophageal reflux disease (heartburn).

Because other acute respiratory tract infections such as sinusitis or pharyngitis can also have cough as a symptom, I tend to reserve the diagnosis of acute bronchitis for patients for whom the cough is the dominant symptom (or “chief complaint”). I also reserve acute bronchitis for patients who have been sick for at least 5-7 days, because patients who have been sick only 2 or 3 days with cough illness often resolve by the end of 1 week. Some doctors prefer to use the term “bronchitis” only when sputum production and/or wheezing accompany the cough. Wheezing refers to high-pitched lung sounds that are audible or sometimes heard only by stethoscope, and that usually occur on expiration. Other respiratory symptoms that are common (but not as dominant) among patients diagnosed with acute bronchitis include nasal congestion, sore throat, and low-grade fevers.

What Causes Bronchitis?

• Viruses (> 90%)

• Bacteria (< 10%)

• Allergic and Environmental Exposures (<10%)

Acute bronchitis is usually the result of sequential processes: 1) infection (or exposures) causing inflammation of the airways, and 2) airway inflammation causing cough.

Step 1: Infection

Viruses appear to cause the vast majority of cases of acute bronchitis, although on many occasions there is no specific agent identified. Non-infectious causes include asthma, allergy, and occupational exposures. The specific viruses most frequently associated with acute bronchitis in adults, in descending order of frequency, are influenza, parainfluenza, respiratory syncytial virus (RSV), coronavirus, adenovirus, and rhinoviruses. In children, RSV is the most common cause. Persons at high risk for severe reactions to viral respiratory infections include the elderly, persons in nursing homes, and those living with chronic medical conditions such as heart failure, cancer, or other debilitating disease processes. This underscores the importance of influenza vaccination for persons in these high-risk groups.

A newly discovered virus, human metapneumovirus, has also been shown to cause acute bronchitis. As with most of the viruses above, human metapneumovirus is primarily an illness of the winter months, and most commonly causes significant illness in young children, the immunocompromised, and in elderly individuals. The exact contribution of human metapneumovirus to the burden of acute bronchitis in the US, however, appears to be low.

Bacteria are an uncommon cause (<10% of cases) of acute bronchitis in the general population, with the notable exception of specific outbreaks of Bordetella pertussis, Chlamydia pneumoniae, or Mycoplasma pneumoniae. Some studies have reported the presence of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in adults with acute bronchitis; however, these findings are questionable because these studies generally failed to exclude patients with underlying lung disease (who are susceptible to different kinds of infections than persons without chronic lung disease), failed to distinguish between colonization and infection, or did not adequately differentiate patients with pneumonia from those with acute bronchitis when determining causative agents.

In the US, we have now firmly established that people immunized against pertussis as children are still susceptible to infection with pertussis as adolescents and adults—the result of waning immunity. For this reason, the CDC now recommends that all adolescents receive a pertussis “booster” with their 11-12 year vaccination for tetanus, and at least one more time with their regularly scheduled tetanus booster (every 10 years) before age 65.

Step 2: Bronchial Hyperresponsiveness

The hacking cough that characterizes acute bronchitis is primarily due to hyperreactive bronchial airways that follow the initial infection. Infection of the bronchial airways causes inflammation, destruction, and sloughing of the cells that line the airways. Thus, early in the course of acute bronchitis, patients will report fevers, fatigue, congestion, and cough (the "catarrhal" period). After 5-7 days, the fever and fatigue usually resolve, but the cough persists and seems to become more bothersome. At this stage of disease, the bronchial airways have become hyperreactive to many different types of stimuli such as dust, smoke, perfumes, and cold air that previously would not have elicited any. The key symptom that patients experience with hyperreactive airways is cough. Wheezing suggests more severe bronchospasm, but is not a necessary finding for hyperreactivity and abnormal breathing tests to present.

Figure: Illness Duration and Illness Features

Day 0 ------------------> Day 7 -------------------> Day 14 -------------------> Day 21

catarrhal period                               bronchial hyperresponsiveness period

In research studies where pulmonary function tests are performed on consecutive patients with acute bronchitis, breathing abnormalities are found in approximately 40% of patients. These abnormalities are identical to those observed in patients with asthma, except that they will resolve within 2-3 months (by definition) in most patients. Suspicion and work-up for asthma should be reserved for patients with cough lasting longer than 3-6 weeks. On the other hand, recurrent episodes of "acute bronchitis" may suggest underling asthma and could justify more aggressive treatment and evaluation earlier in the acute bronchitis episode.

