Disorders of the Upper Airway
The larynx or “voice box” includes the epiglottis and the vocal cords. It is the narrowest site of the upper airway and is the site where croup and laryngomalacia occur. The orange arrow represents a camera looking down into the airways at the voice box can reveal the images below. Cartoon drawn by Breathing NYC team.
Croup
Croup or “laryngotracheobronchitis” can be a terrifying condition, often with a rapid onset in the middle of the night. It is typically caused by a virus called parainfluenza virus, but there are many others that can cause this syndrome. The infection causes swelling around the area of the voice box (larynx) or just below it. This swelling leads to a narrowing of the airway and the very typical harsh stridor on inspiration or the barky cough (“barking seal”) characteristic of the condition.
A cartoon of a normal (left) larynx and a larynx with croup (right). Note the swelling of the epiglottis and the surrounding muscles of the vocal cords. As an infant inhales, these partially occlude the trachea and cause the loud, harsh, inspiratory stridor very characteristic of croup. Cartoons drawn by the Breathing NYC team.
Management of Croup
Fortunately, croup is fairly brief and typically lasts for 24 to 48 hours with its most severe symptoms. It is often preceded by a viral prodrome of runny nose, congestion and occasionally fevers. Treatment is “supportive” meaning there are no specific treatments for croup. Instead, physicians aim to reduce the swelling through a variety of therapies. A nebulized version of epinephrine is often used in emergent scenarios. Epinephrine acts rapidly on receptors in our blood vessels to cause them to constrict. This constriction may help reduce the amount of edema or swelling of the airway. The effect is usually short lasting (~30 minutes) but rarely do children require a second dose of this medication. More commonly, if a child has received a dose of nebulized epinephrine, it is likely they will have received an intramuscular injection or oral dose of a systemic steroid. This steroid (dexamethasone or prednisolone) may also help reduce some of the inflammation that leads to swelling of the airway, but it takes time to begin working. Steroids often provide a longer lasting effect than the short acting epinephrine.
While there are no great therapies available for home use (unless prescribed by a physician), parents often report a steamy bathroom or the cold air of the outdoors have provided some relief. There may be some truth behind these interventions and in mild episodes, or while waiting for the ambulance to arrive, these may be worth attempting.
NOTE: If you are ever concerned about your child’s respiratory status, we at Breathing NYC urge you to seek medical attention urgently or call 911.
A cartoon of the larynx with a laryngeal web occluding a large portion of the trachea. This is a rare cause of recurrent croup.
Recurrent Croup
Recurrent croup can be incredibly challenging. On one level it may represent an unfortunate and unlucky series of infections leading to multiple croup-like syndromes. On the other hand, it can rarely be associated with a hypersensitivity or an anatomic abnormality of the upper airway (such as a narrowing, instability or abnormal vocal cord movement). We encourage you to consult your pediatrician or your pediatric pulmonologist to help understand the reasons behind your child’s recurrent symptoms.
Cartoon of a normal larynx (left) and a larynx with laryngomalacia or floppiness of the cartilage making up components of the epiglottis. This can lead to the defect flopping on top of the airway during rapid inspiration leading to stridor.
Laryngomalacia
Laryngomalacia is a common abnormality in very young infants. It often presents with stridor (that harsh or sharp noisy breathing on inspiration) and can be associated with an increased work of breathing but also may not have any negative consequences. The noise occurs due to the instability of either the epiglottis (a cartilaginous structure that covers the voice box when swallowing) or the arytenoids (muscles that help move the vocal cords). Most infants will grow out of this condition. Laryngomalacia may worsen during times of upper respiratory infections, but typically is not problematic unless it chronically causes difficulty breathing, challenges with feeding or poor weight gain. Consult your pediatrician or pediatric pulmonologist if your child has any challenges with breathing.