Acute and chronic bronchitis

Acute and chronic bronchitis

Background

Acute bronchitis is a clinical syndrome produced by inflammation of the trachea, bronchi, and bronchioles. In children, acute bronchitis usually occurs in association with viral respiratory tract infection. Acute bronchitis is rarely a primary bacterial infection in otherwise healthy children.

Examples of normal airway color and architecture and an airway in a patient with chronic bronchitis are shown below.

Symptoms of acute bronchitis usually include productive cough and sometimes retrosternal pain during deep breathing or coughing. Generally, the clinical course of acute bronchitis is self-limited, with complete healing and full return to function typically seen within 10-14 days following symptom onset.

Chronic bronchitis is recurring inflammation and degeneration of the bronchial tubes that may be associated with active infection. Patients with chronic bronchitis have more mucus than normal because of either increased production or decreased clearance. Coughing is the mechanism by which excess secretion is cleared.

Chronic bronchitis is often associated with asthma, cystic fibrosis, dyskinetic cilia syndrome, foreign body aspiration, or exposure to an airway irritant. Recurrent tracheobronchitis may occur with tracheostomies or immunodeficiency states. (See Diagnosis.)

Defining chronic bronchitis and its prevalence in childhood has been complicated by the significant clinical overlap with asthma and reactive airway disease states. In adults, chronic bronchitis is defined as daily production of sputum for at least 3 months in 2 consecutive years. Some have applied this definition to childhood chronic bronchitis. Others limit the definition to a productive cough that lasts more than 2 weeks despite medical therapy.

Chronic bronchitis has also been defined as a complex of symptoms that includes cough that lasts more than 1 month or recurrent productive cough that may be associated with wheezing or crackles on auscultation. Elements of these descriptors are present in the working definitions of asthma, as well.

Treatment of chronic bronchitis in pediatric patients includes rest, use of antipyretics, adequate hydration, and avoidance of smoke.

Analgesics and antipyretics target the symptoms of pediatric bronchitis. In chronic cases, bronchodilator therapy should be considered. Oral corticosteroids should be added if cough continues and the history and physical examination findings suggest a wheezy form of bronchitis.

Pathophysiology

Acute bronchitis leads to the hacking cough and phlegm production that often follows upper respiratory tract infection. This occurs because of the inflammatory response of the mucous membranes within the lungs’ bronchial passages. Viruses, acting alone or together, account for most of these infections.

In children, chronic bronchitis follows either an endogenous response (eg, excessive inflammation) to acute airway injury or continuous exposure to certaioxious environmental agents (eg, allergens or irritants). An airway that undergoes such an insult responds quickly with bronchospasm and cough, followed by inflammation, edema, and mucus production. This helps explain the fact that apparent chronic bronchitis in children is often actually asthma.

Mucociliary clearance is an important primary innate defense mechanism that protects the lungs from the harmful effects of inhaled pollutants, allergens, and pathogens. Mucociliary dysfunction is a common feature of chronic airway diseases.

The mucociliary apparatus consists of 3 functional compartments: the cilia, a protective mucus layer, and an airway surface liquid (ASL) layer, which work together to remove inhaled particles from the lung. Animal study data have identified a critical role for ASL dehydration in the pathogenesis of mucociliary dysfunction and chronic airway disease. ASL depletion resulted in reduced mucus clearance and histologic signs of chronic airway disease, including mucous obstruction, goblet cell hyperplasia, and chronic inflammatory cell infiltration. Study animals experienced reduced bacterial clearance and high pulmonary mortality as a result.

The role of irritant exposure, particularly cigarette smoke and airborne particulates, in recurrent (wheezy) bronchitis and asthma is becoming clearer. Kreindler et al demonstrated that the ion transport phenotype of normal human bronchial epithelial cells exposed to cigarette smoke extract is similar to that of cystic fibrosis epithelia, in which sodium is absorbed out of proportion to chloride secretion in the setting of increased mucus production. These findings suggest that the negative effects of cigarette smoke on mucociliary clearance may be mediated through alterations in ion transport.

McConnell et al noted that organic carbon and nitrogen dioxide airborne particulates were associated with the chronic symptoms of bronchitis among children with asthma in southern California.

A chronic or recurrent insult to the airway epithelium, such as recurrent aspiration or repeated viral infection, may contribute to chronic bronchitis in childhood. Following damage to the airway lining, chronic infection with commonly isolated airway organisms may occur. The most common bacterial pathogen that causes lower respiratory tract infections in children of all age groups is Streptococcus pneumoniae. Nontypeable Haemophilus influenzae and Moraxella catarrhalis may be significant pathogens in preschoolers (age < 5 y), whereas Mycoplasma pneumoniae may be significant in school-aged children (ages 6-18 y).

Children with tracheostomies are often colonized with an array of flora, including alpha-hemolytic streptococci and gamma-hemolytic streptococci. With acute exacerbations of tracheobronchitis in these patients, pathogenic flora may include Pseudomonas aeruginosa and Staphylococcus aureus (including methicillin-resistant strains), among other pathogens. Children predisposed to oropharyngeal aspiration, particularly those with compromised protective airway mechanisms, may become infected with oral anaerobic strains of streptococci.

Etiology

Acute bronchitis is generally caused by respiratory infections; approximately 90% are viral in origin, and 10% are bacterial. Chronic bronchitis may be caused by repeated attacks of acute bronchitis, which can weaken and irritate bronchial airways over time, eventually resulting in chronic bronchitis. Industrial pollution is also a common cause; however, the chief culprit is heavy long-term cigarette smoke exposure.

Viral infections include the following:

Adenovirus

Influenza

Parainfluenza

Respiratory syncytial virus

Rhinovirus

Human bocavirus[8, 9, 10]

Coxsackievirus

Herpes simplex virus

Secondary bacterial infection as part of an acute upper respiratory tract infection is extremely rare in non–smoke-exposed patients without cystic fibrosis or immunodeficiency but may include the following:

S pneumoniae

M catarrhalis

H influenzae (nontypeable)

Chlamydia pneumoniae (Taiwan acute respiratory [TWAR] agent)

Mycoplasma species

Air pollutants, such as those that occur with smoking and from second-hand smoke, also cause incident bronchiolitis.  Tsai et al demonstrated that in utero and postnatal household cigarette smoke exposure is strongly linked to asthma and recurrent bronchitis in children.

Other causes include the following:

Allergies

Chronic aspiration or gastroesophageal reflux

Fungal infection

Plastic bronchitis

Plastic bronchitis is an unusual but potentially devastating form of obstructive bronchial disease. The disease is characterized by the development of arborizing, thick, tenacious casts of the tracheobronchial tree that produce airway obstruction.

Patients with congenital heart disease who have undergone a Fontan operation are a group at high risk for development of this problem, for unknown reasons. In some cases, plastic bronchitis appears many years after the Fontan procedure is performed.  Zahorec et al describe cases occurring in the immediate postoperative period following a Fontan procedure. These patients were successfully managed with short periods of high-frequency jet ventilation and vigorous pulmonary toilet.  

Therapies include endoscopic debridement of the airway, vigorous pulmonary toilet, and aerosolized tissue plasminogen activator. Shah et al performed thoracic duct ligation, resulting in complete resolution of the formation of casts in 2 patients with plastic bronchitis refractory to medical management.  These results suggest that high intrathoracic lymphatic pressures are related to the development of the recurrent bronchial casts seen in this disorder.

Epidemiology

Data collected from the National Ambulatory Care Survey 1991 Summary showed that 2,774,000 office visits by children younger than 15 years resulted in a diagnosis of bronchitis.[16] Although the report did not separate diagnoses into acute and chronic bronchitis, the frequency of visits made bronchitis just slightly less common than otitis media and slightly more common than asthma. However, in children, asthma is often underdiagnosed and is frequently misdiagnosed as chronic or recurrent bronchitis. Since 1996, 9-14 million Americans have been diagnosed with chronic bronchitis annually.

Bronchitis, both acute and chronic, is prevalent throughout the world and is one of the top 5 reasons for childhood physician visits in countries that track such data. The incidence of bronchitis in British schoolchildren is reported to be 20.7%.

Weigl et al noted an overall increase in hospitalization for lower respiratory tract infection (laryngotracheobronchitis, bronchitis, wheezing bronchitis, bronchiolitis, bronchopneumonia, pneumonia) among German children from 1996 to 2000; this is consistent with observations among children from the United States, United Kingdom, and Sweden.  The incidence rate of bronchitis in children in this German cohort was 28%.

