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Bronchiolitis: symptoms, causes, therapy

by Josephine Andrews
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Bronchiolitis is an inflammatory disease of the lower airways. The acute form is usually caused by viruses and occurs mainly in children under the age of two during the winter months. However, there are other possible causes of bronchiolitis, and in principle all age groups can suffer from it. You can find out more about this and about the symptoms, course and treatment of bronchiolitis here!

ICD codes for this disease:

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctor’s letters or on certificates of incapacity for work.

J68 J21

quick overview

  • What is bronchiolitis? Collective term for inflammatory diseases of the lower, finely branched airways ( bronchioles ), which can be acute or chronic.
  • Forms and causes : acute bronchiolitis – mostly triggered by viruses (esp . RS virus ), more rarely by other factors such as bacteria or inhaled toxins (toxic bronchiolitis), chronic bronchiolitis – for example as a result of other diseases or after a transplant , special form of bronchiolitis obliterans (chronic bronchiolitis with scarring in the area of ​​the smallest airways)
  • Symptoms : in acute, infectious bronchiolitis (such as RSV bronchiolitis) runny nose , fever, sore throat, cough , wheezing, possibly shortness of breath. In bronchiolitis obliterans, especially a dry cough and slowly increasing shortness of breath.
  • Diagnosis : Collection of the medical history, physical examination, imaging (X-ray, high-resolution CT), lung function test , measurement of oxygen saturation , if necessary, lung endoscopy and lung biopsy
  • Treatment : Depending on the cause, course and severity of the disease, eg purely symptomatic therapy for RSV bronchiolitis (antipyretic drugs, home remedies such as inhalation , if necessary oxygen supply or ventilation, etc.). In bronchiolitis obliterans, including cortisone, immunosuppressants, cough suppressants, oxygen therapy .

What is bronchiolitis?

“Bronchiolitis” is a collective term for various diseases of the lower respiratory tract, which can arise in different ways and also vary in course. It is either an inflammation or an inflammation-related blockage (obliteration) of the finest airways (bronchioles) and the adjacent tissue.

The Lower Airways

The lower airways begin after the larynx . They are visually reminiscent of an upside down tree: the trachea is its trunk, which branches down into large “branches” – the bronchi . These, in turn, continue to branch out and become increasingly fine. The finest branches are called bronchioles.

Their diameter is less than a millimeter. Smooth muscle fibers run in their thin walls, which regulate the diameter of the airways through relaxation and contraction. The walls are covered on the inside with a mucous membrane (as in the entire respiratory tract). The bronchioles direct the inhaled air into the actual places of gas exchange – the air sacs in the lungs (alveoli).

Causes and forms of bronchiolitis

Bronchiolitis can be divided according to very different criteria – for example according to the course of the disease:

  • Acute bronchiolitis : Mostly caused by viruses or other infectious agents (infectious bronchiolitis), in other cases, for example, by inhaling gases/toxic substances, liquids or solids, or as a result of Wegener’s granulomatosis (granulomatosis with polyangiitis).
  • Chronic bronchiolitis : Develops on the basis of other diseases – such as bronchiectasis , vascular inflammation (vasculitis), collagenosis (connective tissue diseases), ulcerative colitis , allergic asthma , tuberculosis – or as a result of transplant rejection.

If the cause of acute or chronic bronchiolitis remains unknown, doctors speak of idiopathic bronchiolitis .

A special form of chronic bronchiolitis is bronchiolitis obliterans (BO) . The chronic inflammatory processes here are associated with fibrotic remodeling (“scarring”) and closure of the bronchioles. This can happen after an infection (post-infectious) – for example after an infection with adenoviruses (triggers of respiratory and gastrointestinal infections, among other things), influenza viruses, RS viruses, measles viruses or mycoplasma (bacteria).

Other possible causes of bronchiolitis obliterans are diseases of the lung parenchyma (internal pulmonary diseases), rheumatic diseases, toxic gases or medication. Rejection reactions after a heart-lung, lung or bone marrow transplant can also cause the clinical picture. Then one speaks of bronchiolitis obliterans syndrome (BOS) .

Other designations for forms of bronchiolitis (according to different classifications) are, for example, diffuse panbronchiolitis (hereditary/ethnic factors involved), inhalation bronchiolitis (due to inhaled irritants or toxins) and mineral dust-associated bronchiolitis (consequence of dust lung disease ). ).

