Bronchiolitis is an acute viral infection of the small air passages of the lungs called the bronchioles.
Bronchiolitis is extremely common. It occurs most often in children between the ages of two and 24 months, with peak infection occurring between three and six months of age. About 25% of infants have bronchiolitis during their first year, and 95% have had the disease by their second birthday. In temperate climates, bronchiolitis peaks from winter to late spring. In subtropical climates, the disease peaks from October to February.
Children who attend daycare or who live in crowded conditions and those who are exposed to second-hand smoke at home are more likely to develop bronchiolitis. Premature infants and children born with heart and lung defects or HIV/AIDS are more likely to have severe, life-threatening infections. Bronchiolitis occurs more often in boys than girls, with boys being hospitalized at 1.5 times the rate of girls. Bronchiolitis is a significant cause of respiratory disease worldwide. The World Health Organization (WHO) has funded research to develop a vaccine against the disease, but thus attempts have been unsuccessful.
Causes and symptoms
Bronchiolitis is caused by several different viruses. The most common of these is respiratory syncytial virus (RVS), which is responsible for about 100,000 hospitalizations of children under age four each year. Two subtypes of RSV have been identified, one of which causes most of the severe bronchiolitis infections. In addition, bronchiolitis can be caused by influenza, parainfluenza, and adenoviruses, all of which are common from fall through spring. These viruses are spread in tiny drops of fluid from an infected person's nose and mouth through direct contact, such as shaking hands, or kissing. The viruses can also live several hours on countertops, toys, or used tissues and easily infect people who handle contaminated items. The time from infection to the appearance of symptoms varies from two to seven days.
Bronchiole— A thin air passage in the lung that branches off a larger airway.
Congenital— A condition that an individual is born with.
Bronchiolitis affects individuals differently depending on their age. In adults, older children, and some infants, bronchiolitis viruses causes symptoms similar to a mild cold—runny nose, stuffy head, and mild cough. The lungs are not involved, and these symptoms clear up without any medical treatment. In some children under age two, the cold-like upper respiratory symptoms worsen after a day or two. The lung tissue begins to swell and produce mucus, and the cells lining the bronchioles begin to slough off into the air passages. As the airways narrow from swelling, and mucus accumulation, breathing becomes difficult, and the child makes a wheezing or whistling sound with each breath. Lung involvement can occur quite rapidly.
The most common signs of bronchiolitis involve the infant's struggle to breathe. The child may take 50-60 breaths per minute and may develop brief periods when they stop breathing (apnea) and begin to turn blue (cyanosis ). This occurs most often in babies who were born very prematurely or who are under six weeks of age and babies with congenital heart and lung problems and compromised immune systems. Babies may also stop eating, because it is becomes difficult for them to swallow and breathe at the same time. They may have a low fever, cough, and vomiting.
Bronchiolitis is usually diagnosed through a physical examination by a pediatrician or family physician. The physician often finds an increased heart rate, rapid, labored breathing, and crackles in the lungs when the child inhales. Signs of ear infection (otitis media ) and throat infection (pharyngitis) are sometimes present.
Although laboratory tests are available that can within in a few hours confirm the presence of RSV, these tests are not routinely necessary. The oxygen level in the blood may be measured through pulse oximetry in babies who are having difficulty breathing. Inadequate oxygen in the blood is an indication that hospitalization is necessary. Chest x-rays may be done on severely ill children to rule out other conditions.
The degree of respiratory distress determines treatment. Individuals with mild symptoms are treated as if they have a cold with rest, fluids, and a cool air humidifier. Babies who are struggling to breath may hospitalized and given supplemental humidified oxygen. Their breathing will be monitored and if necessary fluids will be given intravenously to prevent dehydration. Occasionally infants need mechanical ventilation to fill and empty the lungs until the airways open.
Those children with compromised immune systems from diseases such as congenital HIV/AIDS and transplant patients are at highest risk for severe infections, serious complications, and death. Children with congenital heart and lung disorders are also at higher risk, as are infants under six weeks old. These high risk children may be admitted to pediatric intensive care units and treated with ribvarin (Virazole), a drug that keeps the virus from reproducing. This drug is reserved for the most critical cases.
Although there are alternative treatments for cold symptoms, such as echinacea and zinc, parents should consult their health practitioner about the appropriateness of using these treatments in very young children.
The majority of children who get bronchiolitis, even severe infections, recover without complications in one to two weeks, although fatigue and a light cough may linger longer. About 60% of people develop only cold-like symptoms without lung involvement. However, the disease accounts for about 100,000 pediatric hospitalizations and 4,500 deaths each year. Deaths usually occur because medical care is not sought soon enough.
Although many viral illnesses, like chicken pox, can be contracted only once, after which individuals develop immunity, people can get bronchiolitis multiple times. However, after the first infection, the symptoms are usually mild.
