Croup- A Common Problem Just For Kids.
What Causes Croup?
Croup, technically called laryngotracheobronchitis, is caused by various viruses including influenza virus, parainfluenza virus, adenovirus and some others. The virus infects the airway causing swelling and inflammation resulting in narrowing. The narrower the airway, the worse the symptoms of respiratory difficulty and the sicker the child.
Why Does Croup Only Affect Children?
In kids, as opposed to adults, the narrowest portion of the upper airway is the area just below the vocal cords, called the sub-glottic region. (In adults, the narrowest point is at the vocal chords themselves.) When this area becomes inflamed, the opening of the airway can be severely narrowed. Combining this with the fact that a child's trachea is much softer and more pliable than that of the adult, makes this area particularly susceptible. The peculiar "barking" cough seen with croup results from the dynamic effects of airflow through this narrowed area just below the vocal cords. Also, a particular sound is produced when the child breathes in across this mechanical obstruction, between coughs, and it is referred to as "stridor."
Why Does Aggitation Make Things Worse?
If we use the analogy of a drinking straw to represent the upper airway (trachea and bronchi), and the adult airway is compared to a plastic straw, a child's airway is more like one made of paper. In other words, the harder the child sucks through this "soft" airway, the easier it collapses. When a child with croup begins to sense that he is experiencing difficulty breathing through his inflamed, narrowed trachea, he reacts by breathing even harder, increasing the velocity of air moving through this collapsible tube, further narrowing and already compromised airway, making his problems even worse. This is why most experts suggest minimizing pain, fear and anxiety in children with croup so as not to worsen the underlying problem.
How Is Croup Medically Managed?
It is important that a child with croup who requires acute treatment be taken to a hospital E.R. equipped and used to caring for children. Here, they will understand the issues of minimizing stress and maximizing oxygenation in children, and proceed appropriately.
First, if the child's airway is narrowed enough to limit oxygen supply, then supplemental oxygen will be supplied. If the stridor is severe enough, racemic epinephrine is given to the child. This substance, a chemically altered for of adrenaline, is used to treat allergies and asthma. It's main action is to decrease swelling by constricting the blood supply to inflamed areas, in this case the trachea. It works quickly, but it doesn't last long and often the "rebound" from racemic epinephrine produces even greater stridor. Once administered, therefore, the child is must remain in the hospital for a period of time to watche for recurrence.
Commonly, steroids are also administered either orally or through an IV. They are beneficial also because of their anti-inflammatory effect which is more gradual, and effective. Occasionally antibiotics are also administered, but theoretically they are not required because this is usually caused by a virus.
What Else Causes Stridor?
Epiglottitis is a bacterial disorder that can cause upper airway obstruction by infecting the epiglottis. Fortunately this disorder has been all but eradicated since the advent of the HIB (Haemophilus influenza B) vaccine. Other structural disorders of the upper airway, such as laryngomalacia, can produce similar symptoms, but are usually more chronic in nature.
Croup remains a quite common cause for respiratory distress due to upper airway inflammation in children. Although not always well understood, it almost always presents with the classic symptoms of fever, barking cough and stridor. Usually it resolves without long term consequences. Treatment consists of well accepted modes of pediatric airway management along with an understanding of children's unique anatomic and physiologic features.
John E. Monaco, M.D., is board certified in both Pediatrics and Pediatric Critical Care. He lives and works in Tampa, Florida. He welcomes your comments, suggestions, and criticisms.
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|Author:||Monaco, John E.|
|Publication:||Pediatrics for Parents|
|Date:||Jun 1, 1998|
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