Other disease: bronchiolitis obliterans with organizing pneumonia

“Bronchiolitis obliterans with organizing pneumonia” (BOOP) is the old name for cryptogenic organizing pneumonia (COP). This is a disease of the lung parenchyma of unknown cause (idiopathic interstitial lung disease). It is associated with chronic inflammation and scarring of the lung tissue, especially in the area of ​​the alveoli. It is therefore not a form of bronchiolitis – that is why the name has been changed (to prevent confusion with the independent clinical picture bronchiolitis obliterans).

Children very often affected

Acute, infectious bronchiolitis is widespread and is usually caused by viruses, mainly respiratory syncytial virus (RS virus). This primarily affects children between the ages of two and six months. Acute bronchiolitis is the most common viral infection of the lower respiratory tract in infancy. Bronchiolitis is the most common reason for hospitalization in the first year of life.

Can bronchiolitis be cured?

The course and chances of recovery from bronchiolitis can vary depending on the cause and individual state of health. Two examples:

RSV bronchiolitis

Bronchiolitis (RSV bronchiolitis) triggered by RS viruses is an acute disease that occurs primarily in infants and small children. With early, correct treatment, the prognosis is good. Only a small proportion of the small patients show a severe course of the disease. If there are no risk factors for such a severe course (e.g. pre-existing lung disease), bronchiolitis ends in death in less than one percent of cases.

There is a slightly higher mortality rate for RSV bronchiolitis in premature babies (1.2 percent), children with the chronic lung disease bronchopulmonary dysplasia (4.1 percent) and children with congenital heart defects (5.2 percent).

You can find out here which factors – in addition to premature birth, bronchopulmonary dysplasia and congenital heart defects – favor a severe course of RSV infection.

bronchiolitis obliterans

Bronchiolitis obliterans is a chronic disease that limits the life expectancy of those affected. In the course of chronic inflammation, “scarring” (fibrosis) occurs in the area of ​​the bronchioles. Ultimately, the fine airways close, which causes increasing shortness of breath. The large airways, on the other hand, are hardly or not at all affected by the disease.

Bronchiolitis: what are the symptoms?

Acute, infectious bronchiolitis generally manifests itself with unspecific symptoms of a respiratory infection such as a runny nose, mild fever, sore throat and cough. It is usually RSV bronchiolitis :

Infection with the RS virus initially triggers symptoms of an upper respiratory tract infection – runny nose, dry (unproductive) cough, possibly also a sore throat . The inflammation can then spread to the lower airways within one to three days, which can develop into RSV bronchiolitis.

The cough then usually becomes clearer and more productive (i.e. associated with sputum production), and breathing difficulties up to and including shortness of breath occur: the respiratory rate increases, i.e. the patient breathes faster. When breathing, the nostrils are often set up and the auxiliary respiratory muscles used for support. The latter can be recognized by retractions of the skin in the throttling pit or between the ribs when breathing.

A whistling or wheezing sound is heard when exhaling. When listening to the lungs , breathing sounds can be detected as crackling or wheezing.

In severe cases, the poor oxygen supply is reflected in a bluish discoloration of the skin/mucous membranes ( cyanosis ).

Other symptoms of RSV bronchiolitis are a restricted general condition and problems with eating (reflux, vomiting, refusal to drink in infants). The latter can quickly lead to dehydration in babies .

In children under the age of three months, shortness of breath is often the only symptom of RSV bronchiolitis.

Chronic forms of the disease such as bronchiolitis obliterans develop slowly: the chronic inflammatory processes and the fibrotic remodeling of the small and very small airways are expressed in a dry cough and slowly progressive shortness of breath. When subjected to stress, those affected can tire quickly.

Bronchiolitis: Diagnosis

In order to be able to diagnose bronchiolitis, the doctor must rule out other lung diseases with similar symptoms. This requires various investigations.

History and physical examination

For the diagnosis of bronchiolitis, the collection of the medical history ( anamnesis ) is first necessary. The treating doctor asks the patient or – in the case of a sick child – the parents about the existing symptoms, possible previous illnesses and the use of medication. Possible questions include:

  • How long have the symptoms existed? Did you come on suddenly or rather slowly?
  • What are the exact symptoms?
  • Is breathing difficult or is there shortness of breath?
  • Are there any previous illnesses known, such as a connective tissue disease (collagenosis)?
  • Have you/the child had an organ or bone marrow transplant in the past?
  • Are you/your child on any medication? If yes, which?
  • Are there smokers in your household?
  • Have you/was your child been exposed to noxious fumes, irritants, etc.?

