April 14, 2023

Dear colleagues:

Welcome to UH EMS-I’s Pharmacy Phriday.  In this installment, we will review the use of Racemic Epinephrine for cases of respiratory distress caused by upper airway diseases.  Recently there have been reported shortages of this medication, so we will also review the alternative treatment listed in the UH Protocols when Racemic Epi is not available.

Racemic Epi is a medication that is a combination of two different isomers of epinephrine, and as typically provided in our UH drug boxes, is much more concentrated.  The medication is typically provided as a single unit dose of 0.5 ml of a 2.25% concentration.  The 2.25% concentration equals 22.5 mg/ml.  With the 0.5 ml dose, the provider is administering a dose of 11.25 mg.  It is indicated for nebulized administration to the pediatric patient in cases of moderate to severe upper airway distress, croup being the most common.  It is also indicated in the adult protocols for respiratory distress caused by asthma or COPD, and the patient has severe distress along with stridor.

As you may recall, croup is a common childhood viral illness characterized by barky cough, stridor, hoarseness, and respiratory distress. Children with severe croup are at risk for intubation. It causes upper airway obstruction through edema of the upper airway. Nebulized epinephrine, via its Alpha-1 effect of vasoconstriction, is a highly effective treatment for upper airway obstruction caused by croup.  Epinephrine also has a Beta-2 effect of smooth muscle relaxation that is beneficial in these cases. The result of the racemic epinephrine nebulizer should be decreased edema and bronchospasm.

Albuterol has no real effect on the upper airway swelling and thus an ineffective treatment.  In fact, its’ Beta effect could potentially cause vasodilation and theoretically worsen upper airway edema.  Differentiating upper and lower airway obstruction and understanding the actions of inhaled medications are fundamental in the treatment of those emergencies. A study that looked at a four-year period from 2008-2011 in a large urban EMS system found that upper airway obstruction was frequently treated inappropriately with albuterol in children (44%).  Possible causes considered for such errors included a lack of recognition of upper airway obstruction on physical exam and correct recognition of upper airway obstruction on the exam and choosing inappropriate treatment. [1]

UH protocols refer to two distinct differences that can assist in determining which protocol to follow.  Stridor and/or the “seal bark cough” is often related to an upper airway obstruction, and in cases of moderate to severe distress, can be present even at rest.  Racemic Epi is the treatment of choice in these cases following initial assessment, airway control, and oxygen.  When one encounters wheezing, the provider is directed to the “Respiratory Distress Lower Airway” protocol which indicates the use of Albuterol or a DuoNeb.

When administering Racemic Epi, the provider is directed to administer the 0.5 ml dose of the 2.25% concentration, diluting the medication in 3 ml of normal saline via the nebulizer.  The medication is administered only once and is not repeated in the prehospital setting.  Side effects may include tachycardia, agitation, and hypertension, so the patient should be monitored carefully. It also is a reason the provider is cautioned about its use with the geriatric or cardiac patient.

As mentioned earlier, there have been recent reports of shortages of the Racemic Epi in some UH pharmacies and drug boxes.  It is widely cited that an alternative to the use of Racemic Epi for respiratory distress caused by upper airway diseases can include the nebulized treatment with the 1mg/ml Epinephrine (0.1%) carried in our drug boxes.  In the UH protocols, this is listed as an acceptable alternative.  The dosing in those cases would be 3 ml of the 1mg/ml concentration for a pediatric patient <10 kg or 5 ml for the pediatric patient >10 kg. The 5 ml dose is also the appropriate dose for the adult patient.  These doses would not be diluted prior to administration.

In cases when the patient fails to respond to these treatments, remember to consider other possible causes and be prepared to assist ventilations with a BVM in cases of respiratory failure!

As always, stay safe

Sincerely,



The UH EMS-I Team

University Hospitals