Stridor

Dr. med. Fabian Sinowatz is a freelancer in the medical editorial team.

More about the experts All content is checked by medical journalists.

A stridor is an audible hiss or whistle when you breathe that is caused by the narrowing of your airways. There can be many causes. Infants and young children are particularly susceptible to a stridor because they have relatively narrow airways. If the wheezing sound is accompanied by shortness of breath, you should consult a doctor immediately! Read more about the causes and treatment of stridor here!

Brief overview

• What is a stridor? a whistling or hissing sound when you inhale and / or exhale due to a narrowing or obstruction of the airway
• Causes: very diverse, e.g. inhaled foreign bodies, pseudo croup, epiglottis, excessively soft larynx cartilage (laryngomalacia), asthma, COPD, "goiter" (goiter), allergic reactions, congenital malformations
• Diagnosis: recording of the medical history in conversation (anamnesis), physical examination, measurement of the oxygen saturation in the blood, further examinations depending on the suspected cause (e.g. larynx or bronchoscopy, blood tests, computed tomography, etc.)
• Treatment: depending on the underlying disease, e.g. inhalation medication for asthma and COPD
• You can do that yourself at Stridor: among other things, have the cause clarified by a doctor, conscientiously take medication for the treatment of underlying diseases, quit smoking

Stridor: description

The term stridor (Latin: strīdor, "the hissing, buzzing, whistling") describes a whistling or hissing breath sound that occurs when the airways are narrowed. Under normal circumstances, the air can circulate freely between the outside world and the lungs when breathing in and out. However, if an obstacle occurs in the airways (e.g. a constriction), the air swirls at this point. This turbulence can be heard as a stridor with the bare ear.

Depending on when the noise can be heard, doctors differentiate:

• inspiratory stridor: whistling or hissing sound only when inhaling; it typically arises from an obstruction or narrowing in the pharynx, trachea, larynx, or main bronchi
• Expiratory stridor: whistling or hissing sound only when exhaling; there is usually a constriction in the bronchi (e.g. due to bronchial asthma)
• biphasic stridor: whistling or hissing sound when inhaling and exhaling; possible indication that the area of ​​the larynx or windpipe is more narrow.

Stridor and Wheezing: What's the Difference?

First of all, both terms denote an audible breath sound. In contrast to the stridor, wheezing (also: wheezing) can usually only be heard when breathing out, only with severe constrictions also when breathing in. The breathing sound is dry, high-pitched, rattling or whistling. While stridor is mostly located in the area of ​​the larynx or the upper airways, the narrowing of the airways during wheezing is usually in the bronchi.

Stridor: causes and possible diseases

A stridor is caused by a narrowing or obstruction of the airway. This can be in different places, congenital or acquired through underlying diseases. The inspiratory stridor usually occurs in children, whereas the expiratory stridor is more common in adults.

Causes of stridor in children

Children's airways differ significantly from those of adults depending on their age. The windpipe (trachea), which consists largely of cartilage, is much narrower and less stiff. Even a slight restriction can massively impede the flow of air. In addition: Due to its softer structure, the windpipe tends to contract more easily under suction (for example when breathing in) than in adults, which also reduces the diameter of the windpipe.

In children, the cause of a stridor can usually be found in the area of ​​the windpipe or larynx, which is associated with an inspiratory stridor.

Congenital causes of stridor in the child

The so-called laryngomalacia (also called benign congenital stridor) is the most common cause of a child's stridor. Here the larynx cartilages are overly soft. The inhaled air sucks in the epiglottis and the windpipe narrows - an inspiratory stridor results.

This is the most likely cause of stridor in infancy and early childhood. The stridor increases with food intake, excitement and crying. On the other hand, it decreases at rest and in the prone position. In about 80 to 90 percent of cases, the stridor is harmless and has no disease value. However, if it is very pronounced, a thorough investigation is necessary.

In tracheomalacia, the cartilage braces in the windpipe are too soft. As with laryngomalacia, the airways then partially collapse while breathing, and an inspiratory stridor is usually audible.