This is followed by the physical examination . The doctor listens to the patient’s lungs with a stethoscope and listens for breathing sounds: Crackling or rustling breathing sounds are common signs of bronchiolitis. If the lungs are overinflated due to illness, the breathing sounds are weakened.

Not every patient with bronchiolitis has abnormal breathing sounds.

The suspicion of an RSV infection as the cause of the symptoms can be determined with an RSV antigen test , for example , for example . This is a quick test that uses a nasal swab, for example, to quickly show whether a patient is infected with RS viruses. This test is most meaningful in infants and young toddlers during the RSV season (Central Europe: November to April).

Imaging diagnostics

Some patients may need a chest x-ray ( thoracic x-ray ). This is particularly the case with a severe and atypical course of the disease.

The pictures sometimes show overinflation of the lungs ( pulmonary emphysema ). However, not all patients with bronchiolitis have an abnormal X-ray picture. In addition, overinflation of the lungs can also have other causes. Further examinations and tests are therefore necessary in order to be able to diagnose bronchiolitis with certainty.

Imaging by HRCT can also be used to clarify bronchiolitis. It is a high-resolution computed tomography . The examination works like an ordinary CT, but the image resolution is improved through technical settings. In this way, even changes in the finest airways can be made visible. They are evidence of bronchiole disease. The form in which the lung tissue has changed narrows down the possible causes of bronchiolitis.

Lung function test and oxygen saturation

lung function test is used to diagnose various diseases of the lungs and airways. In the case of bronchiolitis, the test shows narrowing of the airways and obstructive ventilation disorders in most of those affected. Overinflation of the lungs is also noticeable in the lung function test. These findings can strengthen the suspicion of the presence of bronchiolitis. You can read more about the various test methods for examining lung function here .

Pulse oximetry measures how much oxygen is transported in the blood . If the lung tissue is damaged, the oxygen exchange can no longer take place to the usual extent. This reduces the oxygen saturation of the blood. If the saturation is normal, no further investigation is necessary. If the pulse oximetry shows a value that is too low and there are breathing difficulties up to and including shortness of breath, this supports the diagnosis of bronchiolitis.

Lung endoscopy & biopsy

In some cases, a lung endoscopy with the taking of a tissue sample (lung biopsy) is necessary to clarify bronchiolitis:

During a lung examination ( bronchoscopy ), the doctor guides a flexible, tube-shaped instrument (endoscope) through the mouth or nose into the trachea. The thin tube carries a small camera and a light source at its front end. The doctor can use it to view the airways from the inside and thus detect any changes in the mucous membranes.

In addition, fine instruments can be inserted into the lungs via the endoscope in order to take tissue samples for more detailed analysis (lung biopsy).

Bronchiolitis: treatment

Bronchiolitis therapy depends on the cause and severity of the disease. Because generally valid therapy recommendations are missing in many cases, the treatment is usually individually adapted to each patient.

If bronchiolitis is associated with another condition (such as asthma, rheumatoid arthritis, ulcerative colitis, etc.), it must also be treated appropriately.

Treatment of RSV bronchiolitis

If – as in many cases – the RS virus is the trigger for the bronchiolitis, doctors can only treat the symptoms:

Sufficient fluid intake is important. This makes the mucus in the airways more fluid and easier to cough up.

Patients are also given medication as needed. A fever-reducing drug (e.g. paracetamol , ibuprofen) helps against a high fever )A decongestant nasal spray can improve breathing in heavily congested airways.

In the case of narrowed bronchioles, patients are given special medication to widen the airways (bronchodilators) via an inhaler.

If a bacterial infection has joined the viral infection, the doctor will prescribe antibiotics.

home remedies

If the course of RSV bronchiolitis is mild, home remedies can support recovery:

Inhalation is a proven home remedy for coughs and colds: the patient puts a towel over their head, holds their uncovered face over a pot or bowl of hot water and takes a deep breath of the rising vapors. This soothes the attacked mucous membranes, widens the airways and helps the secretion to be coughed up.

With small children, however, this “normal” inhalation involves a risk of scalding (hot water!). An inhalation device is therefore the better choice for them. Discuss this with your pediatrician.

Another home remedy for bronchiolitis is a nasal rinse ( nasal douche ). It also helps with colds and congested airways. During this procedure, the nasal cavity is thoroughly rinsed with saline solution. This removes germs from the upper respiratory tract and loosens the secretion.

