Bronchiolitis

(medicine) Inflammation of the bronchioles.

Definition

Bronchiolitis is a lung infection that affects children of any age; however, it is much more severe when it occurs in young infants.

Description

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.

Demographics

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.

Diagnosis

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

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.

Prognosis

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.

Prevention

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.

Parental Concerns

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.

Resources

Books

Goodman, Denise. "Inflammatory Disorders of the Small Airways." In Nelson Textbook of Pediatrics, edited by Richard E. Behrman et al. Philadelphia: Saunders, 2004.

Lazarus, Stephen. "Disorders of the Intrathoracic Airways." In Textbook of Respiratory Medicine, 3rd ed. Edited by John F. Murray and Jay A. Nadel. Philadelphia: Saunders, 2000.

Tristram, Debra A., and Robert C. Welliver. "Bronchiolitis." In Principles and Practice of Pediatric Infectious Diseases, 2nd ed. Edited by Sarah S. Long et al. St. Louis, MO: Elsevier, 2003.

Periodicals

Davison, C. "Efficacy of interventions for bronchiolitis in critically ill infants: a systematic review and meta-analysis." Pediatric Critical Care Medicine 5 (September 2004): 482–3.

Dayan, P. "Controversies in the management of children with bronchiolitis." Center for Pediatric Emergency Medicine 5 (March 2004): 41.

Steiner, R. W. "Treating acute bronchiolitis associated with RSV." American Family Physician 86 (January 2004): 325–30.

[Article by: Rosalyn Carson-DeWitt, MD]

Inflammation of the bronchioles; bronchopneumonia. See also chronic obstructive pulmonary disease.

• catarrhal b. — acute, mild irritation of the mucosa with excess mucus production, necrosis of epithelial cells, and transient exudation of leukocytes into the lumen.
• chronic b.–emphysema complex, horses — see chronic obstructive pulmonary disease.
• b. fibrosa obliterans — see obliterative bronchiolitis (below).
• obliterative b. — response to necrosis of the lining epithelium at the bronchiolar–alveolar junction and subsequent fibroblastic organization of the fibrin exudation, obliterating the bronchiolar lumen.
• purulent b. — more severe than catarrhal; a viscid exudate characterized by a predominance of neutrophils, with mucus and sloughed epithelial cells.
• ulcerative b. — inflammation characterized by the loss of large areas of epithelium with exposure of the underlying tissue and the development of ulcers.
• vesicular b. — bronchopneumonia.

Bronchiolitis
Classification and external resources
A chest X-ray demonstrating lung hyperinflation with a flattened diaphragm and bilateral atelectasis in the right apical and left basal regions in a 16-day-old infant with severe bronchiolitis.
ICD-10	J21.
ICD-9	466.1
DiseasesDB	1701
MedlinePlus	000975
eMedicine	emerg/365
MeSH	[1]

Not to be confused with bronchitis.

Bronchiolitis is inflammation of the bronchioles, the smallest air passages of the lungs. This inflammation is usually caused by viruses.

Contents 1 Causes 2 Diagnosis and Recovery 3 Treatment 4 Complications 5 Prevention 6 See also 7 References 8 External links

Causes

The term usually refers to acute viral bronchiolitis, a common disease in infancy. This is most commonly caused by respiratory syncytial virus (RSV, also known as human pneumovirus). (J21.0)

Other viruses which may cause this illness include metapneumovirus, influenza, parainfluenza, coronavirus, adenovirus, and rhinovirus.

The American Academy of Pediatrics has published a clinical practice guideline for the Diagnosis and Management of Bronchiolitis, including a review of the evidence and recommendations.

Diagnosis and Recovery

In a typical case, an infant under two years of age develops cough, wheeze, and shortness of breath over one or two days. The diagnosis is made by clinical examination. Chest X-ray is sometimes useful to exclude pneumonia, but not indicated in routine cases.

Testing for specific viral cause (e.g. RSV by nasopharyngeal aspirate) is common, but has little effect on management. Identification of RSV-positive patients can be helpful for:

• disease surveillance
• grouping ("cohorting") patients together in hospital wards as to prevent cross infection
• predicting whether the disease course has peaked yet
• reducing the need for other diagnostic procedures (by providing confidence that a cause has been identified).

The infant may be breathless for several days. After the acute illness, it is common for the airways to remain sensitive for several weeks, leading to recurrent cough and wheeze.

There is a possible link with later asthma: possible explanations are that bronchiolitis causes asthma by inducing long term inflammation, or that children who are destined to be asthmatic are more susceptible to develop bronchiolitis.

Bronchiolitis Obliterans occurs rarely in rheumatoid lung disease when small airway obstruction develops into a necrotizing bronchiolitis.

Treatment

There is no effective specific treatment for bronchiolitis. Therapy is principally supportive.^[1] Frequent small feeds are encouraged to maintain hydration as evidenced by good urine output, and sometimes oxygen may be required to maintain blood oxygen levels. Suction of the nasopharynx is often performed to maintain a clear airway. In severe cases the infant may need to be fed via a nasogastric tube or it may even need intravenous fluids. In extreme cases, mechanical ventilation (for example, using CPAP) might be necessary.