Differences in population prevalences have been identified in patients with chronic bronchitis. For example, because of the association of chronic bronchitis with asthma and the concentration of asthma risk factors among inner-city populations, this population group is at higher risk.

The incidence of acute bronchitis is equal in males and females. The incidence of chronic bronchitis is difficult to state precisely because of the lack of definitive diagnostic criteria and the considerable overlap with asthma. However, in recent years, the prevalence of chronic bronchitis has been reported to be consistently higher in females than in males.

Acute (typically wheezy) bronchitis occurs most commonly in children younger than 2 years, with another peak seen in children aged 9-15 years. Chronic bronchitis affects people of all ages but is more prevalent in persons older than 45 years.

Prognosis

Acute bronchitis is almost always a self-limited process in the otherwise healthy child. However, it frequently results in absenteeism from school and, in older patients, work. Chronic bronchitis is manageable with proper treatment and avoidance of known triggers (eg, tobacco smoke). Proper management of any underlying disease process, such as asthma, cystic fibrosis, immunodeficiency, heart failure, bronchiectasis, or tuberculosis, is also key. These patients need careful periodic monitoring to minimize further lung damage and progression to chronic irreversible lung disease.

History

Acute bronchitis begins as a respiratory tract infection that manifests as the common cold. Symptoms often include coryza, malaise, chills, slight fever, sore throat, and back and muscle pain.

The cough in these children is usually accompanied by a nasal discharge. The discharge is watery at first, then after several days becomes thicker and colored or opaque. It then becomes clear again and has a mucoid watery consistency before it spontaneously resolves within 7-10 days. Purulent nasal discharge is common with viral respiratory pathogens and, by itself, does not imply bacterial infection.

Initially, the cough is dry and may be harsh or raspy sounding. The cough then loosens and becomes productive. Children younger than 5 years rarely expectorate. In this age group, sputum is usually seen in vomitus (ie, posttussive emesis). Parents frequently note a rattling sound in the chest. Hemoptysis, a burning discomfort in the chest, and dyspnea may be present.

Brunton et al noted that adult patients with chronic bronchitis have a history of persistent cough that produces yellow, white, or greenish sputum on most days for at least 3 months of the year and for more than 2 consecutive years.  Wheezing and reports of breathlessness are also common. Pulmonary function testing in these adult patients reveals irreversible reduction in maximal airflow velocity.

Physical Examination

Lungs may sound normal. Crackles, rhonchi, or large airway wheezing, if any, tend to be scattered and bilateral. The pharynx may be injected.

Bronchitis and Asthma

Recurrent episodes of acute or chronic infectious bronchitis are unusual in children and should alert the clinician to the likelihood of asthma. Bronchitis is often repeatedly diagnosed in children in whom asthma has remained undiagnosed for many years.

Similarly, a family history of asthma in parents or siblings may be masked within a history of “recurrent bronchitis.” The diagnosis of “asthmatic bronchitis” or “wheezy bronchitis” is simply asthma.

Bronchitis and Immunodeficiency

Recurrent episodes of acute or chronic bronchitis may be associated with immunodeficiency. Stiehm identifies the 4 most common immunodeficiencies in pediatric patients:

Transient hypogammaglobulinemia of infancy (THI)

Immunoglobulin G (IgG) subclass deficiency

Impaired polysaccharide responsiveness (partial antibody deficiency)

Selective IgA deficiency (IgAD)

A summary of immunodeficiency registries in 4 countries listed IgAD in 27.5% of the patients, IgG subclass deficiency in 4.8%, and THI in 2.3%. Patients typically have normal cellular immune systems, phagocyte function, and complement levels. All 4 immunodeficiency states are characterized by recurrent bacterial respiratory infections, such as purulent rhinitis, sinusitis, otitis, and bronchitis. Some patients with selective immunodeficiency may benefit from the use of intravenous immunoglobulin (IVIG), and the long-term prognosis is generally excellent.

Ozkan studied immunoglobulin A (IgA) and IgG deficiency in children who presented with recurrent sinopulmonary infection[20] and found that the overall frequency of antibody defects was 19.1%. IgA deficiency was observed in 9.3%, IgG subclass deficiency was observed in 8.4%, and both IgA and IgG subclass deficiencies were observed in 1.4%. The prevalence of IgA and/or IgG subclass deficiency was 25% in patients with recurrent upper respiratory tract infections, 22% in patients with recurrent pulmonary infections, and 12.3% in patients with recurrent bronchiolitis.

Common variable immunodeficiency is the most frequent of the primary hypogammaglobulinemias. In a Finnish study by Kainulainen et al of patients with common variable immunodeficiency receiving immunoglobulin replacement therapy,[21] sinopulmonary infections were the most common clinical presentation: 66% had recurrent pneumonia, 60% had recurrent maxillary sinusitis, and 45% had recurrent bronchitis.

In the Kainulainen study, the mean interval from the time of onset of symptoms to diagnosis was 8 years. Evidence of chronic lung damage was noted in 17% of patients at the time of diagnosis, highlighting the importance of early recognition in the prevention of chronic pulmonary sequelae.

To improve the recognition of common variable immunodeficiency, the authors suggest consideration of this condition in patients with recurrent sinopulmonary infection. In addition to a low serum IgG concentration, measurement of specific antibody production is recommended to establish the diagnosis.

Diagnostic Considerations

Consider the following in the diagnosis of bronchitis in pediatric patients:

Retained foreign body

Bronchopulmonary allergy

Immunosuppression

Chronic bronchitis is often part of an underlying disease process, such as asthma, cystic fibrosis, dyskinetic cilia syndrome, foreign body aspiration, or exposure to an airway irritant. Recurrent tracheobronchitis may also be seen in patients with tracheostomy or with certain forms of immunodeficiency. In all of these patient groups, chronic bronchitis should not be the primary diagnosis, because it does not describe the pathology of the underlying disorder.

Differential Diagnoses

Aspergillosis

Aspiration Syndromes

Asthma

Atypical Mycobacterial Infection

Bacterial Tracheitis

Bronchiectasis

Bronchiolitis

Bronchogenic Cyst

Bronchopulmonary Dysplasia

Common Variable Immunodeficiency

Cystic Fibrosis

Gastroesophageal Reflux

IgA and IgG Subclass Deficiencies

Influenza

Inhalation Injury

Passive Smoking and Lung Disease

Pneumonia

Respiratory Syncytial Virus Infection

Rhinovirus Infection

Sinusitis

Tracheomalacia

Tuberculosis

Approach Considerations

For maximal cost-effectiveness, diagnostic laboratory tests for bronchitis should be performed in a stepwise manner. Patients with uncomplicated acute respiratory illness who are cared for in an outpatient setting need little, if any, laboratory evaluation.

Testing in Hospitalized Children

For hospitalized children, serum C-reactive protein screen, respiratory culture, rapid diagnostic studies, and serum cold agglutinin testing (at the appropriate age) help to classify whether the infection is caused by bacteria, atypical pathogens (eg, Chlamydia pneumoniae, Mycoplasma pneumoniae), or viruses. Obtain a blood or sputum culture if antibiotic therapy is under consideration.

For the child admitted to the hospital with a possible chlamydial, mycoplasmal, or viral lower respiratory tract infection for which specific therapy is considered, test nasopharyngeal secretions for these pathogens, using antigen or polymerase chain reaction testing for Chlamydia species and respiratory syncytial, parainfluenza, and influenza viruses or viral culture. Results will guide appropriate antimicrobial selection.

For the child who has been intubated, collect a specimen of deep respiratory secretions for Gram stain, chlamydial and viral antigen assays, and bacterial and viral cultures.

Asthma Testing

A clinical response to daily high-dose oral corticosteroids may be considered as a diagnostic and therapeutic trial to confirm asthma. Evidence of reversible airflow obstruction revealed by pulmonary function testing confirms the diagnosis of asthma.

Cystic Fibrosis Testing

A negative sweat test result using pilocarpine iontophoresis should exclude cystic fibrosis. Many states are now using CFTR mutational analyses iewborn screening programs.

Immunodeficiency Testing

For children in whom immunodeficiency is suspected, measurement of total serum immunoglobulins, immunoglobulin G (IgG) subclasses, and specific antibody production is recommended to establish the diagnosis.

Chest Radiography

Chest films generally appear normal in patients with uncomplicated bronchitis. Abnormal findings are minimal and may include atelectasis, hyperinflation, and peribronchial thickening. Focal consolidation is not usually present. These findings are similar to the radiographic findings in patients with asthma. Radiographic findings may help exclude other diseases or complications, particularly when abnormalities in either vital signs or pulse oximetry findings are present.

