Airway & Respiratory, Cardiac & Resuscitation, Patient Care

Push Dose Epinephrine as a Temporizing Measure for Drugs Causing Hypotension

Issue 9 and Volume 39.

You transport a 55-year-old male to the hospital on continuous positive airway pressure (CPAP) for respiratory distress and fever. Initially, the CPAP at a pressure of 10 cm of water improved the patient’s oxygen saturation from 73% to 93%. An IV is established and a bolus of normal saline is started. During transport the patient has increasing difficulty keeping his eyes open. His end-tidal carbon dioxide (EtCO2) has gradually trended up from 40 to 6 5mm Hg. On arrival, the patient is very drowsy even though the oxygen saturation has remained about 93%. Current vitals are a blood pressure of 82/50 and heart rate of 120 bpm.

The ED physician asks you to stay and assist with the intubation, but the patient is in shock. If intubation is attempted in the current physiologic state it will likely be a terminal procedure or “clean kill” because many induction agents for intubation cause hypotension. Ideally, there would be time to fluid resuscitate this patient before attempting induction and intubation. However, a patient in shock who requires emergent airway management often requires vasopressor support.1 Dopamine is usually used as the first-line vasopressor in EMS, but epinephrine is a readily available vasopressor carried on every ALS unit. It has both vasoconstrictive, chronotropic and ionotropic effects that make it a good choice for distributive and cardiogenic shock.

Push Dose Pressors
It’s an established practice in anesthesia to use small doses of vasopressors for a short period of time to optimize patient hemodynamics. This is often done as a temporizing measure for drugs or procedures that have the side effect of hypotension.2 Recently, this method of hemodynamic management has made its way into mainstream emergency medicine practice. One of the first to help popularize “push dose pressors” was Scott Weingart, MD, in a segment of his podcast EMCrit. In that podcast, he discussed dosing and characteristics of multiple agents, as well as how to mix syringes of these medications.3

Push dose epinephrine can be made by drawing 1 mL of 1:10,000 cardiac epinephrine (100 mcg) in a 10 mL syringe and then drawing 9 mL of normal saline. The syringe should be mixed by vigorously rolling it between the palms and is then ready to be infused by slow push. Every mL of the now 1:100,000 epinephrine contains 10 mcg of epinephrine. Thus, a dose of 10 mcg per minute is 1 mL every minute. The dose is then titrated to the desired effect.3

The dosing varies slightly depending on the condition being treated. Push dose or mini-bolus epinephrine can be given via slow push to treat hypotension and bradycardia. The dose generally is 2–10 mcg per minute. Dosing for cardiogenic shock is 0.1–0.5 mcg/kg per minute, 10–50 mcg per minute for a 100 kg patient. Severe anaphylaxis is treated with 100–250 mcg IV every 3–5 minutes followed by continuous infusion as needed.4

There are pros and cons to push dose epinephrine in 10 mL syringes. It’s easy to mix from readily available 1:10,000 epinephrine and normal saline. The dosing is relatively straightforward. It doesn’t require a pump on any specialized IV tubing and you’re not left with lots of left over or wasted solution when you reach the hospital. However, it does require a dedicated person to mix and administer the medication. Since the volume is relatively small, on a transport of more than 5–10 minutes it’s likely that more than one syringe will need to be made. These factors make it best suited for situations where it can used for short durations such as transports lasting less than 10–15 minutes, transient hypotension, or as a bridge to fluid resuscitation or vasopressor drips.

If it’s anticipated the patient will require more than just a few minutes of vasopressor support, an epinephrine drip can be mixed and infused at the same dose. To make an epinephrine drip mix 1 mg in NS to make 100 mL total. Using 10 drips per mL IV tubing every drip is about 1 mcg, 10 mcg/ml.

Often, there’s concern with giving vasopressors through peripheral IV lines. This has been shown to be safe until central access can be established.5 There are two other strong arguments that infiltration is of minimal risk. The above 1:100,000 epinephrine is the same concentration that’s used in lidocaine for local anesthesia. And, 300 mcg of 1:1000 epinephrine subcutaneous or intramuscularly, is the standard route and dose for severe allergic reactions. However, caution should be used to make sure there are no signs of IV infiltration. If the IV was difficult to start or took multiple attempts, it should not be used for vasopressor infusion. Medication that infiltrates will not be as active as the IV route.

Given the ubiquity of epinephrine in ALS units, it’s an obvious choice for EMS to use as a temporizing vasopressor. Literature also supports the use of epinephrine. The evidence shows that norepinephrine is superior to dopamine for cardiogenic shock and suggests it’s also better in distributive shock.6,7 Epinephrine appears to have no significant difference in outcomes compared to norepinephrine.8,9

Case Conclusion
The patient is exhibiting declining mental status due to carbon dioxide retention, and impending respiratory failure. This has forced the ED physician to intubate the patient prior to proper fluid resuscitation or the mixing and initiation of vasopressor drips. The doctor anticipates that the rapid sequence induction (RSI) agents and intubation will likely result in further hypotension, and possibly cardiac arrest. While one nurse gathers the intubation supplies and calls the respiratory therapist, the other starts a second IV and continues to bolus the patient with fluid.

As the doctor gets a nasal cannula with high-flow oxygen ready to place for apneic oxygenation, she instructs you how to mix 1:100,000 epinephrine in a 10 mL syringe. She then directs you to infuse approximately 1 mL every minute slow push. The patient’s blood pressure rises to 112/68, his heart rate goes to 125 bpm and he’s no longer mottled.

You continue to give epinephrine at 10 mcg per minute while diligently watching the second hand on the clock and the volume hash marks on the syringe. Since the patient is on CPAP with 100% oxygen,
he’s preoxygenated.

References
1. Yoon SH. Concerns of the anesthesiologist: Anesthetic induction in severe sepsis or septic shock patients. Korean J Anesthesiol. 2012;63(1):3–10.
2. Butterworth JF, Mackey DC, Wasnick JD. Morgan and Mikhail’s clinical anesthesiology, 5th edition. McGraw-Hill: New York, pp. 245–247, 2013.
3. Weingart SD. (2009) EMCrit podcast 6: Push-dose pressors. Retrieved May 15, 2014, from www.emcrit.org/podcasts/bolus-dose-pressors.
4. Lexi-Drugs. Epinephrine (systemic, oral inhalation). Lexicomp. Retrieved Aug. 7, 2014, from http://online.lexi.com/lco/action/doc/retrieve/docid/patch_f/1827041.
5. Ricard JD, Salomon L, Boyer A, et al. Central or peripheral catheters for initial venous access of ICU patients: A randomized controlled trial. Crit Care Med. 2013;41(9):2108–2115.
6. Patel GP, Grahe JS, Sperry M, et al. Efficacy and safety of dopamine versus norepinephrine in the management of septic shock. Shock. 2010;33(4):375–380.
7. De Backer D, Biston P, Devriendt J, et al. Comparison of dopamine and norepinephrine in the treatment of shock. N Engl J Med. 2010;362(9):779–789.
8. Annane D, Vignon P, Renault A, et al. Norepinephrine plus dobutamine versus epinephrine alone for management of septic shock: A randomized trial. Lancet. 2007;370(9588):676–684.
9. Levy B, Perez P, Perny J, et al. Comparison of norepinephrine-dobutamine to epinephrine for hemodynamics, lactate metabolism, and organ function variables in cardiogenic