Cool, damp calf wraps help against fever . They dissipate body heat to the environment, which lowers the elevated body temperature. You can find out how to make and use the wraps here .

Any bronchiolitis should be evaluated and treated by a doctor. After consultation with the pediatrician, home remedies are only used for supportive treatment in the event of a mild course of the disease.

treatment in hospital

In the case of a severe course of the disease with shortness of breath and low oxygen saturation in the blood, the person concerned has to go to the hospital. Even if an infant is affected, who refuses to drink due to bronchiolitis and is at risk of dehydration, inpatient treatment cannot be avoided.

In addition to the necessary medication, those affected often receive infusions in the hospital to balance the fluid balance. If you have breathing problems, oxygen can be supplied via a nasal tube, for example. Under certain circumstances, respiratory support using a CPAP mask or ventilation via a ventilation tube that is inserted into the trachea ( intubation ) is also required.

Treatment of other forms of bronchiolitis

For example, if a bacterial infection is the underlying cause of bronchiolitis, the treating doctor will prescribe antibiotics . These drugs can also be used as needed for some other forms of illness, such as diffuse panbronchiolitis or bronchiolitis obliterans. In the case of acute forms of the disease, the administration of antibiotics is normally limited to a few weeks; in chronic forms of bronchiolitis, it can also extend over months or even years.

In bronchiolitis obliterans, drug therapy primarily includes glucocorticoids (” cortisone “). The strong anti-inflammatory active ingredients must be used here for several months. Drugs that suppress the immune system ( immunosuppressants ) are often given as well. The doctor treating you can prescribe cough suppressants ( antitussives ) to combat the cough. When normal breathing does not get enough air into the lungs, patients are given oxygen (oxygen therapy).

Virus-inhibiting agents ( virostatics ) are available for the treatment of some forms of viral bronchiolitis. If there is an infection with herpes simplex virus (HSV), for example, aciclovir can help.

In the past, an antiviral drug was also given for RSV infection or RSV bronchiolitis – ribavirin. It had been shown in the test tube (in vitro) to be effective against RS viruses. However, studies with patients did not show a clearly positive effect. Therefore, ribavirin is not routinely given for RSV bronchiolitis.

Bronchiolitis: prevention

Since there are different forms of bronchiolitis, no general recommendations for disease prevention can be given. Basically, however, the following tips can help to keep the lungs healthy and reduce the risk of lung diseases:

  • Balanced diet : Antioxidants (mainly found in plant-based foods) and omega-3 fatty acids (e.g. in rapeseed oil, linseed oil, fatty fish such as mackerel or salmon) have a positive effect on lung health.
  • Sufficient fluid intake : Drink at least 1.5 liters a day (water, mineral water, tea, etc.) – this liquefies the secretion in the respiratory tract
  • Avoiding Nicotine : Quit smoking or don’t even start. Also avoid passive smoking (e.g. staying in smoky interior rooms).
  • regular exercise : It promotes general health and the strength of the immune system.
  • Avoiding irritants and toxins (gases, dusts, etc.): When handling gases, toxins, chemicals or dusts, wear appropriate respiratory protection (e.g. breathing mask). Store all chemicals (cleaning agents, etc.) properly and safely in the household – so that they do not leak and cannot get into the hands of children.
  • Use medication as directed : Always follow the directions your doctor or pharmacist has given you when using any medication (even over-the-counter).

Breastfeeding is also beneficial for infants . Children who are breastfed are less likely to suffer from respiratory diseases than bottle-fed children.

RSV bronchiolitis: prevention

To protect against the common RSV bronchiolitis, experts recommend hygiene measures and RSV vaccination for children at increased risk.

hygiene measures

The best measure to prevent RSV infection and thus RSV bronchiolitis is consistent hygiene. Especially in the winter months, the RS viruses often spread in a pandemic. The following tips reduce the risk of infection for you or your child:

  • Regular and proper hand washing
  • Sneeze and cough into the crook of your arm or into a handkerchief (not your hands)
  • Regular and thorough cleaning of children’s toys
  • Refrain from visiting community facilities if you or your child is showing symptoms
  • Refrain from smoking (especially around children)

RSV vaccination

There is a preventive vaccination against an infection with RS viruses, which in many cases are the trigger for bronchiolitis, with the inactivated vaccine palivizumab. Immunization is recommended for children with an increased risk of disease. You can find out what these are and how the immunization works in the article RS virus .

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