Pulmonary Function Testing

Pulmonary function tests may show airflow obstruction that is reversible with bronchodilators. Bronchial challenge, such as with exercise or with histamine or methacholine exposure, may demonstrate the airway hyperreactivity characteristic of asthma.

Bronchoscopy

On fiberoptic bronchoscopy, a diagnosis of chronic bronchitis is suggested if the airways appear erythematous and friable. Bronchoalveolar lavage may be useful in establishing an infectious cause. Bronchoalveolar lavage may reveal numerous monocytic or polymorphonuclear inflammatory cells. In children with chronic aspiration of gastric contents, lipids may be present within macrophages.

Approach Considerations

Emergency care for acute bronchitis or exacerbation of chronic bronchitis must focus on ensuring that the child has adequate oxygenation. Outpatient care is appropriate unless bronchitis is complicated by severe underlying disease. General measures include rest, use of antipyretics, adequate hydration, and avoidance of smoke.

Proper care of any underlying disorder is of paramount importance. Consideration of asthma and adequate therapy are critical to an early response.

Febrile patients should increase oral fluid intake. Instruct the patient to rest until the fever subsides.

Resolution of symptoms, normal findings on physical examination, and normal pulmonary function test results indicate the end of the need for acute treatment. Patients in whom asthma is diagnosed will likely require ongoing therapy for that disease. Patients with defined hypogammaglobulinemia may need periodic immunoglobulin replacement treatments. These are best coordinated with the assistance of a pediatric allergy and immunology or pulmonary specialist.

Pharmacologic Therapy

Acute bronchitis

Medical therapy generally targets symptoms and includes use of analgesics and antipyretics. Antitussives and expectorants are often prescribed but have not been demonstrated to be useful. Few data outside of the research laboratory support the efficacy of expectorants.

The prototype antitussive, codeine, has been successful in some chronic-cough and induced-cough models, but few clinical data address upper respiratory infections, and the data that are available suggest little benefit. Data show codeine is little or no better than guaifenesin or dextromethorphan.

In otherwise healthy individuals, the use of antibiotics has not demonstrated any consistent benefit in relieving symptoms or improving the natural history of acute bronchitis. Placebo-controlled studies using doxycycline, erythromycin, and trimethoprim-sulfamethoxazole have failed to show significant benefit in patients with acute bronchitis.

Preliminary studies suggest a possible role for EPs 7630, an herbal drug preparation derived from Pelargonium sidoides roots, in the treatment of pediatric patients (1-18 y) with acute bronchitis outside the strict indication for antibiotics. Kamin et al demonstrated reduced bronchitis severity symptom scores in patients treated with EPs 7630, with good overall tolerability.  

Bronchodilators have failed to demonstrate efficacy in some studies of acute bronchitis. Nevertheless, a trial of inhaled albuterol may be worthwhile, as it may provide significant relief of symptoms for some patients.

Chronic bronchitis

Bronchodilator therapy should be considered and instituted; either a beta-adrenergic agonist, such as albuterol or metaproterenol, or theophylline may be effective. Beta-adrenergic agents are less toxic, have a more rapid onset of action than theophylline, and do not require monitoring of levels. Inhaled corticosteroids may be effective.

In the child who continues to cough despite a trial of bronchodilators and in whom the history and physical examination findings suggest a wheezy form of bronchitis, oral corticosteroids should be added. If the response is suboptimal or if fever persists, antibiotic therapy with an agent such as a macrolide or beta-lactamase–resistant antimicrobial may be considered.

Antibiotics should not be the primary therapy. They usually do not result in a cure and may delay the start of more appropriate asthma therapies. However, antibiotics may be appropriate in children with chronic wet cough, most of whom have protracted bacterial bronchitis.

Consultations

Referral to a pediatric pulmonologist may be helpful for patients experiencing persistent or recurrent symptoms and whose histories suggest the possibility of tracheobronchial foreign body aspiration, cystic fibrosis, immunodeficiency, or persistent asthma for which appropriate first-line symptom or controller therapies have failed.

Complications

Complications are extremely rare and should prompt evaluation for anomalies of the respiratory tract, including immune deficiencies. Complications may include the following:

Bronchiectasis

Bronchopneumonia

Acute respiratory failure

 

Common Cold

Definition

The common cold is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although more than 200 different viruses can cause a cold, 30-50% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.

Description

Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although pre-school and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.

Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multi-million dollar industry in over-the-counter medications.

Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:

·  fatigue and overwork

·  emotional stress

·  poor nutrition

·  smoking

·  living or working in crowded conditions

Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to middle ear infection, bronchitis, pneumonia, sinus infection, or strep throat. People with chronic lung disease, asthma, diabetes, or a weakened immune system are more likely to develop these complications.

Causes and symptoms

Colds are caused by more than 200 different viruses. The most common groups are rhinoviruses and coronaviruses. Different groups of viruses are more infectious at different seasons of the year, but knowing the exact virus causing the cold is not important in treatment.

People with colds are contagious during the first two to four days of the infection. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus are expelled. If these are breathed in by other people, the virus may establish itself in their noses and airways.

Colds may also be passed through direct contact. If a person with a cold touches his runny nose or watery eyes, then shakes hands with another person some of the virus is transferred to the uninfected person. If that person then touches his mouth, nose, or eyes, the virus is transferred to an environment where it can reproduce and cause a cold.

Finally, cold viruses can be spread through inanimate objects (door knobs, telephones, toys) that become contaminated with the virus. This is a common method of transmission in child care centers. If a child with a cold touches her runny nose, then plays with a toy, some of the virus may be transferred to the toy. When another child plays with the toy a short time later, he may pick up some of the virus on his hands. The second child then touches his contaminated hands to his eyes, nose, or mouth and transfers some of the cold virus to himself.

Once acquired, the cold virus attaches itself to the lining of the nasal passages and sinuses. This causes the infected cells to release a chemical called histamine. Histamine increases the blood flow to the infected cells, causing swelling, congestion, and increased mucus production. Within one to three days the infected person begins to show cold symptoms.

The first cold symptoms are a tickle in the throat, runny nose, and sneezing. The initial discharge from the nose is clear and thin. Later it changes to a thick yellow or greenish discharge. Most adults do not develop a fever when they catch a cold. Young children may develop a low fever of up to 102°F (38.9°C).

In addition to a runny nose and fever, signs of a cold include coughing, sneezing, nasal congestion, headache, muscle ache, chills, sore throat, hoarseness, watery eyes, tiredness, and lack of appetite. The cough that accompanies a cold is usually intermittent and dry.

Most people begin to feel better four to five days after their cold symptoms become noticeable. All symptoms are generally gone within ten days, except for a dry cough that may linger for up to three weeks.

Colds make people more susceptible to bacterial infections such as strep throat, middle ear infections, and sinus infections. A person whose cold does not begin to improve within a week; or who experiences chest pain, fever for more than a few days, difficulty breathing, bluish lips or fingernails, a cough that brings up greenish-yellow or grayish sputum, skin rash, swollen glands, or whitish spots on the tonsils or throat should consult a doctor to see if he or she has acquired a secondary bacterial infection that needs to be treated with an antibiotic.

People who have emphysema, chronic lung disease, diabetes, or a weakened immune system—either from diseases such as AIDS or leukemia, or as the result of medications, (corticosteroids, chemotherapy drugs)—should consult their doctor if they get a cold. People with these health problems are more likely to get a secondary infection.

Diagnosis

Colds are diagnosed by observing a person’s symptoms. There are no laboratory tests readily available to detect the cold virus. However, a doctor may do a throat culture or blood test to rule out a secondary infection.

Influenza is sometimes confused with a cold, but flu causes much more severe symptoms and generally a fever. Allergies to molds or pollens also can make the nose run. Allergies are usually more persistent than the common cold. An allergist can do tests to determine if the cold-like symptoms are being caused by an allergic reaction. Also, some people get a runny nose when they go outside in winter and breathe cold air. This type of runny nose is not a symptom of a cold.

Treatment

There are no medicines that will cure the common cold. Given time, the body’s immune system will make antibodies to fight the infection, and the cold will be resolved without any intervention. Antibiotics are useless against a cold. However, a great deal of money is spent by pharmaceutical companies in the United States promoting products designed to relieve cold symptoms. These products usually contain antihistamines, decongestants, and/or pain relievers.