Who Gets Bronchitis?

-Smokers
-Exposure to Children

Persons who are more frequently exposed to respiratory viruses at school, work or home are also more likely to acquire the infection. This includes children in school and day care, as well as adults who work or take care of children (eg, parents).

A second group of people who are more likely to “catch” a respiratory infection when exposed is those who have weakened immune systems. Of course, people who have conditions that suppress their immune system such as HIV or AIDS, and people who take medications or treatments that suppress their immune system such as prednisone, methotrexate, and chemotherapy, are more likely to acquire and have severe responses to viral respiratory infections. However, a much larger group of otherwise healthy people at increased risk for acquiring respiratory infections are those who smoke cigarettes, those who are sleep deprived, and those who are experiencing excess emotional or physical stress.

How Do I Know if I Have Bronchitis? 

Development of a new cough illness that has lasted for more than 5-7 days is the first clue that you could have bronchitis, especially if it began with other symptoms of a cold or sinus infection such as runny nose, fevers, and fatigue. Coughing up phlegm and mild wheezing on expiration are other common findings in patients with acute bronchitis. It is also common for patients to report that the cough is worse at night, when they are exposed to cold air, perfumes, or smoke, and when they try to exercise.

When Should I Seek Care for Bronchitis?

The most important condition that could cause all of the same symptoms as acute bronchitis is pneumonia, which could be life-threatening if left untreated. I have provided a list of some of the symptoms or conditions that should lead you to contact a health care provider. These symptoms may indicate pneumonia, may put you at increased risk of developing pneumonia, or may indicate another more serious illness:

• Fever

• High fever (>102 F.) outside of flu season or when known flu is not circulating.

• Fever (>100 F.) that lasts more than 5 days.

• Feeling short of breath or winded at rest or with mild exertion

• Cough producing blood
• Cough lasting more than 3 weeks
• Light-headedness or feeling faint
• Confusion or not thinking clearly
• Severe headache, ear pain, sinus pain, or chest pain
• Fast pulse (>100 beats per minute at rest in adult)
• Prior history of pneumonia
• Suppressed immune system due to underlying conditions or medications
• Congestive heart failure, chronic lung disease, cirrhosis/liver disease, chronic kidney disease, sickle cell anemia
• Possible exposure to tuberculosis

The key things that currently can only be done at the doctor’s office are the accurate measurement of your vital signs (temperature, heart rate, blood pressure, and oxygen levels in your blood), and physical examination of your heart and lungs. If your cough has lasted more than 3 weeks, then your health care provider may order a chest x-ray.

What Treatments Are Available For Acute Bronchitis?

1. The Antibiotic Myth.

The public frequently expects or demands, and doctors frequently prescribe, antibiotics for acute bronchitis even though 10 different clinical trials that have been published in the medical literature do not show any major benefit to antibiotic treatment with regard to cough severity, cough duration, or illness resolution. Unless your doctor suspects pneumonia, pertussis, or that you have been exposed to a Chlamydia or Mycoplasma outbreak, antibiotics are not likely to have any benefit for you. On some occasions, patients who think they have acute bronchitis actually have sinusitis, and for some of these patients antibiotic treatment is warranted.

The Antibiotic Travesty - Unnecessary antibiotic use for viral respiratory infections contributes to many millions of antibiotic prescriptions in the US (the last estimate being > 20 million in 1998). This contributes to the emergence and epidemic of new strains of bacteria that are resistant to common antibiotics. We have already seen this in bacteria that cause ear and respiratory tract infections, skin infections, intestinal infections, and urinary tract infections. Many experts believe that we are close to returning to the “pre-antibiotic era” – we will have created an environment in which we have no defenses against bacteria --if we do not get this problem under control.

Using antibiotics also increases the individual’s personal risk of acquiring and spreading resistant bacteria. Although most persons do not feel sick when they are colonized with resistant bacteria, they spread these germs to their family and friends through hand-to-hand/casual contact… and increase the chances that a new infection among these persons will be caused by resistant bacteria.