The viruses that cause bronchiolitis spread very easily, making prevention difficult. Common sense measures such as frequent hand washing and keeping children away from crowds and sick individuals are only partially effective. Certain very high risk babies can be treated during the peak virus season with monthly injections of antiviral immunoglobulins to protect against RSV infection. These injections cost several thousand dollars per child per season and are reserved for children whose life could be at risk if they became infected. Antiviral immunoglobulins are used only for prevention and are not effective as a treatment once the infection has been acquired.
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DeNicola, Lucian K. and Michael Gayle. Bronchiolitis, 17 July 2003 [cited 16 February 2005]. 〈http://www.emedicine.com/ped/topic287.htm〉.
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Bronchiolitis (brong-kee-o-LYE-tis) is an infection that causes inflammation of the lung’s smaller airways, also called the bronchioles (BRONG-kee-oles). It is common among very young children, particularly during the winter months.
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Respiratory syncytial virus (RSV)
Bronchiolitis is caused by a virus that infects the bronchioles, the smallest airways that carry air through the lungs. The linings of these airways swell and become blocked with fluid and mucus*, making it difficult to breathe. The virus that most often causes bronchiolitis is called respiratory syncytial virus* (RSV). Other viruses, such as rhinovirus, parainfluenza* virus, influenza A*, and adenovirus*, also can cause bronchiolitis. Bronchiolitis is most common in late fall, winter, and early spring. It typically affects younger children, with most cases occurring in children 2 years old or younger. About 90,000 children are hospitalized for bronchiolitis each year in the United States.
- (MYOO-kus) is a thick, slippery substance that lines the insides of many body parts.
- *respiratory syncytial
- (RES-puhruh-tor-e sin-SIH-she-ul) virus , or RSV, is a virus that infects the respiratory tract and typically causes minor symptoms in adults but can lead to more serious respiratory illnesses in children.
- (pair-uh-in-floo-EN-zuh) is a family of viruses that cause respiratory infections.
- (in-floo-EN-zuh) A , is one member of a family of viruses that attack the respiratory tract.
- (ah-deh-no-VY-rus) is a type of virus that can produce a variety of symptoms, including upper respiratory disease, when it infects humans.
The viruses that cause bronchiolitis are contagious. They usually are spread through the air when infected drops of fluid are released during a sneeze or cough. RSV stays alive on surfaces, such as countertops and toys, for long periods of time. When children touch these infected surfaces, they can easily pick up the virus. A child who is infected with RSV, however, may just get a bad cold and may not experience the symptoms of bronchiolitis.
An infected child typically has a runny nose, mild cough, and low fever for a few days. Then the infection peaks; at this stage the cough may worsen, and breathing sometimes becomes difficult. The child may have rapid breathing and begin to wheeze. The child usually will not eat or sleep well because of these symptoms. The nostrils may flare (that is, they will open wide when the child breathes) and the upper belly and the skin covering the chest may retract (that is, it will look as though it is caving in) with each intake of breath. Sometimes the symptoms of bronchiolitis are so severe that the child needs extra oxygen and inhaled medications. If the child is not getting enough oxygen, cyanosis* may develop.
- (sye-uh-NO-sis) is a bluish or purplish discoloration of the skin and mucous membranes due to a lack of oxygen in the blood.
It is important for children who have breathing problems to be examined by a doctor to make sure that they are getting enough oxygen. The doctor also will check for signs of dehydration*. The child’s nasal fluid can be examined for the presence of RSV in a laboratory with the rapid antigen* detection test. This test often is used to diagnose the infection in the emergency room during the winter months.
- (dee-hi-DRAY-shun) is a condition in which the body is depleted of water, usually caused by excessive and unre-placed loss of body fluids, such as through sweating, vomiting, or diarrhea.
- (AN-tih-jen) is a substance that is recognized as a threat by the body’s immune system, which triggers the formation of specific antibodies against the substance.
Most children can be treated at home. Doctors typically recommend that children with bronchiolitis drink lots of fluids and sleep with a cool-mist vaporizer or humidifier in the bedroom, to ease breathing. Over-the-counter medications for pain and fever, such as acetaminophen (uh-SEE-teh-MIH-noh-fen), also can help children feel better. Antibiotics do not help bronchiolitis, because a virus causes the illness and antibiotics treat only infections caused by bacteria. Decongestants (medications that decrease the amount of mucus) should not be used, because they often produce unwanted side effects in very young children. Instead, a child’s nose can be cleared of mucus with suction from a rubber bulb and saltwater nose drops. Occasionally, a child with bronchiolitis, especially one who was born prematurely or who has heart or lung problems, may have to be hospitalized so that extra oxygen and fluids can be given. Sometimes breathing treatments are required.
Most children with bronchiolitis do well with treatment at home guided by the child’s doctor. A doctor should be called right away if the child has any signs of difficulty in breathing, such as breathing very fast or experiencing retractions or if the skin or lips turn pale or bluish. The doctor also should be called if the child is not able to take and hold down fluid by mouth. Most children get better after about a week, but the cough may last longer. In some cases the cough may not clear up for several weeks, even though the child is back to normal otherwise. Complications of bronchiolitis include pneumonia*, apnea*, and respiratory failure*. These are more common in children who are born prematurely or who have heart, lung, or other health problems. Children who have had bronchiolitis are more prone to asthma* later in childhood.