Antihistamines block the action of the chemical histamine that is produced when the cold virus invades the cells lining the nasal passages. Histamine increases blood flow and causes the cells to swell. Antihistamines are taken to relieve the symptoms of sneezing, runny nose, itchy eyes, and congestion. Side effects are dry mouth and drowsiness, especially with the first few doses. Antihistamines should not be taken by people who are driving or operating dangerous equipment. Some people have allergic reactions to antihistamines. Common over-the-counter antihistamines include Chlor-Trimeton, Dimetapp, Tavist, and Actifed. The generic name for two common antihistamines are chlorpheniramine and diphenhydramine.

Decongestants work to constrict the blood flow to the vessels in the nose. This can shrink the tissue, reduce congestion, and open inflamed nasal passages, making breathing easier. Decongestants can make people feel jittery or keep them from sleeping. They should not be used by people with heart disease, high blood pressure, or glaucoma. Some common decongestants are Neo-Synepherine, Novafed, and Sudafed. The generic names of common decongestants include phenylephrine, phenylpropanolamine, pseudoephedrine, and iasal sprays naphazoline, oxymetazoline and xylometazoline.

Many over-the-counter medications are combinations of both antihistamines and decongestants; an ache and pain reliever, such as acetaminophen (Datril, Tylenol, Panadol) or ibuprofen (Advil, Nuprin, Motrin, Medipren); and a cough suppressant (dextromethorphan). Common combination medications include Tylenol Cold and Flu, Triaminic, Sudafed Plus, and Tavist D. Aspirin should not be given to children with a cold because of its association with a risk of Reye’s syndrome, a serious disease.

Nasal sprays and nose drops are other products promoted for reducing nasal congestion. These usually contain a decongestant, but the decongestant can act more quickly and strongly than ones found in pills or liquids because it is applied directly in the nose. Congestion returns after a few hours.

People can become dependent on nasal sprays and nose drops. If used for a long time, users may suffer withdrawal symptoms when these products are discontinued. Nasal sprays and nose drops should not be used for more than a few days. The label lists recommendations on length and frequency of use.

Scientists reported in 2004 the possibility of a new oral drug for use in relieving common cold symptoms. Called pleconaril, it inhibited viral replication in at least 90% of rhinoviruses if taken within 24 hours of onset.

People react differently to different cold medications and may find some more helpful than others. A medication may be effective initially, then lose some of its effectiveness. Children sometimes react differently than adults. Over-the-counter cold remedies should not be given to infants without consulting a doctor first.

Care should be takeot to exceed the recommended dosages, especially when combination medications or nasal sprays are taken. Individuals should determine whether they wish to use any of these drugs. None of them shorten or cure a cold. At best they help a person feel more comfortable. People who are confused about the drugs in any over-the-counter cold remedies should ask their pharmacist for an explanation.

In addition to the optional use of over the counter cold remedies, there are some self-care steps that people can take to ease their discomfort. These include:

·       drinking plenty of fluids, but avoiding acidic juices, which may irritate the throat

·       gargling with warm salt water—made by adding one teaspoon of salt to 8 oz of water—for a sore throat

·       not smoking

·       getting plenty of rest

·       using a cool-mist room humidifier to ease congestion and sore throat

·       rubbing Vaseline or other lubricant under the nose to prevent irritation from frequent nose blowing

·       for babies too young to blow their noses, the mucus should be suctioned gently with an infant nasal aspirator. It may be necessary to soften the mucus first with a few drops of salt water.

Alternative treatment

Alternative practitioners emphasize that people get colds because their immune systems are weak. They point out that everyone is exposed to cold viruses, but not everyone gets every cold. The difference seems to be in the ability of the immune system to fight infection. Prevention focuses on strengthening the immune system by eating a healthy diet low in sugars and high in fresh fruits and vegetables, practicing meditation to reduce stress, and getting regular moderate exercise.

Once cold symptoms appear, some naturopathic practitioners believe the symptoms should be allowed to run their course without interference. Others suggest the following:

·  Inhaling a steaming mixture of lemon oil, thyme oil, eucalyptus, and tea tree oil (Melaleuca spp.). (Aromatherapy)

·  Gargling with a mixture of water, salt, and turmeric powder or astringents such as alum, sumac, sage, and bayberry to ease a sore throat. (Ayurvedic medicine)

·  Taking coneflower or goldenseal (Hydrastis canadensis). Other useful herbs to reduce symptoms include yarrow (Achillea millefolium), eyebright (Euphrasia officinalis), garlic (Allium sativum), and onions (Allium cepa). (Herbal)

·  Microdoses of Viscue album, Natrum muriaticum, Allium cepa, or Nux vomica. (Homeopathy)

·  Taking yin chiao (sometimes transliterated as yinquiao) tablets that contain honeysuckle and forsythia when symptoms appear. Natural herb loquat syrup for cough and sinus congestion and Chinese ephedra (ma-huang) for runny nose. (Chinese traditional medicine)

·  The use of zinc lozenges every two hours along with high doses of vitamin C is suggested. Some practitioners also suggest eliminating dairy products for the duration of the cold. (Nutritional therapy).

The use of zinc lozenges may be moving toward acceptance by practitioners of traditional medicine. In 1996 the Cleveland Clinic tested zinc gluconate lozenges and found using zinc in the first 24 hours after cold symptoms occurred shortened the duration of symptoms. The mechanism by which zinc worked was not clear, but additional studies are underway.

At one time, the herb (Echinacea spp.) was touted as a remedy to relieve cold symptoms. However, a study published in 2004 reported that the herb failed to relieve cold symptoms in 400 children taking it and caused skin rashes in some children.

Prognosis

Given time, the body will make antibodies to cure itself of a cold. Most colds last a week to 10 days. Most people start feeling better within four or five days. Occasionally a cold will lead to a secondary bacterial infection that causes strep throat, bronchitis, pneumonia, sinus infection, or a middle ear infection. These conditions usually clear up rapidly when treated with an antibiotic.

Prevention

It is not possible to prevent colds because the viruses that cause colds are common and highly infectious. However, there are some steps individuals can take to reduce their spread. These include:

·  washing hands well and frequently, especially after touching the nose or before handling food

·  covering the mouth and nose when sneezing

·  disposing of used tissues properly

·  avoiding close contact with someone who has a cold during the first two to four days of their infection

·  not sharing food, eating utensils, or cups with anyone

·  avoiding crowded places where cold germs can spread

·  eating a healthy diet and getting adequate sleep

 

Pharyngitis

TIt is an inflammation of the throat. In most cases it is quite painful, and is the most common cause of a sore throat.

Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic. Pharyngitis can result in very large tonsils which cause trouble swallowing and breathing. Pharyngitis can be accompanied by a cough or fever, for example, if caused by a systemic infection.

Most acute cases are caused by viral infections (40–80%), with the remainder caused by bacterial infections, fungal infections, or irritants such as pollutants or chemical substances. Treatment of viral causes is mainly symptomatic while bacterial or fungal causes may be amenable to antibiotics and anti-fungal medicines respectively.

Classification

Pharyngitis is a type of inflammation, most commonly caused by an upper respiratory tract infection. It may be classified as acute or chronic. An acute pharyngitis may be catarrhal, purulent or ulcerative, depending on the virulence of the causative agent and the immune capacity of the affected individual. Chronic pharyngitis is the most common otolaringologic disease and may be catarrhal, hypertrophic or atrophic.

If the inflammation includes tonsillitis, it is called pharyngotonsillitis. Another sub classification is nasopharyngitis (the common cold).

Cause

The majority of cases are due to an infectious organism acquired from close contact with an infected individual.

Infectious

Viral

These comprise about 40–80% of all infectious cases and can be a feature of many different types of viral infections.

Adenovirus – the most common of the viral causes. Typically the degree of neck lymph node enlargement is modest and the throat often does not appear red, although it is very painful.

Orthomyxoviridae which cause influenza – present with rapid onset high temperature, headache and generalised ache. A sore throat may be associated.

Infectious mononucleosis (“glandular fever”) caused by the Epstein-Barr virus. This may cause significant lymph gland swelling and an exudative tonsillitis with marked redness and swelling of the throat. The heterophile test can be used if this is suspected.

Herpes simplex virus can cause multiple mouth ulcers.

Measles

Common cold: rhinovirus, coronavirus, respiratory syncytial virus, parainfluenza virus can cause infection of the throat, ear, and lungs causing standard cold-like symptoms and often extreme pain.