2. Effective Treatments

• Rest. There is good evidence that sleep deprivation, and emotional and physical stress suppress the body’s immune system and increase the severity and duration of these illnesses. For example, research studies show that persons with high levels of emotional stress are more likely to get sick when exposed to a respiratory virus; and that up to 50% of persons completing marathons will catch a cold afterward. Although there are no studies that have rigorously compared rest with no rest, there is a strong rationale for recommending that persons get enough sleep and do not physically overexert themselves when they have acute bronchitis.

• Hydration and Humidifier. Although never studied in persons with acute bronchitis in the community, studies of hospitalized patients show that humidified air can improve mobilization of lung secretions. I recommend to all patients that they try to stay well-hydrated (ie, drink at least 8 cups, or 2 liters of fluids per day), and that persons living at high altitude (>5000 ft above sea level) or whose homes use a lot of dry heat in the winter use a humidifier at night..

• Dextromethorphan. This medication can be purchased over-the-counter, can be found in many different brands of cough syrup, and does not generally cause drowsiness. Research studies show that it can have a mild-to-modest benefit on cough frequency and severity.

• Albuterol Inhaler. This is a prescription medication that is most commonly used in patients with asthma to reverse tightening of their airways. Because tightening of the airways is present in up to half of all adults with acute bronchitis, it makes sense that this medication can help. In patients diagnosed with acute bronchitis, it decreases total cough duration by about 1 day. I reserve albuterol treatment for patients seeking cough relief who have been sick for at least 7 days. Albuterol does not help seem to help patients with nonspecific cough illness who have been sick fewer than 7 days.

• Pelargonium sidioides. This is an herbal therapy derived from a South African geranium plant. It is available in the US from a variety of producers. When started within 48 hours of illness onset, studies in Germany and Russia have reported a big decrease in cough and illness duration… greater than any other published treatments for acute bronchitis. However, the validity of these results is suspect because the principal manufacturer of the formulation (EPs 7630; Iso-Arzneimittel, Ettlingen, Germany) would not provide approval for our research group at UCSF to confirm their study’s findings in a US patient population.

• Anti-influenzal Therapy. There are 4 treatments available in the US, and all must be started within 48 hours (and preferably within 30 hours) of illness onset in order to be beneficial. Amantadine, rimantadine, zanamivir, and oseltamivir have all been shown to decrease illness duration by approximately 1 day, and may lead to a ½ day quicker return to normal activities. Side effects are more common with rimantadine (most commonly, altered mentation) than with the neuraminidase inhibitors. Currently, the US Centers for Disease Control (CDC) recommend use of either zanamivir or oseltamivir as first-line treatment of influenza.

3. Ineffective Treatments

• Antibiotics (see above). Antibiotics might be effective if you have chronic lung disease, have been exposed to pertussis, or have a suppressed immune system.

• Guaifenesin. This is the active ingredient in Robitussin and many other over-the-counter formulations. Manufacturers claim that is is effective in loosening and helping to mobilize your lung secretions. But well-designed research studies do not show it to be beneficial.

• Echinacea. Research studies have shown no difference between Echinacea (all types) and placebo.

• Zinc gluconate and zinc acetate. For cough illness, there is no evidence that zinc works. For the common cold, there is 1 study that showed benefit, but several other studies that showed no benefit.

• Vitamin C. Even at appropriate doses (1 gram/day), studies show that Vitamin C is no better than placebo at improving illness resolution with the common cold or acute bronchitis.

What Can I Do to Prevent Getting Acute Bronchitis?

• Hand Hygiene. The germs that cause acute bronchitis are spread not only by respiratory droplets (from a cough), but just as commonly by hand contact. After you have touched a contaminated surface, you inoculate yourself with the germs when you touch or itch your eyes, nose, or mouth. Therefore, wash or disinfect your hands frequently when you’re in public or in close contact with sick persons. The CDC recommends the following techniques:

• Wet hands with running water; place soap in palms; rub together to make a lather; scrub hands vigorously for 20 seconds (about the time it takes to sing “Happy Birthday twice through”; rinse soap off hands.
• If possible, turn off the faucet by using a disposable paper towel.

• Dry hands with a disposable paper towel. Do not dry hands on clothing.

• Assist young children with washing their hands.