Unilateral or bilateral vocal cord paralysis can be responsible for the stridor, especially in infants. Since the air is very obstructed in bilateral vocal cord paralysis, shortness of breath and a biphasic stridor can develop. The cause of the vocal cord paralysis should definitely be clarified!

Malformations can also narrow the larynx or windpipe and represent an obstacle to breathing that leads to a stridor. This can happen, for example, with the so-called laryngeal gel or a blood sponge (hemangioma) in the area of ​​the windpipe.

Acquired causes of stridor in the child

• An inhaled foreign body is a common cause of stridor, especially up to the age of three - the little ones like to put everything in their mouths, and the breathing protection reflexes are not yet fully developed. Depending on how deep the foreign body has penetrated the airways, an inspiratory, biphasic or expiratory stridor and shortness of breath occur.
• With pseudo croup, a barking cough occurs in addition to the stridor.
• An inflammation of the epiglottis is noticeable by a lumpy language, high fever and severe pain in swallowing. This is an emergency that requires immediate medical attention.
• In tracheitis, the windpipe (trachea) is inflamed, which can also be associated with a stridor.
• Allergic reactions, for example after an insect bite in the back of the throat, can quickly swell the mucous membrane and narrow the airways. In addition to pain, the first symptom is often a stridor. In addition, life-threatening shortness of breath can quickly develop!

If you suspect an allergic reaction, you should call the emergency doctor immediately!

Cause of stridor in adults

The causes of a stridor in adults are mainly to be found in the bronchi and less in the windpipe or the larynx. As a result, an expiratory stridor is more common.

Causes of Expiratory Stridor

Common causes of expiratory stridor in adults are the chronic respiratory diseases bronchial asthma and COPD (chronic obstructive pulmonary disease). In the late stages of both diseases, overinflation of the alveoli (pulmonary emphysema) can occur. In all three cases normal exhalation is difficult. Often a whistling, often "polyphonic" stridor can be heard.

Even with acute or chronic inflammation of the bronchial tubes (bronchitis), a loud or low hissing or whistling sound can be heard when you exhale.

A cancer such as larynx cancer rarely obstructs or constricts the airways and thus causes breathing sounds when exhaling (expiratory stridor).

Causes of Inspiratory Stridor

• A greatly enlarged thyroid gland (goiter) can press on the trachea from outside and cause an inspiratory strifor. Other possible symptoms are shortness of breath and a feeling of lump in the throat.
• As in children, inflammation or a foreign body in the neck area can cause an inspiratory stridor - as can allergic reactions in which the lining of the airways swells.
• In rare cases, the vocal folds can be damaged after artificial ventilation with intubation, which can also manifest itself in a stridor.
• If a certain nerve (recurrent nerve) is damaged by a disease or an operation in the neck area, for example on the thyroid gland, a mostly unilateral vocal cord paralysis can occur, which creates a stridor.

Stridor: When should you see a doctor?

There are a number of innocuous reasons for a stridor. Nevertheless, a visit to the doctor makes sense in principle: On the one hand, a serious illness can be the trigger. On the other hand, the situation can quickly deteriorate drastically. If (acute) shortness of breath occurs in addition to the stridor, you should call the emergency doctor immediately!

Stridor: What is the doctor doing?

A specialist in ear, nose and throat medicine or a general practitioner is the right contact for a Stridor. The pediatrician can also be a first point of contact for children. If necessary, they can then issue a referral to a specialist in pulmonology (pulmonology).

The first step in clarifying a stridor is taking a medical history (anamnesis). This can be followed by various examinations - depending on what the doctor suspects about the cause of the stridor.

anamnese

First, the doctor gets an overview of the possible triggers and the characteristics of the stridor in a conversation. Possible questions are, for example:

• How long has the stridor been around?
• Does breathlessness occur? If so, in which situations?
• Has a foreign body been swallowed or inhaled?
• Does the stridor depend on the body position?
• Are there any known diseases of the respiratory tract or the lungs (such as asthma or COPD)?
• Do you currently have a cold or was it when the stridor first appeared?
• Does the voice sound different?
• Do you smoke? If so, how much and how long?
• Have you noticed any hardening, swelling or a feeling of pressure in the neck area?
• What medication are you currently taking?

