child with stridor and/or a barking cough

•Stridor and a barking cough are both signs of a narrowing of the upper airway.

•Stridor can be difficult to recognise, and may easily be mistaken for wheeze.

•It is important to recognise the difference because the causes and treatment of stridor are different to that of acute wheeze.

•Stridor has many possible causes, each affecting different age groups. Some causes are common and others are rare. Knowing what the possible causes are and the way that they present will lead to a speedy diagnosis in most cases.

The most important step is deciding that the child has a stridor. To begin with, the child needs to have noisy breathing. Sometimes this can be quite subtle but, unlike wheeze, a subtle stridor is usually an early stridor (remember that wheezes often get quieter as air entry diminishes and the child deteriorates), so a quiet noise is reassuring unless the child has an altered consciousness. If it is an obvious noise, then determining whether it is a wheeze or a stridor is easier. In this case the timing and the character of the noise will help to determine which of these two phenomena you are hearing.

Because the upper airways are opened by air pushing through them in expiration, and relatively collapsed when air is sucked through in inspiration, stridor is predominantly a noise of inspiration. Therefore, if the noise accompanies chest expansion or intercostal recession (ie the noise occurs in inspiration) then you should call it a stridor.

A wheeze follows the opposite pattern and is predominantly a noise of expiration. However, note that both wheeze and stridor can occur in inspiration and expiration because the constriction narrows, causing turbulence to occur when air is flowing in either direction.

Figure 4.1 The physics of stridor

The character of the sound is also helpful in deciding what you are dealing with. While a wheeze is a whistling sound, stridor is a rasping sound. The notable exception to this is the baby with stridor. When they have a stridor, these tiny tots make a sound which can only be described as a squeak. If you ever hear one, you will be struck by the oddness of the sound.

A barking cough is just what it says it is. It sounds unmistakably like a seal or a dog barking. This sound is similarly created by collapse of the upper airway during expiration. It may be present along with a stridor or it may occur on its own and later possibly progress to a stridor.

How to assess

If a child presents with stridor or a barking cough then they have an airway problem. In assessing your patient you therefore have two main tasks:

1. Assess quickly.

2. Do not upset your patient.

Therefore this is one situation where the more that you assess from a distance, the better the outcome is likely to be. So without upsetting the child, assess the following:

•Is the child in respiratory distress? Assess the work and efficacy of breathing.

•If the child is distressed or hypoxic, give facial oxygen where available as long as this does not upset the child too much.

•If the child looks unwell or is working moderately hard, then call for help now.

•If the child is extremely well and tolerating the examination, take a full history and do a full examination.

•Ask about the onset of symptoms. What started this off? How quickly have they become this bad?

•Have there been any choking episodes, especially at meal times or play times?

•Has the child had this problem before and how bad has it been at its worst?

•Has the child ever had endotracheal intubation? Have they had any operations? Have they been on the special care baby unit (SCBU) as a baby?

•If possible, examine the child in the order of what you most want to determine, but be prepared to stop if you make the child cry, or the stridor becomes worse. Look especially for the following:

–Listen to the chest for air entry and to assess whether there is also a wheeze and therefore a lower respiratory component.

–Palpate for lymph nodes in the neck, as a way of assessing whether there might be infection.

–Assess the circulation. What is the pulse? What is the capillary refill time? What are the heart sounds like?

•You must not forcefully examine the throat, as this can cause a sudden deterioration by precipitating further swelling as you stretch the soft tissues of the neck.

The information that you have gathered will now almost certainly allow you to make a diagnosis based on one of the following patterns of signs and symptoms.

Condition	Typical age at onset	Signs and symptoms
Laryngomalacia	From shortly after birth to one year	Squeaking stridor. Often intermittent and with a non-acute onset. May have been present from shortly after birth but not usually at birth. Not usually associated with a cough. May suddenly get worse during times of upper respiratory tract infection. Otherwise well child. These children usually do not look distressed when they present.
Sub-glottic stenosis	From birth onwards	This is a narrowing of the trachea due to scar tissue. There is almost always a past history of endotracheal intubation, though the stridor often occurs well after the initial trauma. The stridor may be intermittent and may be worsened during times of upper respiratory tract infection. Usually a well child with no worrying findings on examination.
Foreign body inhalation	From the age when the child can crawl (may be earlier if siblings are giving small objects to them)	Sudden onset of stridor, without fever or systemic illness. There may or may not be a history of choking. If there is a possible episode, then it will usually be very recent- you cannot tolerate a foreign body in your upper airway or trapped in your oesophagus for long. Note that if the foreign body moves into the lower airways, it will produce a wheeze or cough, not a stridor. It is also possible for foreign bodies to remain undetected for much longer once they are intrathoracic.
Croup	Usually over one year of age	Tends to start with a characteristic and impressive barking cough before usually, but not always, progressing to stridor. There is often a coryza which precedes the onset. The degree of respiratory distress is very variable but very important. It is often the case that the child has had previous episodes of croup.
Epiglottitis and bacterial tracheitis	Rare in any age group	These children are usually severely unwell. The non-immunised child should be considered most at risk of these deadly infections. Typically the child will look very ill and sit forward, drooling forth the saliva which they cannot swallow due to the painful swelling in the laryngo-pharynx. They are pyrexial, systemically unwell and become more unwell by the minute. Although they are septic, it is the rapid worsening of the upper airway that is most dramatic. A stridor in a very unwell child is due to bacterial infection until proved otherwise.