• Quit Smoking and Avoid Second Hand Smoke. Tobacco smoke impairs the lungs’ natural immune defenses, and increases susceptibility to catching colds and other respiratory viruses. Tobacco smokers are also more likely to get severe bacterial infections, and these complicate routine acute bronchitis.

•  Influenza vaccination. Preventing flu is perhaps the best thing you can do to prevent at least 1 episode (but not all potential episodes) of acute bronchitis.

• Pertussis booster. This is a new recommendation that all health care providers should be following. When you receive your next scheduled tetanus shot (routinely, or when you have a cut or skin wound), the new tetanus booster also includes a pertussis booster. If you are someone who works in health care settings, or in childcare settings/schools, check with your health care provider sooner.

• Vitamin C. Although ineffective for treatment of cough illness after it has developed, Vitamin C (1 gm/day) has been shown to help prevent cold and other respiratory tract infections among persons with increased physical stress (such as the malnourished or post-marathon).

What are Complications of Acute Bronchitis?

Besides difficulty sleeping, painful coughing, and being a nuisance to people around you, persons with acute bronchitis can rarely develop complications that should lead them to consult their health care provider, such as:

• Rib Fractures. This usually manifests as severe, localized pain with inspiration (breathing in).

• Vomiting. Recurrent vomiting associated with severe coughing spasms warrants stronger cough suppression.

• Pneumonia. Even if you do not have pneumonia at the initial doctor’s visit, the viruses that cause acute bronchitis can put you at increased risk for developing a subsequent bacterial pneumonia. After 3-5 days if your cough illness begins to get worse instead of better (such as difficulty breathing, fever, or nausea and vomiting), see a doctor right away.

What if My Acute Bronchitis/Cough Doesn’t Go Away After 3-6 Weeks?

A very small proportion of patients who look like they have acute bronchitis may, in fact, have other conditions that are causing their persistent cough. The most common of these are asthma, postnasal drip, and gastroesophageal reflux disease (GERD; also commonly known as heartburn). If you cough and produce phlegm for more than 6 months, you have likely developed chronic bronchitis.

Where Can I get More Information?

The Centers for Disease Control and Prevention http://www.cdc.gov/drugresistance/community/files/ads/cough.htm

The American College of Chest Physicians http://chestnet.org/patients/guides/cough.php

References

Aagaard E, Gonzales R. Management of Acute Bronchitis. Infectious Disease Clinics in North America, 2004;18:919-37.  PMID: 15555832

Bent S, Saint S, Vittinghoff E, Grady D. Antibiotics in acute bronchitis: a meta-analysis.
Am J Med. 1999 Jul;107(1):62-7.  PMID: 10403354

Douglas RM, Hemilä H, Chalker E, Treacy B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000980.  PMID: 17636648

Fiore AE, Shay DK, Haber P, Iskander JK, Uyeki TM, Mootrey G, Bresee JS, Cox NJ; Advisory Committee on Immunization Practices (ACIP), Centers for Disease Control and Prevention (CDC).  Prevention and control of influenza. Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2007. MMWR Recomm Rep. 2007 Jul 13;56(RR-6):1-54.  PMID: 17625497

Gonzales R, Bartlett JG, Besser RE, Cooper RJ, Hickner JH, Hoffman JR, Sande MA. Principles of appropriate antibiotic use for treatment of uncomplicated acute bronchitis: background. Clinical Practice Guideline, Part 2.  Annals of Internal Medicine, 2001;134:521-529. PMID: 11385346

 Gonzales R.  Curbside Consultation: Patients’ preconceptions and convictions about antibiotics. American Family Physician, 2005;72:1900-03.  (no PMID)

Irwin RS, Baumann MH, Bolser DC, Boulet LP, Braman SS, Brightling CE, Brown KK, Canning BJ, Chang AB, Dicpinigaitis PV, Eccles R, Glomb WB, Goldstein LB, Graham LM, Hargreave FE, Kvale PA, Lewis SZ, McCool FD, McCrory DC, Prakash UB, Pratter MR, Rosen MJ, Schulman E, Shannon JJ, Smith Hammond C, Tarlo SM; American College of Chest Physicians (ACCP). Diagnosis and management of cough executive summary: ACCP evidence-based clinical practice guidelines. Chest. 2006 Jan;129(1 Suppl):1S-23S.  PMID: 16428686