- (nu-MO-nyah) is inflammation of the lung.
- (AP-nee-uh) is a temporary stopping of breathing.
- *respiratory failure
- is a condition in which breathing and oxygen delivery to the body are dangerously altered. This may result from infection, nerve or muscle damage, poisoning, or other causes.
- (AZ-mah) is a condition in which the airways of the lungs repeatedly become narrowed and inflamed, causing breathing difficulty.
The viruses that cause bronchiolitis, especially RSV, are spread easily. It is almost impossible to keep children away from others who are sick, but it is important to wash the hands often (children as well as the people caring for them, as in day care centers) to prevent the spread of RSV. Keeping sick children home from school and day care can help control the spread of infection to others. Children who are considered to be at high risk of becoming seriously ill from bronchiolitis, such as premature infants and those with chronic heart or lung disease, can be immunized against RSV to prevent infection.
American Academy of Family Physicians, 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. The American Academy of Family Physicians posts information about bronchiolitis at its website.
Telephone 800-274-2237 http://www.familydoctor.org
Bronchiolitis is a lung infection that affects children of any age; however, it is much more severe when it occurs in young infants.
The bronchioles are small branches off of the more major bronchi or airway tubes that run through the lungs. When these bronchioles are infected, they become inflamed, and breathing may become difficult.
Bronchiolitis is a particularly important problem in babies who are born prematurely or who have other chronic medical illness. These children are at greatly increased risk of contracting bronchiolitis and of having a more severe course of the illness. Bronchiolitis is the most common reason that babies are hospitalized in the winter. Most cases of bronchiolitis occur between the months of December and May.
Every year, 1–2 percent of all babies under 12 months of age require hospitalization due to bronchiolitis. At highest risk are boys, premature infants, infants living in urban locations, babies who have not been breastfed, and babies with chronic pulmonary, cardiac, or immune conditions.
Causes and symptoms
Most cases of bronchiolitis are caused by viruses, the most common of which is respiratory syncytial virus. Other common viral causes include parainfluenza, influenza , and adenovirus. Like most types of respiratory viruses, the viruses that cause bronchiolitis are usually contracted through breathing in infected droplets that are sprayed out by another ill individual during coughing or sneezing.
Most cases of bronchiolitis start with symptoms of a cold: sneezing, runny nose, fatigue, decreased appetite, fever . After two or three days of these symptoms, the bronchiole inflammation becomes severe enough to cause cough , wheezing, and rapid breathing.
Severely ill babies or children show signs of difficulty breathing. Their neck muscles and the muscles between their ribs will contract with each effort to breathe, and their chest may cave in as well. Smaller babies may make grunting sounds as they struggle to take in air. Babies will have difficulty nursing or taking bottles and may not be able to feed at all.
When to call the doctor
A doctor should always be called when a child appears to be in any respiratory distress. Fast breathing rates, wheezing, abnormal muscle contractions, or a blue cast to the lips or fingernails should all alert the parent that the child is having difficulty breathing and should be seen immediately by a healthcare provider.
Initial diagnosis of respiratory distress is made based on clinical signs of difficulty breathing. A pulse oximeter or arterial blood gas measurement reveals the presence of decreased oxygen in the blood. Chest x rays may show characteristic patterns of lung involvement. Nasal swabs can be taken in order to identify the causative viral agent, although viral culture takes long enough that the patient is usually on the way to recovery by the time the viral agent has been identified.
Treatment at home should consist of acetaminophen for fever and comfort (not aspirin, which has been implicated in Reye's syndrome in children), increased intake of liquids, and a cool water vaporizer. The utility of asthma medications, like bronchodilators, is as of 2004 still undecided.
Children who require hospitalization receive fluids intravenously and supplemental oxygen through a mask or nasal cannulae (small tubes into the openings of the nostrils). Ten percent of all hospitalized infants require mechanical ventilation. Children who are severely ill may be given antiviral medications, such as ribavirin, which is thought to shorten the length of illness and decrease its severity.
Most children recover uneventfully from bronchiolitis, although some studies have suggested that children who have had bronchiolitis may be at higher risk for reactive airway disease throughout the remainder of their lives.
Bronchiolitis is spread the same way that most other respiratory viruses are communicated, through droplets and contact with infected nasal secretions. Good hand washing is paramount to prevention, as is keeping children out of public places while they are acutely ill and coughing and sneezing.
Bronchiole —Tubes in the lungs that carry air from the bronchi to lung tissues.
A doctor should always be called when a child appears to be in any respiratory distress. Severe breathing difficulties need immediate medical treatment. Parent should educate their children about good personal hygiene to avoid spreading the germs that cause colds and bronchiolitis.
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Rosalyn Carson-DeWitt, MD