Investigations

During the physical examination, the doctor first gets an impression of the general state of health of the patient. For example, he listens to the lungs with a stethoscope (auscultation) and inspects the throat with a lamp and tongue depressor.

In the case of a stridor, it is also important for the doctor to feel the larynx and throat in order to detect any swelling or hardening.

When you speak to the doctor, he or she will get clues as to whether your voice sounds normal or changed. You may need to repeat sentences or sounds so that he can better assess the function of your voice.

In the event of breathlessness, the doctor will perform what is known as pulse oximetry. This is a procedure that can be used to determine the amount of oxygen in your blood. This is possible with a finger clip, without taking any blood.

A laryngoscopy allows a close look at the larynx and the vocal folds. The doctor examines the neck directly using a mirror or a special camera (laryngoscope). This procedure is used when the suspected cause is in the trachea or larynx.

You don't have to be afraid of a laryngoscopy! If you relax a bit, there are usually no problems whatsoever. In the case of children, the doctor usually uses a so-called nasal fiberscope for the examination. This works like the laryngoscope, but is inserted through the nose and not the throat under local anesthesia.

Sometimes a stridor is followed by further examinations to determine the cause. The doctor usually uses them when the breathing sounds have been around for a long time or are very strong. Even if additional symptoms such as shortness of breath, coughing up blood or difficulty swallowing occur, the following examinations can be useful:

• Bronchoscopy: This is useful if the doctor suspects the cause of the stridor below the larynx or in the bronchi. He then inserts a flexible bronchoscope through the mouth or nose under local anesthesia. A light sleeping pill can make the procedure easier, but general anesthesia is rarely necessary.
• Checking the lung function using spirometry or body plethysmography
• Ultrasound examination (sonography) of the thyroid gland and the neck region
• Chest x-rays (chest x-ray)
• Blood tests
• Tissue removal (biopsies) from the lining of the larynx or bronchi
• Computed tomography (CT) or magnetic resonance imaging (MRI) scan of the neck, chest, or brain

therapy

How the doctor treats the stridor depends on the underlying cause.

For example, if there are congenital malformations or cancers in the respiratory tract, an operation may be necessary. Chronic lung diseases (bronchial asthma, COPD) are treated depending on their severity in order to slow the progression of the disease and alleviate the symptoms. In addition, various drugs are usually used for inhalation.

If, in addition to the stridor, there is also shortness of breath, the doctor immediately takes measures to secure the airways. This includes letting the person inhale cortisone and adrenaline so that the mucous membrane swells. In the case of extreme shortness of breath, artificial ventilation with intubation, i.e. the insertion of a tube, may be necessary.

Stridor: You can do that yourself

With a stridor, it is better to see a doctor. Depending on the reason for the breathing noises, you can, if necessary, do something yourself to alleviate or turn off the stridor before you go to the doctor or in principle.

HiB vaccination

Haemophilus influenzae type b is a bacterium that can cause respiratory infections and is particularly important up to the age of five. On the other hand, there is a protective vaccination (HiB vaccination), which can be used to prevent epiglottis, bronchitis and pneumonia.

Inhaled / swallowed foreign bodies

Especially in (small) children, a stridor is often caused by an inhaled / swallowed foreign body. This can result in acute shortness of breath! In such an emergency, strong blows between the shoulder blades often help - you can place a child on your knees in a prone position. If the inhaled foreign body cannot be loosened as a result, you should use the Heimlich maneuver - but only for children over a year old and if the foreign body is neither water nor a fishbone! You can find out more about carrying out these emergency measures and when you must not use them in the article First aid if swallowed.

These maneuvers can be lifesaving. However, do not use it if you are unsure about the causes of the stridor or the correct execution of the hand movements. In the event of acute shortness of breath caused by a foreign body, call the emergency doctor immediately!

Chronic lung disease

If chronic lung diseases are the cause of the stridor (bronchial asthma and COPD), it is very important that you take the prescribed medication consistently and reliably. In doing so, you are making a decisive contribution to preventing the disease from progressing.

Also, follow your doctor's other recommendations, such as quitting smoking. Smoking promotes, among other things, laryngitis, larynx cancer and asthma - diseases which, as the most harmless symptom, can cause stridor.

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