Stridor is an abnormal inspiratory sound, and a sign of upper airway obstruction that requires immediate attention.
Stridor can be heard without a stethoscope. It is usually a high pitch sound that occurs during the inspiratory phase. Observe your patient from the end of the bed and see if the noise is worse when their chest expands (inspiration) or falls (expiration). A noise on inspiration is consistent with stridor, and indicates an upper airway obsctruction. A noise on expiration indicates lower airway obstruction such as bronchospasm. Respiratory Wiki has two sound file examples of stridor.
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.
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 make the following preparations:
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. I’ll also check to see if the respiratory therapist is setting up heliox at this time.
3. Bring to the bedside medications to support endotracheal intubation.
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.
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.
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.
If stridor does not resolve, endotracheal intubation will be necessary before the patient experiences respiratory failure. Check out episode 15 to hear me talk about the pharmacist’s role and expectations during endotracheal intubation.
More information on stridor
This episode focused on the pharmacotherapy interventions that may be called for in the management of stridor in adult ICU patients. Other articles provide a more thorough review of stridor, and I encourage you to read them!
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