Bacterial

A number of different bacteria can infect the human throat. The most common is Group A streptococcus, however others include Streptococcus pneumoniae, Haemophilus influenzae, Bordetella pertussis, Bacillus anthracis, Corynebacterium diphtheriae, Neisseria gonorrhoeae, Chlamydophila pneumoniae, and Mycoplasma pneumoniae.

Streptococcal pharyngitis

Streptococcal pharyngitis or strep throat is caused by group A beta-hemolytic streptococcus (GAS). It is the most common bacterial cause of cases of pharyngitis (15–30%). Common symptoms include fever, sore throat, and large lymph nodes. It is a contagious infection, spread by close contact with an infected individual. A definitive diagnosis is made based on the results of a throat culture. Antibiotics are useful to both prevent complications and speed recovery.

Fusobacterium necrophorum

Fusobacterium necrophorum are normal inhabitants of the oropharyngeal flora. Occasionally however it can create a peritonsillar abscess. In 1 out of 400 untreated cases Lemierre’s syndrome occurs.

Diphtheria

Diphtheria is a potentially life threatening upper respiratory infection caused by Corynebacterium diphtheriae which has been largely eradicated in developed nations since the introduction of childhood vaccination programs, but is still reported in the Third World and increasingly in some areas in Eastern Europe. Antibiotics are effective in the early stages, but recovery is generally slow.

Others

A few other causes are rare, but possibly fatal, and include parapharyngeal space infections: peritonsillar abscess (“quinsy”), submandibular space infection (Ludwig’s angina), and epiglottitis.

Fungal

Some cases of pharyngitis are caused by fungal infection such as Candida albicans causing oral thrush.

Non-infectious

Pharyngitis may also be caused by mechanical, chemical or thermal irritation, for example cold air or acid reflux. Some medications may produce pharyngitis such as pramipexole and antipsychotics.

Diagnostic approach

It is hard to differentiate a viral and a bacterial cause of a sore throat based on symptoms alone. Thus often a throat swab is done to rule out a bacterial cause.

The modified Centor criteria may be used to determine the management of people with pharyngitis. Based on 5 clinical criteria, it indicates the probability of a streptococcal infection.

One point is given for each of the criteria:

Absence of a cough

Swollen and tender cervical lymph nodes

Temperature >38.0 °C (100.4 °F)

Tonsillar exudate or swelling

Age less than 15 (a point is subtracted if age >44)

The McIsaac criteria adds to the Centor:

Age less than 15: add one point

Age greater than 45: subtract one point

The Infectious Disease Society of America however recommends against empirical treatment and considers antibiotics only appropriate following positive testing. Testing is not needed in children under three as both group A strep and rheumatic fever are rare, except if they have a sibling with the disease.

Management

The majority of time treatment is symptomatic. Specific treatments are effective for bacterial, fungal, and herpes simplex infections.

Medications

Analgesics such as NSAIDs and acetaminophen can help reduce the pain associated with a sore throat. (Note: Don’t use salicylates, like aspirin, for influenza: Increased risk of Reye’s syndrome)

Steroids (such as dexamethasone) have been found to be useful for severe pharyngitis.

Viscous lidocaine relieves pain by numbing the mucus membranes.

Antibiotics are useful if a bacterial infection is the cause of the sore throat. For viral infections, antibiotics have no effect.

Oral analgesic solutions, the active ingredient usually being Phenol, but also less commonly Benzocaine, Cetylpyridinium chloride and/or Menthol. Chloraseptic and Cēpacol are two examples of brands of these kinds of analgesics.

 

Croup

Definition

Croup is a common childhood ailment. Typically, it arises from a viral infection of the larynx (voice box) and is associated with mild upper respiratory symptoms such as a runny nose and cough. The key symptom is a harsh barking cough. Croup is usually not serious and most children recover within a few days. In a small percentage of cases, a child develops breathing difficulties and may need medical attention.

Description

At one time, the term croup was primarily associated with diphtheria, a life-threatening respiratory infection. Owing to widespread vaccinations, diphtheria has become rare in the United States, and croup currently refers to a mild viral infection of the larynx. Croup is also known as laryngotracheitis, a medical term that describes the inflammation of the trachea (windpipe) and larynx.

Parainfluenza viruses are the typical root cause of the infection, but influenza (flu) and cold viruses may sometimes be responsible. All of these viruses are highly contagious and easily transmitted between individuals via sneezing and coughing. Children between the ages of three months and six years are usually affected, with the greatest incidence at one to two years of age. Croup can occur at any time of the year, but it is most typical during early autumn and winter. The characteristic harsh barking of a croupy cough can be very distressing, but it rarely indicates a serious problem. Most children with croup can be treated very effectively at home; however, 1-5% may require medical treatment.

Croup may sometimes be confused with more serious conditions, such as epiglottitis or bacterial tracheitis. These ailments arise from bacterial infection and must receive medical treatment.

Causes and symptoms

The larynx and trachea may become inflamed or swollen from an upper respiratory viral infection. The hallmark sign of croup is a harsh, barking cough. This cough may be preceded by one to three days of symptoms that resemble a slight cold. A croupy cough is often accompanied by a runny nose, hoarseness, and a low fever. When the child inhales, there may be a raspy or high-pitched noise, called stridor, owing to the narrowed airway and accumulated mucus. In the presence of stridor, medical attention is required.

However, the airway rarely narrows so much that breathing is impeded. Symptoms usually go away completely within a few days. Medical treatment may be sought if the child’s symptoms do not respond to home treatment.

Emergency medical treatment is required immediately if the child has difficulty breathing, swallowing, or talking; develops a high fever (103°F/39.4°C or more); seems unalert or confused; or has pale or blue-tinged skin.

Diagnosis

Croup is diagnosed based on the symptoms. If symptoms are particularly severe, or do not respond to treatment, an x ray of the throat area is done to assess the possibility of epiglottitis or other blockage of the airway.

Treatment

Home treatment is the usual method of managing croup symptoms. It is important that the child is kept comfortable and calm to the best degree possible, because crying can make symptoms seem worse. Humid air can help a child with croup feel more comfortable. Recommended methods include sitting in a steamy bathroom with the hot water running or using a cool-water vaporizer or humidifier. However, research in 2004 found that although cool-mist therapy at home or in the hospital may add to the child’s comfort, it does little to treat the actual condition. The child should drink frequently in order to stay well hydrated. To treat any fever, the child may be given an appropriate dose of acetaminophen (like Tylenol). Antihistamines and decongestants are ineffective in treating croup. All children under the age of 18 should not be given aspirin, as it may cause Reye’s syndrome, a life-threatening disease of the brain.

If the child does not respond to home treatment, medical treatment at a doctor’s office or an emergency room could be necessary. Based on the severity of symptoms and the response to treatment, the child may need to be admitted to a hospital.

For immediate symptom relief, epinephrine may be administered as an inhaled aerosol. Effects last for up to two hours, but there is a possibility that symptoms may return. For that reason, the child is kept under supervision for three or more hours. Steroids (corticosteroids) such as prednisone may be used to treat croup, particularly if the child has stridor when resting.

Of the 1-5% of children requiring medical treatment, approximately 1% need respiratory support. Such support involves intubation (inserting a tube into the trachea) and oxygen administration.

Alternative treatment

Botanical/herbal medicines can be helpful in healing the cough that is commonly associated with croup. Several herbs to consider for cough treatment include aniseed (Pimpinella anisum), sundew (Drosera rotundifolia), thyme (Thymus vulgaris), and wild cherry bark (Prunus serotina). Homeopathic medicine can be very effective in treating cases of croup. Choosing the correct remedy (a common choice is aconite or monkshood, Aconitum napellus) is always the key to the success of this type of treatment.

Prognosis

Croup is a temporary condition and children typically recover completely within three to six days. Children can experience one or more episodes of croup during early childhood; however, croup is rarely a dangerous condition.

Prevention

Croup is caused by highly transmissible viruses and is often difficult to impossible to prevent.

 

Tracheitis

Tracheitis is a bacterial infection of the windpipe (trachea).

Causes

Bacterial tracheitis is most often caused by the bacteria Staphylococcus aureus. It often follows a recent viral upper respiratory infection. It affects mostly young children, possibly because their small trachea is easily blocked by swelling.

Symptoms

Deep cough (similar to that caused by croup)

Difficulty breathing

High fever

High-pitched breathing sound (stridor)

Exams and Tests

The health care provider will perform a physical exam and listen to the child’s lungs. The muscles between the ribs may pull in as the child tries to breathe. This is called intercostal retractions.

