Episode 308: Causes, treatment, and prevention of stridor

In this episode, I’ll discuss the causes, treatment, and prevention of stridor.

Causes

Stridor is an abnormal inspiratory sound and is a sign of airway obstruction that requires immediate attention.

Stridor can be caused by a mass or foreign body in the upper airway, or by laryngeal edema. Laryngeal edema post endotracheal extubation is the most likely cause of stridor in an adult patient in the ICU.

Treatment

Stridor can indicate impending respiratory failure, and should be treated as a medical emergency. If I hear a stridorous patient, or hear other clinicians saying that a patient has stridor, I do the following immediately:

1. Bring 2 ampules of racemic epinephrine (2.25%, 0.5 mL) and 8 mg IV dexamethasone to the bedside immediately.
2. Observe the patient, including their mental status and vital signs. If the patient with stridor is drowsy, intubation will be immediately necessary.
3. Bring to the bedside medications to support endotracheal intubation if needed.

Racemic epinephrine via nebulization

Epinephrine causes vasoconstriction and decreased blood flow, which diminishes edema formation. Randomized controlled trials that prove efficacy of epinephrine in post-extubation laryngeal edema in adults are lacking. There is no consensus about the potentially effective dosage of epinephrine nebulization. Rebound edema is known to occur and the patient should be monitored for this. At my institution the respiratory therapists like to repeat a dose of nebulized epinephrine, so I make sure I have two ampules available of 2.25%, 0.5 mL racemic epinephrine.

Dexamethasone

Corticosteroids reduce edema by down-regulating inflammatory response and decreasing capillary vessel dilatation and permeability. The most effective dose has not been determined. I use 8 mg of dexamethasone based on prescribing patterns at my institution.

Heliox

Helium administration can also be considered. Explaining heliox to my pharmacy students is a great way to illustrate how many therapies can be boiled down to simple high school level science. Air is approximately 20% oxygen and 80% nitrogen. Replacing the nitrogen with helium results in a lower density gas. Because stridor is caused by turbulence in the airway, using a lower density gas causes less turbulence and therefore is beneficial in stridor. At my hospital our standard concentration for heliox is 30% oxygen and 70% helium. Evidence of its usefulness in adults with laryngeal edema is limited to case reports and nonrandomized trials.

Intubation

If stridor does not resolve, endotracheal intubation will be necessary before the patient experiences respiratory failure. Intubation in the setting of stridor is often difficult as a result of the airway obstruction that is causing the stridor.  Check out episode 15 for more about the pharmacist’s role and expectations during endotracheal intubation.

Prevention

Corticosteroid administration before elective extubation has been used to prevent post-extubation stridor and reintubation.

Multiple steroid regimens have been studied to prevent post-extubation stridor and re-intubation. To my knowledge, no one regimen has been proven superior. Three example regimens are:

1. Dexamethasone 5 mg IV q6 hours x 4 doses the day prior to extubation
2. Methylprednisolone 20 mg IV q4 hours x 4 doses prior to extubation
3. Methylprednisolone 40 mg IV once 4 hours prior to extubation

The authors of a recent meta-analysis concluded:

Administration of prophylactic corticosteroids before elective extubation was associated with significant reductions in the incidence of post-extubation airway events and reintubation, with few adverse events. It is reasonable to select patients at high risk for airway obstruction who may benefit from prophylactic corticosteroids.

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If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.

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