Bronchodilator drugs such as salbutamol/albuterol or ipratropium are no longer recommended, but many clinicians offer a trial dose to see if there is any benefit (especially if there is a family history of asthma, since it can be difficult to clinically distinguish bronchiolitis from a viral-induced asthma). Racemic epinephrine is another drug that is sometimes given.

Ribavirin is an antiviral drug which has a controversial role in treating RSV infection. There is no proven benefit but it is used sometimes for infants with pre-existing lung, heart or immune disease. Antibiotics are often given in case of a bacterial infection complicating bronchiolitis, but have no effect on the underlying viral infection.

Corticosteroids have no proven benefit in bronchiolitis treatment and are not advised.

DNAse has not been found to be effective.^[2]

There is some interest in the use of hypertonic saline in bronchiolitis. Initially recommended for use in cystic fibrosis patients, it is speculated to increase hydration of secretions, thus facilitating their removal. ^[3]

Complications

Middle ear bacterial infection

Development of asthma later (bronchial hyperactivity)

Prevention

In general, prevention of bronchiolitis relies on measures to reduce the spread of the viruses that cause respiratory infections (that is, handwashing, and avoiding exposure to those symptomatic with respiratory infections).

Premature infants, and others with certain majory cardiac and respiratory disorders, can receive passive immunization with Palivizumab (a monoclonal antibody against RSV). This form of passive immunization therapy requires monthly injections every winter. Whether it could benefit infants with lung problems secondary to muscular dystrophies and other vulnerable groups is currently unknown

See also

• Respiratory syncytial virus

References

1. ^ Wright, M; Mullett CJ, Piedimonte G et al. (October 2008). "Pharmacological management of acute bronchiolitis". Veterinary Research 4 (5): 895–903. PMID 19209271. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=19209271. 
2. ^ "BestBets: Do recombinant DNAse improve clinical outcome in an infant with RSV positive bronchiolitis?". http://www.bestbets.org/bets/bet.php?id=847. 
3. ^ B. Kuzik, S. Al Qadhi, S. Kent, M. Flavin, W. Hopman, S. Hotte, S. Gander Nebulized Hypertonic Saline in the Treatment of Viral Bronchiolitis in Infants The Journal of Pediatrics, Volume 151, Issue 3, Pages 266-270.e1

External links

• Bronchiolitis. Patient information from NHS Direct
• Bronchiolitis in children - A national clinical guidelinePDF (1.74 MiB) from the Scottish Intercollegiate Guidelines Network

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v • d • e Inflammation Acute Plasma derived mediators Bradykinin · complement (C3, C5a, MAC) · coagulation (Factor XII, Plasmin, Thrombin) Cell derived mediators preformed: Lysosome granules · vasoactive amines (Histamine, Serotonin) synthesized on demand: cytokines (IFN-γ, IL-8, TNF-α, IL-1) · eicosanoids (Leukotriene B4, Prostaglandins) · Nitric oxide · Kinins Chronic Macrophage · Epithelioid cell · Giant cell · Granuloma Processes Traditional: Rubor · Calor · Tumor · Dolor (pain) · Functio laesa Modern: Acute-phase reaction/Fever · Vasodilation · Increased vascular permeability · Exudate · Leukocyte extravasation · Chemotaxis Specific types Nervous CNS (Encephalitis, Myelitis) · Meningitis (Arachnoiditis) · PNS (Neuritis) · eye (Dacryoadenitis, Scleritis, Keratitis, Choroiditis, Retinitis, Chorioretinitis, Blepharitis, Conjunctivitis, Iritis, Uveitis) · ear (Otitis, Labyrinthitis, Mastoiditis) Cardiovascular Carditis (Endocarditis, Myocarditis, Pericarditis) · Vasculitis (Arteritis, Phlebitis, Capillaritis) Respiratory upper (Sinusitis, Rhinitis, Pharyngitis, Laryngitis) · lower (Tracheitis, Bronchitis, Bronchiolitis, Pneumonitis, Pleuritis) · Mediastinitis Digestive mouth (Stomatitis, Gingivitis, Gingivostomatitis, Glossitis, Tonsillitis, Sialadenitis/Parotitis, Cheilitis, Pulpitis, Gnathitis) · tract (Esophagitis, Gastritis, Gastroenteritis, Enteritis, Colitis, Enterocolitis, Duodenitis, Ileitis, Caecitis, Appendicitis, Proctitis) · accessory (Hepatitis, Cholangitis, Cholecystitis, Pancreatitis) · Peritonitis Integumentary Dermatitis (Folliculitis) · Hidradenitis Musculoskeletal Arthritis · Dermatomyositis · soft tissue (Myositis, Synovitis/Tenosynovitis, Bursitis, Enthesitis, Fasciitis, Capsulitis, Epicondylitis, Tendinitis, Panniculitis) Osteochondritis: Osteitis (Spondylitis, Periostitis) · Chondritis Urinary Nephritis (Glomerulonephritis, Pyelonephritis) · Ureteritis · Cystitis · Urethritis Reproductive female: Oophoritis · Salpingitis · Endometritis · Parametritis · Cervicitis · Vaginitis · Vulvitis · Mastitis male: Orchitis · Epididymitis · Prostatitis · Balanitis · Balanoposthitis pregnancy/newborn: Chorioamnionitis · Omphalitis Endocrine Insulitis · Hypophysitis · Thyroiditis · Parathyroiditis · Adrenalitis Lymphatic Lymphangitis · Lymphadenitis

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