Tests that may be done to diagnose this condition include:

Blood oxygen level

Nasopharyngeal culture to look for bacteria

Tracheal culture to look for bacteria

X-ray of the trachea

Treatment

The child ofteeeds to have a tube placed into the airways to help with breathing. This is called an endotracheal tube.

The child will receive antibiotics through a vein. The health care team will closely monitor the child’s breathing and use oxygen, if needed.

Outlook (Prognosis)

With prompt treatment, the child should recover.

Possible Complications

Airway obstruction — can lead to death

Toxic shock syndrome — if caused by the bacteria Staphylococcus

 

Bronchiolitis

 

Practice Essentials

Bronchiolitis is an acute inflammatory injury of the bronchioles that is usually caused by a viral infection (most commonly respiratory syncytial virus). This condition may occur in persons of any age, but severe symptoms are usually evident only in young infants.

Essential update: On-demand inhaled adrenaline superior to fixed-schedule inhaled adrenaline

A randomized, double-blind study of 404 Norwegian infants with bronchiolitis found on-demand inhaled racemic adrenaline therapy to be superior to inhaled adrenaline therapy given on a fixed schedule.Regardless of the schedule employed, when inhaled adrenaline was compared with inhaled aerosolized saline, length of hospital stay, supplemental oxygen use, clinical scores, and other measures were essentially the same.

However, when on-demand inhalation was compared with fixed-schedule treatment regardless of whether adrenaline was used, the mean length of hospital stay was reduced from 61.3 hours in the fixed-schedule group to 47.6 hours in the on-demand group, and the number of infants requiring oxygen supplementation was reduced from 48.7% to 38.3%.The average number of inhalation treatments was 17.0 with the fixed schedule and 12.0 with on-demand treatment.

Signs and symptoms

Because bronchiolitis primarily affects young infants, clinical manifestations are initially subtle, such as the following:

·  May become increasingly fussy and have difficulty feeding during the 2 to 5-day incubation period

·  Low-grade fever (usually < 101.5°F); possible hypothermia in infants younger than 1 month

·  Increasing coryza and congestion

·  Apnea: May be the presenting symptom in early disease

Severe cases of bronchiolitis may progress to the following signs and symptoms:

·  Respiratory distress with tachypnea, nasal flaring, retractions

·  Irritability

·  Possibly cyanosis

Diagnosis

The diagnosis of bronchiolitis is based on clinical presentation, the patient’s age, seasonal occurrence, and findings from the physical examination, which may reveal the following:

·  Tachypnea

·  Tachycardia

·  Fever (38-39°C)

·  Retractions

·  Fine rales (47%); diffuse, fine wheezing

·  Hypoxia

·  Otitis media

Laboratory tests

When the clinical presentation, patient’s age, seasonal occurrence, and findings from the physical examination are consistent with the expected diagnosis of bronchiolitis, few laboratory studies are necessary.Diagnostic testing is controversial but is typically used to exclude other diagnoses (eg, bacterial pneumonia, sepsis, or congestive heart failure) or to confirm a viral etiology and determine required infection control for patients admitted to the hospital.

Commonly used tests in the evaluation of patients with bronchiolitis include the following:

·  Rapid viral antigen testing of nasopharyngeal secretions for respiratory syncytial virus

·  Arterial blood gas analysis

·  White blood cell count with differential

·  C-reactive protein level

·  Pulse oximetry

·  Blood cultures

·  Urine analysis, specific gravity, and culture

·  Cerebrospinal fluid analysis and culture

·  Serum chemistries

Electrocardiography or echocardiography should be reserved for those few children who display arrhythmias or cardiomegaly.

Imaging studies

Chest radiographs are not routinely necessary.A practical approach is to obtain a chest radiograph in children who appear ill, are experiencing clinical deterioration, or are at high risk (eg, those with underlying cardiac or pulmonary disease).

This imaging modality is most useful in excluding unexpected congenital anomalies or other conditions; it may also yield positive evidence of alternative diagnoses (eg, lobar pneumonia, congestive heart failure, or foreign body aspiration).

Procedures

In rare situations (eg, severe immunodeficiency, strong history of possible foreign body aspiration), bronchoscopy may be indicated for diagnostic bronchoalveolar lavage or therapeutic foreign body removal.

Management

Among numerous medications and interventions used to treat bronchiolitis, thus far, only oxygen appreciably improves the condition of young children.Therefore, therapy is directed toward symptomatic relief and maintenance of hydration and oxygenation.

Nonpharmacotherapy

Supportive care for patients with bronchiolitis may include the following:

·  Supplemental humidified oxygen

·  Maintenance of hydration

·  Mechanical ventilation

·  Nasal and oral suctioning

·  Apnea and cardiorespiratory monitoring

·  Temperature regulation in small infants

Pharmacotherapy

Medications have a limited role in the treatment of bronchiolitis. Healthy children with bronchiolitis usually have limited disease and usually do well with supportive care only.

The following medications are used in selected patients with bronchiolitis:

·  Alpha/beta agonists (eg, racemic epinephrine, albuterol)

·  Monoclonal antibodies (eg, palivizumab)

·  Antibiotics (eg, ampicillin, cefotaxime, ceftriaxone)

·  Antiviral agents (eg, ribavirin)

·  Intranasal decongestants (eg, oxymetazoline)

·  Corticosteroids (eg, prednisone, methylprednisolone)

Background

Bronchiolitis is an acute inflammatory injury of the bronchioles that is usually caused by a viral infection. Although it may occur in persons of any age, severe symptoms are usually only evident in young infants; the larger airways of older children and adults better accommodate mucosal edema.

Obliterative bronchiolitis (OB) was first described in 1901; in 1985,bronchiolitis obliterans-organizing pneumonia (BOOP) was described as a condition distinct from OB, with different clinical, radiographic, and prognostic features. BOOP is a histopathologic lesion, not a specific diagnosis. Its pathologic hallmark is proliferative bronchiolitis or bronchiolitis obliterans in association with organizing pneumonia. BOOP and OB are beyond the scope of this article and are not discussed further.

Bronchiolitis usually affects children younger than 2 years, with a peak in infants aged 3-6 months. Acute bronchiolitis is the most common cause of lower respiratory tract infection in the first year of life. It is generally a self-limiting condition and is most commonly associated with respiratory syncytial virus (RSV) .

Despite the increasing hospitalization rate for patients with bronchiolitis, controversy still exists regarding optimal treatment of these patients. As a result, the use of management tools among physicians and between hospitals varies greatly. The use of clinical practice guidelines can standardize care, reduce admissions, manage resources better, and shorten the length of hospital stays without increasing readmission rates or decreasing family satisfaction.

Pathophysiology

Bronchioles are small airways (< 2 mm in diameter) and lack cartilage and submucosal glands. The terminal bronchiole, a 16th-generation airway, is the final conducting airway that terminates in the respiratory bronchioles. The acinus (ie, the gas exchange unit of the lung) consists of respiratory bronchioles, the alveolar duct, and alveoli. The bronchiolar lining consists of surfactant-secreting Clara cells and neuroendocrine cells, which are the source of bioactive products such as somatostatin, endothelin, and serotonin.

Bronchiolar injury and the consequent interplay between inflammatory and mesenchymal cells can lead to diverse pathologic and clinical syndromes. The effects of bronchiolar injury include the following:

·  Increased mucus secretion

·  Bronchial obstruction and constriction

·  Alveolar cell death, mucus debris, viral invasion

·  Air trapping

·  Atelectasis

·  Reduced ventilation that leads to ventilation-perfusion mismatch

·  Labored breathing

Complex immunologic mechanisms play a role in the pathogenesis of bronchiolitis. Type 1 allergic reactions mediated by immunoglobulin E (IgE) may account for some clinically significant bronchiolitis. Infants who are breastfed with colostrum rich in immunoglobulin A (IgA) appear to be relatively protected from bronchiolitis.

Necrosis of the respiratory epithelium is one of the earliest lesions in bronchiolitis and occurs within 24 hours of acquisition of infection.Proliferation of goblet cells results in excessive mucus production, whereas epithelial regeneration with nonciliated cells impairs elimination of secretions. Lymphocytic infiltration may result in submucosal edema.

Cytokines and chemokines, released by infected respiratory epithelial cells, amplify the immune response by increasing cellular recruitment into infected airways. Interferon and interleukin (IL)–4, IL-8, and IL-9 are found in high concentrations in respiratory secretions of infected patients.

