A Specialist Weighs In: Stridor Is the Siren You Cannot Overlook

In this month’s issue, 3 separate cases of stridor with unusual causes are presented, and these cases illustrate the wide and potentially serious differential diagnosis of this relatively common chief complaint. There are certain sounds in pediatric emergency medicine that immediately heighten your awareness. Stridor is one of them. It is not subtle. When I hear it echoing down the hallway before I even see the patient, my mindset shifts instantly to airway. What could be narrowing, what could be swelling, and what could be obstructing?But, before anything else, I have learned the first question must be: Is it really stridor? There are plenty of other noisy breath sounds, such as stertor (more of a snoring quality sound from the nasopharynx) or even wheezing from the lower airways. While stertor is usually lower pitched, it can be easily mistaken for mild stridor. As a trainee, I once made the mistake of pinching the nostrils of a sleeping toddler to try and distinguish stertor from stridor. That was not a great idea; I would not recommend it.The sound itself tells a story. Inspiratory stridor makes me think higher obstruction, usually at the level of the larynx or above. Biphasic stridor suggests something fixed and more distal, such as subglottic stenosis or a foreign body wedged in a critical spot. Additional sounds may offer clues as well. The characteristic hoarse cough of viral croup (often described as like a dog or seal barking) can often be heard from down the hall. A muffled voice combined with stridor might be more indicative of a supraglottic process, such as epiglottitis.And then there is the moment you finally enter the room. The visual cues hit you as strongly as the sound. Is this a toddler sitting comfortably in mom’s lap with a barking cough and mild stridor when agitated? That is almost certainly viral croup, an illness that virtually every pediatrician has seen in their lifetime. Viral croup is common, familiar, and usually responsive to a dose of dexamethasone and nebulized racemic epinephrine. Or is this a child leaning forward, drooling, wide-eyed, afraid to swallow, barely moving air, and with a muffled voice? That is a child in real danger, and, suddenly, everything slows down. Do not agitate them, and do not stick anything in the mouth. Call anesthesia or Ear, Nose, and Throat (ENT). Start preparing for managing a potentially difficult airway.Age frames the story too. The infant with persistent noisy breathing since birth is more likely to have laryngomalacia or a congenital anomaly (such as the laryngeal cleft presented in this month’s issue). The preschooler with an abrupt onset after a choking episode makes me think of a foreign body until proven otherwise. Epiglottitis typically occurred in children 2 to 6 years of age (as in the case presenting in this month’s issue). Incidence of epiglottitis in young children fell dramatically following the successful implementation of the Haemophilus influenzae type B vaccine in the early 1990s. I was lucky enough to not have seen a single case in a young child during my residency. Unfortunately, we are very likely to see a resurgence of cases in this potentially fatal disease as vaccination rates fall, and that possibility should unsettle us all. For the older child with fever, neck stiffness, and stridor, I will consider a retropharyngeal abscess or bacterial tracheitis.Other than age, the onset and duration of symptoms help to shape the narrative. An acute onset generally suggests an infectious cause or a foreign body. Other etiologies could include trauma or allergy. Spasmodic croup will present acutely but will also have recurrent episodes. Other causes of chronic and recurrent stridor include laryngomalacia, laryngeal papillomatosis (as in the case described in this month’s issue), anatomic malformations, vocal cord paralysis, various webs, cysts, and other growths.But beyond the cause, what matters most in those first moments of encountering stridor is the child’s stability. A loud, crying, stridulous child can be strangely reassuring, as they are moving air and perfusing. They have reserve. The quiet child, the one with barely audible stridor, sucking in their neck with every breath, eyes glassy, lips dusky: that is the child who quickens your heart rate. In those cases, you do not have time to deliberate; you have to be prepared for the possibility of losing the airway quickly.By far the most common cause of stridor is acute infectious croup. Common things being common, I think it is reasonable to diagnose viral croup clinically in most children of the right age with the usual presentation. Patients will usually have viral symptoms (rhinorrhea, cough, and fever), but sometimes, stridor is the presenting symptom. These patients are typically not ill appearing but may have some degree of respiratory distress. Anecdotally, many children are markedly improved by the time I see them, perhaps lending some credence to the old wives’ tale of cool night air being beneficial, as the majority of patients seem to present at night. (Multiple randomized controlled trials with cool mist/humidified air have not demonstrated a benefit, although a recent publication showed mild improvement with outside cold air after oral corticosteroid treatment.) In these patients, I do not routinely obtain radiography of the neck if the clinical picture fits, and my main decision point at that point is determining whether the child has stridor at rest (which, as I indicated earlier, can sometimes be hard to distinguish from stertor). Nothing pleases a pediatric emergency provider more than a calm toddler. Stridor at rest warrants treatment with nebulized racemic epinephrine (and an oral corticosteroid) with further observation for 2 to 4 hours, while the child who does not have stridor at rest can be discharged home following a dose of an oral corticosteroid. Hence, it is a decision that is not without ramifications. Failure to improve after racemic epinephrine or facing a clinical presentation that is not classic may warrant further investigation, which usually begins with airway radiography. The history or clinical picture may suggest a more worrisome etiology, and ENT consultation may be warranted. My institution has implemented a critical airway alert pathway, which is activated in the emergency department (ED) in appropriate situations, brings ENT and anesthesia among others rapidly to the ED, and has been a boon to the safe management of these children.The treatment of viral croup, while relatively simplistic, also seems to be established in dogmatic roots (which also seem to be common in medicine). As a trainee, I was taught to observe a patient for 2 hours following resolution of stridor after racemic epinephrine and to admit the patient if they required a second dose of racemic epinephrine. As I progressed through my training at various different institutions, I learned that those recommendations did not seem to be entirely based on quality evidence, and one study showed wide variation in practice on managing croup among children’s hospitals. Indeed, recommendation times seem to vary between 2 and 4 hours, which itself is based primarily on retrospective studies. Furthermore, there does not seem to be any quality evidence to suggest that a child should be admitted after 2 doses of racemic epinephrine. I personally observe a child with croup for a minimum of 2 hours. A second dose of racemic epinephrine is not an automatic admission but will prompt a family-centered care conversation. Perhaps a robust randomized clinical trial is needed to answer some of these questions.Stridor is humbling. Most days, it is routine croup; I can fix it quickly and reassure the parents, and the patient and family go home. But every pediatric emergency physician carries the memories of the ones that were not routine, such as the foreign body that was not obvious, the epiglottitis that demanded an expeditious trip to the operating room, or the bacterial tracheitis that decompensated despite antibiotics. These are the cases that remind you that stridor is not just a sound; it is a siren. And that is why stridor never becomes background noise. Every child with stridor pulls you into the moment. It demands that balance between calm and urgency (or at least looking calm). Stridor reminds you that in pediatrics, the distance between noisy but stable and suddenly catastrophic can be frighteningly thin.Most importantly, stridor reminds me of why I am in pediatric emergency medicine. Each moment at the bedside is a test of recognizing patterns learned through training, softened by humility, and refined through experience. And always, the task is to listen—to the breath that whistles like a warning note, to the family’s unspoken fear, to the spaces between words—and to be ready when the alarm bell rings.Because with stridor, it always does.