Johnson et al analyzed autopsy findings from children who died of possible RSV infection between 1925 and 1959 (before modern intensive care) and those from a child with RSV bronchiolitis who died in a motor vehicle accident.They found that small bronchiole epithelium was circumferentially infected but basal cells were spared. Both type 1 and type 2 alveolar pneumocytes were also infected.

In this study, airway obstruction was due to epithelial and inflammatory cell debris mixed with fibrin, mucus, and edema fluid but not to bronchial smooth muscle constriction.Other research revealed that neutrophil inflammation, but not eosinophil inflammation, is related to the severity of a first infection in infants.

The inflammation, edema, and debris result in obstruction of bronchioles, leading to hyperinflation, increased airway resistance, atelectasis, and ventilation-perfusion mismatching. Bronchoconstriction has not been described.

Infants are affected most often because of their small airways, high closing volumes, and insufficient collateral ventilation. Recovery begins with regeneration of bronchiolar epithelium after 3-4 days; however, cilia do not appear for as long as 2 weeks. Mucus plugs are predominantly removed by macrophages.

Infection is spread by direct contact with respiratory secretions. In the United States, epidemics last 2-4 months, beginning in November and peaking in January or February. Whereas 93% of cases occur between November and early April, sporadic cases may occur throughout the year. Attack rates within families are as high as 45% and are higher in childcare centers. Rates of hospital-acquired infection range from 20-47%.

Virtually all children experience RSV infection within the first 3 years of life, but previous infection does not convey complete immunity. Reinfection is common; however, significant antibody titers from previous infection ameliorate the severity of symptoms.

Etiology

Most cases of bronchiolitis result from a viral pathogen, such as RSV, parainfluenza virus, influenza virus, or adenovirus. Bronchiolitis is highly contagious. The virus that causes it is spread from person to person through direct contact with nasal secretions, airborne droplets, and fomites. RSV is the most commonly isolated agent in 75% of children younger than 2 years who are hospitalized for bronchiolitis. RSV is an enveloped RNA virus that belongs to the Paramyxoviridae family within the Pneumovirus genus.

RSV causes 20-40% of all cases and 44% of cases that involve children younger than 2 years. Two RSV subtypes, A and B, have been identified on the basis of structural variations in the G protein. Subtype A causes the most severe infections. One subtype or the other usually predominates during a given season; thus, RSV disease has “good” and “bad” years.Viral shedding iasal secretions continues for 6-21 days after symptoms develop. The incubation period is 2-5 days.

Parainfluenza virus causes 10-30% of all bronchiolitis cases.Epidemics of bronchiolitis due to parainfluenza virus usually begin earlier in the year and tend to occur every other year. Adenovirus accounts for 5-10% of bronchiolitis cases. Influenza virus accounts for 10-20%. Mycoplasma pneumoniae infection accounts for 5-15%, particularly among older children and adults.

In a prospective multicenter study of the viral etiology of bronchiolitis in the emergency department (ED), 277 samples were tested, and positive samples were obtained for the following viruses:

·  RSV – 64%

·  Rhinovirus – 16%

·  Human metapneumovirus (hMPV)- 9%

·  Influenza A virus – 6%

The paramyxovirus hMPV, first identified in the Netherlands in 2001,has been increasingly implicated as an etiologic agent in bronchiolitis.Serologic studies indicated that by age 5 years, all Dutch children had seroconverted and that the virus had been prevalent in the population for at least 50 years.

In a retrospective examination of nasal washings obtained between 1976 and 2001 from 2009 children with acute respiratory tract illness, 248 had identifiable viruses.In 20% of these, hMPV was identified, accounting for 12% of all viral lower respiratory illness in children younger than 2 years. The mean age in the hMPV group was 11.6 months, with a male-to-female ratio of 1.8:1. They most often had illnesses between December and April, and 2% were hospitalized. The virus was associated with bronchiolitis in 59% of patients.

Subsequent studies showed that hMPV accounts for 5-50% of bronchiolitis cases, seems to occur later in the bronchiolitis season, occurs with higher fevers, affects somewhat older children, and causes more wheezing but less requirement for oxygen (possibly because the children are older and have less atelectasis).Other studies found that combined hMPV-RSV infections were strongly associated with severe bronchiolitis, with a 10-fold increase in pediatric intensive care unit (PICU) admission.

Human bocavirus (HBoV), discovered in 2005, is known to cause both upper and lower respiratory tract infections and has been implicated in both pertussis and bronchiolitislike syndromes. Arnold et al demonstrated that 5.6% of 1474 nasal scrapings collected over a 20-month period at San Diego Children’s Hospital tested positive for HBoV, mostly from March through May.

Risk factors

Risk factors for the development of bronchiolitis include the following:

·  Low birth weight, particularly premature infants

·  Gestational age (independently associated with hospital resource use and outcome among infants hospitalized for RSV infection)

·  Lower socioeconomic group

·  Crowded living conditions, daycare, or both

·  Parental smoking

·  Chronic lung disease, particularly bronchopulmonary dysplasia

·  Severe congenital or acquired neurologic disease

·  Congenital heart disease (CHD) with pulmonary hypertension; however, a study of Swiss children with CHD did not show increased risk

·  Congenital or acquired immune deficiency diseases

·  Age less than 3 months

·  Airway anomalies

In a study that collected epidemiologic, clinical, and virologic data to determine the incidence and predisposing factors for severe bronchiolitis in 310 previously healthy term infants younger than 12 months who were experiencing their first episode of bronchiolitis,the infants with severe disease were found to present with lower birth weight, younger gestational age, lower postnatal weight, younger postnatal age, and a stronger likelihood of having been born via cesarean delivery.

Positive C-reactive protein (CRP) results (>0.8 mg/dL) and pulmonary consolidation on chest radiographs were more common among infants with severe disease, though no significant differences in epidemiologic variables were found.Although severe bronchiolitis is uncommon in infants with these characteristics (ie, previously healthy term infants younger than 12 months), severity is predicted by young age and RSV carriage; when severe bronchiolitis is present, it typically develops soon after disease onset.

Epidemiology

United States statistics

Respiratory infection is observed in 25% of children younger than 12 months and 13% of children aged 1-2 years.Of these 25%, one half have wheezing-associated respiratory disease.RSV can be cultured from one third of these outpatients and from 80% of hospitalized children younger than 6 months.

Nearly 100% of children experience an RSV infection within 2 RSV seasons, and 1% are hospitalized.Among healthy full-term infants, 80% of hospitalizations occur in the first year, and 50% of hospitalizations occur in children aged 1-3 months.Fewer than 5% of hospitalizations occur in the first 30 days of life, presumably because of transplacental transfer of maternal antibody.

Descriptive analysis of the US National Hospital Discharge Survey data from 1980 through 1996 showed that admissions associated with bronchiolitis totaled 1.65 million.During this period, the hospitalization rate for children younger than 1 year increased from 12.9 to 31.2 per 1000 population, and the percentage of hospitalizations for lower respiratory tract illnesses among children younger than 1 year associated with bronchiolitis increased from 22.2% to 47.4%.

In a retrospective analysis of data from the same source for 1997-2006, RSV-coded hospitalizations accounted for 24% of an estimated 5.5 million LRTI hospitalizations among children younger than 5 years.An estimated 132,000 to 172,000 RSV-associated hospitalizations occurred annually in this pediatric population

In this analysis, the RSV-coded hospitalization rate in infants younger than 1 year old was 26.0 per 1000, with no significant difference between study years.The hospitalization rate was highest among infants younger than 3 months (48.9/1000), followed by infants aged 3 to 5 months old (28.4 per 1000), and was substantially lower among those older than 1 year (1.8/1000).

The increase in hospitalizations is attributable not to increased aversion risk on the part of pediatricians but, rather, to physicians’ desire to treat the condition with bronchodilators.The cost of hospitalization for bronchiolitis in children younger than 1 year is estimated to be more than $700 million per year.

In the United States, the highest RSV activity usually occurs in winter, except in the subtropical areas of the southeastern United States (eg, Florida) where RSV is endemic throughout the year, with peaks from October to February and relative subsidence only from March to July.

Secondary infections occur in 46% of family members, 98% of other children in daycare, 42% of hospital staff, and 45% of previously uninfected hospitalized infants.Infection is spread through self-inoculation of fomites via direct contact and environmental surfaces to nasopharyngeal or ocular mucous membranes. RSV can survive for several hours on hands and surfaces; therefore, handwashing and using disposable gloves and gowns may reduce nosocomial spread.

International statistics

Bronchiolitis is a significant cause of respiratory disease worldwide. According to the World Health Organization bulletin,an estimated 150 millioew cases occur annually; 11-20 million (7-13%) of these cases are severe enough to require hospital admission. Worldwide, 95% of all cases occur in developing countries.

The frequency of bronchiolitis in developed countries appears to be similar to that in the United States. Epidemiologic data for underdeveloped countries are incomplete. Epidemiologic data from underdeveloped countries show that RSV is a predominant viral cause of acute lower respiratory tract infections and accounts for about 65% of hospitalizations due to viruses.

However, less is known about RSV-associated mortality in developing countries. Morbidity and mortality may be higher in less-developed countries because of poor nutrition and lack of resources for supportive medical care.

In the northern hemisphere, RSV epidemics generally occur annually in winter and late spring, whereas parainfluenza outbreaks usually occur in the fall. Conversely, in the southern hemisphere, wintertime epidemics occur from May to September.

Descriptive epidemiologic data from a population-based cohort (Georgia Air Basin, Canada) reported by Koehoorn et al indicated that from 1999 through 2002, bronchiolitis was associated with 12,474 inpatient and outpatient physician contacts during the first year of life.This equates to 134.2 cases per 1000 person-years. In total, 1588 bronchiolitis cases resulted in hospitalization (17.1 cases per 1000 person-years).

Age-related demographics

Although infection with the agents that cause bronchiolitis may occur at any age, the clinical entity of bronchiolitis includes only infants and young children. About 75% of cases of bronchiolitis occur in children younger than 1 year and 95% in children younger than 2 years. Incidence peaks in those aged 2-8 months.

Age is a significant factor in the severity of infection: The younger the patient is, the more severe the infection tends to be, as measured by the lowest oxygen saturation. Infants younger than 6 months are most severely affected, owing to their smaller, more easily obstructed airways and their decreased ability to clear secretions.

Intrauterine cigarette-smoke exposure may impair in utero airway development or alter the elastic properties of the lung tissue. Second-hand cigarette smoke (eg, by a parent or family member) in the postnatal period compounds the severity of RSV bronchiolitis in infants.

Although RSV bronchiolitis is clearly a significant disease of the young child, immunity has been shown to wane over time; susceptible adults may be asymptomatic or mildly symptomatic and act as carriers. With the increasing use of treatment modalities that compromise cellular immunity, RSV infection may be life-threatening to older children and adults undergoing organ and bone marrow transplantation, as well as to the elderly.

Sex-related demographics

Bronchiolitis occurs as much as 1.25 times more frequently in males than in females; the exact reason for this difference is unknown.Death is 1.5 times more likely in males.

Race-related demographics

Race and low socioeconomic status may adversely affect outcome in patients with acute bronchiolitis. In one study,RSV bronchiolitis seemed to be more severe in white children than in black children. The reason for this finding is unknown.

A study by La Via et aldemonstrated that although more minority children than white children were hospitalized with RSV infection, nothing indicated that the infections in minority children were more or less severe than those in white children.

Lower socioeconomic status may increase the likelihood of hospitalization. Hospitalization rates are higher in Native American, Alaskan, and Hispanic populations, but it is not clear if this is due to more severe infection or to a lower threshold for admission.

Prognosis

Acute respiratory tract infection in children younger than 5 years is still the leading cause of childhood mortality in the world. In 2000, acute respiratory tract infection accounted for an estimated 1.9 million deaths worldwide; 70% of these deaths occurred in Africa and Southeast Asia.

Bronchiolitis is an infectious, self-limited disease. Therapy is based on supportive care, oxygenation, hydration, and fever control. With early recognition and treatment, prognosis is usually very good. Most children with bronchiolitis, regardless of severity, recover without sequelae. The course of disease is usually 7-10 days, but a few remain ill for weeks. Studies suggest that IgE levels can be used as a marker of acute disease severity.Some infants who recover from acute bronchiolitis have an increased frequency of recurrent wheezing.

Hospitalization is required in as many 2% of cases (mostly patients younger than 6 months). These patients account for as many as 17% of all infant hospitalizations. Annually, RSV bronchiolitis accounts for about 50,000-80,000 hospitalizations.In a prospective, population-based surveillance of acute respiratory infections, RSV accounted for 20% of hospitalizations, 18% of ED visits, and 15% clinic visits in winter.Hospitalization is significantly more likely at altitudes above 2500 meters (8000 ft).

A retrospective study of 740 infants (aged 2 to 12 months) hospitalized with bronchiolitis found that the use of deep suctioning in the first 24 hours after hospital admission was associated with increased mean length of hospital stay (2.35 days for deep suctioning, 1.75 days for noninvasive suctioning), as were lapses longer than 4 hours between suctioning events .There was also a dose-dependent relation between increased number of suctioning lapses and increased length of stay (2.64 days with 3-4 lapses, 1.62 days with 0 lapses).

Overall, the mortality in children hospitalized for bronchiolitis in different series ranges from 0.2% to 7%. This large variability is based on investigations of different cohorts with different risk factors and different points in time relative to modern intensive care. Morbidity and mortality from RSV mostly occur in children younger than 2 years. Other high-risk infants and children include premature infants younger than 6 months, infants and children with underlying pulmonary or cardiac disease, and those an immune deficiency.

Studies in pediatric ICUs (PICUs) of children with RSV bronchiolitis without comorbidities show a 2-3% death rate, regardless of whether the children had CHD with pulmonary hypertension.In a cohort study from 1999-2007 in the United Kingdom, RSV bronchiolitis-related mortality was 1.7% with higher risk of death associated with preexisting conditions, especially cardiac anomalies.

Although significant morbidity is unusual, multiple small studies suggest that children who have been hospitalized with RSV bronchiolitis have a higher incidence of reactive airway disease and more abnormalities in pulmonary function than childreever hospitalized for RSV.These abnormalities may persist for as long as 5 years, eventually normalizing. Conflicting small studies have failed to prove whether early treatment of acute RSV bronchiolitis with ribavirin reduces the persistence of pulmonary dysfunction.

Although bronchiolitis has been identified as a risk factor for asthma, this does not necessarily imply causation. Children already predisposed to asthma may be more likely to wheeze when exposed to RSV or other respiratory infectious or allergic stimuli. On the other hand, it is postulated that RSV infection may predispose an individual to later bronchospasm by selective promotion of specific subsets of helper T cells.

Multiple studies have shown that children, including febrile infants younger than 8 weeks, with confirmed RSV infection have a lower risk of serious bacterial infections or secondary bacterial superinfection than controls (eg, 0% vs 2.7% for bacteremia, and 2% vs 14% for urinary tract infection).The risk of concurrent bacterial infections is low.

Patient Education

Education should be provided regarding the following:

·  Importance of RSV prophylaxis for high-risk patients

·  Importance of avoiding RSV exposure in the first 2-3 months of life

·  Natural history of bronchiolitis

Instructions to be provided at discharge should include the following:

·  Positioning

·  Maintenance of oral hydration

·  Temperature control

·  Use of prescribed medications

·  Avoidance of exposure to tobacco smoke or other irritants

·  Methods for limiting transmission (eg, handwashing and avoiding childcare centers while ill)

·  Criteria for return to the ED

Most cases of bronchiolitis are not readily preventable, because the viruses responsible are ubiquitous. However, careful attention to frequent handwashing, especially around infants, can aid in the prevention of infection or spread of viruses.

 

 

References:

1. Daniel Bernstein, Steven P. Shelov. Pediatrics for medical students. – USA: Lippinkot Williams & Wilkins. – 2008. – 650 p.

2. Nelson Textbook of Pediatrics, 19th Edition. – Expert Consult Premium Edition – Enhanced Online Features and Print / by Robert M. Kliegman, MD, Bonita M.D. Stanton, MD, Joseph St. Geme, Nina Schor, MD, PhD and Richard E. Behrman, MD. – 2011. – 2680 p.

3. Pediatric Skills /Jean W. Solomon, Jane Clifford O`Brien/ . USA: Mosby. – 2011. – 630 p.

4. Pediatrics / Edited by O.V. Tiazhka, T.V. Pochinok, A.M. Antoshkina/ – Vinnytsa: Nova Knyha Publishers, 2011. – 584 p.

5. www.tdmu.edu.ua

6. www.bookfinder.com/author/american-academy-of-pediatrics

7. www.emedicine.medscape.com

8. http://www.nlm.nih.gov/medlineplus/medlineplus.html